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Do Omega-3s and Antioxidants Fight Cancer?

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WebMD Feature
Reviewed by Laura J. Martin, MD

Keep eating fish, nuts, fruits, and vegetables. Two superstar heart disease protectors in these foods may also help fight cancer. Antioxidants and omega-3 fatty acids may be more powerful than we knew.

Omega-3s

Found in fatty fish and certain nuts and seeds, omega-3 fatty acids help protect your heart. Studies show they help maintain brain function. Experts are also looking at how well omega-3 fatty acids can protect against age-related mental decline, eye diseases, arthritis, and others conditions.

Some experts think omega-3s may help protect against cancer. "Omega-3 fatty acids are thought to reduce inflammation in the body. And a variety of cancers have been linked to chronic inflammation," says Sarah Rafat, RD, a senior dietitian at MD Anderson Cancer Center.

Cancers with a link to inflammation include:

  • Colorectal
  • Liver
  • Lung
  • Prostate

Omega-3s also seem to restrict tumor cell growth, and may cause cancer cells to self-destruct.

What we know so far: Diet and cancer studies show mixed results. Some suggest that a diet that's rich in omega-3s can protect you against certain cancers. Other studies show no benefit.

There's not enough proof to conclude that loading up on fatty fish or taking fish oil capsules will slow down or reverse your condition if you already have cancer. But several studies do suggest that a diet rich in omega-3s helps some cancer patients tolerate chemotherapy better. Fatty acids from fish may also help patients maintain weight and muscle mass.

Expert suggestions: The American Heart Association recommends eating at least two servings of fatty fish a week. If you don't eat fish, you can get omega-3s from canola oil and flax. Talk to your doctor before you start taking supplements. There is a link between high levels of omega-3s in the blood and an aggressive form of prostate cancer, according to scientists at Fred Hutchinson Cancer Research Center.

Antioxidants

Many fruits, vegetables, and other foods that are rich in antioxidants lower the risk of heart disease, high blood pressure, some eye diseases, and various forms of cancer. Getting a single antioxidant from a pill, such as vitamin C or beta carotene, isn’t as protective. Supplements don't seem to protect against cancer or help fight it. Some antioxidants may even increase the risk of certain cancers. Experts also worry that high doses of antioxidants may reduce the effectiveness of chemotherapy.

What we know so far: "We tell our patients to focus on food," says Veronica McLymont, PhD, director of food and nutrition services at Memorial Sloan-Kettering Cancer Center. "Foods contain a mix of many different antioxidants, along with other nutrients and fiber. The more colorful your diet is the better, since antioxidants and other phytochemicals are often what give fruits and vegetables their color."

The best thing to do is to fill your plate with antioxidant-rich foods:

  • Berries
  • Leafy green vegetables
  • Sweet peppers
  • Tomatoes

Expert suggestions: Each day, eat up to nine servings of fruits and vegetables. Most Americans have a long way to go before reaching that goal. Eat fruit or vegetables with every meal. Be creative about adding them to your daily snacks.

"The emphasis should be on plant-based foods, not supplements," says Kim Jordan, RD, nutrition director for the Seattle Cancer Care Alliance. "When you have cancer, it's important to give your body everything it needs to stay nourished and maintain a healthy immune system. The only way to do that is with a balanced diet of real food."

Reviewed on August 10, 2012

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