Sunday 30 November 2014

An Apple a Day Keeps The Doctor Away

Fruit consumption is associated with improved health outcomes. In particular those who consume more fruit have been observed to have lower rates of Western lifestyle diseases such as cancer, cardiovascular disease and obesity. The reason that fruit is beneficial to the health is not known, but likely relates partly to the nutrient content of the fruit and partly because consumption of fruit tends to be at the expense of other foods that may be less healthy. Apples have been extensively researched for their health effects and the findings from such studies support the contention that they are protective of disease. Apples like most fruits contain sugars, but the sugars content of apples is low, and apples do not cause the stimulation of large quantities of insulin. This likely relates to the water and fibre content of the fruit, as well as the type of sugar present. The water and fibre in apples limits the amount of sugar that can be ingested because the water decreases the concentration of the sugars and the fibre provides bulk which slows ingestion rates. The sugars in apples are also not rapidly absorbed. The pectin may also have other beneficial health effects such as decreasing postprandial glycaemic effects of other foods, lowering cholesterol levels, and stimulating the growth of beneficial gut bacteria.
Apples are also a good source of polyphenols. Polyphenols are plant metabolites that are used for host defence. Plants use polyphenols to protect from environmental damage including ultraviolet light, parasites and pests. When we ingest apples, we consume a range of polyphenols that have been shown to be bioavailable. The main polyphenolic substances found in apples include flavonoids, hydroxycinnamates and chalcones. The flavonoids in apples include quercetin and epicatechin, both of which have been shown to possess beneficial health effects. Epicatechin is also present in green tea and may partly responsible for the benefits of drinking green tea. Quercetin is a common flavonoid in many fruits and vegetables and has been shown to cause anti-cancer effects in human cells. Polyphenols may be beneficial to human health because they have antioxidant effects, and in this respect can reduce inflammatory. Polyphenols also possess anti-microbial, anti-cancer and cardioprotective effects. The polyphenolic and fibre content of apples is concentrated in the skin and so consuming the skin with the rest of the pulp is an important nutritional consideration if health is a concern. Other beneficial substances in apples include the phenolic phloretin, as well as vitamin C and minerals.

Saturday 29 November 2014

Biochemical Individuality

The Niacin Paradox

The niacin paradox describes the paradoxical situation that results from some important sources of niacin being low in actual niacin. This arises because while some foods are low in niacin, they are high in tryptophan, itself being able to be converted into niacin through the kynurenine pathway. The observation that rats could synthesise niacin, and that the synthesis of that niacin was related to the protein content of the diet lead some researchers to investigate the effects of amino acids on niacin metabolism. From this research it was found that administration of tryptophan to rats increased the urinary excretion of niacin. The realisation that administration of tryptophan was effective at reversing and preventing pellagra confirmed that niacin was likely synthesised from tryptophan. Initially it was thought that the tryptophan to niacin conversion may occur in the intestinal tract through the action of bacteria, but experiments administering injections of tryptophan showed immediate elevations of niacin metabolites.
Around 10 % of dietary tryptophan may be used for niacin synthesis. Niacin is therefore technically not a vitamin as it can be synthesised endogenously if adequate tryptophan is present in the diet. The niacin requirement in man is likely related to the total calorie intake, with higher energy intakes requiring larger intakes of niacin. A figure of around 5 mg of niacin per 1000 kcal is suggested to be the minimum required to prevent pellagra, assuming more than 2000 kcal in total are consumed. The realisation that some foods provide their niacin content as tryptophan has lead some to suggest that instead of absolute niacin concentrations, the niacin equivalents should be used. As a rough approximation the tryptophan concentration of protein is 1 %, and around 1 mg of niacin is obtained from 60 mg of tryptophan. From these figures a rough approximation of the niacin equivalents of food can be made. Some foods such as beef are high in tryptophan and niacin, and as a result are excellent sources of vitamin B3.
Horwitt, M. K., Harper, A. E. and Henderson, L. M. 1981. Niacin-tryptophan relationships for evaluating niacin equivalents. American Journal of Clinical Nutrition. 34: 423-427
Goldsmith, G. A. 1958. Niacin-tryptophan relationships in man and niacin requirement. American Journal of Clinical Nutrition. 6: 479-486

