Long-chain polyunsaturated fatty acids (LCPUFAs) derived from linoleic (18:2n-6) and alpha-linolenic (18:3n-3) acids are required for the normal development of the retina and central nervous system, but the extent to which they can be synthesized from the parent fatty acids is debated. Consuming LCPUFAs markedly increases their proportions in tissue lipids compared with their parent fatty acids. Thus, it has been argued that LCPUFAs must be supplied in the diet. LCPUFAs are generally absent from plant foods, thus it is important find out how essential fatty acid requirements are met by vegetarians. A developing fetus obtains LCPUFAs via selective uptake from its mother's plasma and LCPUFAs are present in the breast milk of vegetarians. There is no evidence that the capacity to synthesize LCPUFAs is limited in vegetarians. However, there are greater proportions of n-6 LCPUFAs and lower proportions of n-3 LCPUFAs in vegetarians compared with omnivores. This difference is probably a consequence of the selection of foods by vegetarians with high amounts of linoleic acid. Although lower concentrations of docosahexaenoic acid (22:6n-3; DHA) have been observed in blood and artery phospholipids of infants of vegetarians, it is uncertain whether their brain lipids contain lower proportions of DHA than do those of infants of omnivores. On the basis of experiments in primates that showed altered visual function with a high ratio of linoleic acid to alpha-linolenic acid, it would be prudent to recommend diets with a ratio between 4:1 and 10:1 in vegetarians and that excessive intakes of linoleic acid be avoided.
"Vegans, who consume no animal fats, get all of their PUFA in this form, and then metabolically must biosynthesize all long chain PUFA from these parent PUFA. Their breast milk DHA levels are the lowest recorded for otherwise well nourished women (Sanders, 1999). "
[Show abstract][Hide abstract] ABSTRACT: Humans evolved a uniquely large brain among terrestrial mammals. Brain and nervous tissue is rich in the omega-3 polyunsaturated fatty acid (PUFA) docosahexaenoic acid (DHA). Docosahexaenoic acid is required for lower and high order functions in humans because of understood and emerging molecular mechanisms. Among brain components that depend on dietary components, DHA is limiting because its synthesis from terrestrial plant food precursors is low but its utilization when consumed in diet is very efficient. Negligible DHA is found in terrestrial plants, but in contrast, DHA is plentiful at the shoreline where it is made by single-celled organisms and plants, and in the seas supports development of very large marine mammal brains. Modern human brains accumulate DHA up to age 18, most aggressively from about half-way through gestation to about two years of age. Studies in modern humans and non-human primates show that modern infants consuming infant formulas that include only DHA precursors have lower DHA levels than for those with a source of preformed DHA. Functional measures show that infants consuming preformed DHA have improved visual and cognitive function. Dietary preformed DHA in the breast milk of modern mothers supports many-fold greater breast milk DHA than is found in the breast milk of vegans, a phenomenon linked to consumption of shore-based foods. Most current evidence suggests that the DHA-rich human brain required an ample and sustained source of dietary DHA to reach its full potential.
Journal of Human Evolution 04/2014; 77. DOI:10.1016/j.jhevol.2014.02.017 · 3.73 Impact Factor
"Lc-PUFA derived from linoleic and linolenic acids are required for the normal development of the central nervous system, but the extent to which they can be synthesized from the parent fatty acids is debated  . It was reported that dietary n-3 PUFA deprivation for 15 weeks upregulates elongase and desaturase expression and subsequently enhances the conversation of linolenic acid to docosahexaenoic acid in rat liver but not in brain  . "
[Show abstract][Hide abstract] ABSTRACT: Perilla frutescens seed oil (PFSO) represents a rich source of unsaturated fatty acids, especially of omega-3 linolenic acid and is commonly used as herbal food supplement with beneficial effects on the vascular system. The present study investigated the effects of PFSO on the central nervous system (CNS) and provides new insight into potential mechanisms for protective properties of unsaturated fatty acids within the CNS. PFSO was administered chronically to guinea pigs and neuroprotective properties were assessed ex vivo in dissociated brain cells. Dissociated brain cells isolated from PFSO treated guinea pigs were less vulnerable against nitrosative stress as indicated by decreased levels of reactive oxygen species, by stabilized mitochondrial membrane potential and enhanced levels of adenosine-triphosphate. In the brain, levels of oleic, linoleic, arachidonic and docosahexaenoic acids were significantly enhanced. However, fatty acid composition and membrane dynamics of isolated synaptosomal plasma membranes were not affected. Our findings provide new insights into the potential mechanisms for the neuroprotective actions of unsaturated fatty acids and identified PFSO as promising nutraceutical and possible alternative to fish oil supplements to provide healthful activities in the brain.
Pharmacological Research 03/2010; 61(3):234-41. DOI:10.1016/j.phrs.2010.01.005 · 4.41 Impact Factor
"After birth, the fatty acid status of the mother continues to impact on her newborn via the delivery of breast milk; a naturally rich source of DHA (Crawford et al., 1981). Breast milk reflects the habitual fatty acid intake of the mother, e.g. the breast milk of vegans contains relatively low levels of DHA (Sanders, 1999), whereas mothers who regularly eat fish produce breast milk with a high DHA content (Jørgensen et al., 2001). The fatty acid composition of breast milk has changed over the last few years in Western countries and now tends towards a higher n-6 : n-3 ratio. "
[Show abstract][Hide abstract] ABSTRACT: The UK dietary guidelines for cardiovascular disease acknowledge the importance of long-chain omega-3 polyunsaturated fatty acids (PUFA) - a component of fish oils - in reducing heart disease risk. At the time, it was recommended that the average n-3 PUFA intake should be increased from 0.1 to 0.2 g day(-1). However, since the publication of these guidelines, a plethora of evidence relating to the beneficial effects of n-3 PUFAs, in areas other than heart disease, has emerged. The majority of intervention studies, which found associations between various conditions and the intake of fish oils or their derivatives, used n-3 intakes well above the 0.2 g day(-1) recommended by Committee on Medical Aspects of Food Policy (COMA). Furthermore, in 2004, the Food Standards Agency changed its advice on oil-rich fish creating a discrepancy between the levels of n-3 PUFA implied by the new advice and the 1994 COMA guideline. This review will examine published evidence from observational and intervention studies relating to the health effects of n-3 PUFAs, and discuss whether the current UK recommendation for long-chain n-3 PUFA needs to be revisited.
Journal of Human Nutrition and Dietetics 07/2007; 20(3):275-85. DOI:10.1111/j.1365-277X.2007.00770.x · 1.99 Impact Factor
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