RESUMO
The effect of breast-feeding was compared with that of two fat-modified milk formulas in 45 infants (15 per group) studied by assessing body weight gain for 4 months and plasma lipids, lipoprotein profiles, fatty acid profiles of plasma and red blood cells, and plasma tocopherol status 3 months after birth. A saturated fat formula with coconut oil/soybean oil (COCO/SOY) had a fatty acid content and polyunsaturated/saturated ratio (P/S, 0.55) comparable with that of human milk fat (P/S, 0.39) and had the same fat energy content (50% kcal). The second formula, with corn oil/soybean oil (CORN/SOY), was highly unsaturated (P/S, 4.6), with only 35% kcal from fat. Energy intake and body weight gain were similar for all groups. Plasma total cholesterol, triglyceride, and phospholipid levels were significantly lower (greater than 20% on average) in infants fed the CORN/SOY formula than in infants fed either the COCO/SOY formula or human milk. Infants fed the CORN/SOY formula also had lower (25% to 35%) plasma low-density lipoprotein cholesterol and apolipoprotein B levels and low-density lipoprotein/high-density lipoprotein and apolipoprotein B/apolipoprotein A-I ratios. Plasma, red blood cell, and cholesteryl ester fatty acids from infants fed COCO/SOY contained less 18:1 and more 18:2; cholesterol esters in plasma from breast-fed infants had the highest 20:4n-6 levels. Plasma tocopherol levels were higher in infants consuming formulas. The presence of cholesterol in human milk appeared to expand the low-density lipoprotein pool and exert an "unfavorable" increase in the low-density lipoprotein/high-density lipoprotein ratio. Thus modulation of infant lipoproteins by changing dietary fat and cholesterol is feasible and in keeping with the known response in adults.