Sunday 23 November 2014


The mukul myrrh tree (Commiphora mukul) is a one meter tall thorny tree found in the Middle East and India. A yellowish resin called guggulu (gum guggul) derived from the tree can be collected and used for medicinal purposes. This guggulu is processed with solvents to remove the gum carbohydrate fraction which is not medicinal but can possess toxic effects in animals. The remaining gugulipid fraction produces neutral, acidic and basic components. The most important of these is the neutral component, which makes up around 98 % of the total gugulipid fraction and contains two groups of chemicals. A ketonic group includes a number of phytochemicals called guggulsterones, plant sterols with cholesterol lowering properties. A non-ketonic fraction includes phytochemicals including diterpene, lignans and fatty acids. The other important component of gugulipid is an acid component which makes up about 4 % of the final product and this contains a number of anti-inflammatory compounds including the non aromatic acid ferulic acid and a number of phenolic and non-phenolic aromatic acids.
Standardising the extract of gugulipid to contain 50 mg of guggulsterones per gram produces the most beneficial health benefits. Extracts of gugulipid have been researched primarily for their ability to modulate plasma lipoprotein levels. In particular standardised extracts of gugulipid can lower plasma levels of low density lipoprotein (LDL) cholesterol and very low density lipoprotein (VLDL) cholesterol (also called plasma triglycerides), as well as raise levels of high density lipoprotein (HDL) cholesterol. As high levels of LDL and VLDL and low levels of HDL are associated with cardiovascular disease, gugulipid may be cardioprotective. Cholesterol can be lowered by three 25 mg doses of guggulsterones from standardised gugulipid extract per day. The anti-inflammatory effects of gugulipid has also been extensively researched with studies showing that the standardised extract of gugulipid can be as effective as hydrocortisone, phenylbutazone or ibuprofen at reducing the symptoms of chronic inflammation. The amount required for an effective anti-inflammatory effect likely depends on the severity of the inflammation.

Saturday 22 November 2014

Do Low Sodium Diets Lower Blood Pressure?

Protect Your Liver: Milk Thistle

Milk thistle (Silybum marianum) is a three foot high thistle that grows in rocky parts of Western Europe. The reddish purple flowers and shiny prickly leaves give it an easily recognisable appearance. Milk thistle is interesting nutritionally because it contains a number of bioactive phytochemicals that may have useful health properties. In particular, milk thistle contains a number of flavonolignans (phenolic compounds composed of part flavonoid and part lignan) that include silybin, silidianin and silychristin. These compounds are present in the seeds and leaves, but are found in their highest concentrations in the fruits. Collectively these compounds are referred to as silymarin, and they can be found in standardised extract that have been shown to have liver protecting effects. This protective ability of silymarin on the liver relates to the ability of flavonolignans to prevent the mechanisms by which liver damage can be induced. It is thought that this damage results from the generation of free radicals which increases the oxidative stress on hepatic tissue.
The antioxidant effects of silymarin have been well reported and as well as a direct antioxidant effect, silymarin also increases cellular levels of glutathione, presumably through its ability to spare reduced glutathione (GSH). In addition silymarin is an inhibitor of the enzyme lipoxygenase, an enzyme responsible for the transfer of oxygen molecules to long chain polyunsaturated fatty acids in the membranes of cells. This reaction yields leukotrienes, eicosanoid hormones that have pro-inflammatory effects. Milk thistle therefore has potent anti-inflammatory effects and can protect the liver from the deleterious effects of leukotrienes. The beneficial effects of milk thistle have been demonstrated in a number of animal models using chemically induced liver damage (using the death cap mushroom Amanita phalloides). Death Cap mushroom causes severe liver damage and death is induced in around 30 % of those who ingest it as a result of liver failure. Silymarin extract can counteract the poisonous effects of this mushroom and prevent the deaths of animals in 100 % of cases.
Another benefit of milk thistle is the its ability to increase protein synthesis rates in hepatic tissue. In this way milk thistle can rebuild damaged liver tissue and thus repair diseased tissue. Many studies have shown that milk thistle supplements containing silymarin are effective at treating patients with damaged livers such as might occur in cirrhosis, chronic hepatitis and both alcoholic and non-alcoholic fatty liver disease. Silymarin may also have beneficial effects at increasing the solubility of bile, and in this way may be a useful treatment and prevention of gallstones, which are largely caused by the insolubility of bile leading to obstructions in the gallbladder. Milk thistle is available as a supplement and the best supplements are standardised for around 70 to 80 % silymarin. Milk thistle can also be purchased as a tea and consumed in its whole herb form, but it makes sense to obtain a standardised extract because it is known that the presence of silymarin is required for its liver protecting effects.

