Is It Wise to Restrict Fat in the Diets of Children

The proponents of fat-restricted diets for children argue that low-fat diets given in childhood will prevent the development of atherosclerosis in adulthood, low-fat diets given a childhood will condition children to prefer low-fat diets in adulthood, and low-fat diets for children are safe. There is no evidence that low-fat diets in childhood will prevent atherosclerosis in adulthood. In fact, studies of migrating populations indicate that immigrants to the United States from Third World countries who consumed low-fat diets in childhood take on the character of their new environments, including higher serum cholesterol levels and more coronary disease. The prevalence of fatty streaks in childhood bears little relationship to the prevalence of atheromatous plaques in adulthood. In fact, girls have more aortic fatty streaks and higher serum cholesterol values in childhood than boys, but fewer plaques in adulthood and less coronary disease. From the PDAY study, it has also been learned that hypercholesterolemia in childhood enhances fatty streak formation, but not that of plaques. It now seems established from autopsy studies that the progression of atherosclerosis from fatty streaks to plaque is arrested in childhood and does not begin to a significant extent until after puberty in males and after menopause in females. So the oft-repeated statement that atherosclerosis begins in childhood is semantically true but very misleading. The particularly harmful form of atherosclerosis (the plaque) does not become significant until much beyond puberty. The effects of low-fat, low-cholesterol diets on serum lipids and lipoproteins are of a lesser magnitude in children than in adults. The 0.78 mmol/L decrease in LDL cholesterol in the intervention group from controls (change 1.5%) in the DISC study was biologically insignificant and reflects the tighter control of lipoprotein and cholesterol synthesis in children compared with adults. It must be remembered that the human body synthesizes all of the cholesterol it needs from acetyl CoA. In general, the larger the amount of dietary cholesterol absorbed, the smaller the rate of biosynthesis of cholesterol. In some adults and most children this homeostatic control is nearly perfect, but in many adults the correction in biosynthesis of cholesterol with increased dietary input is imperfect and LDL cholesterol values increase. The second argument of the proponents of low-fat diets for children is that they are conditioned to continue low-fat diets in adulthood. From the studies of Birch and Fisher (51) this prediction seems unlikely. These investigators found that restricting access to palatable foods enhanced the interest of 3- to 5-year-old children in those foods and increased their desire to obtain and consume those foods. They concluded that "stringent parental controls can potentiate preference for high-fat energy-dense foods, limit children's acceptance of a variety of foods and disrupt children's regulation of energy intake." Brosin (52) has also observed that food restriction in childhood may lead to gluttony in adulthood. Finally, the claim that low-fat diets are safe in childhood is based on observations over too short a time to establish safety. It is true that growth and development of children studied in the DISC study was not changed from the expected increments, but that is not proof of long-term safety. In addition, the lower content of essential nutrients in low-fat, low-cholesterol diets (calcium, zinc, magnesium, phosphorus, vitamin E, vitamin B-12, thiamin, niacin, and riboflavin) must be considered along-term risk (53,54). Furthermore, the published studies of the safety of low-fat diets have been conducted under intensive surveillance in medical centers, conditions very different from those in the homes of free-living families.