Lactose intolerance is very common disease caused by the inability to digest lactose, a sugar found in milk and dairy products. The absence of lactase enzyme that digests the lactose, leads to the appearance of gastrointestinal symptoms when a milk-based product is consumed.
The usual adult Western diet contains about 300 grams of sugars (carbohydrates). Of these, about 52% are starch (present in cereals, rice and potatoes), 37% are sucrose (present in table sugar), 5% are lactose (in milk and its derivatives) and 3% are fructose (found in fruits and honey).
The intolerance to milk and milk products occurs in individuals who have insufficient levels of the lactase enzyme responsible for digesting lactose, the type of sugar present in milk. Lactose is about 5% of cow's milk usually marketed.
Lactose intolerance is not the same as milk allergy. Lactose intolerance occurs by an enzyme failure and has nothing to do allergy processes of those who have food allergies.
Lactose is a disaccharide, a large sugar molecule, formed by fusion of two simple sugars: glucose and galactose. The body can not absorb large sugar molecules therefore our digestive system has special enzymes that break down complex sugars to simple sugars (monosaccharides), allowing their absorption in the intestines.
Lactase is one of those enzymes being produced in the small intestine. Its action is specific to break down lactose into glucose and galactose, allowing the intestines are able to absorb the sugars in the milk.
When the lactase levels are insufficient, the lactose is not digested in the small intestine and reaches the colon in large amounts, part of the intestine rich in bacteria. Various bacteria from our large intestine are capable of fermenting lactose, a process that results in the production of hydrogen gas and acids. Furthermore, lactose is a highly osmotic substance which "pulls" water and minerals from the colon wall, increasing stool volume.
Lactase deficiency can be primary, that is, the individual is born with a propensity to have it; or secondary, when lactose intolerance is acquired throughout life, due to some intestinal problem.
The amount of lactase produced in the small intestine usually high during the first years of life, but it will be reducing as the diet becomes more varied, less dependent on milk and dairy products. In some ethnic groups, such as Asians, a mild to moderate lactose intolerance usually arise from 5 years old. In African Americans and Latinos, the reduction in lactase levels usually occur around 10 years. In Caucasians (whites) this reduction is often only appear after adolescence.
It is important to note that not all reduced production of lactase leads to symptoms of lactose intolerance. Often, the amount of lactase is reduced but is still sufficient not to cause a large intake of lactose into the colon. As people age, production of lactase is becoming smaller and smaller, to the point of lactose intolerance is extremely common in the older population, mainly black, Latino and Asian.
Rarely, lactose intolerance may already be present in the first months of life due to a genetic defect that makes the patient not produce any amount of lactase. The baby is intolerant to milk, which naturally tends to have more lactose than cow's milk, and needs to be fed with special formulas without lactose.
The secondary lactose intolerance is that which arises by disease or after bowel surgery. Examples of diseases that cause lactase deficiency are:
The signs and symptoms of lactose intolerance usually begin between 30 minutes to 2 hours after eating or drinking foods containing lactose.
The most common symptoms include diarrhea, abdominal cramps, bloating and a distended abdomen. In adolescents, nausea and vomiting are also common. The lactose fermentation by bacteria to produce acids, which becomes more acidic and can cause irritation feces (diaper rash) in the anal region.
The severity of symptoms of lactose intolerance varies from person to person. This variability depends on the amount of lactose present in the diet and the degree of insufficiency of enzyme lactase to the individual. Small amounts of lactose can cause severe symptoms in people with severe lactase deficiency, but only mild or no symptoms in people with mild to moderate disabilities. There are also cases of people with diets and similar levels of lactase which have different degrees of symptoms. The reason for this is not clear but may be related to the type and amount of intestinal bacteria present in each.
The symptoms of lactose intolerant are not specific and can occur in a variety of gastrointestinal diseases, primarily in acute gastroenteritis. The tip to think of lactose intolerant is the appearance of symptoms when a patient ingests food with milk or dairy products, including ice cream, yogurts, cheeses, etc.
If you feel bad after drinking a glass of milk once, not necessarily you have lactose intolerance. But if you feel bad every time you drink milk (or dairy) lactose intolerance should be suspected.
The diagnosis of lactose intolerance is usually made clinically, based on the clinical history and symptoms of the patient. Rarely are necessary laboratory tests. However, if the doctor feels the need to confirm the diagnosis with laboratory tests, two tests are the most commonly used:
1. Breath test to investigate the elimination of hydrogen
In general, we eliminate only small amounts of hydrogen into the lungs. Patients with lactose intolerance produce large amounts of hydrogen in the colon, being part of this gas reabsorbed into the blood and eliminated by the lungs through breathing. This test thus consists in hydrogen research in expired air after consumption of lactose.
2. Lactose tolerance test
After ingestion of lactose, measured blood glucose to whether there elevation of their levels. In healthy people, the lactose is broken down into glucose and galactose, being reabsorbed by the intestine and released into the bloodstream. In patients with lactase deficiency, lactose is not digested and glucose contained therein is not absorbed. Therefore, the elevation of blood glucose is only discrete in these patients.
In general, we do not need any medical treatment for lactose intolerance. The reduction in consumption of dairy products usually sufficient in most cases. Some patients tolerate cheeses and margarines and need to suspend only the milk itself.
For more serious cases, there are already on the market milk and other dairy products without lactose, which is a good solution for the patient to be sure to consume dairy products. There are products with 0% lactose and products with a reduction of 80 to 90% lactose.
Even in the most severe cases, when the patient needs to suspend the consumption of dairy products, this interruption may be only temporary. After a while without symptoms, the patient can gradually reinstate the dairy diet. The organism is able to readapt to the lack of the enzyme lactase, and if it is "used" gradually, the patient can get back to ingest milk without having severe symptoms.
There are drugs on the market to replace the lactase. The patient can take lactase (powder, pills or liquid) just before the meal, allowing for better digestion of dairy products.