Gary A. Emmett, M.D., is director of hospital pediatrics at Thomas Jefferson University Hospital. He wrote this for the kids health blog on Philly.com and Inquirer.com.

As you've probably noticed, peanut allergies appear to be increasing in the United States, but not in other countries. We do not know the reason yet, but there are a number of proposed theories.

Once you have a peanut allergy, it can be very serious, causing any allergic symptom from a mild itchy rash to complete lung closure and death.

There was a flurry of news stories over the summer about a 13-year-old at a California summer camp who died - despite being given epinephrine - from eating a Rice Krispies treat she did not know contained peanuts.

Our synagogue school has banned any product that does not state it was made in a factory without peanuts. Some parents are frightened by nuts around their children.

If your child isn't allergic to nuts, a recent study in the New England Journal of Medicine suggests you should incorporate them into your family's diet.

The study found consumption of peanuts and tree nuts was strongly associated with decreased mortality from all causes in a large group of medical professionals (about 120,000) followed in detail for almost 30 years.

This was a strong study because it can state other variables that may be associated with eating nuts (such as getting more exercise or smoking less or eating a healthier diet) was not different among the groups.

The only difference was people who ate nuts lived longer. Also, the more days per week you eat nuts, the more you reduce your chance of dying at any given age.

This wasn't a small difference, either. If you eat peanuts and/or tree nuts daily, you increase your chance of not dying at any given age by 20 percent of any cause.

Your chance of having a heart attack goes down, but so does your chance of having cancer. Why? We do not know, but this work should be taken seriously because it was a large and well-done study.

We in pediatrics are not big on peanuts or tree nuts for very young children because of allergic reactions and because peanuts are a major cause of aspirating a foreign body into the lungs.

But as children get older, encouraging them to eat more nuts could be good.

Penny M. Kris-Etherton, a professor of nutrition at Pennsylvania State University who has studied the effects of nuts on heart disease, described them as "complex plant foods that are not only rich sources of unsaturated fat, but also contain several nonfat constituents," including protein, fiber, plant sterols that can lower cholesterol, and micronutrients like copper and magnesium.

A recent New York Times column cited Kris-Etherton and other evidence that shows eating nuts is associated with a reduced risk of major chronic diseases, including heart and blood vessel disorders and Type 2 diabetes.

This latest study shows we could prevent thousands and thousands of early adult deaths every year by eating a load of nuts every day.

Should we allow nuts in public places, and encourage or discourage eating them?

I really do not know, but the numbers are fascinating to me as I sit here at age 63 eating peanut butter on a cracker.