If you are confused about whether certain vitamins, supplements or foods can prevent L cancer, you're not alone. The results of several recent studies have been conflicting and perplexing-which is why this topic has raised questions for consumers as well as members of the health-care and research communities.
What you need to know: Cancer is not a single disease, and it can have many different causes. That makes it virtually impossible for any one nutrient to protect against all types of cancer. In fact, studying whether single nutrients reduce the risk for cancer often is like looking for a magic bullet-more wishful thinking than good science.
Nothing can absolutely guarantee that you'll remain cancer free. However, good nutrition and a healthful overall lifestyle—not smoking, not abusing alcohol, limiting exposure to pollutants, eliminating food additives, exercising and controlling stress-can lower your odds of developing cancer. Here are my top five foods and top five supplements that definitely can lower your long-term risk of getting cancer.
My Top Anti-Cancer Foods
Consume a diet that emphasizes a variety of fresh, natural and minimally processed foods. Include a selection of vegetables, some fruits (such as berries and kiwifruit), fish, chicken (free-range or organic), legumes, nuts and modest amounts of healthful starches (such as sweet potatoes and whole grains). Eat healthfully and you will lay the foundation for everything else that you can do to lower your long-term risk for cancer.
My favorite anticancer foods…
- Broccoli. Cruciferous vegetables are my top anticancer food, and broccoli heads the list. It is rich in sulforaphane, an antioxidant that helps the liver break down and destroy cancer-causing toxins. Sulforaphane also increases the activity of liver enzymes that help to get cancerous substances out of the body. (Sulforaphane is available as a supplement, although I recommend people get this phytonutrient through food) Even better, broccoli sprouts contain 50 times more sulforaphane than that found in regular broccoli. A product called BroccoSprouts is available at select supermarkets (877-747-1277, www.broccosprouts.com). Broccoli sprouts also have been shown to fight H. pylori, a type of bacteria believed to cause stomach cancer.
Advice: Eat one-half cup of raw or lightly steamed broccoli daily. Boiling reduces its nutritional value) Add some broccoli sprouts to your salads or sandwiches.
- Tomatoes. This fruit is rich in lycopene, the antioxidant that gives tomatoes their red color. Studies have found that tomatoes reduce the risk for prostate cancer-and also might reduce the risk for lung and stomach cancers.
Advice: Consume cooked tomatoes or tomato sauce. Lycopene is best absorbed from cooked tomatoes because cooking breaks down the fiber in the tomatoes. A little fat (e.g., olive oil) also enhances absorption. Include one serving of tomato sauce (one-half cup) in your diet several times a week. Watermelon and guava also contain a lot of lycopene.
- Cold-water fish. Salmon, sardines and trout are rich in healthy omega-3 fats—specifically eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). EPA and DHA have potent anti-inflammatory benefits. Low intake of these fats appears to be a factor in breast, colon, pancreatic and stomach cancers.
Advice: Eat cold-water fish at least once or twice a week, or take a fish oil supplement daily that contains 1 gram of EPA and DHA. Or consider using krill oil, a type of fish oil from shrimplike crustaceans.
- Garlic. Slice or dice a garlic clove, and a relatively inert compound called allicin undergoes an amazing cascade of chemical changes. Nearly all allicin-generated compounds function as antioxidants that prevent the types of cell mutations that give rise to cancer. Evidence suggests that garlic might help protect against cancers of the colon, prostate, esophagus, larynx, ovaries and kidneys
Advice: Consume garlic regularly. Because chopping and cooking garlic seem to increase its biological activity, sauté or bake it rather than eating it whole or raw. There is no recommended serving size for garlic, but the more you consume, the better.
- Spinach. Spinach and other greens," such as chard and collard greens, are rich in antioxidants that protect cells from the type of damage that can create cancerous mutations. One study published in Journal of Agricultural and Food Chemistry gave spinach the top "bioactivity index" ranking of vegetables for its ability to protect against cancer.
