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The Anti-Asthma Diet

child eating fruit salad

Every weekday for the last 10 years, professor Shane Broughton, Ph.D., has scurried around his lab at the University of Wyoming in Laramie looking for clues to help fight childhood asthma -- a disease that has reached epidemic proportions right under his nose.

For his long hours of work, Dr. Broughton has amassed five filing cabinets packed with data and collected hundreds of cell cultures for analysis. His research has benefited his wife, an asthmatic whose attacks have decreased dramatically, and his 16-year-old daughter, who has remained asthma-free. But unlike most researchers who study asthma, Dr. Broughton isn't focused on dust mites, pollen, or pollution. "Many people believe contaminants are to blame for the drastic increase in asthma rates, but my studies suggest it has much more to do with what we're feeding children," he says. "Diet is key."

The notion that potato chips may be more problematic than pollution, desserts more devilish than dust mites, seems suspect until you realize that Dr. Broughton isn't the only researcher who attributes escalating asthma rates at least in part to dismal diets. In the United Kingdom, Ireland, New Zealand, and Australia -- countries where asthma now affects 30% of kids and is still climbing -- the link between the disease and diet has been studied by leading scientists for more than a decade. "Our research suggests that it's a combination of dietary factors, rather than a single nutrient or food, that protects children from asthma or puts them at increased risk," says Anthony Seaton, M.D., a professor of environmental medicine at Aberdeen University Medical School in Scotland.

Although the research is still preliminary, scientists worldwide gave Child five healthy eating principles that may help reduce asthma symptoms or avoid the disease entirely. They're intended to be an addition to -- not a substitute for -- the advice or treatment from your child's pediatrician. And there's a bonus: The same nutrition suggestions also protect your child against obesity, high cholesterol, and type 2 diabetes, which can crop up in adolescence or even earlier. Take a deep breath -- and dig in.

Several years ago, Dr. Seaton traveled with his colleagues to Saudi Arabia to compare asthma and allergy rates of city-dwelling kids -- who tend to eat a produce-poor American-style diet -- and rural children of similar heritage who continue to follow the traditional Arab diet, which is rich in fruits and vegetables.

The upshot: Even after controlling for pollution and other major risk factors, asthma was three times more prevalent in city kids. "You can't blame diet for the entire increase, but it appeared to account for a substantial part of it," says Dr. Seaton, who is now studying how eating habits during pregnancy affect a child's chance of developing asthma.

In fact, city or rural kids who consumed the least vegetables and milk were two to three times more likely to develop asthma or allergies than kids who ate the most. Although fruit didn't seem to play a big role in Dr. Seaton's analysis, a handful of studies on adults, including a recent British one that looked at apple consumption, showed that it too may help reduce asthma symptoms.

Why is produce protective? Researchers think that it cleans up after your child's immune system. Thanks to vaccinations and better healthcare, kids come down with fewer infections, reducing the need for their immune systems to produce Th1 helper cells that fight disease. With little to do, the immune system gets into trouble, making Th2 cells instead. These cells inflame and injure airways -- increasing the risk of asthma. The vitamins in produce, especially A, C, and E, as well as many plant compounds called phytochemicals, act as antioxidants, helping to reduce airway stress and tissue damage. "As a result, antioxidant-rich produce may help prevent or manage asthma," explains Lawrence S. Greene, Ph.D., director of the Biology of Human Populations Program at the University of Massachusetts in Boston.

In general, kids eat enough fruit, though they fall short on vegetables. Between 1977 and 1996, vegetable consumption among 6- to 11-year-olds dropped 26% to a measly four ounces daily, according to the USDA.

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Breath-Saving Strategy: Increase your little one's vegetable intake to three servings daily. For kids 1 to 6, a serving is one tablespoon for each year of age. For older children, figure on half a cup cooked veggies or one cup raw greens such as lettuce. Jack Bishop, author of Vegetables Every Day and father of two girls ages 6 and 2, offers advice for accomplishing what seems impossible:

Think "Twice is nice." Bishop cooks up at least two vegetables for dinner every night. Then he lets the kids select which one they want and scoops it onto their plates. Sometimes, they surprise him and ask for both! "I used to put vegetables on the kids' plates and they would protest," he says. "When I began offering them a choice, they started to eat more vegetables."

Savor simplicity. The more sauces and toppings you add, the more likely your kids are to run across an ingredient they don't like. So Bishop usually tosses vegetables with just a bit of olive oil. "Now and then, the kids ask to dip the vegetables in ketchup -- and that's okay with me -- but most often, they prefer plain," he says.

