Sunday 15 November 2015

Green Tea Studies: Are They Conclusive?

Fat As A Storage Compound

Fatty acids are a group of non-polar (non-water soluble) molecules that comprise of a carbon chain with a hydroxyl group and oxygen molecule at one end and a methyl group at the other. The chain lengths vary, but generally the shorter the chain length, the more polar (water soluble) the fatty acid becomes. Formic acid and acetic acid with 1 and 2 carbon are actually short enough to be water soluble. Nutritionally important fatty acids have even numbers of carbons in their chain, with chain lengths of common dietary fatty acids varying in chain length from short chain fatty acids with fewer than 6 carbons, to medium chain fatty acids having between 6 and 12 carbons, to long chain fatty acids having between 12 and 22 carbons and to very long chain fatty acids having more than 22 carbons in their chain. Adipose tissue is composed primarily of stearic acid, an 18 carbon saturated fatty acid, the same fatty acid that predominates in the fat tissue of most animal, which can be seen on red meat as a white solid fat.
Fatty acids are stored in adipose tissue in the form of triglycerides. Triglycerides (also called triacylglycerols) comprise of three fatty acids joined to a molecule of glycerol. Triglycerides provide 9 kcals per gram when oxidised, which is higher than both carbohydrate and protein, which yield 3.75 and 4.1 kcal per gram, respectively. This makes triglycerides a highly efficient storage substance from an energy perspective. The fact that triglycerides can also be stored in the absence of water, further increases the efficiency of storage when compared to glycogen, with every gram of glycogen having 2 to 3 grams of water associated with it. Although many consider body fat to be unsightly, body fat is necessary, for as adipose tissue falls below 3 % of total body weight the risk of death increases significantly. The disadvantage of storing fatty acids is that they cannot be oxidised in the absence of oxygen like carbohydrate, and for this reason are not a good source of instant energy in short duration activities of high intensity.

Sunday 1 November 2015

DHEA As A Testosterone Booster?

Fruit Juice And Insulin Resistance

Fruit contains high amounts of sugars, particularly fructose and sucrose. Sucrose is a disaccharide made up of a molecule of glucose joined through a glycosidic bond to a molecule of fructose. Therefore fructose is the primary sugar in fruit, its name actually meaning fruit sugar. Fructose has been shown to cause insulin resistance in mammals including mice, rats, monkeys and humans in a short amount of time, perhaps a few weeks, when consumed in high concentrations. The amount of fructose used in studies to induce insulin resistance in animals has been shown to be equivalent to the high intakes of fructose associated with soft drinks. Soft drinks are rich in fructose, either in the form of sugar or high fructose corn syrup, in Europe and the United States, respectively. Soft drinks are associated with obesity and have been shown to cause insulin resistance in humans. However, fruit does not cause insulin resistance, despite the fact that it contains high amounts of fructose.
The reason that fruit does not cause insulin resistance, as mentioned previously, is that it contains fibre. Fibre slows the digestion and absorption rate of any concomitantly eaten carbohydrates and this reduces the nutrient overload experienced by the cells. Although fruit does not cause insulin resistance, fruit juice does, and this is a reflection of the fact that the fibre has been removed. Studies show that fruit juice is no less detrimental to the health than soft drinks and high intakes of fruit juice may induce insulin resistance and lead to obesity. Many people consume fruit juice and give it to their children under the impression that it is a healthy food, but increasingly it is being shown that the decision to consume fruit juice is not a sound nutritional one. Consuming fruit juice with high fibre foods may negate some of the detrimental effects as the fibre in the gut can limit the absorption of the fructose and inhibit nutrient overload in the cells. However, the nutritional literature suggests that consumption of fruit juice should be severely limited.

Sunday 25 October 2015

Resistance Versues Endurance Training: Insulin Sensitivity

Insulin Resistance And Oxidative Stress

Insulin resistance is a likely driver of weight gain. Insulin resistance is characterised by a deterioration of the strength of the signal elicited by insulin on the cell, and as a result the insulin signal becomes less efficient at stimulating the transport of glucose from the blood into the cell. This causes fasting blood glucose levels to rise, a condition known as hyperglycaemia. In response to the higher than normal fasting blood glucose levels, the body's homeostatic mechanisms, controlled by the hypothalamus, increase the release of insulin to counter the effects of too much glucose in the blood. The pancreas therefore releases more insulin and this raises fasting insulin levels, a condition known as hyperinsulinemia. It these changes to the insulin system that need to be reversed in order to cause successful long term fat loss, as body fat levels cannot be brought under control with raised levels of insulin. This is because insulin stimulates the fat accumulation pathways inhibits the fat breakdown pathways.
The role of oxidative stress in insulin resistance has be suspected for some time based on the observation that antioxidant nutrients improve insulin sensitivity. Oxidative stress is a condition that describes a state in cells and tissues whereby free radical activity is chronically increased above normal physiological levels. Free radicals are chemicals with unpaired electrons, and these unpaired electrons cause the molecules to be very reactive. Free radicals therefore react with components in the body, and this causes these components themselves to become free radicals, setting up a chain reaction that damages tissues and cells and leads to disease. Free radicals are generated naturally by metabolic activity, but they are kept in check at manageable levels by a network of antioxidants, some of which are vitamins and some of which are naturally produced in the body. Possibly the most important exogenous antioxidants are vitamin C and vitamin E and the most important endogenous antioxidant is glutathione.
Overproduction of free radicals leads to oxidative stress, and this may cause interference with the insulin signal cascade, the metabolic steps that describe the transfer of the insulin signal from the membrane to the interior of the cell. Alternatively the oxidative stress may disrupt the membrane structure and interfere with the binding of insulin to its receptor. Oxidative stress can result from either an increase in free radical production or from a depletion of the antioxidants that normally prevent oxidative stress. Sources of free radicals include pollution, food components, inflammatory, stress and intense physical activity. All of these factors contribute to the production of oxidative stress. In such a circumstance, an increase in antioxidants will be required to prevent the metabolic damage from the increased free radical generation. Antioxidant vitamins and plant antioxidants have therefore been shown to be beneficial at improving insulin sensitivity through their inhibitory effects on cellular oxidative stress.

