The first step is a nutritious diet, which decreases consumption of foods made with added fat and sugar. The National Cancer Institute reports that only one per cent of U.S. children consume a well-balanced diet and only about a third meet the government's food-pyramid targets for fruits, vegetables, grains, meat and dairy. Most surveys over-estimate vegetable intake because they classify french fries and potato chips as vegetables, accounting for about a fourth of alleged vegetable consumption among children. Previous studies from the U.S., Britain and Australia have shown that the eating of fish and tomatoes and the intake of minerals like magnesium and selenium are inversely related to the risk of developing asthma.

Detailed guidelines for feeding children in every age group, along with recipes, are supplied in my first book, Superimmunity for Kids. Recommendations for nutritional supplementation are listed below.

The second step is provision of a hygienic home environment. The three most important areas to control are smoke, dust and humidity. Children exposed to cigarette smoke at home have a higher frequency of asthma, respiratory infection and otitis. House dust can contains surprisingly high levels of lead and toxic waste, tracked in and concentrated from roadside soil, accumulating for years despite routine vacuum cleaning, sometimes exceeding concentrations found at superfund sites. House dust is especially hazardous to toddlers crawling on carpets, because carpet pile is a repository for dust. Excess moisture in the home (a relative humidity of fifty-five per cent or more) encourages the growth of dust mites and of mold. Mites secrete an enzyme which damages the lining of the respiratory tract; children with a high mite exposure are at increased risk for developing asthma. Children who live in homes with visible mildew or moisture are at increased risk for developing repiratory illness and for missing days from school. I describe nine simple steps for parents to take to ensure an environmentally safe home in previous issues of this column.

The third area is regularity of rest and exercise. Exercise of moderate intensity, such as brisk walking or cycling, thirty minutes a day, improves immune function and mood and prevents migraine headache. Most older children, high school students especially, are sleep-de-prived. Sleep deprivation or interrruption reduces natural killer cell activity. Parents should help their children plan schedules that permit eight to ten hours of sleep a night. Daytime relaxation also has important health benefits. A period of quiet, focused relaxation each day relieves anxiety, improves nighttime sleep, and stimulates immune function of stressed individuals.

Nutritional supplements and herbs can make a substantial contribution to childhood health. Omega-three essential fatty acids, found in fish oils and flax oil, are essential for normal immune regulation and brain function. The past century has witnessed a dramatic decline in omega-three consumption, due to changes in food processing, food choices and animal husbandry practices. Cod liver oil, which can be a rich source of omega-three's, has long been used as a food supplement for children. A recent double-blind placebo-controlled study found that capsules of flax oil, two grams per day, decreased frequency, severity and duration of illness and days missed from school among children suffering from recurrent respiratory infection. I frequently recommend flax oil as a preventive supplement for children and adolescents at a dose to two to six grams per day.