Lactose & Other Sugar Intolerance

Lactose, fructose and sucrose intolerance is the body’s inability to absorb these basic sugars. Of these three, the most common is lactose intolerance.

Causes of Lactose Intolerance

Lactose intolerance is caused by deficiency in the enzyme lactase. This enzyme is produced by the lining of the small intestine, and is responsible in breaking down sugars into absorbable forms.

Without the enzyme, bacteria that normally live in the digestive tract ferment them into gasses that can cause uncomfortable symptoms.

Symptoms of Lactose Intolerance

The symptoms of lactose intolerance include:

  • Diarrhea
  • Bloating
  • Flatulence
  • Excess gas or burping

These symptoms usually appear 2 to 6 hours after consuming lactose-containing food or drink.

What Foods Have These Sugars?

Fructose is commonly found in:

  • Fruits, such as grapes, apples, and pears
  • Fruit juices
  • Honey
  • Nuts and figs
  • Soft drinks

Sucrose is found in:

  • Table sugar
  • Fruits
  • Sugar cane

Lactose is found in:

  • Milk
  • Dairy products

Some foods also contain small amounts of lactose that are “hidden”, i.e. not listed in their list of ingredients. These include:

  • Breads
  • Cereals
  • Cookies and biscuits
  • Prepared foods, such as instant soups and mashed potatoes
  • Coffee creamers

Diagnosis of Lactose Intolerance

The following tests are often used to diagnose lactose intolerance:

  • Hydrogen breath test
    Hydrogen is not normally present in the breath. In people with lactose intolerance, however, bacteria in the digestive tract convert the undigested sugars into various gasses, including hydrogen. This gas is absorbed into the bloodstream, circulated to the lungs, and exhaled.

  • Lactose tolerance blood test
    Blood glucose level is taken before and after lactose consumption.

    In normal people, lactose is broken down and converted into glucose (and another sugar called galactose). This causes the blood glucose level to rise.

    In lactose intolerant people, however, since lactose is not broken down, the blood glucose level does not change.

  • Stool acidity test
    This test is usually done to diagnose lactose intolerance in infants and young children. In cases of lactose intolerance, the sugar is fermented by bacteria in the colon into lactic acid, which is measurable in stool.

Who Gets It?

Lactose intolerance is actually very common – approximately 50 million people in the United States have it. This condition is more prevalent in people of the following ethnicities:

  • Asians (about 90% of Asian adults are lactose intolerant!)
  • African Americans
  • Jewish
  • Native Americans
  • Hispanics

This condition usually develops over years or decades – however, some children are born with congenital lactose intolerance.

Temporary lactose intolerance is common after a stomach infection, food poisoning, and after taking antibiotics.

Treatment for Sugar Intolerance?

If you are lactose intolerant, take lactase enzyme supplement before consuming milk or lactose-containing food (remember that many foods contain small yet “hidden” amounts of lactase). You can also substitute regular milk for lactose-free or soy milk.

If you are fructose or sucrose intolerant, the only thing that works is avoiding foods that contain these sugars.

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