Incorporating macadamia oil and butter to reduce dietary omega-6 polyunsaturated fatty acid intake

Reducing dietary intake of linoleic acid of mouse dams during lactation increases offspring brain n-3 LCPUFA content

Omega (n-)3 and n-6 long chain polyunsaturated fatty acids (LCPUFA) accumulation in the infant brain after birth is strongly driven by dietary supply of n-3 and n-6 LCPUFAs and their C18 precursors through breast milk or infant formula. n-3 LCPUFA accretion is associated with positive effects on neurodevelopmental outcome whereas high n-6 LCPUFA accumulation is considered disadvantageous. Maternal diet is crucial for breast milk fatty acid composition. Unfortunately, global increases in linoleic acid (C18:2n-6; LA) intake have dramatically increased n-6 LCPUFA and reduced n-3 LCPUFA availability for breastfed infants. We investigated the effects of reducing maternal dietary LA, or increasing n-3 LCPUFA, during lactation on milk and offspring brain fatty acids in mice. Offspring brain n-3 LCPUFA was higher following both interventions, although effects were mediated by different mechanisms. Because of competitive interactions between n-3 and n-6 fatty acids, lowering maternal LA intake may support neurodevelopment in breastfed infants.

Linoleic acid and the pathogenesis of obesity

The modern Western diet has been consumed in developed English speaking countries for the last 50 years, and is now gradually being adopted in Eastern and developing countries. These nutrition transitions are typified by an increased intake of high linoleic acid (LA) plant oils, due to their abundance and low price, resulting in an increase in the PUFA n-6:n-3 ratio. This increase in LA above what is estimated to be required is hypothesised to be implicated in the increased rates of obesity and other associated non-communicable diseases which occur following a transition to a modern Westernised diet. LA can be converted to the metabolically active arachidonic acid, which has roles in inducing inflammation and adipogenesis, and endocannabinoid system regulation. This review aims to address the possible implications of excessive LA and its metabolites in the pathogenesis of obesity.

Historical perspectives on the impact of n-3 and n-6 nutrients on health

Current public advice from the Food and Nutrition Board (FNB) about essential fatty acids (EFA) has limited quantitative details about three processes: (1) similar dynamics for n-3 linolenic and n-6 linoleic polyunsaturated fatty acids (PUFA) in maintaining 20- and 22-carbon n-3 and n-6 highly unsaturated fatty acids (HUFA) in tissues; (2) different dynamics for tissue n-3 and n-6 HUFA during formation and action of hormone-like eicosanoids; (3) simultaneous formation of non-esterified fatty acids (NEFA) and low density lipoprotein (LDL) from very low density lipoprotein (VLDL) formed from excess food energy and secreted by the liver. This report reviews evidence that public health may benefit from advice to eat less n-6 nutrients, more n-3 nutrients and fewer calories per meal. Explicit data for linoleic acid fit an Estimated Average Requirement (EAR) near 0.1 percent of daily food energy (en%) meeting needs of half the individuals in a group, a Recommended Dietary Allowance (RDA) near 0.5 en% meeting needs of 97-98 percent of individuals, and a Tolerable Upper Intake Level (UL) near 2 en% having no likely risk of adverse health effects. Quantitative tools help design and monitor explicit interventions that could beneficially replace imprecise advice on "healthy foods" with explicit preventive nutrition.

A low omega-6 polyunsaturated fatty acid (n-6 PUFA) diet increases omega-3 (n-3) long chain PUFA status in plasma phospholipids in humans

This study aimed to determine the effect of reducing the dietary linoleic acid (LA) intake from ~5% to <2.5% energy (%E) on n-3 long chain PUFA (LCPUFA) status in humans. Thirty-six participants followed a <2.5%E LA diet for 4 weeks. Nutrient intakes were estimated from diet diaries and blood samples were collected for assessment of fatty acid composition in plasma and erythrocyte phospholipids. LA intakes were reduced from 4.6%E to 2%E during the low LA intervention (P<0.001) while n-3 LCPUFA intakes were unchanged. LA and total n-6 PUFA content of plasma and erythrocyte phospholipids were significantly reduced after the low LA diet phase (P<0.001). The n-3 LCPUFA content of plasma phospholipids was significantly increased after the low LA diet compared to baseline (6.22% vs. 5.53%, P<0.001). These data demonstrate that reducing LA intake for 4 weeks increases n-3 LCPUFA status in humans in the absence of increased n-3 LCPUFA intake.