Lactose Intolerance




Introduction

Lactose intolerance, also called lactase deficiency, means you aren't able to fully digest milk sugar (lactose) in dairy products. It's not usually dangerous, but symptoms of lactose intolerance can be uncomfortable enough to steer you clear of the dairy aisles. Lactose intolerance can make dining a challenge, requiring some recipe substitutions or avoidance of some foods altogether.

The problem underlying lactose intolerance is a lack of lactase — an enzyme produced by the lining of your small intestine. Lactase breaks down lactose so that it can be absorbed into your bloodstream. A deficiency of lactase leads to problems in breaking down and absorbing milk sugar.

Some people who think they are lactose intolerance actually don't have impaired lactose digestion. And not everyone with low levels of lactase is lactose intolerant. Only people with low lactase levels and symptoms are considered to have lactose intolerance.

Intolerance to a food isn't the same as a food allergy. Lactose intolerance doesn't involve your immune system, as an allergy does, and doesn't necessarily require complete avoidance of milk products. You can control symptoms of lactose intolerance through a carefully chosen diet that limits lactose without cutting out calcium, and possibly by taking supplements.

Signs and symptoms

The signs and symptoms of lactose intolerance usually begin 30 minutes to two hours after eating or drinking foods that contain lactose. Common signs and symptoms include:
  • Diarrhea, which is the most common symptom
  • Nausea
  • Abdominal cramps
  • Bloating
  • Gas
Symptoms are usually mild but may sometimes be severe. The severity of symptoms doesn't correlate with the degree of lactose malabsorption. Instead, symptoms relate to a range of factors, including ethnicity, age and how fast you digest food.

Lactose intolerance isn't easily diagnosed by signs and symptoms alone. Many other conditions, including stomach flu and irritable bowel syndrome, can give you similar symptoms. In young children, diarrhea along with certain other symptoms may be a sign of milk protein allergy.



Causes

The cells that line your small intestine produce an enzyme called lactase. Lactase breaks down lactose into two simple sugars — glucose and galactose — which can be absorbed into your bloodstream. Without lactase, the unprocessed lactose moves on to the colon, where the normal intestinal bacteria contend with it. This causes the symptoms of lactose intolerance— gas, bloating and diarrhea.

There are three types of lactose intolerance:
  • Primary lactose intolerance. Normally, your body produces large amounts of lactase at birth and in early childhood, when milk is the primary source of nutrition. Usually your lactase production decreases as your diet becomes more varied and less reliant on milk. This gradual decline may cause symptoms of lactose intolerance.
  • Secondary lactose intolerance. This form of lactose intolerance occurs when your small intestine decreases lactase production after an illness, surgery or injury to your small intestine. It can occur as a result of intestinal diseases such as celiac disease, gastroenteritis or an inflammatory bowel disease, especially Crohn's disease. This type of lactose intolerance may last only a few weeks and be completely reversible. However, if it's caused by a long-term illness, it may be permanent.
  • Congenital lactose intolerance. It's possible for babies to be born with lactose intolerance. This rare disorder is passed from generation to generation in a pattern of inheritance called autosomal recessive. This means that both the mother and the father must pass on the defective form of the gene for a child to be affected. Infants with congenital lactose intolerance are intolerant of the lactose in their mothers' breast milk and have diarrhea from birth. These babies require lactose-free infant formulas.
Risk factors

A few risk factors can make you or your child more prone to lactose intolerance:
  • Age. Lactose intolerance usually starts in adolescence and early adulthood. However, the condition is uncommon in babies and young children. A child with chronic diarrhea before age 1 usually has another underlying problem.
  • Ethnicity. Lactose intolerance is more common in certain ethnic and racial populations. Lactose intolerance is more common in black, Asian, Hispanic and Native American populations.
  • Premature birth. Infants born prematurely (28 to 32 weeks of gestation) may have reduced levels of lactase, because this enzyme increases in the fetus late in the third trimester


Informations obtained from National Institute of Health.
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