Advice: Eat spinach and other greens daily. You can make spinach salads or 50/50 lettuce and spinach salads, or gently sauté spinach. A single serving is equivalent to one cup of raw or one-half cup of cooked spinach or greens.
My Top Anticancer Supplements
Research on the role of individual supplements in reducing cancer risk has been especially confusing. Taking all evidence into account, I'm convinced that these five supplements have clear benefits…
- Vitamin D. If you were to take just one immune-enhancing supplement to lower your long-term risk for cancer, vitamin D would be the one to choose. More than 60 studies have found that high levels of vitamin D offer broad protection against many types of cancer. A recent German study reported that people with low vitamin D levels were one-third more likely to die of any type of cancer.
Advice: Take at least 1,000 international units (IU) of vitamin D-3 daily. Vitamin D-3, with its slightly different molecular structure than D-2, is a more bioactive form of the vitamin, which means that the body can use it more readily. Take 2,000 IU if you don't get much sun or have a dark complexion. (Dark skin absorbs less of the rays necessary for conversion to vitamin D.)
Best: Have your blood tested to determine how much vitamin D you need.
- Vitamin K. Two recent studies have shown an unexpected benefit of vitamin K-that it reduces the odds of developing breast and liver cancers.
Possible mechanism: Vitamin K activates osteocalcin, a protein involved in making strong bones. Recent research found that osteocalcin also may function as an anticancer nutrient.
Advice: Take 300 micrograms (mcg) of either vitamin K-1 or vitamin K-2, the forms most often studied.
Caution: Vitamin K may increase blood clotting. Do not take vitamin K if you also are taking blood-thinning medication unless you are being monitored by a doctor.
- Selenium. This essential dietary mineral forms part of glutathione peroxidase, an antioxidant enzyme that helps the liver break down cancer-causing toxins. A study published in The Journal of the American Medical Association found that 200 mcg daily of selenium led to significant reductions in the risk for prostate, colon and lung cancers within just a few years.
Advice: Take 200 mcg daily. Don't take a higher dose (which could be toxic) without the supervision of a nutrition-oriented doctor.
- Coenzyme Q10 (CoQ10). I believe that modest amounts of this vitamin-like nutrient may reduce an individual's general risk for cancer. Studies have shown that large amounts of COQ10 can inhibit the spread of breast cancer and boost immunity...and may have benefits in other types of cancer as well. A recent study of women with breast cancer who were on the drug tamoxifen found that a combination of 100 milligrams (mg) of CoQ10 daily and vitamins B-2 (10 mg) and B-3 (50 mg) boosted the activity of enzymes that can repair genes.
Advice: Take 100 mg daily. If you already have been treated for cancer, take 300 mg daily.
- Lycopene. This antioxidant helps prevent cell damage. Several small studies have shown that lycopene supplements can reduce the size of prostate tumors and their tendency to spread. They also can lower levels of prostate-specific antigen (PSA), a common marker of prostate cancer risk.
Advice: For prostate cancer prevention and for men with elevated PSA levels, I recommend taking 5 mg to 10 mg of lycopene daily, even if you eat lycopene-rich foods. If you have been diagnosed with prostate cancer, discuss taking 30 mg daily with your physician. Use tomato-based (not synthetic) lycopene, which contains other beneficial antioxidants.
Note: Some multivitamins may contain these nutrients but not in the amounts recommended for cancer prevention. Check the label of your multivitamin, and add to it, based on the recommendations above.
New Study Proves Antioxidants Don't Raise Melanoma Risk
A recent study of 13,017 people suggested A that supplementing with vitamins C and E, beta-carotene, selenium and zinc quadrupled women's risk for melanoma skin cancer.
Update: In a new study of 69,671 people, these antioxidant supplements did not increase melanoma risk.
Explanation: The smaller study did not adequately adjust for some risk factors, such as number of moles, sunburn history, hair color and family history of skin cancer