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.