Lactose Intolerance


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If you were asked to give an example of a type of food intolerance, most people would probably say lactose intolerance. It is probably the most widely known food intolerance due the huge part milk and other dairy products have in the western diet. When unpleasant side effects mean you aren’t able to eat such foods it can be a big inconvenience.

What is lactose?

Lactose is a type of milk sugar which forms a major constituent of dairy products. It is a type of disaccharide sugar, which means it is made up of two sugars called monosaccharides bonded together. Lactose is present in milk and dairy products. Lactose is too large to pass across the gut wall and enter the bloodstream, so an enzyme called lactase is needed for its digestion.

What is lactase?

Lactase is an enzyme of the digestive system which is responsible for the digestion of the milk sugar, lactose. Lactase is found in the intestinal lining in the small intestine. It enables lactose to be broken down into its constituent parts; the monosaccharides - glucose and galactose. The galactose is then also converted to glucose by the liver. Glucose is small enough to be absorbed through the gut wall into the bloodstream, where is it distributed to cells around the body. Glucose the commonly called the ‘fuel’ of the body and so it’s production is essential. Without the enzyme lactase glucose isn’t produced and this digestion of lactose can’t occur, and subsequently gives rise to the symptoms associated with lactose intolerance.

What causes it?

It occurs when your body can’t digest the lactose. It is caused by a deficiency in the enzyme (lactase) in the gut. Lactase breaks down lactose into small enough constituents that it can be absorbed through the gut wall into the bloodstream. Most dairy products contain this type of milk sugar. The problem lies when the ingested dairy product reaches the gut, where it should be broken down into simple sugars to then be absorbed into the bloodstream.  Normally, it would be broken down by the enzyme lactase which lines your small intestine. Instead in the lactose intolerant, it remains undigested and interacts with normal bacterial flora to cause a variety of unpleasant symptoms, which include: bloating and flatulence.


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