Wednesday 19 November 2014

Whole Olives

Olive oil has been researched with regard its beneficial effects on cardiovascular disease. While polyunsaturated fatty acids do appear to show some protective effects against cardiovascular disease, the cardioprotective effects of the monounsaturated fatty acids that predominate in olive oil are less clear. In fact it appears from research that most of the cardioprotective effects of consuming olive oil comes not from the fatty acids but the phytonutrients within the oil. These phytonutrients survive the oil processing steps and are then consumed along with the oil. That extra virgin olive oil is more beneficial than non-extra virgin olive oil supports this theory because extra virgin olive oil contain higher concentrations of these plant chemicals due to its less refined nature. Based on the logic that it is the phytonutrients within the olives rather than the oil itself that is cardioprotective, consuming whole olives as part of a high quality diet makes sense from a health perspective. Olives are likely protective of cardiovascular disease because they contain high levels of antioxidants.
The olive tree (Olea europaea) produces fruits which we call olives. Olives are commercially available as both green and black fruits, but they are infact the same produce at different degrees of ripeness. As the olive ripens it passes from green to black, and as such black olives are fully ripe while green olives are slightly unripe. Olives have a fat content of around 20 to 35 %, the oil containing high concentrations of the omega-9 fatty acid oleic acid (OA, C18:1 (n-9)). As with all plant material containing fatty acids, olives are also a good source of vitamin E, as this is used by the plant to protect the oils from rancidity. In addition, olive contain a number of phytochemicals including the phenolic terpene compounds oleuropein, tyrosol and hydroxytyrosol. These phytochemicals are bioavailable in humans and may have antioxidant effects. In particular the phenolic compounds in olives may prevent oxidative stress in the epithelial cells of arteries and this may in turn prevent the development of endothelial dysfunction and high blood pressure. Olives also contain melatonin, a signal molecule that induced sleep and relaxation in humans.

Monday 17 November 2014

A Word On The Potato

The potato (Solanum tuberosum) is a plant that belongs to the nightshade family that also includes tomatoes, aubergines and bell pepper. There are hundreds of varieties of potato, but in reality the large potato manufacturing countries rely on a handful of varieties to maintain supply. The potato is important nutritionally because it contributes such a large part to the energy needs of the population of the World. Because a small portion of land can produce such a large crop of potatoes, they were historically important as a food crop for resource poor individuals. Potatoes can be eaten at full maturity or before this time, the latter often being referred to a baby potatoes. In the United state almost half of the potatoes are sold to food manufacturers to be turned into chips (french fries) and obviously in this form the potato is not a good food choice. However, the potato if prepared well is a good source of nutrients and can be consumed as part of a healthy diet.
The fibre in potatoes is also nutritionally interesting because it is located on the outside of the vegetable as a tough outer skin. Peeled potatoes therefore lose much of their fibre content and this can detrimentally affect the glycaemic index of the potato. Nutritionally potatoes contain a wide range of micronutrients, the exact content of which can vary somewhat depending on growing conditions. Generally, potatoes can contain potassium, vitamin B6, niacin and pantothenic acid. Potatoes are also a good source of vitamin C and this stems not from a high content, but because we eat some many potatoes. As with the fibre, most of the nutrients in potatoes are located in the skin and so eating potatoes whole is recommended. The protein content of the potato is moderate with similar levels to rice or corn, but potatoes do contain good amounts of lysine, an amino acid that is lacking from grains. Combining potatoes with grains can therefore improve the amino acid profiles of grains.