Show their sweet side. Roasting or grilling vegetables such as carrots and asparagus brings out their natural sweetness, making them more appealing to kids, says Bishop.

For nearly a decade, researchers from the International Study of Asthma and Allergies in Childhood (ISAAC), an Auckland, New Zealand-based group, have been studying the diets of more than 700,000 children ages 6, 7, 13, and 14 from 53 countries, including the U.S. One of their conclusions, published in the European Respiratory Journal earlier this year: Kids who got more calcium from food were less likely to wheeze. And calcium-rich milk reduced asthma in Dr. Seaton's study.

Additional research from the University of Nottingham in England suggests that calcium may account for only part of milk's anti-asthma benefits -- its high magnesium content may play a role. The scientists studied the diet and measured the lung function of more than 2,600 adults. After adjusting for risk factors like age and smoking, they found that subjects whose magnesium intake was 100 milligrams (mg) above the mean of 380 mg had significantly calmer lungs and better airflow. While they haven't repeated the trial in children, they advise that kids eat plenty of magnesium-rich foods.

Breath-Saving Strategy: Make sure that your child meets her daily calcium and magnesium requirements from food. One- to 3-year-olds need 500 mg of calcium and 80 mg of magnesium daily, while kids 4 to 8 require 800 mg of calcium and 130 mg of magnesium. Older children should shoot for 1,300 mg of calcium and 240 mg of magnesium every day.

Milk is a great source because it supplies 300 mg of calcium and 34 mg of magnesium per cup. So if your 6-year-old drinks two cups daily, she'll get 75% of the calcium and 50% of the magnesium she needs. (If your child is allergic to cow's milk, serve fortified soy milk instead.)

Round out your child's calcium needs with a serving of yogurt or cheese; use low-fat varieties for kids 2 and over. And make sure your child polishes off her magnesium requirement by regularly offering her cereal, green veggies, beans, fish, and, if she's 4 or older, nuts.

Children require two kinds of polyunsaturated fats, omega-6 and omega-3, for the best growth and development. Corn, sunflower, and safflower oils, used in commercial cookies, chips, cakes, and salad dressings, are rich in omega-6s. Fish, canola oil, and walnuts supply the most omega-3s. When in balance, these two fats help kids' immune systems fight off disease. The best ratio of omega-6s to omega-3s is 2.5 to 1, according to the USDA.

Unfortunately, USDA research shows that the typical American diet has about 10 teaspoons of omega-6 for every one teaspoon of omega-3, which is more than four times the optimum level. The result: Too much omega-6 prompts the immune system to overproduce chemicals called cytokines that inflame airways and make lung tissue very sensitive to irritants like dust, dander, and pollution. "Omega-3-rich fish oil dampens cytokine production and calms airways," explains Robert F. Grimble, Ph.D., professor of nutrition at the University of Southampton in England.

An Australian study of 574 children found that kids who ate fresh fish -- particularly the fatty kind that is high in omega-3s -- were 75% less likely to be asthmatic. In the ISAAC study, children in countries with the highest seafood consumption were least likely to have asthma. Several additional reports, including Dr. Broughton's, suggest that fish oil supplements improve asthma symptoms in at least half of sufferers.

While omega-3s seem to prevent asthma, new research suggests that high levels of omega-6s increase its likelihood. An Australian study examined risk factors for asthma in 974 children 3 to 5 years old and found that those who ate a lot of omega-6 fatty acids from margarine and vegetable oil were twice as likely to develop asthma as children whose fat usually came from canola oil, olive oil, or even butter. "The high intake of these polyunsaturated fats may account for 17% of the asthma cases in the study," says Michelle Haby, Ph.D., a researcher at Royal Children's Hospital in Melbourne.

Breath-Saving Strategy: Serve more foods rich in omega-3s and fewer loaded with omega-6s. Here, four ways to strike a better balance:

Hook 'em on fish. Twice a week, replace a serving of meat with fish for kids over age 1. (Delay to age 3 if your family has a history of food allergies.) Fish like salmon, herring, and anchovies pack the most omega-3s. But white tuna in water has an ample amount -- in fact, any kind of seafood has more omega-3s than meat.

To convince picky eaters to try seafood, start with mild-tasting white fish, marinating it in a flavor they enjoy, like honey mustard or barbecue sauce. You can also make fish nuggets -- cut the filet into strips, coat with bread crumbs, and bake in the oven. Serve with your child's favorite dip. Make tuna sandwiches more fun by using cookie cutters to shape them like flowers, hearts, or stars.

