Changes in plasma triacylglycerol concentrations after sequential lunch and dinner in healthy subjects.

OBJECTIVES: The present study examines the kinetic of plasma triacylglycerol (TAG) after sequential ingestion of lunch and dinner as well as the contribution of dietary fat ingested at lunch to subsequent post-dinner TAG composition. METHOD: Six healthy subjects were included. After standardized breakfast (7: 30AM), 2 mixed meals with fat loads composed of 44 g olive oil (rich in oleic acid) at lunch (12PM) and 44 g sunflower oil (rich in linoleic acid) at dinner (7PM) were ingested. [1-13C] palmitate was added in lunch only. Plasma TAG and chylomicron-TAG (CMTAG) levels were measured sequentially after meals. [1-13C] palmitate enrichment and concentrations of oleic acid and linoleic acid were measured in all lipid fractions. RESULT: Post-dinner plasma TAG peak was delayed as compared to lunch (3 hours vs 1 hour, p=0.002) whereas the magnitude of the postprandial peaks was not significantly different between lunch and dinner (2.4+/-0.3 vs 2.0+/-0.4 mmol/L, p=0.85). [1-13C] palmitate enrichment was maximal 5 hours after lunch in all lipid fractions and decreased slowly thereafter. After dinner ingestion, the rate of decline of [1-13C] palmitate enrichment plateaued during the first 60 minutes. Oleic acid increased slightly and immediately after dinner and remained the predominant fatty acid in all lipid fractions during the first hour after dinner. A delayed peak of plasma and CM-TAG was observed after dinner as compared to lunch without difference in the magnitude of peaks. CONCLUSION: The contribution of dietary fat ingested at lunch to post-dinner lipemia is confirmed despite the relatively long lasting interval between the 2 meals (7 h) and the absence of any early peak of plasma TAG after dinner.

Blood lipid concentrations of docosahexaenoic and arachidonic acids at birth determine their relative postnatal changes in term infants fed breast milk or formula.

BACKGROUND: Factors other than dietary fatty acids could be involved in the variability observed in blood docosahexaenoate (22:6n-3) and arachidonate (20:4n-6) status in formula-fed infants. OBJECTIVE: We considered the 22:6n-3 and 20:4n-6 status at birth to be one of these factors and studied its influence on postnatal changes in term infants fed 4 different diets. DESIGN: The blood phospholipid composition was determined at birth and on day 42 of feeding in 83 term infants fed breast milk, nonsupplemented formula, or 2 different 22:6n-3-supplemented formulas. Relations between 22:6n-3 and 20:4n-6 status at birth and their relative postnatal changes, calculated by the difference between status at the end of the feeding period (6 wk of age) and at birth, were assessed. RESULTS: Postnatal changes in the plasma and erythrocyte phospholipids 22:6n-3 and 20:4n-6 were negatively related to their respective concentrations at birth (P < 0.01) and the slopes of the regression lines were not significantly affected by the type of milk ingested. Adjusted mean values for phospholipid 22:6n-3 in nonsupplemented-formula-fed infants and for 20:4n-6 in formula-fed infants decreased significantly more than they did in the other infant groups (P < 0.02). The status at birth and the type of milk ingested explained 33-64% and 7-47%, respectively, of the variability in postnatal changes. CONCLUSIONS: The status of 22:6n-3 and 20:4n-6 at birth in term infants is one of the major determinants of postnatal changes in these fatty acids. This finding indicates that research is required to characterize environmental, genetic, or both factors, which, in addition to maternal diet, could influence fatty acid status at birth.

Effect of two types of fish oil supplementation on plasma and erythrocyte phospholipids in formula-fed term infants.

We studied the effect of docosahexaenoic acid (DHA) supplementation of infant formulas on fatty acid composition of blood phospholipids in term infants. Two fish oil supplemented formulas containing 0.45 wt% DHA and high (0.35%) or low (0.10%) eicosapentaenoic acid (EPA) were fed for 42 days and compared with a standard formula and breast milk. Infants fed supplemented formulas and breast milk had similar time-dependent changes for DHA from birth to day 42, i.e., slight decreases in plasma phospholipids and erythrocyte phosphatidylcholine and no change in erythrocyte phosphatidylethanolamine. Low-EPA formula prevented EPA accumulation but did not limit the significant decrease in arachidonic acid (AA) noted in infants fed high-EPA formula. These results suggest that term infant formulas should be supplemented with DHA-rich EPA, low fish oil and AA to achieve a fatty acid status in formula-fed infants similar to that of breast-fed infants.

Long-term supplementation of culture medium with essential fatty acids alters alpha-linolenic acid uptake in Caco-2 clone TC7.

We investigated the influence of four different culture media: 20% fetal bovine serum (FBS), 5% FBS, 5% FBS supplemented with 10 mg x L(-1) linoleic acid (18:2(n-6)) or alpha-linolenic acid (18:3(n-3)) on alpha-linolenic acid apical uptake in clone TC7 of human intestinal Caco-2 cell line. Neither cellular viability nor cell monolayer integrity and permeability were altered by the four culture conditions. Our results show that the different culture media led to changes in alpha-linolenic acid maximal rate of uptake (Vmax) but did not alter the apparent transport constant (Km). Reducing FBS concentration from 20% to 5% increased significantly the rate of alpha-linolenic acid uptake, which was further increased by supplementation of the medium with 18:2(n-6) or 18:3(n-3). Supplementation with essential fatty acids led to a marked enrichment of brush-border membrane phospholipids in polyunsaturated fatty acids of the corresponding series and decreased significantly the levels of monounsaturated fatty acids. Saturated fatty acids, unsaturation index, and cholesterol/fatty acid ratios were unchanged. No clear relation could be established between the changes in membrane lipid composition and the alterations of alpha-linolenic acid uptake. These results indicate a weak influence of membrane lipid composition in the modulation of the uptake. Therefore, the increase of uptake following long-term supplementation of TC7 cells with essential fatty acids could be attributed to an increase of the expression of membrane protein(s) involved in the apical uptake of long-chain fatty acids. This remains to be established.