No abstract

Lipids are considered the most important energy source in the infant diet and are necessary for normal growth and physical activity. Human milk, in which most of the energy is present as fat, provides a relatively high cholesterol intake. Formula provides a much lower cholesterol intake. Infants fed human milk have higher total and LDL-cholesterol concentrations in plasma than do formula-fed infants (P: < 0.05), whereas plasma HDL- and LDL-cholesterol concentrations are lower in formula-fed infants if a formula high in linoleate is fed (P: < 0.05). Infants adapt to the high cholesterol content of human milk through a decrease in cholesterol synthesis; in contrast, the addition of cholesterol to formula does not suppress synthesis. Measurements of serum lipoproteins and LDL-receptor activity suggest that it is the fatty acid content, rather than the cholesterol content, of the diet that regulates cholesterol homeostasis. We studied the effect of total energy, source of energy, and fat on growth indexes of children <6 y of age in Latin America with use of food balance data. With respect to availability of animal fat, a negative relation was evident for being underweight (percentage weight-for-age <2 SDs of the World Health Organization-National Center for Health Statistics standards) and for having a low birth weight; the latter was also negatively related to energy. Wasting (percentage weight-for-height <2 SDs) was not related to dietary factors. These results suggest that diets that provide <22% of energy from fat and that are low in animal fats may restrict growth. The coexistence of early stunting with adult obesity in Latin America creates a dilemma for public nutrition intervention programs.

Two siblings with Refsum's disease, an inherited disorder of lipid metabolism, oxidized intravenously injected uniformly labeled phytanic acid-C(14) at rates less than 5 percent of those found in normal subjects. The defect in oxidation of phytanic acid persisted in cultures of fibroblasts from the patients' skin. The rate of oxidation of the phytanic acid-C(14) was less than 1 percent of that found in cultures of fibroblasts from normal skin. However, pristanic acid, previously shown to be the first product of phytanic acid degradation, was oxidized at a normal rate in the patients' cultures. These results indicate that the enzymatic defect in Refsum's disease is in the first step of the pathway for degradation of phytanic acid, that is, in the unusual alpha-oxidative process that leads to a shortening of phytanic acid by one carbon atom.

No abstract