Understanding your Results – LI

Lactose intolerance is the inability to absorb sufficient amounts of the milk sugar lactose. If you don’t absorb sufficient amounts of lactose, it passes into your large intestine (colon) and may cause diarrhea, flatulence (gas) and abdominal pain.

Gut-chek for lactose intolerance checks how much of the lactose is not absorbed in your small intestine but passes through into your colon. Bacteria in your colon exposed to lactose forms hydrogen and methane gas. We detect hydrogen and methane gas in the breath that forms originally in your colon.

Gut-chek for lactose intolerance consists of four breath collections. One collection is before we give you 25 grams lactose. We measure hydrogen, methane and carbon dioxide gas in all four tubes by gas chromatography.

The carbon dioxide gas level allows us to check if (a) the breath sample is valid and (b) normalizes the results in case the breath collection is not perfect.

We compare the hydrogen and methane levels in the 1-, 2- and 3-hour breath samples to the baseline (0 minute) sample. If any of the post-lactose samples contain 20 parts per million (ppm) hydrogen and methane gas above the baseline sample, you have an intolerance to lactose.

What if I have a Positive Lactose Intolerance Breath Test?

Limit the amount of milk and milk products in your diet

If your hydrogen breath test indicates lactose intolerance, it would be best to avoid foods that are high in lactose. The most common high-lactose foods include:

Milk and milk containing beverages

Ice cream

Soft and processed cheeses

Puddings and custards

Cream soups and cream sauces

Lactose is also hidden in many foods such as:

Baked goods

Milk chocolate

Salad dressings and sauces

Instant oatmeal and cereal bars

Instant mashed potatoes, soups, rice and noodle mixes

Lunch meats


Pancake, biscuits and cookie mixes

A more complete list of lactose containing foods is available in our Learning Center.

If you are unsure if a food item contains enough lactose to cause a problem, try a small amount and wait to see how you feel. If you don’t feel any gastric distress after a few hours, you can consume small amounts of this food.

Ingest foods containing lactase

LACTAID® milk and dairy products are lactose free and easy to digest by people who are lactose intolerant. Click for more information about LACTAID®.

Spread lactose intake throughout the day

If you can stand some lactose in your diet, try to spread lactose foods throughout the day rather than ingest in one meal. Lactose intolerance is an individual condition. What works best for some may not work for you. Try to reduce the intake of lactose foods. For example, if you drink an 8 ounce glass of milk with a meal, reduce it to 4 ounces.

Take lactase supplements

Tablets of lactase enzyme supplements are available at most pharmacies. Follow the package directions and take these supplements when you eat or drink lactose-containing foods.

Pick foods that have reduced lactose content

Many manufacturers have created alternative products with low or no lactose. For example, you can purchase yogurt with no lactose, soy milk, and many cheeses. Use non-diary creamers in coffee. Hard cheeses have little or no lactose.

Try adaptation and probiotics

One method that may work to increase your ability to tolerate lactose is to slowly increase your lactose in your diet weekly. As you increase your total daily amount of lactose, bacteria in the colon can adapt to digesting larger loads of lactose. Let your pain be your guide to how much lactose to increase weekly. Some people find that intake of a high-quality probiotics supplement may seed the colon with bacteria that are beneficial to lactose digestion.

Eat yogurt with live cultures

Yogurts with live cultures (not pasteurized) do not cause gastric distress for many people with lactose intolerance.

Increase your calcium intake

If you do need to reduce your amount of milk and dairy in your diet, be sure to increase your calcium intake in other ways. For example, high amounts of calcium can be found in:

  • Vegetables: broccoli, kale, collards, turnip greens, and okra
  • Fish: tuna and salmon
  • Calcium fortified drinks: orange juice and soy milk
  • Other foods: tofu and almonds

What if I have a Negative Lactose Intolerance Breath Test?

If you have abdominal pain, bloating, flatulence or diarrhea when you eat milk and dairy products but received a negative lactose intolerance breath test, there may be several reasons for this result.


You may not have lactose intolerance but have an allergy to milk or dairy protein. The problem is a reaction to the proteins casein or whey. A simple test is to purchase pure whey protein. Mix the protein with water and drink a recommended serving size. If your symptoms occur, it is a good chance you are allergic to dairy proteins. In which case, a dairy-free diet will reduce your symptoms.


Your symptoms could also indicate that you have bacterial overgrowth. Consider taking the Gut-chek small intestinal bacterial overgrowth test.


5-10% of people do not produce hydrogen and methane gas. The bacteria in your intestine do not digest lactose to hydrogen or methane. The test will not be able to confirm lactose intolerance. Try reducing milk and dairy from your diet and see if your symptoms are reduced.