Saturday 24 October 2015

Fibre And Insulin Resistance

Nutrient overload is one of the primary, if not the primary drivers, of insulin resistance. Too much energy in the form of fructose can overload the hepatocytes of the liver with energy and this stimulates the de novo lipogenesis pathway. The resulting fatty acids may accumulate in skeletal muscle and liver tissue where they cause insulin resistance by interfering with the insulin signal cascade. In addition, too much energy in too short a period of time overloads the cells with energy, including glucose and fatty acids, and as a result oxidation of the energy proceeds at an accelerated rate leading to the generation of free radicals. As a compensatory mechanism, the insulin receptor is desensitised in order to prevent further nutrient uptake by the cells. Refined carbohydrates, including refined crystalline sugar and refined crystalline fructose contribute to this nutrient overload as the fibre in the original plant material, which normally controls the rate of digestion and absorption, is absent.
Low fibre diets high in refined carbohydrates are therefore one of the contributory factors in nutrient overload. This explains the association between the typical Western diet, which is high in refined carbohydrate, and insulin resistance and obesity. Fibre is protective of insulin resistance because it can limit the rate at which the starch in carbohydrate foods is digested and absorbed. In this way fibre slows the rate of absorption of the glucose that is digested from the starch, and this prevents nutrient overload. Soluble fibre appears to be particularly effective in this regard because when in the gut it absorbs water and forms a gel. This gel acts as a physical barrier between the starch and the digestive enzymes required for its digestion, slowing the rate of digestion considerably. In addition this gel creates a barrier on the walls of the gut to inhibit the passage of glucose from the gut to the blood. The fibre in plant foods may also slow the gastric emptying rate, further reducing the rate of starch digestion.
Low fibre diets such as the typical Western diet are associated with obesity and insulin resistance. Therefore adding more fibre to the diet should provide benefits to weight loss because dietary fibre has the potential to improve insulin sensitivity. Soluble fibre is present in high concentrations in oats and legumes, and this may explain the weight loss, blood glucose and insulin lowering, as well as the insulin sensitising effects of these foods. Fruits are high in fructose, which would suggest they may contribute to insulin resistance. However, fruits also contain the soluble fibre pectin, which may neutralise the damaging effects of fructose in fruits. Vegetables also contain soluble fibre in the form of pectin, as well as cellulose and other insoluble fibres. Whole plant foods such as fruits and vegetables and whole grains have been shown to produce weight loss effects when they replace refined carbohydrates in the diet. Supplemental fibre may not be as effective as that from whole plant foods.

Sunday 18 October 2015

Algal DHA Versus Fish DHA and EPA

Is Oxidative Stress The Maid Driver of Insulin Resistance?

Obesity, cardiovascular disease and type 2 diabetes are all aetiologically linked through the metabolic syndrome. The observation that all three diseases are associated with oxidative stress, has lead some to speculate that oxidative stress is the causative factor in metabolic syndrome. In fact evidence suggests that free radicals and oxidative stress are indeed a causative factor in insulin resistance and the development of insulin resistance then causes the development of secondary diseases characterised by the metabolic syndrome including cardiovascular disease, obesity and type 2 diabetes. Since Denham Harman first postulated about the role of oxidative stress in ageing and disease, many studies have confirmed the link between high levels of oxidative stress and disease and the aging process. It is not known what causes the generation of the oxidative stress that leads to the development of insulin resistance, but stress, poor diet, recreational drugs both legal and illegal as well as pollution may play a role.
However, adipocytes may generate free radicals through exposure to excessive energy. As energy, particularly in the form of free fatty acids and glucose, accumulates in the adipocytes, the energy pathways of the cell overproduce acetyl CoA and this in turn increases production of energy donors such as reduced NAD (NADH). As the electron donors accumulate, they increase the hydrogen ion membrane potential in the mitochondria, and this inhibits the flux of electrons down the electron transport chain. Inhibition of complex III of the electron transport chain increases the half life of the free radical intermediates of coenzyme Q and this results in superoxide generation. As superoxide accumulates it leads to the formation of oxidative stress. Over time, the generation of superoxide radicals would deplete the body of cellular antioxidants, which may explain the association between obesity and low antioxidant status. This theory also explains nicely why animals on reduced energy intakes have longer lifespans.
Accumulation of free fatty acids in adipocytes may also reduce the translocation of glucose transporters (GLUT4) to the cell membrane surface and this may inhibits the efficient uptake of glucose to the cells, causing insulin resistance. This process may be a reaction by the cell to prevent further uptake of energy in order to limit the production of free radicals. Insulin resistance can therefore be thought of, if this theory is correct, as a compensatory mechanism to prevent the cellular generation of oxidative stress. Refined carbohydrates and fructose may therefore be a source of free radical generation as they cause an overload of energy in the blood following consumption. Whole grains prevent this as the fibre content slows the absorption of the glucose and other sugars. Further, beta cells of the pancreas may be particularly susceptible to oxidative stress as they have low levels of endogenous antioxidants such as catalase, superoxide dismutase and glutathione peroxidase.

Saturday 17 October 2015

The Major Fat Constituents in the Typical Western Diet

The typical Western diet is the modern diet of the developed nations of North America, Western Europe and Australasia. Evidence suggests that insulin resistance is caused by consumption of the typical Western diet, and this relates to the presence of refined and processed foods within the diet that can alter the biochemical balance of the body through changes to normal metabolic regulation. Of the food components that may contribute to these metabolic changes, dietary fats have been identified as playing a role. The typical Western diet is generally high in both cholesterol and saturated fat, and these have been blamed for both the cardiovascular disease epidemic that is currently sweeping through developed nations and for the rise in the rates of obesity. However, this might be unfair and a gross oversimplification of human nutrition as both dietary cholesterol and saturated fat have been part of the human diet since history began, but the cardiovascular disease and obesity epidemics are only recent phenomenon.
The main problem identified with saturated fat is the amount of calories that it contains. We are told that this increases the risk of overeating and this is turn increases the risk of weight gain. However, as we have seen previously, the energy balance theory of weight gain is not established as the cause of weight gain or obesity. While it is possible to overeat saturated fat, it is just as likely that carbohydrate could be overeaten, and there is with carbohydrate, particularly that which is refined, good reason to suspect that it can cause metabolic dysfunction. Many of the detrimental effects of saturated fats on human physiology have also been, either deliberately or mistakenly, attributed to plasma levels of fasting triglycerides, the largest contribution to which originates not from the diet, but from the de novo lipogenesis pathway using carbohydrate as a substrate. That the Massai of Africa eat large amounts of saturated fat but are not overweight also argues against its role in weight gain.
A number of modified fats are present in the typical Western diet. These include oxidised fats that are the products of lipid peroxidation and trans fats that are the result of the hydrogenation of vegetable oils. Both of these groups of fats are novel dietary additions that were not present in the human diet in great quantities before the mass processing of food, and as such are a relatively new addition to the nutritional research. Increasingly oxidised and trans fats are being identified as possible metabolic poisons. In particular, they may lead to inflammation, oxidative stress and this may subsequently lead to a decrease in insulin sensitivity. Both trans fats and oxidised fats may therefore contribute towards the development of insulin resistance. Interestingly, trans fats may be responsible for some or all of the detrimental effects of saturated fats. This relates to some earlier research that did not differentiate between trans and saturated fats in studies, but simply grouped them together as a single category.

