DEAR DR. ROACH: My nephew has foot odor. Even after showering, his feet have a bad odor. His shoes smell bad and have to be replaced often. What is the remedy for this problem?

— B.C.

ANSWER: Foot odor is caused mostly by bacteria living on your feet. Bacteria thrive in warm and moist environments, so people who sweat a lot from their feet are at high risk. Some people are also colonized with particularly bad bacteria, such as Kytococcus (formerly Micrococcus), Corynebacterium or Dermatophilus. These bacteria do not cause disease, but they break down dead skin cells into unpleasantly smelly chemicals. A careful look at the skin on his feet may reveal small pits in the skin, especially around the heel, after a long day in socks and shoes.

Treatment may include disinfecting skin solutions (such as chlorhexidine), antibiotics (topical erythromycin or clindamycin), and keeping the feet as dry as possible. This may require application of antiperspirants to the feet, either regular over-the-counter or prescription varieties. He also should wear lighter, more breathable footwear. Washing (and then drying) the feet several times daily and putting on new socks each time may also help during the treatment phase.

Although ultraviolet-light shoe sanitizers exist, I’d recommend getting new footwear while trying to get rid of as much of the bacteria as possible.

DEAR DR. ROACH: At 75, I had my first ever kidney stone in December. The urologist told me to stop drinking so much milk. But he never asked if my diet had changed. I had been eating almonds by the handful every day. I felt certain this was the cause of the stone.

I drink skim milk, which is practically tasteless. I started adding a slight bit of almond milk to the skim to give it a more pleasant taste. Should I not be doing this?

— P.T.

ANSWER: I am not certain why the urologist told you to stop drinking cow’s milk. We used to believe that the calcium in milk increased risk for kidney stones, especially calcium oxalate stones, which are the most common type; however, dietary calcium paradoxically decreases risk of kidney stones, whereas calcium supplements increase risk of stones. What makes the biggest difference in diet is the oxalate content. Almonds, as well as almond milk, are very high in oxalate; cow’s milk is not. I don’t know what you mean by a “slight bit” of almond milk, but I would try to avoid taking too much (more than a few teaspoons a day), and find another way to flavor the milk if you really don’t like it. I know a few people who add a drop of vanilla. Coconut milk — which I don’t recommend consuming in large quantities due to the saturated fat content — does not have oxalate.

Essentially, everybody with kidney stones should drink plenty of water, and nearly everyone should be very careful not to have too much sodium.

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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 ToYourGoodHealth@med.cornell.edu or send mail to 628 Virginia Dr., Orlando, FL 32803.