Impact of consumption of milk and milk products on human health

Abstract

AbstractThe nutritive value of milk has long been recognised. In the 1920's and 30's several clinical trials explored the influence of a milk supplement on the growth of children. These studies universally showed that milk had a beneficial effect on height gain. The effects of milk on childhood growth were attributed to the impact of the additional dietary calcium on the skeleton, although energy and protein intakes may have been limiting.Contemporary research on the effects of nutrition on growth has the advantage of being able to focus much more specifically on the strength and mineral mass of the skeleton. Curiosity about the relationship between nutrition and skeletal development has arisen because maximising skeletal development in childhood and adolescence is a recognised preventative strategy against osteoporosis. The effect of additional dietary calcium has been explored in a number of clinical trials of children and teenagers using both supplemental calcium and milk and milk products. The studies have generally shown that the rate of skeletal accrual is greater in the supplemented groups, at least in the short-term. Similarly, clinical trials in post-menopausal women show positive effects of calcium in attenuating bone loss and fracture risk.While calcium has been the main nutrient of interest in relation to milk and milk products and their effects on bone growth there is also the possibility that other nutrients which are found in milk may be important. Energy and protein modulate bone growth and micronutrients such as zinc may also have an effect. The form of calcium salt may also be important. It has been proposed that the calcium phosphate in milk may have different mechanistic effects on bone compared to other calcium salts.While these studies show that milk and milk products may decrease the risk of osteoporosis through their effects on growth, recent epidemiological evidence may point to negative influences of childhood growth on later human health. Cancer mortality rates seem to be associated with nutritional conditions which encourage growth in childhood, while the opposite is true for risk of cardiovascular disease.Milk and milk products have also been vilified because of their fat content and the link between fat, particularly saturated fatty acids, and coronary heart disease. The classical diet heart hypothesis centres on the relationship between saturated fatty acids, blood cholesterol and risk of coronary heart disease. This classic diet hypothesis has formed the basis of dietary recommendations to reduce the incidence of coronary heart disease. Dietary change in the direction of reduced consumption of saturated fatty acids, particularly changes in the consumption of milk and milk products has been a bastion of UK dietary recommendations. However, there is debate as to the efficacy of such an approach as a method to reduce deaths from coronary heart disease.Milk protein and lactose may cause adverse reactions in a small proportion of the population. However, exact figures for the prevalence of cow's milk allergy and lactose maldigestion are difficult to estimate.