The last group of fats that make up the typical Western diet are the unsaturated fats. There are two nutritional groups of unsaturated fats and these include the monounsaturated fatty acids and the polyunsaturated fatty acids. Unsaturated fatty acids have one or more double bond in their carbon chains, and this gives the molecules less stability in the presence of oxygen, heat and light when compared to saturated fat. This means that unsaturated oils are prone to rancidity, and when consumed in their rancid state, can cause specific health problems. Olives contain high amounts of monounsaturated fatty acids, and vegetable oils such as sunflower, rape, safflower and corn oils contain high amounts of polyunsaturated fatty acids. Because of their chemical structure unsaturated fats tend to be liquid oils at room temperature in contrast to saturated fats which tend to be solid at room temperature. Some animal products such as lard and fish contain high amounts of unsaturated fatty acids.
One subgroup of polyunsaturated fats are the omega-3 and omega-6 categories of fatty acids. These groups are championed by alpha linolenic acid and linoleic acid, the parent compounds and the omega-3 and -6 metabolic pathways, respectively. Both alpha linolenic acid and linoleic acid have vitamin like effects, as they are both essential nutrients and they are required to form short-lived hormone molecules called eicosanoids. Generally the typical Western diet contains too many omega-6 fatty acids and too few omega-3 fatty acids and this causes an imbalance in eicosanoid formation in cells. As eicosanoids regulate inflammation, and imbalance of omega-6 to omega-3 fat in the diet leads to a proinflammatory state, and this subsequently causes oxidative stress and associated metabolic damage. Trans fats also interfere with essential fat metabolism. Metabolites of alpha linolenic acid in the diet include eicosapentaenoic acid and docosahexaenoic acid from fish.

Sunday 11 October 2015

What Is A High Quality Diet?

Brown Versus White Fat

There are two main types of adipose tissue in human physiology. These are designated white and brown adipose tissue (BAT). Discussion of their different physiological roles is important in any exploration of weight gain and fat loss. White adipose tissue is the most well known sort of fat. If anyone has cooked and eaten a joint of red meat they will have seen the white adipose tissue of the animal around the meat. The distinctive white colouration can be seen. The fat is humans is very similar to this and quantitatively white adipose tissue makes up most of the fat we carry on our frames. The white nature of this tissue relates to its low concentration of mitochondria, because it is metabolically not very active. The physiological function of white adipose tissue is mainly as a store of energy, but white fat does fulfil other roles such as acting as a shock absorbed to delicate structures such as internal organs and joints. When we gain weight, it is the white adipose tissue that becomes engorged with triglycerides.
Brown adipose tissue is much less common in humans. Babies possess a fair amount of brown adipose tissue, but as we age the amount we carry seems to diminish. The presence of brown adipose tissue in babies confirms the conclusions of scientific studies, that brown adipose tissue is a source of heat. The brown colour of the tissue is related to the presence of a high number of mitochondria in the cells of brown adipose tissue, and this makes the cells very metabolically active. Brown adipose tissue is able to perform a special metabolic trick called uncoupling, which it achieves with the help of special uncoupling proteins. In normal cells when glucose or triglycerides are oxidised, a high energy compound called ATP is produced and this adds to the energy content of the cell. Only the workings of the cell can remove this energy. However, uncoupling proteins uncouple the glucose and triglycerides from the production of ATP, and instead divert the resulting energy to produce heat.
This uncoupling of energy has two important consequences in the body. The first is that the cells can manufacture heat from stored energy and in this way can increase the temperature of the body. Small animals that have relatively small surface areas use this trick to maintain warmth, and as a result small mammals have high amounts of brown adipose tissue. Babies too have a small surface area and so require brown adipose tissue. The adult human has less need for this process because they have a larger surface area and also because they are able to move themselves from the cold to the warmth. Adaptive thermogenesis describes the ability of brown adipose tissue quantity to upregulate following chronic exposure to cold. Another consequence of the ability of brown adipose tissue to uncouple energy production is the fact that this allows the wasting of energy. Brown adipose tissue can be stimulated through the release of hormones such as adrenaline, to waste energy, and the consequence of this is a reduction in body fat.

Saturday 10 October 2015

Do I have Metabolic Syndrome?

The metabolic syndrome is a cluster of metabolic disorders that are likely caused by the insulin resistance that characterises the condition. These metabolic disorders include, but are not limited to, changes to plasma lipoproteins, raised levels of fasting blood glucose, raised levels of fasting insulin, systemic inflammation, oxidative stress, immune dysfunction, the development of nonalcoholic fatty liver, high blood pressure and weight gain, particularly around the waist. The changes to plasma lipoproteins that occur with development of the metabolic syndrome include increases in plasma triglycerides (also called very low density lipoprotein (VLDL)), increases in the small dense low density lipoprotein (LDL) particle, and decreases in the high density lipoprotein (LDL) particle. While developing one or two of these disorders in no way confirms the metabolic syndrome, they can be used as a guide to determine if the disorder is present. This is because there is no defined medical definition for the metabolic syndrome.
Diagnosing the metabolic syndrome can therefore be very difficult without a detailed clinical examination and careful analysis of blood tests. However, there are a number of easy ways to determine if the metabolic syndrome is likely present without detailed biochemical tests. A simple oral glucose tolerance test is one of the best ways to determine the health of the insulin system. Following an overnight fast, a glucose drink is consumed and then periodically blood glucose measurements are taken using a finger prick lancet and a simple blood glucose measuring device. Under normal circumstances, following ingestion of glucose, there will be a rapid increase in blood glucose, and then as insulin is released, that blood glucose will fall to baseline over the course of around 90 minutes. Blood glucose falls because the insulin facilitates the transport the glucose into the cells. If insulin resistance in present, the glucose stays in the blood for longer and blood sugar may not return to baseline for some hours.
Another of the classic signs of insulin resistance that strongly suggests that the metabolic syndrome might be present is a large amount of deep abdominal fat. This gives the individual a rotund appearance, and this characteristic body shape is described as android or apple shaped. Measuring the waist to hip ratio of an individual is a good indicator if they have such a body composition. This can be done by dividing the waist measurement in cm by the hip measurement is cm. A waist to hip ratio of above 1.00 or 0.85 strongly suggests that insulin resistance is present in men and women, respectively. Abdominal fat is associated with insulin resistance, but the cause and effects are not fully understood. The storage of fat preferentially in the viscera of the abdomen may relate to changes in hormones that occurs during the development of the metabolic syndrome. Much of the metabolic damage that occurs from the presence of the metabolic syndrome results from the accumulation of visceral fat in and around the liver.

