Lactose Intolerance Test: The New DNA Way To Detect Lactose Intolerance

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Lactose Intolerance Test

Lactose intolerance test is used to measure how well your body processes lactose, a sugar present in dairy products. The body processes milk and other dairy products using lactase, an enzyme in the intestines that breaks lactose down during digestion.

Some people, however, have lower levels of lactase , which leads to their inability to break down lactose and its persistence in the intestines. The lactose then gets fermented and leads to abdominal discomfort. This inability to break down lactose is known as lactose intolerance.


Everyone drinks milk during childhood, yet why does it cause intolerance only among some during adulthood?

Most humans have the ability to break down lactose , the major carbohydrate found in milk and one of the important sources of nutrition among infants till weaning. Studies have shown that nearly 75% of children, between the ages of 2 to 12 years lose this ability to produce lactase as they grow into adulthood.


Lactose Intolerance and Lactase Persistence

The disaccharide lactose is abundantly present in mammalian milk and is an essential source of  nourishment for newborns. This sugar is hydrolyzed by lactase, the intestinal brush-border enzyme into glucose and galactose. Intestinal lactase activity is maximum during the perinatal period in most infants.; However, as children grow into adulthood, there are two groups that emerge-

  1. lactose intolerant or lactase non persistence
  2. lactose tolerant or lactase persistent.


Why should you opt for Lactose Intolerance Test?

  1. Identifying asymptomatic cases: Lowered lactase activity is found to be associated with primary maldigestion of lactose, which in most cases is unnoticed or asymptomatic. When symptoms begin to show, lactose intolerance is diagnosed. A lactose intolerance test will help in identifying the presence of this condition, even if symptoms have not become apparent.
  2. Distinguishing from other associated conditions: It is important to distinguish between lactose intolerance and other reasons behind abdominal discomfort, like gluten intolerance, Crohn’s disease or infectious enteritis. A lactose intolerance test will determine the presence or absence of this condition, removing ambiguity.

Non Genetic Lactose Intolerance tests and Drawbacks

There are other lactose intolerance tests that are available.

    • Lactase Activity from Jejunal Sample: A glucose oxidase reagent is used to detects glucose released from lactose.  Since a jejunal biopsy is invasive, it has been replaced with an endoscopic duodenal biopsy
      Since intestinal biopsies are invasive, other lactose intolerance tests were developed to determine the ability of intestinal lactase to hydrolyze and absorb lactose
    • Blood Glucose levels: An oral load of lactose is administered at specific time intervals and blood glucose levels were measured. The presence of a maximum of  20 mg/dL is indicative of lactose tolerance. An oral administration of ethanol is also carried out before lactose load to inhibit galactose metabolism, this is to determine maximum rise of glucose (at least 20 mg/dl) and galactose (at least 10 mg/dl), indicating lactose tolerance. The concentration of glucose and galactose in combination will help in improving the correlation with jejunal lactase. This test involves the ingestion of lactose with resultant symptoms produced.
    • Breath hydrogen test: This was considered the most popular test for population screening. 50g of lactose is provided (about 4 to 5 cups of milk) This lactose intolerance test is based on fermentation of undigested lactose by intestinal flora, which results in the production of hydrogen, carbon dioxide and methane that are absorbed and eliminated by the lungs. These gases lead to symptoms of lactose intolerance like flatulence, abdominal pain, diarrhea and bloating.  

Though this test is used, the reliability depends on the bacterial flora present. The use of antibiotics are known to lead to false negative results. Other reasons for false negative results include acidic colonic pH that could inhibit the growth of bacteria or an adaptation in the bacterial flora due to constant exposure to lactose.


Genetic testing as a lactose intolerance test

The drawbacks faced in the other lactose intolerance tests are not present in genetic testing as

  1. There is no need for ingestion of lactose.
  2. The test is non invasive
  3. The test can be used to determine the presence or absence of lactose intolerance
  4. It will not give rise to false negative results


Genetic variation behind lactose intolerance

Humans are the only mammals who continue to drink milk into adulthood. As with all mammals, there is a decrease in production of lactase in humans post weaning.However,  among populations that carried out intensive dairy farming, genetic variations that were protective developed approximately 7,500 years ago. This ensured that there was lifelong lactase persistence among people who carried these variations, but not everyone has such a genetic variant required for lifelong dairy digestion.  Such people have lowered lactase production that affects their ability to tolerate lactose.

Studies state that the genetic variation associated with lactase persistence originated in Europe, to adapt to the lifelong consumption of lactose. The variation is found in the gene MCM6 at the position -13910, where a cytosine (C = lower lactase production) is changed for a thymidine (T =continued lactase production).

A gene based lactose intolerance test will help in identifying if this protective gene variant for lactase persistence is present or whether there is a predisposition to primary adult lactose intolerance.


Treatment for people with lactose intolerance

A genetic lactose intolerance test will help in identifying the condition and such people can reduce their signs and symptoms by restricting consumption of dairy products.

It is important to note that most people depend on dairy products for calcium. Below are a few dietary sources of calcium.

  • Spinach
  • Canned salmon
  • Broccoli
  • Pinto beans
  • Breads and juices fortified with calcium
  • Soy milk, almond milk and rice milk
  • Oranges
  • Rhubarb

A genetic lactose intolerance test is non invasive, can be taken at any time of the day and can be used to identify lactose intolerance without the need to ingest excess amount of lactose for testing. 

Want to know if you are lactose intolerant? Grab your Nutrigenomics report now!

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