Decreasing Linoleic Acid with Constant α-Linolenic Acid in Dietary Fats Increases (n-3) Eicosapentaenoic Acid in Plasma Phospholipids in Healthy Men1

Abstract

High linoleic acid (LA) intakes have been suggested to reduce alpha-linolenic acid [ALA, 18:3(n-3)] metabolism to eicosapentaenoic acid [EPA, 20:5(n-3)] and docosahexaenoic acid [DHA, 22:6(n-3)], and favor high arachidonic acid [ARA, 20:4(n-6)]. We used a randomized cross-over study with men (n = 22) to compare the effect of replacing vegetable oils high in LA with oils low in LA in foods, while maintaining constant ALA, for 4 wk each, on plasma (n-3) fatty acids. Nonvegetable sources of fat, except fish and seafoods, were unrestricted. We determined plasma phospholipid fatty acids at wk 0, 2, 4, 6, and 8, and triglycerides, cholesterol, serum CRP, and IL-6, and platelet aggregation at wk 0, 4, and 8. LA and ALA intakes were 3.8 +/- 0.12% and 1.0 +/- 0.05%, and 10.5 +/- 0.53% and 1.1 +/- 0.06% energy with LA:ALA ratios of 4:0 and 10:1 during the low and high LA diets, respectively. The plasma phospholipid LA was higher and EPA was lower during the high than during the low LA diet period (P < 0.001), but DHA declined over the 8-wk period (r = -0.425, P < 0.001). The plasma phospholipid ARA:EPA ratios were (mean +/- SEM) 20.7 +/- 1.52 and 12.9 +/- 1.01 after 4 wk consuming the high or low LA diets, respectively (P < 0.001); LA was inversely associated with EPA (r = -0.729, P < 0.001) but positively associated with ARA:EPA (r = 0.432, P < 0.001). LA intake did not influence ALA, ARA, DPA, DHA, or total, LDL or HDL cholesterol, CRP or IL-6, or platelet aggregation. In conclusion, high LA intakes decrease plasma phospholipid EPA and increase the ARA:EPA ratio, but do not favor higher ARA.

Plasma n-6 and n-3 polyunsaturated fatty acids as biomarkers of their dietary intakes: a cross-sectional study within a cohort of middle-aged French men and women

“…Moreover, the plasma levels of long-chain n-3 PUFA were negatively correlated with that of linoleic acid, which indicates that the conversion of a-linolenic into long-chain derivatives can be inhibited by high linoleic acid intakes. This has been confirmed in recent intervention studies, in which the intakes of high levels of linoleic acid (7-10% of calories compared to 3-4%) were found to lower the conversion of a-linolenic into EPA, in subjects maintained on diets devoid of fish and seafood (Goyens et al, 2006;Liou et al, 2007). In our study, where the intake of long-chain n-3 PUFA was fairly high (95% of the population consumed more than 0.06% of energy or 100 mg/day) (Astorg et al, 2004), the levels of linoleic acid and a-linolenic intakes were not found to influence the long-chain n-3 PUFA plasma levels, since the endogenous biosynthesis of these PUFA from a-linolenic was likely to be negligible compared to their direct dietary supply.…”

Fatty acid profile and meat quality of young bulls fed ground soybean or ground cottonseed and vitamin E

“…Moreover, animals fed ground cottonseed exhibited greater n-6 fatty acid concentrations in muscle, and n-6/n-3 ratio in both tissues, compared with those fed ground soybean. The relationship between these fatty acids is important because high intake of n-6 fatty acids can inhibit conversion of α-linolenic to EPA (Liou et al, 2007). Oliveira et al (2011) also observed a greater n-6/n-3 ratio in the muscle and subcutaneous fat from animals fed cottonseed diets compared with animals fed soybean or linseed diets.…”

Change in the fatty acid pattern of erythrocyte membrane phospholipids after oral supplementation of specific fatty acids in patients with gastrointestinal diseases

“…AA is the substrate for the production of a wide variety of pro-inflammatory eicosanoids (Harris et al, 2009). Although the metabolites of ALA possess anti-inflammatory actions, higher n-6 PUFA intakes can inhibit the conversion of ALA to EPA (Das, 2006;Liou et al, 2007). De Vizia et al (2003) reported an increase in EPA and DHA in erythrocyte membrane phospholipids after supplementation with fish oil as a source of EPA and DHA in patients with CF.…”