Sunday 4 October 2015

Vitamin D From Sunbeds

How Do Trans Fats Contribute to Insulin Resistance?

Oxidised fats can interfere with insulin resistance because they initiate free radical chain reactions that can lead to oxidative stress. This oxidative stress then interferes with the insulin signal cascade decreasing the strength of the insulin signal reaching the interior of the cell. This then leads to a decrease in the uptake of glucose from the blood to the cells. Trans fats are another group of modified fats that may decrease insulin sensitivity. Like oxidised fats, trans fats may decrease insulin sensitivity through the generation of oxidative stress. However, unlike oxidised fats, trans fats are not thought to decrease insulin sensitivity through the direct initiation of free radical chain reactions, but through an indirect immune related mechanism. The ability of trans fats to initiate oxidative stress likely relates to their ability to interfere with the metabolism of the essential fatty acids alpha linolenic acid and linoleic acid that belong to the omega-3 and omega-6 families of fat, respectively.
The essential fatty acids alpha linolenic acid and linoleic acid are natural cis-structured fats which are essential to the health. When ingested in the correct ratios they form a number of short lived hormones called eicosanoids that can regulate cell function. One of the main functions they regulate in the cell is that of inflammation. For health to be maintained and for inflammation to be controlled the diet must contain roughly 1 gram of linolenic acid for every 3 grams of linoleic acid. By interfering with the metabolism of the essential fatty acids, trans fats negatively affect the delicate balance between the omega-3 and omega-6 fatty acids and this modifies production of the antiinflammatory eicosanoids. Ingestion of trans fats may therefore result in the generation of inflammation. Inflammation is detrimental to insulin sensitivity, because the inflammatory immune response is a sources of oxidative stress. Indirectly therefore trans fats lead to oxidative stress and this interferes with the insulin signal cascade.
Another possible mechanisms by which trans fats interfere with insulin sensitivity is though changes to the fluidity of membranes. The cell membrane fluidity is regulated by incorporation of different types of lipid into the cell membrane. Increasing the amount of long chain polyunsaturated fatty acids such as the omega-3 and omega 6-fatty acids derived from alpha linolenic acid and linoleic acid into the membranes increases their fluidity because these molecules have many double bonds that gives the carbon tails a pronounced kink. This means that packaging the fats together closely is more difficult, and the extra space within the membrane causes increase fluidity. High fluidity in the beta cells of the pancreas that release insulin as well as the target cells of insulin may increase insulin sensitivity. Trans fats have straight carbon tails, and ingesting trans fats increases their concentration in the cell membranes in place of the polyunsaturated fats, decreasing membrane fluidity and insulin sensitivity.

Saturday 3 October 2015

Oxidised Oils

As well as trans fats the typical Western diet also contains a group of oils called the oxidised fats. Like all biomolecules, fats can react with a number of substances to produce derivatives that change their chemical and physical properties. In particular, fats and oils readily react with oxygen to form a range of chemicals in a process called lipid peroxidation. The products of these reactions can be put under the umbrella heading of oxidised fats. Some fats react more readily with oxygen, and the reactivity with oxygen is generally dependent on the number of double bonds present in the carbon chain of the fat. Polyunsaturated fats have many double bonds and so readily react with oxygen. Monounsaturated fats possess only one double bond and so are more stable than polyunsaturated fats. Saturated fats have no double bonds in their carbon chains and so are the most stable form of fatty acid. Oxidation of fats causes them to become rancid, and rancid fats are now thought to possess a significant detrimental effect on health.
Vegetable oils are generally polyunsaturated oils, and this means that they are highly susceptible to reaction with oxygen. However, fish oils are even more unsaturated than vegetable oils. The vegetable oils linoleic acid and alpha linolenic acid possess two and three double bonds, respectively. However, the eicosapentaenoic acid and docosahexaenoic acid in fish oils possess five and six double bonds, respectively. Fish oils are therefore highly susceptible to oxidation and rancidity and most sources of fish oils possess some concentration of oxidised fats. Although vegetable oils are generally more stable than fish oils, they are just as likely to contain oxidised oils and go rancid. This is because vegetable oils are often extracted from the seed with extreme heat and pressure that can increase the risk of reactions with oxygen occurring. In addition, the oils are often processed further and this involves further adulteration of the delicate polyunsaturated fatty acids in their oils.
Lipid peroxidation produces a number of reactive aldehyde chemicals including malondialdehyde and 4-hydroxynonenal that are able to react with cellular structures when ingested. This process occurs because the lipid peroxides can initiate free radical chain reactions whereby they steal electrons from cellular components to stabilise their own structures. This creates an unstable biomolecule within the tissues that then does the same to another biomolecule, which in turn, reacts with another and so on in a chain reaction. Antioxidants are able to quench such reactions through donation of an electron to the free radical, thus preventing further damage. High intake of oxidised fats, as are present in the typical Western diet, therefore increases free radical chain reactions leading to the development of oxidative stress. Oxidative stress is thought to be responsible for a number of diseases and may contribute to the development of insulin resistance and weight gain.

Sunday 27 September 2015

Is Chocolate A Weight Loss Food?

