The determinants of dairying and milk use in the old world: Ecological, physiological, and cultural

Correlation of lactose maldigestion, lactose intolerance, and milk intolerance

Lactose digestion and tolerance were evaluated in 164 African Americans ranging in age from 12 to 40 y who claimed intolerance to one cup (240 mL) or less of milk. With use of a breath-hydrogen test with 25 g lactose as test dose and the presence or absence of symptoms, 50% of the subjects were classified as lactose maldigesters and intolerant, 8% were maldigesters but tolerant, 15% were digesters but intolerant, and 27% were digesters and tolerant. Forty-five subjects from the lactose maldigesting and intolerant group were further tested for milk intolerance in a double-blind study. Sixty-seven percent of the subjects reacted appropriately to the presence or absence of lactose in ingested milk whereas 33% reported symptoms to both low-lactose milk and milk containing lactose. The results suggest that the cause of milk intolerance in as many as one-third of African Americans claiming symptoms after ingestion of a moderate amount of milk cannot be its lactose content.

Is cow's milk suitable for the dietary supplementation of rural Gambian children? 2. Patterns of cow's milk intake

Cow's milk has been advocated as a source of supplementary diet for children in many parts of the developing world. The frequency and forms of cow's milk intake and the factors regulating its availability and consumption by 507 children aged up to 6 years in three Gambian villages were measured. Nineteen per cent of mothers did not give cow's milk to their children. Of 413 children taking cow's milk, 41% consumed it only once a week, 32% two to four times a week, 19% once a day and 8% more than once a day. Eighty per cent of children took both fresh and sour milk. Forty-one per cent of infants up to 1 year old received cow's milk at some time. There was a decrease with age in the proportion of children taking fresh milk and a rise with age in the proportion taking sour milk alone (p < 0.001) and both forms of milk. Only 2% of children were reported to have an adverse reaction to fresh cow's milk. The main factors affecting intake were the availability of money and milk. The consumption of cow's milk in early life is common and free of adverse effects. When it is available, it should be used to supplement the diet of the weaned child.

The geographic hypothesis and lactose malabsorption. A weighing of the evidence

Reviewed in this article is evidence bearing on the geographic hypothesis advanced eight years ago to explain the striking ethnic or racial differences in prevalence of primary adult lactose malabsorption that are found around the world. Most evidence is found to support the hypothesis and the likelihood that some human groups came to have low prevalences of such lactose malabsorption because of selective pressures over a long historical period that favored the adult lactose absorber under particular ecological conditions.