January 17, 2002 – Researchers have identified the genetic basis responsible for lactose intolerance, that is, the inability to digest this milk sugar and convert it into glucose and galactose so that it is absorbed by intestine. Two differences were found in the DNA sequence of a gene similar to that of lactase (an enzyme that allows the breakdown of lactose) between healthy subjects and subjects with lactose intolerance.1
The researchers do not yet know the means of action of these changes in the structure of DNA, but they are already talking about a genetic test that would make it possible to diagnose lactose intolerance from a drop of blood. Currently, the diagnosis is made by a test measuring exhaled hydrogen.
Although lactose intolerance often appears as a medical problem, it seems to be natural in most people instead. Indeed, the lactase gene is normally activated at birth and deactivated at the time of weaning. This is why some experts do not see the need for a new test which rekindles the debate about the minor or major place to be given to this inconvenience. Lactose intolerance is also often confused with allergy to milk and dairy products or with irritable bowel syndrome (or irritable bowel syndrome).
The main symptoms associated with lactose intolerance are abdominal pain, bloating, gas, rumbling, diarrhea, and nausea. Several solutions are available to people suffering from this inconvenience: take lactase tablets when consuming dairy products, add liquid lactase to milk, eat dairy products without lactose or already added lactase and replace this source of calcium by others.
Among dairy products, aged or firm cheeses, plain yogurts and flavored milks are generally the best tolerated.2 Health Canada recommends certain foods rich in calcium: tofu made with calcium sulfate, whole sesame seeds and herbal fortified beverages as an excellent source (275 mg or more), canned small sardines and canned salmon with bones as a good source of calcium (165 mg or more) and legumes, broccoli, cooked or canned legumes, etc. as a source of calcium (55 mg or more).3 Also watch out for products that may hide lactose such as bread, creamy dressings, instant mashed potatoes, vegetable creams, puddings and candies. The words “milk”, “milk solids”, “milk powder” and “whey” should put you on the spot.
About 70% of the world’s adult population is believed to have incomplete lactose indigestion, but a large majority of symptoms only appear with high doses ingested. Intolerance concerns men as much as women, but affects more Asia, the Middle East, Africa, South America and the aborigines of North America.
Élisabeth Mercader – PasseportSanté.net
According to InteliHealth, January 13, 2002
1. Enattah NS, Sahi T, Savilahti E, Terwilliger JD, Peltonen L, Jarvela I I. Identification of a variant associated with adult-type hypolactasia.Nat Genet 2002 Jan 14.
2. Milk. Info-nutrition. Practical recommendations. [Consulté le 17 janvier 2002]. http://www.lelait.com/nutrition-3-29.html
3. Health Canada. Food sources of calcium, iron and folate. Annex 4, p.113. [Consulté le 16 janvier 2002]. http://www.hc-sc.gc.ca/hppb/la-nutrition/pubf/enceinte/pdf/17.pdf