Oral Glutamine Supplements

L-glutamine is available in powder form and is a popular supplement. The bioavailability of oral glutamine has been questioned because much of the oral glutamine is utilised as a source of energy by the enterocytes of the small intestine. Glutamine can also be released from skeletal muscle in large amounts and this too it utilised by the enterocytes of the small intestine. For this reason oral glutamine is seen as being useful to those with particular gastrointestinal disorders where enterocytes may require a sufficient supply of energy. Cabbage is a good source of glutamine, and its use in the treatment of gastrointestinal lesions is well reported. Oral glutamine may protect the enterocytes from radiation, and rat experiments have shown that oral glutamine can protect irradiated rats from some of the symptoms associated with radiation poisoning including diarrhea and intestinal bleeding. The gut healing properties of oral glutamine are therefore quite well established.
Because of the use of oral glutamine by the gut, little of the orally taken glutamine makes it to the circulation. However, by ingesting oral glutamine, some of the glutamine released from the skeletal muscle may not be used by the gut cells and in this way oral glutamine may raise plasma levels of glutamine indirectly. In this regard oral glutamine before exercise may significantly increase plasma levels of glutamine, as this is a time when skeletal muscle catabolism and release of glutamine to the blood is elevated. The release of glutamine from skeletal muscle is a result of the metabolic acidosis caused by intense exercise. In this role the glutamine is used for base generation by the kidneys. Oral glutamine can therefore decrease muscle catabolism following exercise as there is less need for the muscle glutamine as endogenous supplies are able to supply the substrate for base generation. Animal and human studies show that oral glutamine may therefore be an effective ergogenic aid.
Oral glutamine may also enhance the activity of natural killer cells, and thus have an immune stimulatory effect. The use of glutamine in large amounts by other immune cells including lymphocytes and macrophages suggests that immunity benefits from oral glutamine supplementation if plasma levels rise. Because oral glutamine has an anti-catabolic effect on skeletal muscle, it may be a useful supplement for those with chronic wasting diseases. However, the daily production of glutamine in humans is thought to exceed 100 grams in some cases and therefore small doses orally, most of which would be consumed by the enterocytes of the gut, may not be effective. Glutamine is interconvertible to glutamic acid through loss of a nitrogen group (to form ammonia). Food labels tend not to list glutamine levels separately but list the glutamic acid content as including glutamine. Roughly 50 % of the glutamic acid in animal protein is glutamine, and around 80 % of the glutamic acid in plant proteins are glutamine.

Saturday 26 September 2015


Glycine is the simplest amino acid in human nutrition. The variable group on glycine is composed of just a hydrogen atom and as such L-glycine is the only amino acid in human nutrition that does not demonstrate chirality. Glycine is a non-essential amino acid as it is syntesised from serine and threonine, the latter being an essential amino acid. When taken orally, glycine has a particular sweet taste. Glycine is used metabolically to synthesise purine, porphyrins, glyoxylic acid and creatine. With regards to creatine, glycine and arginine react in the synthesis of creatine, which is subsequently phosphorylated to form the ATP buffer creatine phosphate in cells. Supplements of glycine and arginine are able to increase muscle stores of creatine phosphate, in a similar manner to ingestion of creatine monohydrate supplements. However, while creatine monohydrate supplies the creatine directly, glycine and arginine increase endogenous creatine synthesis rates.
Glycine is also involved in the synthesis of collagen, of which it constitutes around 75 % of the amino acids. Much of the remaining amino content of collagen is taken by proline. Glycine is therefore pivotal to correct join function, although most people consume enough protein in their diet and therefore have an adequate supply of glycine for collagen formation. Collagen however is the most abundant protein in the body and this highlights the importance of glycine. High intakes of up to 10 grams of glycine orally may be able to stimulate growth hormone release. Following oral supplements growth hormone levels rise and peak at around 3 hours. However, it is unclear if the increase in growth hormone has beneficial physiological effect. For example, it is not known whether the glycine induced growth hormone release has an anti-catabolic effect on skeletal muscle. Glycine is also converted to dimethylglycine, which has an important function in the formation of steroid hormones.
Glycine is also an important neurotransmitter in the brain, where it functions as an inhibitory neurotransmitter. Its inhibitory effects in the central nervous system may provide beneficial effects against seizures and epilepsy and may be of some clinical use in treating some mental disorders. Glycine appears to have antiinflammatory and immunomodulatory effects because it can act of immune cells such as macrophages to inhibit cytokine release. Studies have shown that supplemental glycine may be of benefits in cases of fatigue, perhaps because if its creatine synthesising effects. Glycine can also help regulate fat metabolism because it aids in the modulation of bile acid formation. Its sweetness means that glycine also possesses some use in treating type 2 diabetes and obesity by acting as a potential sweetener in place of sugar. Because glycine can be manufactured in the body deficiencies are very rare. Glycine is also commonly found in most protein containing foods and so is abundant in the diet of humans.

Sunday 20 September 2015

Some Thoughts on Glucosamine Sulphate

Eggs: Perfect For Breakfast

Eggs are considered detrimental to the health by many because of their high content of cholesterol and saturated fat. However, the role of the egg in human nutrition has been distorted considerably. This is particularly true when considering the types of lipids in chicken eggs. Eggs are a rich source of cholesterol for example, but the role of cholesterol in cardiovascular disease has been misunderstood. While an association exists between plasma levels of some cholesterol carrying lipoproteins and cardiovascular disease, the cause and effect has never been conclusively evidenced. Rather like a fire engine being present at the scene of an accident, no sane person would conclude that fire engines are the cause of accidents. As with cholesterol, its presence in the plasma and accumulation in the atherosclerotic plaque do in no way implicate it as the causative in cardiovascular disease. Further, dietary intakes of cholesterol are not able to alter plasma levels of cholesterol and so the point is quite moot.
The saturated fat content of eggs has also been misunderstood. Eggs from battery chickens do contain high amounts of saturated fat, and this relates to the sterile grain diets these birds are fed to allow them to be farmed intensively. However, free range chicken eat their natural diet which contains many varied foods including insects and parts of plants. This gives the nutritional content of the egg a quite different appearance. In particular, the saturated fat in the free range egg is replace to some extent by the omega-3 fatty acid alpha linolenic acid. As most Westerners consume too little omega-3 fat, eating free range eggs is a good way to rebalance this deficiency. Further alpha linolenic acid, like other dietary omega-3 fatty acids, may be cardioprotective. That the role of saturated fat in cardiovascular disease has not been conclusively evidenced adds weight to the contention that eggs from healthy free range chickens are not detrimental to the health of the cardiovascular system.
Chicken eggs are also a very good source of protein, and this gives them some useful nutritional properties. Protein is increasingly being seen as a weight loss food. This may relate to the ability of protein to slow the passage of starch through the gut, particularly the stomach, which in turn confers beneficial glycaemic effects. These glycaemic effects reduce the release of insulin and this may produce benefits to satiety, wakefulness and energy production. Consuming eggs for breakfast with starchy foods such as bread or oats therefore produces desirable effects on blood sugar that may reduce the risk of overeating between meals. Regulating blood sugar by controlling insulin levels may improve mental focus because lower insulin levels reduce the transport of blood L-tryptophan into the brain, which can then subsequently be converted to serotonin and melatonin. As melatonin induces sleepiness, higher protein lower starch breakfasts may effectively increase productivity in the early morning through increased wakefulness.

