Review/Oorsig Volume 22, Issue 05 - Page 14

Oorsig/Review Since lactose is the major osmole in milk, anything that affects lactose production will affect milk volume LACTOSE MALDIGESTION/ INTOLERANCE Lactose maldigestion is the difficulty to digest Lactose and is very common. Lactose intolerance is less common and is the term used when lactose maldigestion develops into symptoms. Lactose maldigestion happens due to the natural decline of lactase production in humans after infancy (for the reasons why this happens – see sidebar in this article). The non- persistence of Lactase in adults is normal and therefor Lactose intolerance is the norm rather than the exception. LACTOSE MALDIGESTION VS. MILK ALLERGY Milk allergy is quite rare and is an immunological response to the pro- teins (caseins and whey) that occur in milk. Symptoms include pruritis, urti- caria, swelling, nausea and respiratory distress. Signs usually occur within 72 hours after consuming milk. Lactose maldigestion is the natural occurrence of a reduced production of lactase after infancy. As a result undigested Lactose enters the colon where bacterial fermentation and the osmotic effect of Lactose causes bloat, flatulence, diarrhoea and abdominal discomfort. Lactose is a sugar and is not targeted by the immune system When undigested lactose enters the colon, it is fermented by colon bacteria that produce lactic acid, acetic acid and other short chain organic acids, plus methane, carbon dioxide and hydrogen gas (H2). H2 is absorbed by the intestinal lining, passed into the circulatory system and exhaled via the lungs where increased levels can be detected. The gas production leads to increased colonic 14 Marine mammals such as seals, sea lions and walruses lack alpha-lactalbumin and as a consequence their milk is lacking in lactose and has a very high fat and protein content instead. Not only do these animals lack lactose in their milk, they also lack the lactase enzyme that is needed for its digestion. Feeding cow’s milk (which contains lactose) to a baby walrus will result in severe diarrhoea.. pressure. In addition, Lactose has a strong osmotic effect which draws water into the colon leading to diarrhoea. The acids lead to increased transit time in the colon, exacerbating the problem. The combination of these factors lead to the symptoms which include bloat, flatulence, diarrhoea and abdominal discomfort. The amount of lactose that individuals can tolerate varies between individuals. However, the severity of symptoms is dependent on the volume of undigested lactose that reaches the large intestine. Some individuals retain the production of lactase into adulthood (lactase-persistence) and as a result can digest lactose throughout their lives. This is more common in people of North- European, Middle-Eastern and East-African descent. Lactose-intolerance is much more common in people of African and Asian descent where the inability of adults to digest Lactose can be as high as 90%. The ability to digest milk into adulthood appeared approximately 10,000 years ago as the result of a mutation. Which seems to coincide with the domestication of livestock. As the human population migrated, they took the mutation with them and through interbreeding with the local populations, spread the mutation. Archaeological evidence supports the fact that this mutation spread with the introduction of domesticated livestock as populations migrated. It is theorised that the benefit of lactose tolerance was most probably due to the fact that milk was a readily available source of nutrition and liquid during times of food and/or water scarcity. This improved the chances of survival of populations that could consume milk. In addition, better fed warriors were larger and stronger than their counterparts, which probably assisted the spread of populations that were tolerant to lactose. Since Lactose is associated with the water-soluble fraction of milk, such as whey, it is removed in the fermentation process of milk. Therefor hard