Lactose intolerance

An intolerance to milk due to an inability to digest lactose. This is caused by inadequate production of the digestive enzyme lactase.

Lactose is found in milk (especially cow and human milk). Most small children have higher levels of lactase than adults (because they may be breast feeding), and therefore lactose intolerance (LI) becomes most likely after 4-5 years of age. Most adults have some degree of LI: Asian, native Australian, and many African populations tend to lose lactase as they get older, while European, Arabian, and East African populations are less likely to be LI*

Symptoms include abdominal bloating, excessive intestinal gas, nausea, weight loss, diarrhea, and abdominal cramping. LI may result in intestinal diseases such as celiac sprue and gastroenteritis.

There is no cure. Just stop drinking milk.

*
Africans: 10-30% retain lactase into adulthood.
Orientals: 0-30% retain lactase into adulthood.
Northern Europeans: 80% retain lactase into adulthood.
Haviland, 1994, Anthropology
This is probably due to years of Europeans' drinking fresh milk (souring milk reduces lactose). Humans evolving! A little bit.

• Cats usually love milk.
• Cats usually get a very bad diarrhea from milk.

A better alternative to this would of course be

• Low lactose cow milk - which is available in most stores
• Water with a little cream in it

There are so many misconceptions about lactose intolerance. This node is partially in response to errors in the previous nodes.

"Lactose is found in cow milk". Well, yes it is, it is also found in varying amounts in all other milks from all other mammals. We are just used to drinking cows' milk so we tend to limit our thinking to the familiar.

"LI may result in intestinal diseases such as celiac sprue". Celiac Sprue may co-exist with lactose intolerance but doesn't result from it. They are both malabsorption syndromes but a celiac individual can't tolerate gluten (the protein in wheat and rye and to a lesser degree in oats and barley) while the lactose intolerant individual can't tolerate lactose (the sugar found in milk).

"This is because when the sugar lactose is not digested properly, it lines the colon and ferments." Well, again, yes - sort of... The immediate distress is because of osmosis. When lactose remains intact in the gut, water moves across the membranes to dilute it, causing the sudden distress the lactose intolerant individual feels. Fermentation also happens, but more slowly.

"Mammals usually begin losing their ability to process lactose at or near puberty." OR EARLIER

Soy milk is not really a milk (product of the secretion of a mammary gland of a mammal) and does not contain lactose. In fact, lactose is not found in any other substance other than mammalian milk.

In reference to kittens becoming lactose intolerant as adult cats, yes they do. But the suggestion that they be fed "Low lactose human milk - which is available in most stores" is amusing. Of course the author meant cows' milk with lactase added to it that many humans drink and not human milk which is breastmilk and not yet available in most stores.

Human milk has more lactose than any other mammalian milk. Human infants use lactose to great advantage and are almost never lactose intolerant. Lactose intolerance is something that happens past the natural age of weaning not in infancy. A baby whose parent is lactose intolerant may become lactose intolerant as a young child, adolescent or adult but will not be lactose intolerant as an infant. The infants who are lactose intolerant are very rare and consist of very early premature babies as well as any gestational age infant who has had a bout of gastroenteritis and may have sustained injury to the brush border of the bowel where lactase is produced. Even in these cases the intolerance is often just partial and almost always is outgrown in a matter or weeks. Infants who are lactose intolerant without cause are so rare as to be almost non-existent. True primary lactose intolerance in infancy would not have been compatible with life (outside of the modern world) when lactose free alternatives to breastfeeding did not exist.

Formula companies have recently begun marketing an infant formula based on cows' milk that has no lactose. It is directed at the almost non existent "lactose intolerant infant". This is simply a marketing ploy. It should be used only rarely in the situations mentioned above but I see many parents requesting it for their normal infants because they, the parents, are lactose intolerant. This is silly and probably dangerous. Anything that we evolved to expect should not be removed arbitrarily from an infant's diet.

Growing on lactose is normal for human infants.