FSA links omega 3 consumption to low cardiovascular risk
1. The effects of genotype, gender, and geography on biochemical and physiological responsiveness to low-dose intakes of fish oil have been investigated in a double-blind placebo-controlled trial and are reported in the Food Standard Agency’s News 79 (July/August 2008). The trial investigated “the impact of achievable dietary levels of the fish oil fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on a host of risk factors for coronary heart disease in men and women.” The study also examined the effects on low density lipoprotein (LDL) cholesterol of EPA and DHA intake. The Nutrition Society’s Annual Conference in June 2008 covered similar ground as part of its survey of the European LIPGENE project
2. The FSA’s report referred also to the influence of the ApoE genotype on LDL response to EPA and DHA. A total of 312 participants (163 females and 149 males) aged 20-70 years were recruited at four study centres in Glasgow, Newcastle, Reading and Southampton, of whom, 87 were of the ApoE2 genotype, 111 of the ApoE3 genotype, and 114 of the ApoE4 genotype. (This distribution would represent commonly found proportions in UK populations).
3. During the trial, participants underwent tests based on consumption of the equivalent EPA and DHA to either 2 or 4 portions of oily fish per week, with appropriate intervals and randomization. Blood samples were taken for 33 markers for coronary heart disease, which included plasma lipid concentrations, LDL and HDL (high density lipoprotein) cholesterol subclass profiles, inflammatory markers, markers of endothelial function, glucose and insulin concentration, red cell folate, homocysteine, thrombotic factors and plasma phospholipid fatty acids.
4. The findings of the study indicate that moderate intakes of fish oil (<2g/day of EPA and DHA) affect blood lipid concentrations and lipoprotein composition that “may contribute to the cardioprotective benefits of fish oil. Overall significantly greater responsiveness in lipids was observed in the male participants. Also a greater hypertriglyceridaemic effect (concentrations of blood triglycerides higher than normal values) was evident in ApoE4 carriers relative to non-carriers.”
5. Labelling and claims for contents in foods of omega-3, omega-6, and omega-9 fatty acids may cause some confusion because they omit to specify EPA and DHA. Extreme veggy diets are distinguished by probably unduly high omega-6 to omega-3 ratios and homocysteine levels seem to run high; and there would be neglible intakes of EPA and DHA. Further, biosynthesis of these very long chain polyunsaturated fatty acids (LCPUFAs) is problematical, so the wellbeing of abstainers of fish products, for a number of reasons (some to do with pollution and other environmental concerns), rates attention. Fortunately, marine sources of the missing fatty acids – which are attaining vitamin status – of microalgal origins are becoming available in bioavailable forms suitable for additions to foods and drinks that lack an obtrusive fishy taste.
6. Fish contribute other essential fatty substances to normal diets, such as vitamin D; they are also sources of iodide. Veggies should check that their intakes of these nutrients are adequate (but not too high, if they are taking supplements). Much research is being currently carried out on these matters, on which we shall continue our reports and assessments. Part of the LIPGENE project entailed feeding farm animals rations enriched in fish-derived components or marine biomass to increase levels of the ‘essential’ fatty acids in eggs, milk, and meat. This practice is becoming increasingly questionable because the public are being encouraged on health and environmental grounds, as well as for reasons of farm animal welfare, to cut down on meat and dairy products. The effects of DHA and EPA on cognitive and behavioural performance and the immune system are also gaining much attention, but without clear conclusions.