But when he started second grade, he became agitated, impatient and fought with other students. Tantrums became a daily burden at home and school. At home the tantrums usually built up around bedtime or later when he woke up restless and irritated.

Had he been assigned to a bad teacher? Did something happen at home?

I knew Jeff's mother well. She was a steady, dedicated and loving Mom. Because of the surprising change in Jeff's character, I asked her to keep a record of what Jeff ate and when disruptions happened. She took it as a challenge to note every scrap and snack that he had. In six weeks her records showed a peculiar but common event: every time Jeff had pizza, his behavior got worse.

So we started the pizza experiment. No pizza for two weeks and the frequency of his tantrums went down a little, but his troubles at school and home continued. There was no dramatic result until Jeff's Mom declared all tomato products off limits. That's not an easy task when you think about all the sources - catsup, salads, pizzas, spaghetti, casseroles, and the list goes on. Jeff had an allergy.

Without tomatoes, Jeff's old self started coming back but every time he slipped up (one time we discovered the salad dressing had tomato in it), the irritations returned. To protect Jeff (and everyone else), the whole family went off tomatoes.

Where do such allergies come from? It's a mystery how we get these sensitivities, but our expanding diet certainly helps us find them. Oranges from Florida are not just a Christmas treat any more, and milk no longer comes from a farm in your county. You can't even be sure your food comes from this hemisphere. The more you take in, the more likely you are to take in something that disagrees with you.

A report by Cynthia Ogden, an epidemiologist at the National Center for Health Statistics shows that the average American adult is about an inch taller than he or she was in 1960, but more important, she says males are 25 pounds heavier - now averaging 191 pounds. Females are 14 pounds heavier, averaging 164 pounds. The average 10-year-old, girl or boy, weighed 77 pounds in 1963; now 10-year-olds are up 11 pounds to 88.

All that extra food, 500 more calories per day than in the 1950's, has about 7,000 new food additives, many not approved in that old century.

Northern Europeans are now two inches taller than Americans, said Richard Steckel of Ohio State University, but they haven't gained the fat that we Americans have and only about 70 of our 7,000 food additives are legal over there. That may be to blame for our expanding allergies, We also tend to eat greater quantities of junk food, Steckel said.

Jeff, by the way, grew up to be an emergency room physician. He is still his easy-going self, and he's still off tomatoes.