Modification of dietary polyunsaturated fatty acids via complementary food enhances n-3 long-chain polyunsaturated fatty acid synthesis in healthy infants: a double blinded randomised controlled trial.

OBJECTIVE: To study the effect of modified polyunsaturated fatty acid (PUFA) profiles of complementary food on long-chain (LC) PUFA composition in healthy infants. DESIGN: Double blinded, randomised, controlled intervention trial. SETTING: Dortmund, Germany. PATIENTS: Free-living sample of healthy term infants. METHODS: Participants were randomly assigned within the first 2 months of life. During the intervention period from 4 to 10 months, the control group (n = 53) received commercial complementary meals with corn oil (3.4 g/meal) rich in n-6 linoleic acid (LA), the intervention group (n = 49) received the same meals with rapeseed oil (1.6 g/meal) rich in n-3 alpha-linolenic acid (ALA). Fatty acid intake was assessed from dietary records throughout the intervention period. Fatty acid proportions (% of total fatty acid) in total plasma were analysed before and after the intervention. RESULTS: Plasma fatty acid profiles did not differ between the intervention and control groups before the intervention. During the intervention, the only difference in fatty acid intake between the intervention and control groups was a higher intake of ALA in the intervention group, 21% deriving from study food and a lower ratio of LA/ALA (10.7 vs 14.8). At the end of the intervention, the plasma proportions of total n-3 fatty acids and of n-3 LC-PUFA, but not of ALA, were higher and the ratios of n-6/n-3 fatty acids were lower in the intervention group. CONCLUSIONS: Feasible dietary modifications of the precursor fatty acid profile via n-3 PUFA-rich vegetable oil favoured n-3 LC-PUFA synthesis in the complementary feeding period when LC-PUFA intake from breast milk and formula is decreasing.

Influence of three rapeseed oil-rich diets, fortified with alpha-linolenic acid, eicosapentaenoic acid or docosahexaenoic acid on the composition and oxidizability of low-density lipoproteins: results of a controlled study in healthy volunteers.

OBJECTIVE: To compare the individual effects of dietary alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) on low-density lipoprotein (LDL) fatty acid composition, ex vivo LDL oxidizability and tocopherol requirement. DESIGN, SETTING AND SUBJECTS: A randomized strictly controlled dietary study with three dietary groups and a parallel design, consisting of two consecutive periods. Sixty-one healthy young volunteers, students at a nearby college, were included. Forty-eight subjects (13 males, 35 females) completed the study. INTERVENTIONS: Subjects received a 2-week wash-in diet rich in monounsaturated fatty acids (21% energy) followed by experimental diets enriched with about 1% of energy of ALA, EPA or DHA for 3 weeks. The omega-3 (n-3) fatty acids were provided with special rapeseed oils and margarines. The wash-in diet and the experimental diets were identical, apart from the n-3 fatty acid composition and the tocopherol content, which was adjusted to the content of dienoic acid equivalents. RESULTS: Ex vivo oxidative susceptibility of LDL was highest after the DHA diet, indicated by a decrease in lag time (-16%, P<0.001) and an increase in the maximum amount of conjugated dienes (+7%, P<0.001). The EPA diet decreased the lag time (-16%, P<0.001) and the propagation rate (-12%, P<0.01). Tocopherol concentrations in LDL decreased in the ALA group (-13.5%, P<0.05) and DHA group (-7.3%, P<0.05). Plasma contents of tocopherol equivalents significantly decreased in all three experimental groups (ALA group: -5.0%, EPA group: -5.7%, DHA group: -12.8%). The content of the three n-3 polyunsaturated fatty acid differently increased in the LDL: on the ALA diet, the ALA content increased by 89% (P<0.001), on the EPA diet the EPA content increased by 809% (P<0.001) and on the DHA diet, the DHA content increased by 200% (P<0.001). In addition, the EPA content also enhanced (without dietary intake) in the ALA group (+35%, P<0.01) and in the DHA group (+284%, P<0.001). CONCLUSIONS: Dietary intake of ALA, EPA or DHA led to a significant enrichment of the respective fatty acid in the LDL particles, with dietary EPA preferentially incorporated. In the context of a monounsaturated fatty acid-rich diet, ALA enrichment did not enhance LDL oxidizability, whereas the effects of EPA and DHA on ex vivo LDL oxidation were inconsistent, possibly in part due to further changes in LDL fatty acid composition.

Effects of dietary fatty acids on the composition and oxidizability of low-density lipoprotein.

OBJECTIVE: The objective of this study was to compare the effects of dietary monounsaturated fatty acids (MUFA), n-6 and n-3 polyunsaturated fatty acids (PUFA) on LDL composition and oxidizability. DESIGN, SETTING AND SUBJECTS: Sixty-nine healthy young volunteers, students at a nearby college, were included. Six subjects withdrew because of intercurrent illness and five withdrew because they were unable to comply with the dietary regimen. INTERVENTIONS: The participants received a 2-week wash-in diet rich in saturated fatty acids (SFA) followed by diets rich in refined olive oil, rapeseed oil or sunflower oil for 4 weeks. Intakes of vitamin E and other antioxidants did not differ significantly between the diets. RESULTS: At the end of the study, LDL oxidizability was lowest in the olive oil group (lag time: 72.6 min), intermediate in the rapeseed oil group (68.2 min) and highest in the sunflower oil group (60.4 min, P<0.05 for comparison of all three groups). Despite wide variations in SFA intake, the SFA content of LDL was not statistically different between the four diets (25.8-28.5% of LDL fatty acids). By contrast, the PUFA (43.5%-60.5% of LDL fatty acids) and MUFA content of LDL (13.7-29.1% of LDL fatty acids) showed a wider variability dependent on diet. CONCLUSIONS: Enrichment of LDL with MUFA reduces LDL susceptibility to oxidation. As seen on the rapeseed oil diet this effect is independent of a displacement of higher unsaturated fatty acids from LDL. Evidence from this diet also suggests that highly unsaturated n-3 fatty acids in moderate amounts do not increase LDL oxidizability when provided in the context of a diet rich in MUFA.