Dear Doc,
As I have gotten older, milk products upset my stomach and cause more gas. After eating dairy, it seems like I am blaming that smell on our dog a lot more frequently! Could I be developing lactose intolerance ?

Doc,
Lactose is the sugar in milk. Normally, lactose is broken down in the GI tract by the enzyme lactase. If the lactase enzyme is deficient, lactose makes it way to the large intestine undigested. The lactose is used by normal occurring bacteria in the colon for its own consumption. As the bacteria utilize lactose, they produce hydrogen gas as a byproduct. Some of the excess hydrogen results in abdominal bloating, diarrhea and flatulence (passing gas).
Lactose intolerant or not, the average person, male or female, passes gas about 14 times per day creating about 0.5 liters of gas / day. Only 1% of the gas passed (due to a sulphur component) has a foul odor and yes, due to the flammable compounds hydrogen and methane in flatulence, the gas can be flammable. (Please do not try to light your gas on fire, as injuries have been documented due to such behaviors!)

Someone is said to be lactose intolerant if they cannot fully digest the lactose in dairy and this results in GI distress. About 40 million Americans are considered to be lactose intolerant. Over 60% of adults world wide experience symptoms due to lactose intolerance. Adult rates vary widely based on race. Those of Northern European decent may have a rate of only 10%, Hispanics 50%, African Americans 70%, and some populations of Eastern Asia may have prevalence as high as 90%.

There are three forms of lactose intolerance. Primary lactose intolerance is the normal result of aging for some and the most common form of lactose intolerance. It sounds like this is the case for you! Secondary lactose intolerance results from a disease of the GI tract resulting in less lactase production (an example of this is celiac sprue disease). Finally, congenital lactase deficiency (very rare) is a result of being born with lack of the lactase enzyme.

If it is suspected you have lactose intolerance your doctor may order a lactose free diet for a few weeks and then slowly re introduce milk products to see if the symptoms stop and recur. If it is not clear after adjusting your diet there are more formal tests. A lactose tolerance test measures blood sugars after ingesting lactose. If you have abnormal sugar readings after ingesting lactose you may be diagnosed with lactose intolerance. A hydrogen breath test may measure a high level of hydrogen in your breath after ingestion of lactose, indicating lactose intolerance. If a GI disease is suspected you may be referred to a GI specialist for biopsies of your small intestine.

Most people with lactose intolerance do not have to give up dairy products completely, but avoiding those foods that cause the most symptoms is recommended. Reading food labels is crucial to avoid foods with lactose. Words on labels like whey, curds, and milk by-products indicate the presence of lactose. Other foods that may include lactose include bread, baked goods, processed foods, and protein drinks. Taking over the counter lactase enzymes tablets can lessen the symptoms that come with eating dairy products. These tablets help break down the lactose in the food that your body cannot. Probiotics found in yogurt may also be effective in helping your body digest lactose.

Avoiding dairy products may put you at risk for becoming protein and calcium deficient. So, consume other sources of protein and consider vitamins with calcium and vitamin D.

Stay healthy, modify your diet, and stop blaming the dog! Also, remember the quote by Jeff Foxworthy, “You might be a redneck if... the blue book value of your truck goes up and down depending on how much gas it has in it.”

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