By KEITH ROACH, M.D.

DEAR DR. ROACH: I have seen numerous articles extolling the advantages of eating nuts because they are a good fat. I often have wondered if it matters whether the nuts are raw or roasted. Would you please explain the difference and the impact on one’s health? — D.O.

ANSWER: Scientists believe that nuts are healthy for us based on three different types of evidence. One is called “epidemiological”: People who eat nuts live longer and have less heart disease than people who don’t eat nuts. This suggests nuts are good for you, but it’s not definitive. People who eat nuts may do other healthy things, which could be the real reason they live longer (this is called “confounding”).

A second line of evidence comes from watching what happens to factors that we believe are related to disease. People who add a reasonable amount of nuts to their diet often have improvements in their cholesterol levels. They also help some people lose a few pounds, possibly because the fat and protein in nuts makes them more filling than the (often processed) starches many people eat. This is also not definitive, because there are treatments that lower cholesterol but don’t make people live longer or improve health.

The third is evidence from a large, interventional study on diet. A group of people were randomly assigned to either add more nuts to their diet, or to make no change (or some other change) in their diet. At least one study showed that when people changed their diet to include more nuts and seeds (but also more fruits and vegetables, more healthy oils, like olive oil, and less meat), they had less heart attacks than the group that did not change their diet. This evidence is strong, but it’s not clear whether it’s one change in the diet (just nuts) or all the changes in the diet that are responsible for the observed benefit.

In none of these kinds of studies were raw nuts compared against roasted. However, the composition of the fats does not change in nuts and seeds when roasted, and most experts believe it does not make a difference. So, I recommend partaking in nuts however you like them best.

Just one serving a day (30 grams or an ounce) makes a difference. They are quite high in calories, so it’s wise not to overdo it. If you don’t like nuts (and obviously for those allergic), not eating them is not a major risk for developing heart disease.

DR. ROACH WRITES: A recent column on burning mouth syndrome generated a lot of letters, including several from physicians and dentists. The advice I heard over and over is that some dental products seem to worsen the symptoms, and changing toothpaste or dental rinse can help with symptoms. However, the culprit was not consistent. Some writers told me it was mint, others said cinnamon, while others thought it was the sodium lauryl sulfate that is in many toothpastes. Baking soda (or toothpastes based on them) seemed to be well-tolerated for many.

Some other irritants that made symptoms worse included spicy foods, carbonated beverages, caffeine and acidic foods (like citrus or tomato).

Other advice I heard was soaking the tongue in a solution of Splenda and water; others recommended biotin supplements. The sheer number of letters I received leads me to suspect that this is a more common problem than I would have thought. Very few of my own patients have ever asked me about this in my practice.