Saturday 19 September 2015

Salmon: Fatty Fish for Health

Biologically salmon are amazingly adaptable. They are born in fresh water, spend much of their lives in open sea, and then return to the river of their birth to spawn. A number of different varieties of salmon exist, with the exact classification depending largely on the oceans in which they spend most of their lives. For example, pacific salmon belong to the genus Oncorhynchus and include chinook, silver (coho), chum, pink and red (sockeye). There is only one variety of Atlantic salmon which is Salmo salar. The characteristics of salmon vary with the species, and in particular the colour of the flesh can be different. Generally the colour of the flesh of salmon range from pink through red to orange. The taste and size of the fish can also vary between the species, with chinook salmon being the largest and red salomon being the smallest. Although wild salmon is fished from the seas around Alaska, much of the commercially available fish is farmed, particularly in places such as Scotland, Canada and Norway.
Salmon has historically been an important protein food for humans. In this regard salmon is often salted or smoked in order to preserve it. As well as providing a high protein content, salmon also possesses a high concentration of long chain fatty acids of the omega-3 family including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). These fatty acids are increasingly being found to benefit health because they are deficient from the typical Western diet, and addition of them to the diet corrects the naturally low levels found in most individual’s diets. Wild salmon tends to contain more fat and is therefore richer in energy, but as the fat in salmon is beneficial to the health, this can be seen as an advantage. In addition, farmed salmon has a lower protein content compared to wild salmon. Concerns over dangerous levels of toxins in farmed salmon have also been voiced. Like most seafood, salmon is also a good source of the mineral selenium, and also contains vitamin B12 and niacin.

Sunday 13 September 2015

Weight Loss By Avoiding Cereals Grains

Breast Milk is Superior To Formula Milk

It is becoming increasingly common for infants to be fed using infant formulas. These formulas are developed scientifically to allow adequate nutrition to infants as they grow. However, they are commercial products and are therefore possess compromises that could be considered to detract from the overall quality. Generally infant formula milk is successful at allowing growth and development of healthy human beings. Most people who have been fed on infant formulas appear healthy and happy as adults. However, the definition of true health is more specific than the broad definition given by the laymen or medical practitioner. In this regard, formula milk has been criticised nutritionally for falling short in a number of areas in comparison to human milk. Evidence in the nutritional literature suggests that human breast milk is a superior food in comparison to cow’s milk based formulas for the growth of human beings. This relates to the presence of a number of factors that are not present in cow’s milk.
The most important of the components present in human milk but absent from cow's milk formulas is docosahexaenoic acid (DHA). Docosahexaenoic acid is a long chain polyunsaturated fatty acid required for the correct development of the brain and central nervous system. Increasingly it is being shown that exposure of the foetus and growing infant to DHA is required for the optimal development of the brain. Further certain cognitive aspects of breast fed infants appear to be superior to those who were fed cow’s milk formulas. Analysis of the function of DHA in humans shows that the fatty acid preferentially accumulates in the brain tissue, where it appears to be required to form a number of docosanoids that are required for neuronal function and neuronal health. The polyunsaturated fatty acids in human milk therefore appear to have beneficial neurological effects. These fats are not present in cow’s milk based formulas because they quickly go rancid following processing, and as such are removed from the milk.
Another factor that may make human milk superior to cow’s milk for infants is the presence of particular growth factors within the milk. Both human and cow’s milk contain growth factors that act as prebiotic foods that stimulate the growth of particular bacteria. However, whilst the growth factors in cow's milk stimulate Bifidobacteria species relevant to cow’s health, the growth factor in human milk stimulate Bifidobacteria species relevant to human health. Further, pasteurisation and freeze-drying destroy the activity of these factors and so although cow’s milk possesses growth factors they do not survive to the formula milk. Breast milk on the other hand is fresh and unpasteurised so that it is able to stimulate the growth of potentially beneficial bacteria that may be required for the correct development of the immune system in the growing infant. This may explain the protective effect of breast milk against the development of particular Western diseases in humans that may develop later in adult life.

Saturday 12 September 2015

Do Eggs Raise Blood Cholesterol Levels?

The short answer is no they do not. The long answer is more complicated because some studies that have reported blood cholesterol altering effects from increasing dietary consumption of eggs may not have controlled for confounding variables adequately. In particular changes to the energy, fibre or polyunsaturated fat intakes can all confound the data if they are not carefully controlled. Well controlled studies have generally shown that eggs do not cause changes to blood cholesterol levels in healthy humans. For example, one study added one egg per day1 and another study 2 eggs per day2, to a normal but low cholesterol diet for 3 months and found no significant response to serum cholesterol levels. In another study, two eggs per day were added to the diets of hospitalised patients for 54 days but no changes to serum cholesterol levels occured3. A fourth study added two eggs per day to the normal egg containing diet of healthy men and then removed all eggs from the diet, but this did not alter blood cholesterol levels4.
1Porter, M. W., Yamanaka, W., Carlson, S. D. and Flynn, M. A. 1977. Effect of dietary egg on serum cholesterol and triglyceride of human males. American Journal of Clinical Nutrition. 30(4): 490-495
2Flynn, M. A., Nolph, G. B., Flynn, T. C., Kahrs, R. and Krause, G. 1979. Effect of dietary egg on human serum cholesterol and triglycerides. American Journal of Clinical Nutrition. 32(5): 1051-1057
3Kummerow, F. A., Kim, Y., Hull, J., Pollard, J., Ilinov, D. L. 1977. The influence of egg consumption on the serum cholesterol level in human subjects. American Journal of Clinical Nutrition. 30(5): 664-673
4Slater, G., Mead, J., Dhopeshwarkar, G. and Alfin-Slater. 1976. Effect of eating eggs on plasma cholesterol levels in young and middle aged men. Nutrition Report International. 14: 249

