Lactose intolerance is a condition characterised by a variety of symptoms. They include bloating, stomach pain, gas an diarrhea. It is caused by poor lactose absorption in the gut.
Lactose is a common sugar found in milk and dairy products from most mammals. It is a disaccharide of β-D-galactose and β-D-glucose with a β-(1,4) linkage.
Human milk contains approximately 200 mmol/litre of this sugar.
In most humans we have an enzyme called lactase which catalyses the digestion of this disaccharide into glucose and galactose. The enzyme resides in the brush border of our intestine.
Typical Foods Containing Lactose
Lactose containing foods include:-
- Fresh, skimmed, non fat and condensed milk
- Cheese
- Cream
- Yoghurt
- Confectionary especially chocolate bars
- Processed foods
- Some pharmaceuticals as a filler and excipient
- Soups and stuffings
- Salad dressings
These are a few but lactose is found in many other foods too.
What Is Lactose Intolerance?
Lactose intolerance is often described by the terms of lactase deficiency or hypolactasia. It is simply the inability to digest and metabolize lactose. Lactose intolerance is not an allergy because it is not an immune response.
It occurs in any type of population and age group. It appears to be more prevalent in certain types of peoples such as Africans, Asians, Jewish people, some Middle Eastern groups and Native Americans. It can develop in European and Caucasian peoples although it is not as prevalent. There is some association with people who have not developed a dairy producing culture.
The Main Symptoms
- Abdominal bloating and cramps (very common symptom)
- Flatulence (wind) through gas formation
- Diarrhoea and intestinal
- Borborygmi which is a medical term for a rumbling stomach along with wind.
- Nausea
- Vomiting which often happens in adolescents.
The Two Types Of Lactase Deficiency
There are three main types of lactase deficiency.
The primary type is caused by a missing gene for the enzyme or a severely reduced production of the enzyme. The gut morphology especially in the jejunam of the gut though will appear normal.
In non-Caucasian populations, primary lactase deficiency is abnormal in adults rather than children.
The secondary type is also described as transient or acquired lactase deficiency. This occurs when there has been small intestinal mucosal disease, when there are abnormalities in brush border cells and the various transport processes that move nutrients across the intestinal-blood barrier. It is also commonly associated with celiac sprue.
A very rare form of deficiency is congenital lactase deficiency. This occurs when there is an autosomal recessive genetic issue. It prevents lactase production from the first feed onwards. The situation is extremely serious for newborn babies who simply do not thrive unless they are fed on lactose-free formulas.
Diagnosis
People who complain of all the symptoms listed may well have the condition. It will be reflected in their dietary history including regular bouts of abdominal discomfort, wind and diarrhoea. There can be a record of the deficiency in the family reflecting the genetic nature of the deficiency. Some intestinal procedures such as partial gastrectomy may be responsible.
Typical clinical diagnostic tests include stool acidity test and hydrogen breath tests.
Primary and secondary lactose deficiency can be misdiagnosed for irritable bowel syndrome, Crohn’s disease, celiac disease, gastroenteritis and even food poisoning.
Management Of Lactose Intolerance
The best away to manage the condition is to avoid all lactose-containing foods which usually means cutting out all lactose foods. Alternatives include plant milks especially nut and soy milks.
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