Sunday 16 November 2014

More On Legumes

The Betaine Choline Link

Betaine and choline are closely related compounds from a structural and functional perspective. Betaine is also called trimethylglycine and choline is also called tetramethylglycine. Both compounds function as methyl donors, and when choline donates a methyl group it becomes betaine. A further donation of a methyl group results in the compound dimethylglycine. One important role for betaine is the conversion of homocysteine to methionine, a process that requires methylation of the homocysteine molecule, the methyl group being donated from betaine. An alternative methylation pathway for homocysteine exists and this required the folic acid derived methyltetrahydrofolate molecule donating a methyl group in a reaction catalysed by the vitamin B12 dependent enzyme methylenetetrahydrofolate reductase. Folic acid, vitamin B12 and betaine are therefore integral in the maintenance of low cellular levels of homocysteine.
As high levels of homocysteine in the cells leads to raised plasma levels of homocysteine, and raised plasma levels of homocysteine are associated with cardiovascular disease, betaine, vitamin B12 and folic acid deficiencies increase the risk of cardiovascular disease significantly. Because dietary choline can be converted to betaine, and because cellular methionine levels increase following administration of high amounts of dietary choline (possibly due to increased synthesis from homocysteine), choline may also be protective of cardiovascular disease at high intakes. Choline is usually classed as a member of the B group of vitamins, and although it can be manufactured in the body, it is officially recognised as an essential dietary nutrient. Choline may also have other protective effects against cardiovascular disease, because it is required for the metabolism of fats from the liver, and without choline fatty acids accumulate in the liver causing metabolic dysfunction.

Saturday 15 November 2014

Pepper: More Than Just A Condiment

Black pepper (Piper nigrum) is one of the most widely used seasonings in the Western world, surpassed only by salt. The pepper plant is indigenous to India where its use can be traced back to early human history. In Greece pepper was traded as a currency and commodity, such was it prized by the Greeks. Pepper, like salt was popular because it could hide the taste of unfresh food before refrigeration and also because it could improve the taste of bland food. One quarter of the spice production in the World is accounted for by pepper, which grows as a round peppercon on the pepper plant. Black pepper can be refined with the outer black husk being removed prior to milling, and this leaves just the white inner seed layers that have a more aromatic taste. In addition, peppercorns can be picked in an unripe condition and then pickled producing green pepper. The taste of green pepper is again different and in this regard has a more herb like taste.
Black pepper is traditionally used to treat digestive disorders because of its ability to increase stomach acid production and this is able to improve the digestive process. Black pepper also has calmative, antibiotic, diuretic and diaphoretic properties than can make it useful as a general tonic. The high content of antioxidants also make black pepper a generally healthy food against conditions characterised by systemic oxidative stress, such as metabolic syndrome, obesity and cardiovascular disease. Piperine is an active component in pepper which may increase the absorption of certain nutrients (although care should be made when interpreting such studies: here). Piperine may also have thermogenic properties and be able to enhance liver detoxification rates for particular chemicals. The best way to use pepper is by grinding whole peppercorns as this allows the nutritional content to remain fresher for longer.

Thoughts on Coffee

Friday 14 November 2014

Sunflower Seeds: Not just for The Birds

The sunflower (Helianthus annuus) has a very distinctive flower with amazing geometric patterns. In terms of human nutrition, it is the grey and black seeds of the sunflower plant that are of interest. Sunflower seeds make great bird food because they are a good source of oils and nutrients. However, their nutritional content also makes them a useful addition to any high quality human diet. Sunflower seeds are a rich source of the essential fatty acid linoleic acid (C18:2 (n-6)) and along with this oil they also contain high amounts of vitamin E to protect the delicate fatty acids from rancidity. Sunflower seeds are often turned into sunflower oil and this oil is often refined to produce odourless tasteless supermarket oils through application of high heat and pressure conditions. Such oils are detrimental to the health because they contain oxidised fatty acids. However unrefined virgin sunflower oil contains many of the nutrients in the original seeds and can therefore provide many of the same health benefits.
Minerals in sunflower seeds are dependent on the soil conditions in which the plants are grown because the absence of particular minerals from the soil precludes them from incorporation in the plant tissues. However, in optimal conditions they can be good sources of magnesium, phosphorus, copper, iron and selenium. The vitamins in sunflower seeds include vitamin B1, pantothenic acid and folic acid. Although sunflower seeds are a good source of protein, their high fat content precludes them from contributing significantly to protein intake without a concomitant large increase in fat content. The carbohydrate content of sunflower seeds is generally half that of protein, which in turn is half that of the fat content. Because sunflower seeds are a good source of the omega-6 essential fatty acid linoleic acid, they can contribute to fighting inflammation. However, this can only occur if the omega-6 to omega-3 fatty acid ratio remains at around 1 to 3.

