Nutrition Science and Everyday Application - beta v 0.1

Food Intolerances, Allergies, and Celiac
Disease
Food is a source of nutrients for our bodies, and as we’ve learned, the GI tract functions to
extract those nutrients from food and absorb them into the body. But sometimes, specific
foods can cause problems for the GI tract and the body, including food intolerances, food
allergies, and celiac disease. These conditions are often confused for one another, but they
have different causes, symptoms, and approaches to treatment.
FOOD INTOLERANCES
A food intolerance occurs when a person has difficulty digesting a specific food or nutrient,
causing unpleasant GI symptoms such as gas, bloating, flatulence, cramping, and diarrhea.
Food intolerances are commonly caused by the body not producing enough of a particular
digestive enzyme, so the symptoms generally involve the digestive system, and the severity
of symptoms usually correlates with how much of the food was eaten. Unlike food allergies,
the immune system does not play a role in food intolerance, and while the symptoms are
unpleasant, they are generally not dangerous and will subside once the food passes out of
the GI tract. People with food intolerances can also often consume small amounts of the
offending food without symptoms. 1
Lactose intolerance is a common food intolerance. People with lactose intolerance do not
produce enough of the enzyme lactase, which is responsible for digesting the milk sugar
lactose into single sugar molecules that can be absorbed in the small intestine. Undigested
lactose can’t be absorbed, so it continues on to the large intestine. There, it draws more
water into the large intestine, and bacteria metabolize the lactose, resulting in gas and
acid production. These conditions cause the uncomfortable symptoms of gas, bloating, and
diarrhea within about 30 minutes to two hours of consuming dairy foods.
As with most food intolerances, people with lactose intolerance can often consume some
amount of lactose without discomfort, although this varies from person to person. Aged
hard cheese, buttermilk, and yogurt (as long as it doesn’t include added milk solids) are
often well-tolerated because they are low in lactose, which is consumed by bacteria during
fermentation and aging. In addition, lactose-free milk and lactase enzyme supplements are
available. Dairy products are some of the main dietary sources of calcium and vitamin D, so
people who avoid dairy need to take special care to include other sources of these nutrients
in their diets. 2 161