Your Good Health: Lactose intolerance can be part of aging

dr_keith_roach_with_bkg.jpgDear Dr. Roach: I have seen very little written about lactose intolerance. I am a 79-year-old woman in excellent health. Over the past year or two, I experience gas, loose bowel movements and occasionally explosive diarrhea. A colonoscopy and blood tests revealed no cause.

A few months ago, I decided to monitor all dairy in my diet, and the symptoms have improved with the help of taking lactase tablets when I eat any dairy. I diligently read lists of ingredients and I’m surprised by all the foods that contain milk, such as bread.

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If I forget to take lactase, the symptoms reappear about 2 1/2 hours after eating the culprit food. Is there anything else I can take later at the onset of the symptoms to ward off the digestive distress? And is there any way to regain the missing intestinal enzyme that causes the problems to begin with?


Lactose intolerance is caused by an inability to make the enzyme lactase, which breaks down lactose (a sugar found in milk). Without this enzyme, the sugar cannot be metabolized, and is digested by intestinal bacteria, creating hydrogen gas and short-chain fatty acids, which in turn cause symptoms. The “digestive distress” you delicately mention can include abdominal pain, gas, bloating and diarrhea.

Lactose intolerance is common, and people are more likely to develop it as they get older. The amount of lactose needed to cause symptoms varies greatly between one person and another, depending on the amount of lactase enzyme they make. Those with very little have the worst symptoms. It sounds like you have a very significant loss of the enzyme.

Treatment is to reduce lactose intake, and reading labels is certainly your best bet. People with milder disease can do fine just by eliminating milk and ice cream, which have the highest amount of lactose. The lactase enzyme replacement tablets, such as Lactaid, are effective for many and allow them to consume dairy products.

Once the lactose is in your system, you are out of luck if you haven’t taken the lactase enzyme. There’s no way to get the enzyme in ahead of the lactose load to your intestines. Sadly, gene therapy to replace the enzyme is not a reality.

Dear Dr. Roach: What could precipitate a need to check an 83-year-old man’s carotid arteries for blockage? What percentage of blockage would necessitate surgery?


There are two carotid arteries, running on either side of the neck, bringing blood to the head. They provide a great deal of the blood flow to the brain, and blockages of either can lead to a stroke.

The symptoms that would make a doctor want to check for blockages in the artery are stroke and transient ischemic attack. TIA is a loss of blood and oxygen flow in the brain, leading to temporary symptoms that look very like a stroke.

If, when checked, the carotid artery has blockages on the same side that the TIA or stroke was on, then not only is medical therapy begun to reduce risk of another event, but surgery is considered as well. If the blockage is not very extensive, surgery is not any more beneficial than medical therapy, including dietary changes and exercise counseling. However, for more extensive blockages, surgery can help. Men have been proven to see a benefit when the artery is 50% to 99% blocked; with women, only those with 70% to 99% blockages benefit from surgery.

The short-term risk of dying from the surgery is significant. In large studies, the overall risk was just about 3%, although newer surgical techniques may have brought that number down a bit since those studies were published in the 1990s. Carotid surgery is not to be undertaken lightly, especially since medical therapy is much better than it used to be as well. There are newer and more powerful drugs to reduce the risk of stroke. Surgery should be considered only in someone who is pretty healthy otherwise and who is likely to live at least five more years, since the risk of dying around the time of surgery is significant.

I do not recommend screening for blockages in the carotids in people with no symptoms. It’s more important to identify people who are at risk for stroke and reduce that risk by better lifestyle and medications if needed.

Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to

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