What is lactose intolerance?
Carbohydrate intolerance (lactose, sucrose and fructose) has increased over the last few decades, mostly as a consequence of an increase in carbohydrate consumption, especially for added sugar, in the diet. Amongst them, lactose intolerance is the most common subtype. The intolerance of lactose is due to the deficiency of lactase, an enzyme responsible for lactose digestion. This deficiency can be total or relative and can occur because of three disorders:
- Congenital lactase deficiency, which is extremely rare and whereby the production of lactase is inhibited from birth.
- Secondary lactase deficiency, which occurs after a disease affecting the intestine (acute gastroenteritis, coeliac disease, Crohn’s disease, ulcerative colitis…) and is generally reversible. Adult type lactase deficiency, which is the most common case and might concern up to 70% of the world’s population, with great variations, depending on the geographical area. This condition is due to a modification of the DNA sequence that regulates the lactase gene, thus inducing a gradual reduction of the activity of lactase through life.
Symptoms and diagnostic
In response to lactose intolerance, substantial variability of symptoms is to be expected (nausea, cramping, bloating, diarrhea, and flatulence), as the extent and severity of the condition varies among individuals. In patients with the most common adult-type lactase deficiency, the required amount of ingested lactose to produce symptoms varies from 12 to 18 g, or 8 to 12 ounces of milk. The diagnosis of lactose intolerance can be confirmed by lactose hydrogen breath test, lactose tolerance test, and genetic study. Lactose intolerance is distinct from milk allergy, an immune response to cow’s milk proteins.
Treatment and alternatives like yogurt
The mainstay of lactose maldigestion’s treatment is often the avoidance of all lactose-containing milk and other milk-containing products. However, contrary to conventional wisdom, the consumption of dairy products can be maintained, subject to certain hygiene and dietary rules. It is common for health providers to mistakenly tell the patient not to eat any dairy products, which deprives them of a healthy source of protein and the most bioavailable source of calcium. Lactose-free milk and dairy, soy milk but also hard cheeses, yogurts (unless unfermented milk is added back in) and kefir are allowed. Lactase enzyme supplementation can also be used occasionally and when necessary.
Incorporating dairy products, including yogurt, improves the quality of the diet, and reduces nutrient deficiencies. Indeed, thanks to its specific cultures and its thicker-than-milk texture, yogurt is well tolerated by individuals, who have trouble digesting lactose and can help cover daily calcium requirements.
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