If there is one disease everyone would like to prevent, it’s cancer. Although there’s a lot the medical community still doesn’t understand about this multifarious ailment, studies show that a healthy lifestyle and regular exercise can significantly reduce the risk of developing some cancers. So, too, can taking certain supplemental nutrients, prioritized here based on expert advice and scientific research.

Vitamin D.

“One of the best ways to prevent most major cancers is to maintain an optimal vitamin D level,” says Arizona-based Michael Uzick, NMD, Fellow of the American Board of Naturopathic Oncology. “There’s strong evidence you can reduce your risk of breast, prostate, colon, lung, pancreatic, and ovarian cancers by at least 50 percent by doing so.” Doctors recently reported that women taking vitamin D with calcium had an 18 percent lower overall breast cancer risk and were 20 percent less likely to develop invasive breast cancer; results also showed a 17 percent lower colorectal cancer risk. Taking D with calcium, as well as magnesium, might enhance protection because the nutrients work together. In another study, published in the Journal of the National Cancer Institute, doctors found that high vitamin D levels didn’t prevent prostate cancer, but they did lower the chances of dying from the disease.

Most people need supplementation to achieve optimal vitamin D levels, says Uzick. Ask your doctor for a blood test; if your levels are below the ideal range (55–70 ng/ml), boost your supplement dose for up to six months and get tested again.

Dose: 2,000–5,000 IU daily, plus 400 mg calcium and 400 mg magnesium.

Multivitamins.

A daily multivitamin-mineral supplement may lower your cancer risk by about 8 percent, according to a long-term study of more than 14,000 men recently published in the Journal  of the American Medical Association. Extrapolating from the study’s data, if every American took a multi, there might be 127,000 fewer cancer diagnoses each year in the United States. The JAMA study used a basic one-a-day multivitamin; high-quality formulas with, say, three pills daily deliver more nutrients, especially bulky minerals.

Dose: Follow label directions.

Green tea extract.

One-third of green tea (by weight) consists of epigallocatechin gallate (EGCG), a potent antioxidant that protects against colorectal, prostate, and breast cancer, according to several published studies. You’ll benefit from drinking a few cups of fresh, high-quality green tea daily, but green tea extract supplements provide a more consistent and higher amount of EGCG, says Uzick.

Dose: 500 mg EGCG daily.

Antioxidants.

As long as you’re alive, unbalanced molecules called free radicals oxidize, or damage, cells, setting the stage for cancer-promoting mutations. The countermeasure? Antioxidants (such as vitamins C and E), carotenoids (such as lycopene), and flavonoids (such as bilberry and quercetin), all of which fight free radicals. Eating a colorful array of fresh, organic vegetables and fruits helps, but supplementing may boost protection. Choose an antioxidant-rich multivitamin or a multi-antioxidant supplement.

Dose: Follow label directions.

Lycopene.

Solid research suggests that high-lycopene diets decrease the risk of cancer, especially prostate cancer. Highly bioavailable in cooked tomato sauces, the reddish carotenoid is concentrated and stored in the prostate, suggesting a protective role. Nonsynthetic, tomato-derived lycopene supplements may lower prostate cancer risk by 16 percent to 35 percent, according to several studies.

Dose: 5–10 mg daily.

Curcumin.

Doctors at Houston-based MD Anderson Cancer Center are testing this turmeric extract as a complementary therapy to conventional treatments. But according to other researchers, curcumin’s real benefit may be in prevention. It works in part by blocking inflammation—a key cancer culprit—via 97 separate biochemical paths.

Dose: 300–750 mg daily of standardized curcuminoids.