Sunday 6 September 2015

High Protein Low Glycaemic Index Diets

Polyunsaturated Fatty Acids and Health

Polyunsaturated fatty acids are a double edged sword. On one hand, polyunsaturated fatty acids may hold particular health benefits. However, on the other hand, because of their chemical structure they are particularly prone to rancidity and in this form can actually be a driver of disease. It is therefore essential that all polyunsaturated fatty acids are in their natural unoxidised state in order to confer health benefits. This means that refined ‘supermarket’ oils should be avoided as these are exposed to both light and heat during processing and this can increase the amount of damaging lipid peroxides found in the oils. Plant materials containing polyunsaturated fatty acids should alway be cold pressed and the resulting oils stored in opaque bottles if they are to be healthy. In addition, the natural vitamin E content of the original plant material must remain with the oil to protect the delicate fatty acids. Further, where high intakes of polyunsaturated fatty acids are consumed additional vitamin E is advised.
Although evidence suggests that polyunsaturated fatty acids confer health benefits in humans and may protect from cardiovascular disease, the benefits really relate to the omega-3 polyunsaturated fatty acids found in fish and specific plant foods such as hemp and flax. Already the omega-6 fatty acid content of most diets consumed by Western populations is too high, and this creates an imbalance in the metabolic pathways involving the polyunsaturated fatty acids. The recommended ratio of omega-6 to omega-3 fatty acids is around 3 to 1, but even this ratio may be too heavily stacked in favour of the omega-6 oil. Evidence from Eskimo studies shows that their ratio is closer to 1 to 2.5 in favour of the omega-3 fatty acids. This very high intake of omega-3 fats may explain their very low risk of cardiovascular disease, and casts doubt on the accepts 3 to 1 ratio. As with all nutritional theory, trial and error may therefore be the best way to obtain the correct ratio for an individual's unique biochemistry.

Saturday 5 September 2015

Alcohol and Left Ventricular Hypertrophy

Consumption of high intakes of alcohol can cause damage to the liver if consumed in high amounts over long periods of time. In addition alcohol can induce certain vitamin deficiencies, particularly thiamine, and can cause changes to cognition, motivation and memory. The role of alcohol is preventing cardiovascular disease is controversial, mainly due to the dose response relating to its consumption. Generally low and high intakes do not produce beneficial effects, but moderate consumption has been shown to produce beneficial effects. The benefits of alcohol in terms of cardioprotection have been suggested to relate to its ability to raise plasma levels of high density lipoprotein (HDL). However, alcohol consumption raises levels of HDL2, a fraction that is not associated with a reduced risk of cardiovascular disease. More likely alcohol decreases the thrombotic tendencies of blood cells, an effect that is thought to provide a reduction in myocardial infarction risk for 24 hours post consumption.
Even low intake of alcohol may induce left ventricular hypertrophy and this could suggest that all alcohol is bad for the health. As few as two drinks per day if consumed regularly may produce changes to the heart structure around the left ventricle. Such hypertrophy of the left ventricle is associated with detrimental rhythmic changes to the hearts beating pattern and may increase the risk of sudden cardiac death. This effect appears to show a dose response and so higher intakes of alcohol significantly accelerate the structural changes. These structural changes to the heart are magnified if other risk factors such as high blood pressure or obesity are present. Left ventricular hypertrophy is often detected with electrocardiograms or the more sensitive echocardiograms. Left ventricular hypertrophy likely occur from drinking alcohol because alcohol consumption can increase blood pressure. If this is true it would suggest that other lifestyle habits can modify the association.
Exercise is also known to cause left ventricular hypertrophy. This is a physiological response to the increased demands on the heart for the circulation of blood during physical activity. Just why the left ventricular hypertrophy associated with drinking is detrimental, but that associated with exercise is beneficial, is never fully explained. This likely relates to the fact that those who consume alcohol and who experience left ventricular hypertrophy often have other lifestyle habits that increase the risk of cardiovascular disease. In contrast those who exercise regularly likely have other lifestyle habits that protect from cardiovascular disease. The left ventricular hypertrophy associated with exercise is also not associated with high blood pressure. Although exercise raised blood pressure during activity, following activity blood pressure falls such that the baseline level is lower than in non exercising controls. However, alcohol raises blood pressure, and this is a serious risk factor for cardiovascular disease and sudden death.

Sunday 30 August 2015

Carbohydrate Timing

Taurine and Blood Pressure

Taurine is a non-essential non-protein forming amino acid. It is non-essential because it can be synthesised in humans from methionine and cysteine. Both methionine and cysteine contain a sulphur atom and so it is no surprised that taurine is also a sulphur containing amino acid. However, the sulphur atom in taurine replaces the carboxyl group normally present on amino acids and in this way is structurally distinct from most amino acids. Supplemental taurine has been researched with regard its blood pressure lowering effects. Initial studies on rodents showed that taurine had beneficial effects on the blood pressure of hypertensive rats. Later human studies confirmed the earlier rodent studies. In human studies, hypertensive subjects supplemented with 6 grams of taurine per day experienced significant reductions in blood pressure in as little as 7 days. Therefore taurine seems to produce blood pressure lowering effects in mammals, that are rapid and effective.
The reason that taurine is beneficial to hypertensive mammals is not fully understood. However, the beneficial effects may be dependent on an overactive sympathetic nervous system. The role of taurine in physiology is still being researched, but taurine is known to be critical in maintaining cell membrane potential and also in maintaining a regular heart beat. Interestingly, taurine may also benefit other cardiovascular problems, suggesting that it has more than one mechanism of action. In particular taurine can benefit congestive heart failure, and improve general heart function, and this likely relates to its ability to maintain membrane potential. A taurine rich diet can provide up to 2.5 grams of taurine per day. Cheese, cottage cheese, granola, pork, milk and wild game are good sources of taurine, but it is also available in supplements. Generally animal products are better sources of taurine that plant products. However, to get the cardiovascular benefits supplements are likely necessary.

Saturday 29 August 2015

More on Selenium And Cancer

The clues that selenium is protective of cancer date back many decades. In fact evidence in the nutritional literature dating back to at least the 1970’s suggests that low selenium diets increase the risk of cancer significantly. Selenium is protective of cancer, possibly because it is required as a cofactor for the cellular antioxidant glutathione peroxidase. Low selenium diets cause significant reductions in plasma levels of glutathione peroxidase, and this likely increase oxidative stress in cells and may cause damage to DNA, which initiates cancer formation. Low selenium crops may cause low intake of selenium in a given population if that population relies on that crop as a staple food. However, selenium is also present in meat, with fish being a particularly good source. Epidemiological studies show that as intakes of selenium drop, breast cancer rates increase significantly1 (figure 1). Studies on rodent confirm that low selenium diet cause significant increases in cancer rates amongst the animals.
Figure 1. The inverse association between selenium intake and breast cancer mortality1.

