The power of some foods to prevent and even heal childhood illnesses is nearly miraculous. If Americans ate better, it’s unlikely that one out of three American children would suffer from asthma, birth defects, cancer, lead poisoning, or mental-behavioral disorders. Many of these children are sick because they were exposed to toxins while in their mothers’ wombs or during early infancy. Because their defenses weren’t strong during these periods, they lost the battle against these chemicals.

It is unfortunate that in too many families, neither children nor their mothers eat foods that defend against toxic assaults. No matter how well-nourished people are, everyone has some toxins in them, and some children are genetically more susceptible than others. But the threshold for resisting toxins is usually lower in poorly nourished children and in children with specific nutritional weak spots.

This is more than just “eat an apple a day.” Recent discoveries about how our body’s systems work has led to an awareness of how certain foods protect against specific illnesses.

One battle takes place in our immune system, where we, like all mammals, can generally generate an army of antioxidants whose mission is to fight oxidative stress. Oxidative stress is the ordinary result of our body’s perpetual struggle to rid itself of the by-products of normal cellular metabolism. Normally, our bodies win these daily battles.

But then along come manmade contaminants such as PCBs, which we all have in trace amounts, even though these chemicals (once widely used in electrical equipment) were banned decades ago. Many types of PCBs cause a huge amount of oxidative stress, far more than many people’s antioxidant powers can cope with; the stress ends up inflaming the cells that line blood vessels and damaging the cardiovascular system, as well as the brain and nervous system. A child exposed in the womb to a dose that’s the equivalent of one single drop of PCBs in a bathtub can suffer a lowered IQ and an increased chance of attention deficit disorder and cardiovascular diseases later in life.

Manmade contaminants especially threaten children because their bodies produce lower levels of the master detoxifying antioxidant, glutathione, than adults’ bodies do. And some children produce even lower levels, probably because of inherited genetic variations (see my article “To Vaccinate Your Child or Not”). These children are often the ones with learning and behavioral disorders.

Antioxidants, which you’ll find in many foods, are up there at the top of the list of nutrients we need in order to fight toxins. Cancer, too, is influenced by antioxidants. The higher the mother’s diet in vegetables, fruit, and protein sources (such as beans and lean beef) in the twelve months prior to pregnancy, the lower her risk of having a child with acute lymphoblastic leukemia (ACC). Again, what’s at work here includes the antioxidant glutathione, with its power to help make DNA and repair DNA damage. The study that found this connection also found that pregnant women who consumed cod liver oil and folate supplements similarly reduced the risk of their children suffering from ACC cancer.

If a child during his early years consumes oranges and orange juice, which are packed with the antioxidant vitamin C, and eats potassium-rich bananas, their likelihood of childhood leukemia falls. Consuming fruits and vegetables high in beta-carotene, another dietary antioxidant, and foods with vitamin A (oranges; yellow, orange, and red vegetables), as well as the antioxidant vitamin E (sunflower and safflower oils; hazelnuts and almonds; wheat germ) also builds the body’s defenses against cancer.

How about damage to your child’s brain and nervous system from lead and other heavy metals? It decreases if your child’s body has a good reserve of calcium, iron, and zinc, nutrients found in a good diet.

Certain birth defects, such as neural tube defects, cleft palates, and cleft lips, are linked to a deficiency in folate acid, a B vitamin found in abundance in leafy green vegetables and in lesser amounts in citrus fruits, beans, and whole grains. It’s usually recommended that pregnant women take four hundred micrograms or more of folic acid supplements.

Infertility, which is on the rise in the United States, is also affected by nutrition. Women are more likely to conceive if they follow a Mediterranean diet full of vegetables, vegetable oils, and fish. (Some fish, however, contain high mercury levels, so you have to avoid them. Consult Ewg.org/safefishlist.) Fertility also requires enough iron and folic acid, and folic acid seems to bolster sperm quality.

Endometriosis (where cells lining the uterus grow into other areas of the body), another illness on the rise, also responds to foods with anti-inflammatory powers as well as to foods with lignins, a type of fiber which helps remove toxic manmade hormones from the body. Lignin-rich vegetables include cabbage, broccoli, and brussels sprouts.

The typical American diet contains too much omega 6, which mostly comes from processed foods and industrially raised animals. Nursing mothers pass this along to their children unless they seek out the right foods. The right foods, with their higher levels of omega 3 long-chain polyunsaturated fatty acids, are fish and fish oil, flaxseed, walnuts, canola oil, soybeans, soybean oil, and pumpkin seeds.

Foods high in omega 3s include vegetables, especially green and orange vegetables, which are also high in vitamin C, vitamin E, beta-carotene, and zinc. (By the way, the uptake of zinc is damaged by high fructose corn syrup and artificial colorings.) And let’s not forget garlic, one of the world’s perfect products.

Besides health-giving foods, there are foods that parents should do their best to keep out of their children’s mouths: chicken raised with arsenic, beef raised with antibiotics, milk produced with growth hormones, and non-organic strawberries (doused with a particularly carcinogenic pesticide). It’s wise to be cautious about foods that are high in saturated animal fat, which includes butter, cheese, meat, and processed foods, because many persistent chemicals concentrate in this fat.

When your child is an adult and a parent or a grandparent, she will thank you for all this care. She will have a lower likelihood of getting sick. Research has confirmed that disorders seeded in childhood set a person’s cellular code for life and can cause illness at any time from conception until old age. So defending against these assaults can head off adult and old-age diseases, too. Because disruptions to the way our genes normally work—whether caused by harmful foods or toxins—can be passed down through several generations. So your child’s good or bad health will likely show up in your grandchildren and great-grandchildren.