Q: Are pecans heart-healthy? I understand that nuts are good for you, but people mostly mention almonds and walnuts. I live in Texas, where pecans are by far the most common nut, and they are also my favorite. Pecans are seldom included in the lists of heart-healthy nuts, which makes me wonder if they are less healthy than the nuts included in the lists.

A: You’ll be happy to learn that pecans, like other tree nuts, are beneficial (Nutrition Journal, June 28, 2015). Scientists analyzed data from more than 14,000 Americans and found that people who ate at least a quarter-ounce of almonds, Brazil nuts, cashews, hazelnuts, macadamias, pecans, pine nuts, pistachios or walnuts daily were leaner, had lower blood pressure, less insulin resistance and higher HDL (good) cholesterol.

An experiment in 26 overweight people ran for 12 weeks and compared a diet in which 15% of calories came from pecans with a control diet similar to what Americans usually eat (Nutrients, March 11, 2018). Both regimens had the same amount of calories, fats and fiber. After a month of a pecan-rich diet, these individuals had lower insulin resistance and less insulin in their blood.

The scientists concluded, “Pecan consumption lowered the risk of cardiometabolic disease as indicated by a composite score reflecting a significant change in clinically relevant markers, i.e., blood lipids and glucoregulation.” So you can keep enjoying pecans with a clear conscience.

Q: I’ve heard that sun exposure might be better than pills for getting vitamin D. How much time do you need in the sun without sunscreen to get a good dose?

A: A lot depends on geography, time of year, time of day and the shade of your skin. Someone with fair skin can get adequate vitamin D from about three weekly sessions of 15 to 20 minutes in the summertime. If you were in a northern locale, you might need twice that. People with darker skin need more time in the sun to make the same amount of vitamin D.

Q: I recently read about a 60-year-old man having problems after a colonoscopy. I had similar trouble with alternating diarrhea and constipation, as well as a lot of pain that the doctor called irritable bowel syndrome. I believe the suggested remedy was narcotics, in which I had no interest.

I put up with the pain and mess for about five years. Then I got a cut on my arm while I was working on a construction site. It became infected, and the doctor gave me a broad-spectrum antibiotic. The day I took the last dose of the antibiotic, my bowel problems cleared up and did not return. Apparently, I had picked up a stubborn infection from the colonoscope.

A: Your story is fascinating. Colonoscopes can sometimes be contaminated (American Journal of Infection Control, August 2015). Another possibility is that the “cleansing” of the digestive tract in preparation for the colonoscopy disrupted the balance of microbes in your digestive tract (European Journal of Gastroenterology & Hepatology, May 2016).

Q: I had canker sores for years until I discovered Biotene toothpaste. It is formulated especially for people with dry mouth and does not contain sodium lauryl sulfate. My gums are healthier, and I’ve had no cavities since it contains fluoride. It is more expensive, but it’s worth it.

A: We have heard from many readers that the foaming agent SLS (sodium lauryl sulfate) can be irritating to their mouths and gums.

In their column, Joe and Teresa Graedon answer letters from readers. Send questions to them via www.peoplespharmacy.com.