<h4>Purpose of review</h4>To evaluate the clinical and nutritional significance of genetically determined lactase non-persistence and potential lactose and milk intolerance in 65-70% of the world's adult population.<h4>Recent findings</h4>Milk consumption is decreasing in the USA and is the lowest in countries with a high prevalence of lactase non-persistence. The dairy industry and Minnesota investigators have made efforts to minimize the influence of lactose intolerance on milk consumption. Some lactose intolerant individuals, without co-existent irritable bowel syndrome, are able to consume a glass of milk with a meal with no or minor symptoms. The high frequency of lactase persistence in offspring of Northern European countries and in some nomadic African tribes is due to mutations in the promoter of the lactase gene in association with survival advantage of milk drinking. Educational and commercial efforts to improve calcium and Vitamin D intake have focused on urging consumption of tolerable amounts of milk with a meal, use of lowered lactose-content foods including hard cheeses, yogurt, and lactose-hydrolyzed milk products.

<h4>Background</h4>Although cow's milk allergy (CMA) and cow's milk intolerance (CMI) are two different terms, they are often used interchangeably, resulting in confusion both in clinical practice and in research reports.<h4>Objective</h4>To promote the appropriate differential use of the terms CMA and CMI.<h4>Methods</h4>Highlighting the differences in clinical and laboratory findings between CMA and CMI. Information was derived from reviewing the literature on these two topics, supplemented by the clinical experience of the author.<h4>Results</h4>CMA is an immunologically mediated reaction to cow's milk proteins that may involve the gastro-intestinal tract, skin, respiratory tract, or multiple systems, ie, systemic anaphylaxis. Its prevalence in the general population is probably 1 to 3%, being highest in infants and lowest in adults. Even though it can cause severe morbidity and even fatality, dietary elimination is associated with good prognosis. However, CMI should refer to nonimmunologic reactions to cow's milk (CM), such as disorders of digestion, absorption, or metabolism of certain CM components. The most common cause of CMI is lactase deficiency, which is mostly acquired during late childhood or adulthood. It has high racial predilection, being highest in dark-skinned populations and lowest in northern Europeans. Lactose intolerance is generally a benign condition, with symptoms limited to the gastro-intestinal tract, yet the primary acquired type lasts for a lifetime. Symptoms can be well ameliorated by reducing the intake of CM or using lactose-hydrolyzing agents.<h4>Conclusions</h4>Adverse reactions to CM should be differentiated into immunologic (CMA) and nonimmunologic (CMI). The latter is still a general term that comprises several conditions and requires further differentiation.

Clinical aspects of lactose intolerance in children and adults. The principal carbohydrate of human milk is the disaccharide lactose. In human and all mammalian species, lactose is hydrolyzed in the small intestine by lactase-phlorizin hydrolase, also abbreviated as lactase. The absence of lactase results in the passage of undigested lactose into the large intestine and is associated with a well-known clinical syndrome: lactose intolerance. Low lactase levels result either from intestinal injury or, as in the majority of world's adult population, from alterations in the genetic expression of lactase. In this review terminology, pathophysiology, symptoms, diagnostic procedures, and therapy of lactose intolerance will be discussed. Published in Scandinavian journal of gastroenterology. Supplement (1991)

Lactose intolerance is a lessened ability or a complete inability to digest lactose, a sugar found in dairy products. Humans vary in the amount of lactose Lactose intolerance is a lessened ability or a complete inability to digest lactose, a sugar found in dairy products. Humans vary in the amount of lactose they can tolerate before symptoms develop. Symptoms may include abdominal pain, bloating, diarrhea, flatulence, and nausea. These symptoms typically start thirty minutes to two hours after eating or drinking something containing lactose, with th Worldw…