Saturday 8 November 2014


Halloween is a time when pumpkins become available in the shops and people buy them to carve ornate decorations. However, few consider the nutritional value of the pumpkin during this process. The pumpkin (Cucurbita pepo) is a type of winter squash which means it is part of the Cucurbitaceae family. The pumpkins used for decorations are generally not eaten and it is the smaller varieties such as the small sugar pumpkins that are consumed. Winter squashes are a great source of carotenoids which give them their red, orange and yellow colours. However, they are also rich in vitamin C, folic acid, vitamin B1, vitamin B6, niacin, pantothenic acid, potassium and dietary fibre. The nutty seeds not only have a distinctive taste, but also a distinctive nutritional profile that makes them a great addition to any high quality diet. Native Americans were renowned for eating pumpkin seeds and they also used them in their medicines. It was from the Indians that the English settlers acquired the seeds before introducing them to Europe.
Pumpkin seeds contain high levels of essential fatty acids, zinc and phytosterols that make them an effective nutritional product for maintaining prostate health. It is thought that the phytosterol beta-sitosterol blocks the conversion of testosterone to dihydrotestosterone in humans. As the latter is associated with prostate enlargement, pumpkin seeds may be able to inhibit this process. In fact studies using pumpkin seed oil and isolated beta-sitosterol show they both confer health benefits to the prostate. It is likely that whole seeds have the same effect. The seeds of pumpkins are also rich sources of vitamin A, vitamin B1, vitamin B2, niacin, and also contain protein and monounsaturated fatty acids. Because of the high essential fatty acid content of pumpkin seeds it is important to ensure that they are stored in a cool dry environment and eaten as soon as possible after exposure to air. This prevents the fatty acids turning rancid, a process that can actually initiate disease through the generation of oxidative stress.

Saturday 1 November 2014

Are Peanuts A Red Wine Alternative?

Red wine has been shown to confer certain health benefits. In particular, red wine may protect from the development of cardiovascular disease. The reason for this is not fully understood, but it it known that ethanol (alcohol) is able to decrease the risk of a heart attack for around 24 hours following consumption, and so this may partly explain the cardioprotective effects of red wine. However, red wine is also a good source of a group of phytochemicals (plant chemicals) called polyphenols. One polyphenol in red wine that has been researched for its cardioprotective effect is a resveratrol, a phytochemical from the stilbene family. Resveratrol is a strong antioxidant that is bioactive in humans, and it may protect from cardiovascular disease through its ability to prevent oxidation in the blood vessels. In addition, resveratrol may confer protection from cancer as some evidence suggests that is able to inhibit the growth of new blood vessels that are required for the growth of tumours, a process called angiogenesis.
Red wine may therefore reduce the risk of two Western lifestyle diseases, namely cardiovascular disease and cancer. However, some cannot drink red wine for various reasons and therefore such individuals might think they have to miss out on the benefits of resveratrol. However, other sources of resveratrol are available, one particularly good source being peanuts. Studies have shown that the risk of a heart attack drops by around 20 % with just one month of consuming peanut butter or whole peanuts in those consuming a Western diet. The reason for this is not clear but other research has shown that peanuts are able to favourable alter the low density lipoprotein (LDL) to high density lipoprotein (HDL) ratio and this in turn is known to lower the risk of cardiovascular disease. Peanuts are not actually true nuts (tree nuts) but are pulses that come from plants in the legume family. Studies show that many legumes are cardioprotective and therefore it is not surprising that peanuts also share this effect.
Dr Robert Barrington’s Nutritional Recommendation: Red wine is a great drink to share socially and when consumed in moderation can confer significant health benefits. However, some of the benefits of red wine can be obtained from other foods. Peanuts seem to be a good source of antioxidants and this may explain their cardioprotective effects. Whole unshelled peanuts provide the best nutrition because the shells protect the seeds inside from oxidation and this in turn stops the fatty acids from going rancid.

Can You Overeat High Quality Foods?