Food Intolerances


What Is It?
Many adults and children in the United States suffer from lactose intolerance, which is either the lack of or an insufficient ability to properly digest lactose, which is a sugar found in milk and other milk products. Lactose intolerance is caused when patients do not produce enough of the enzyme lactase. If you have a lactase deficiency, you might not have the same digestive symptoms of other patients. However, you could suffer from lactose intolerance.

What Causes It?
Lactase deficiency is the cause of lactose intolerance. It begins in most patients around the age of 2 and slowly develops over time. If a child has a lactase deficiency, he or she often won’t experience symptoms until he or she becomes a bit older. There is a possible genetic cause of primary lactase deficiency.

Secondary lactase deficiency commonly occurs in infancy. It usually is caused by an injury to the small intestine. This can occur due to celiac disease, Crohn’s disease, a severe diarrheal illness, or chemotherapy.

Who’s At Risk?
More adults than children experience lactase deficiency and lactose intolerance. People of African, Hispanic, Native American, or Asian descent are usually at greater risk than those of Northern European descent. Furthermore, premature infants are also at risk for lactase deficiency, since lactase levels usually do not increase in infants until the final months of pregnancy.

What are the Symptoms?

  • Abdominal bloating and pain
  • Diarrhea
  • Gas
  • Nausea

Keep in mind that symptoms differ from patient to patient and are closely linked to how much milk the patient consumes and can tolerate.

How Is It Diagnosed?
Besides monitoring symptoms, Dr. Donepudi may also recommend one or two different tests to measure how your body is digesting lactose. These tests are the hydrogen breath test and the stool acidity test.

Hydrogen Breath Test
You will drink a lactose-loaded beverage, then we will measure the hydrogen in your breath at regular intervals. Normally, human breath contains very little hydrogen, but undigested lactose causes these levels to rise. (Make sure that you discuss foods you eat and medications you are taking with Dr. Donepudi, as these may affect the results. You also should not smoke before your appointment.)

Stool Acidity Test
Usually this test is performed on infants and small children. Since undigested lactose leaves behind fatty acids such as lactic acid as well as glucose, testing the stool for the presence of these substances can indicate lactose intolerance.

Managing Lactose Intolerance 
The best way to manage lactose intolerance is through diet. Reduce or eliminate lactose-containing foods from your diet. How much change will be necessary depends on how much lactose you can consume before you experience symptoms.

If you have lactose intolerance, the Dietary Guidelines for Americans 2005 recommend that you consume products like yogurt and hard cheese, since they have lower levels of lactose than normal milk. You can also take advantage of the many lactose-free products on grocery store shelves today, such as soy milk and yogurt with active and bacterial cultures. Please see below for a list of foods you should avoid.

In order to ensure you have enough calcium and Vitamin D in your diet, consume eggs and liver and get regular exposure to the sun (wearing appropriate sunscreen, of course).

If after making all of these changes you still experience symptoms, you can take over-the-counter lactase enzyme drops and/or tablets when consuming milk products.

If you have or take care of a child with lactose intolerance, follow the instructions provided by the child’s dietician or doctor.


It’s important for patients of all ages to receive adequate calcium, which is essential to repair and grow bones. Without enough calcium, bones may become fragile and more easily fractured. This condition is called osteoporosis. Furthermore, women who are pregnant or nursing need even more calcium than the typical women of their age group, requiring 1000-1300 mg daily.

See calcium intake recommendations by age group in Table 1 below.

Table 1. Recommended calcium intake by age group
Source: Adapted from Dietary Reference Intakes, 2004, Institute of Medicine, National Academy of Sciences.

Age Group Amount of calcium to consume daily, in milligrams (mg)
0–6 months 210 mg
7–12 months 270 mg
1–3 years 500 mg
4–8 years 800 mg
9–18 years 1,300 mg
19–50 years 1,000 mg
51–70+ years 1,200 mg

Milk and milk products are a major source of this calcium, which means that lactose-intolerant patients must find other ways to get calcium. Luckily, many non-milk products can also provide calcium, such as salmon and sardines (soft-boned fish) and dark green vegetables. See Table 2 for a list of milk and non-milk products that are good sources of calcium.

Table 2. Calcium content in common foods.

Non-milk Products Calcium Content
Rhubarb, frozen, cooked, 1 cup 348 mg
Sardines, with bone, 3 oz. 325 mg
Spinach, frozen, cooked, 1 cup 291 mg
Salmon, canned, with bone, 3 oz. 181 mg
Soy milk, unfortified, 1 cup 61 mg
Orange, 1 medium 52 mg
Broccoli, raw, 1 cup 41 mg
Pinto beans, cooked, 1/2 cup 40 mg
Lettuce greens, 1 cup 20 mg
Tuna, white, canned, 3 oz. 12 mg

Table 2. Calcium content in common foods.

Milk and Milk Products Calcium Content
Yogurt, with active and live cultures, plain, low-fat, vitamin D-fortified, 1 cup 415 mg
Milk, reduced fat, vitamin D-fortified, 1 cup 285 mg
Swiss cheese, 1 oz. 224 mg
Cottage cheese, 1/2 cup 87 mg
Ice cream, 1/2 cup 84 mg

Source: Adapted from U.S. Department of Agriculture, Agricultural Research Service. 2008. USDA National Nutrient Database for Standard Reference, Release 21.

What Foods You Should Avoid if You Have Lactose Intolerance:

  • Baked goods and bread
  • Breakfast cereals that are highly processed
  • Breakfast drinks
  • Breakfast foods that are highly processed, like doughnuts, toaster pastries, frozen pancakes and waffles, and sweet rolls
  • Candy
  • Cookies, biscuits, pancakes, waffles, and any mixes used to make them
  • Highly processed snacks like corn chips and potato chips
  • Instant potatoes and soups
  • Margarine
  • Milk-based meal replacements, liquid and powdered
  • Non-dairy powdered and liquid coffee creamers
  • Non-dairy whipped topping
  • Protein bars and powders
  • Salad dressing

Avoid Foods Labeled with the Following Ingredients: 

  • Curds
  • Dry milk solids
  • Lactose
  • Milk
  • Milk byproducts
  • Non-fat dry milk powder
  • Whey

Keep in mind, too, that some medications (birth control pills, over-the-counter medicine for stomach acid and gas) may contain lactose. Before starting a new prescription, mention your lactose intolerance to your doctor. Be sure to read the labels for any over-the-counter medication carefully before purchasing it.

Remember, if you have questions or are considering how to best manage your lactose intolerance, Dr. Donepudi is always available to help. Whether you’re still seeking a diagnosis, or you need help managing your condition, schedule an appointment today.

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