Get an oil change. Canola contains an ideal ratio of omega-6s to omega-3s, while olive oil offers mostly monounsaturated fat, which may help calm airways, too, says Dr. Broughton. Use either oil when sautéing. To add more flavor to a dish, stick with olive oil. Canola oil works best for stir-frying or baking; swap it for vegetable oil (substitute an equal amount) or margarine (use one-third less canola oil).

Wow them with walnuts. They're the only nut rich in omega-3s. For kids 4 and over, sprinkle walnuts on cereal, stir them in yogurt, or bake them in banana bread.

Go easy on margarine. Most brands are at least 65% vegetable oil. If your child eats margarine only once in a while, don't sweat it. But if she regularly spreads it on her bread and eats foods that are made with margarine, try alternative toppings such as fruit butters and low-fat cream cheese. Or buy a brand of margarine with a lower amount of vegetable oil, such as Smart Balance, which contains just 37%.

Trans-Fat-Free Food Calms Airways

In the ingredients of many processed foods, you'll see "partially hydrogenated oil" -- it means the product likely contains trans fat. This fat starts out as a polyunsaturated oil rich in omega-6 and then is chemically altered when hydrogen is forced into it under pressure. Research suggests that trans fats are more antagonizing to asthma than the unbalanced ratio of omega-6s to omega-3s described in the previous section. Digesting and metabolizing trans fats, studies show, can create prostaglandins and leukotrienes, which are inflammatory chemicals.

The ISAAC study found that 13- to 14-year-olds who ate the most trans fats were most likely to have symptoms of asthma. In a Finnish study evaluating the diets of 231 children ages 3 to 18 for six years, the kids who developed atopic diseases such as eczema and asthma were compared to children who remained healthy. The asthmatic children, it turns out, ate more margarine (high in trans fat and omega-6s) and less butter (low in omega-6s and free of trans fat) than healthy kids.

Breath-Saving Strategy: Don't pile on the butter -- too much saturated fat contributes to heart disease. Rather, avoid trans fats. Major sources are fast food (french fries and chicken nuggets), baked goods, and fried or oily snacks like chips, according to the Center for Science in the Public Interest, a Washington, DC-based advocacy group. Here's how to cut back.

Slow down fast food. Go less often and try healthier kids' meal options -- Boston Market offers a child-size serving of turkey, ham, or chicken with a small side dish (like veggies or rice) while Subway's Kids' Pak offers a small deli sandwich (seven kinds are low-fat), a small drink (you'll probably be able to get bottled water, milk, or juice, depending on the location), and a cookie. When you're at Wendy's, McDonald's, or Burger King, hamburgers are a better choice than chicken nuggets. Opt for milk or water instead of soda.

Shop for better baked goods. Look for items that don't contain partially hydrogenated oil (for the trans fats) or margarine and vegetable oil (for omega-6s). Great cookies with canola oil: Barbara's Bakery Old-Fashioned Oatmeal, Country Choice Organic Sandwich Cookies, and Mi-Del Vanilla or Lemon Snaps.

Snag healthier snacks. Microwave popcorn is often loaded with trans fat, and many brands of potato chips pack trans fat or lots of omega-6s. If you do buy chips and popcorn, try Terra or Michael Season's chips (made with canola oil) or Bearitos No Oil Added Microwave Popcorn.

Americans eat about 50% more meat and poultry than they did in the 1930s, according to the USDA. Researchers believe that this shift to a meat-centered diet may be affecting asthma rates. "In our study, children who got the most calories from cereal and rice and the most protein from cereals, nuts, starch, and vegetables were the ones most protected against wheezing," explains Philippa Ellwood, research manager for ISAAC.

Breath-Saving Strategy: Downsize your family's meat portions and then make sure your children 2 and over get about six servings of grains daily -- half of them should be whole grains like oatmeal or whole-wheat bread. For kids 2 to 3, a serving is 1/2 slice of bread, 2 or 3 crackers, 1/3 cup dry cereal, or 1/4 cup cooked grains like cereal, rice, or pasta. At ages 4 to 6, the dry cereal portion increases to 1/2 cup and cooked grains to 1/3 cup. Kids 7 to 10 jump to 1 slice of bread, 1/2 cup cooked grains, 3/4 to 1 cup dry cereal, or 4 or 5 crackers.

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Copyright © 2001. Reprinted with permission from the November 2001 issue of Child magazine.

All content here, including advice from doctors and other health professionals, should be considered as opinion only. Always seek the direct advice of your own doctor in connection with any questions or issues you may have regarding your own health or the health of others.