1Schnauzer, G. N., White, D. A., Schneider, C. J. 1977. Cancer mortality correlation studies - IV: associations with dietary intakes and blood levels of certain trace elements, notably Se-Antagonists. Bioinorganic Chemistry. 7: 35-36

Sunday 23 August 2015

Foods Associated With Weight Change

Dates: Sugary, But Good For the Health

Dates are the fruits of the date palm tree (Phoenix dactylifera). The tree itself is similar in appearance to the coconut palm, with mature tree reaching a height of around 30 meters. Date are an important Worldwide food and may be one of the oldest agricultural crops. Records suggest that dates have been harvested for around 8000 years. In particular the date is an important crop in the Middle East, where the date is part of the traditional diets of local populations. One of the advantage of dates over other crops is that although they are harvested in the autumn, they store well and so are available all year round. The amount of dates produced by the date palm trees is immense, with clusters of dates weighing up to 10 kg, and each tree containing multiple clusters. Because the trees can live for eighty years or more, and bear fruit after about year 5, it can be seen how economically important dates are as a fruit crop. Around 75 % of the World’s dates are grown in the Middle East, although California, Texas and Arizona also contribute significantly.
Nutritionally dates are very interesting. The carbohydrate content of dates is high, as they contain around 60 to 70 percent sugar. The predominant sugars in dates are sucrose and fructose, as is common in most fruits. However, while the sugar content is high the total energy in a single date only amounts to roughly 20 to 25 kcals. The high carbohydrate content may be seen as a disadvantage, based on the negative connotations associated with sugar. However, dates also contain considerable amounts of fibre, and this improves the glycaemic profile considerably. In fact dates are not associated with negative effects from the sugars, and this likely relates to both the high fibre content and the high levels of certain vitamins, particularly of B vitamins including niacin, folate, pyridoxine, thiamine and pantothenic acid. In addition minerals such as copper, zinc, selenium, potassium, manganese and magnesium can also accumulate in dates, depending on the soil conditions on which the palms are grown.
The fibre in dates is a beta-D-glucan fibre that may have particular health benefits. One physiological effects that beta-D-Glucan fibre has been shown to possess is one of limiting cholesterol absorption. Studies using oats for example have shown beneficial lipid lowering effects, a factor that has been attributed to the soluble beta-D-glucan fibre they contain. However, as oats possess other components that can lower blood cholesterol this is controversial. Beta-D-Glucan can for example limit the rate at which glucose is absorbed. This produces beneficial glycaemic effects that may improve insulin sensitivity, and this decrease metabolic dysfunction, particularly in the liver, that can include detrimental changes to blood lipid levels. The presence of beta-D-glucan fibre may make dates an effective weight loss food, as has been shown for oats. Dates are also rich in antioxidants and this may be another route by which dates provide important health benefits.

Saturday 22 August 2015


Eczema is considered an allergic reaction of the skin, and is often idiopathic in nature. Eczema is characterised by redness, pain, swelling, loss of function and heat, which are the symptoms of inflammation. If eczema is particularly bad and scratching of the affected area is allowed, blisters can develop which may become infected, leading to further inflammatory responses. Eczema may result from contact with an allergen or through ingestion of an allergen. In the case of the former, poison ivy for example is a known irritant that induces contact dermatitis. Household cleaning products are also commonly implicated in contact dermatitis. In the case of the latter, any number of foods or food ingredients may be able to cause eczema in particularly sensitive individuals. Interestingly eczema is more common in children, and many children outgrow eczema, which suggests that it might be related to hypersensitivity in the immune system, something that is not so prevalent as an individual ages.
As allergens are implicated in the development of eczema, the most obvious solution is to identify the allergen and avoid it. This is easy in the case of ivy as it is not commonly encountered and the dermatitis is easy to identify when contact occurs. However, in the case of household cleaning products, cosmetics and food ingredients this is much more difficult to achieve. Further, because multiple foods can trigger eczema, it can be extremely difficult to identify the food or foods involved. However, eggs, peanuts and milk account for the vast majority of cases of childhood eczema, and so these foods are a good place to start. An elimination diet can help identify the foods responsible for triggering eczema. In addition, eczema suffers also appear to have deficiencies of the delta 5-desaturase enzyme necessary for the metabolism of the essential fatty acids. Supplemental fish oils and gamma linolenic acid from starflower oil or evening primrose oil can therefore also be effective treatments.

Sunday 16 August 2015

Fluoride in Toothpaste: Is It Just An Antimicrobial Agent?

Proponent of the fluoridation of drinking water claim that the addition of fluoride compounds to water reduces the incidence of dental caries in children. This is controversial because the scientific evidence for a protective effect in healthy nutritionally replete populations is quite weak. In addition, the mass medication of all humans for the benefit of a small group is unethical and of questionable logic. If fluoride is beneficial to teeth there are better ways to administer it to children than through drinking water. Further, fluoride is already ubiquitous in the diets on most individuals. Most foods and drink contain a small amount of fluoride and it is therefore very doubtful that any human with a balanced healthy diet would develop a fluoride deficiency. Even if fluoride were to be proved to be essential to the health, it would only be needed in minute amounts. Although fluoride is claimed to be essential to human health based on its supposed effects on teeth, fluoride does not satisfy classification to that of an essential minerals in humans.
However, irrespective of the ethical and health implications of this practice, biological mechanisms to explain how the fluoridation of water could affect teeth are available. Proponents of the fluoridation of drinking water state that for fluoride to be beneficial, it must be consumed and absorbed. Fluoride in drinking water increases the fluoride content of tissues and this may then be incorporated into the growing tooth along with other minerals most notably calcium. However, studies have questioned the necessity to actually consume fluoride for it to have beneficial effects. This is because fluoride may be absorbed to teeth through topical application. It is very hard to separate the topical effects of fluoride from the systemic effects, because all systemic fluoride passes through the mouth and comes into contact with teeth. Therefore the systemic effects of fluoride ingestion are confounded by the topical application of fluoride to teeth and studies investigating the two separately have not been forthcoming.
The topical application of fluoride is often used as evidence to support the addition of fluoride in toothpaste. However, controversy also surrounds this practice. The growth in the availability of fluoride free toothpastes would suggest that the public as a whole is becoming suspicious of the medical establishment and their obsession with fluoride. The mineral fluoride and its role in tooth decay receives huge amounts of public campaign money, and yet selenium, a mineral that has been shown to decrease the rate of cancer mortality by 50 % is completely ignored. The use of fluoride in toothpaste is also interesting because fluoride has antimicrobial properties and can significantly reduce the growth of bacteria on tooth enamel, which in turn would prevent dental caries and strengthen the teeth. This fact alone could explain the beneficial effect of fluoride containing toothpaste. However, safer and more effective antimicrobial agents are available to add to toothpaste. The role of refined crystalline sugar in tooth decay is also largely ignored.