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What is Lactose Intolerance Simplified

Understanding Why Lactose Intolerance Exists

With rare exceptions, the milk of all mammals contains lactose.

A human with lactose intolerance can’t digest lactose because the intestinal enzyme lactase, is either inactive, absent, or present only in very small amounts. Symptoms of this condition don’t appear until a child is several years old.

Milk is the sole food of most mammals shortly after birth, and the primary food for various lengths of time until the transition from consuming mother’s milk to eating a diet of solid foods.

This process of transition is called weaning. Once weaned, mammals never again drink milk, except, of-course, for humans.

The developmental mechanisms that turn off lactase production and activity are not firmly established, but they are known to involve decreased transcription of the lactase gene.

Lactose (Milk sugar)
Lactose (Milk sugar)


The principal symptom of lactose intolerance is an adverse reaction to products containing lactose (primarily milk).

Abdominal bloating


Flatulence- gases generated in the intestine or stomach/ the state of having excessive stomach or intestinal gas


Nausea- sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit.

Borborygmi- rumbling stomach


These appear thirty minutes to two hours after consumption. The severity of symptoms typically increases with the amount of lactose consumed.

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