Food and Cancer Risk

Approved by the Cancer.Net Editorial Board, 10/2018

Some foods and the vitamins, minerals, and other nutrients found in them may raise or lower cancer risk.

Researchers have studied how certain foods, nutrients, and patterns of eating are related to cancer risk.

Plant-based foods. These foods contain naturally-occurring substances called phytonutrients. Examples include:

  • Carotenoids, or carotenes found in red, orange, yellow, and some dark-green vegetables

  • Polyphenols, found in herbs, spices, vegetables, tea, coffee, chocolate, nuts, apples, onions, berries, and other plants

  • Allium compounds, found in chives, garlic, leeks, and onions

Antioxidants. Examples include beta carotene, selenium, and vitamins C and E. Antioxidants protect against oxidants, which are substances that can lead to cell damage. Oxidants can be naturally occurring, created by normal cell processes, or environmental, such as pollution or cigarette smoke.

Other vitamins and minerals. These include calcium, iodine, vitamins A, D and K, and the B vitamins.

Dietary fiber. Fiber helps add bulk to stool. It moves food more quickly through the digestive system. Fiber helps nourish a healthy community of microbes living in the digestive tract. This community is called a microbiome. A healthy microbiome has been linked with a lower cancer risk.

Foods that have fiber include:

  • Whole grains and seeds, including barley, oats, kamut, spelt, bulgur, corn, psyllium and rye

  • Whole grain bread and pasta

  • Legumes and pulses, including beans, garbanzo beans, lentils, and split peas

  • Vegetables and fruits

Protein. These are the major sources of animal protein in most diets:

  • Meat

  • Fish

  • Poultry

  • Shellfish

  • Dairy products

  • Eggs

Of these, red and processed meats raise the most concern in terms of cancer risk. Red meat includes pork, beef, veal, and lamb. Processed meat includes bacon, ham, lunch meats, meat jerky, hot dogs, salami, and other cured meat products. Any amount of processed meat and more than around 18 ounces of fresh meat per week are most strongly associated with cancer risk.

Alcoholic beverages. Drinking alcohol increases the risk of developing certain types of cancer. Learn more about alcohol and cancer risk.

Connections between food and cancer

It is challenging to find specific links between a food or nutrient and cancer because:

  • Foods contain many substances that may contribute to cancer risk or prevention.

  • Most people eat and drink a variety of foods. This creates interactions that are hard to study.

  • Effects can vary depending on how much you eat.

  • Some research shows that a food’s preparation may influence its risk or benefits.

Plant-based foods

Fruits and vegetables likely reduce risk of several types of cancer, including:

  • Head and neck cancers

  • Esophageal cancer

  • Stomach cancer

  • Lung cancer

  • Pancreatic cancer

  • Prostate cancer

These findings come from the Continuous Update Project and the Third Expert Report on Diet, Nutrition, Physical Activity and Cancer: a Global Perspective. These reports are funded by the American Institute of Cancer Research (AICR) and World Cancer Research Fund (WCRF).

Phytonutrients found in fruits and vegetables most likely work together to lower cancer risk, rather than a particular food component affecting risk. Some help regulate hormones, such as estrogen. Others slow cancer cell growth or block inflammation. Many lower the risk of damage caused by oxidants.

Plant-based foods researchers have studied for cancer prevention are:

Cruciferous vegetables. These foods include broccoli, cauliflower, cabbage, Brussels sprouts, bok choy, and kale. Frequently eating these foods is associated with reduced cancer risk.

Studies show cruciferous vegetables protect against:

  • Head and neck cancers

  • Esophageal cancer

  • Stomach cancer

Several laboratory studies suggest cruciferous vegetables help regulate enzymes that defend against cancer. Studies also show that cruciferous vegetables may stop cancer cell growth in other ways. But these effects may differ between cells and animals used in the lab and people.

Lycopene. This carotenoid is found in tomato products. Other important sources of lycopene include pink grapefruit, watermelon, and apricots.

Studies show that lycopene may protect against cancers of the:

  • Lung

  • Stomach

  • Prostate

  • Colon

  • Mouth and throat (oral cavity)

  • Esophagus

But researchers have not yet demonstrated a direct link between lycopene and reduced cancer risk in controlled clinical trials.

Soy. Soy contains unique phytonutrients. Laboratory studies suggest that these substances help protect against some types of cancer. Clinical trials are more clearly defining soy’s role in cancer prevention.

The relationship between soy and breast cancer risk is especially complex. Current studies suggest eating up to 3 servings of whole soy foods, such as edamame, tofu, soy milk, and miso, is safe and may reduce breast cancer risk. But guidelines do not specifically recommend adding soy foods into the diet to reduce breast cancer risk. Doctors do recommend avoiding concentrated isoflavone pills and powders.

Vitamins, minerals, and antioxidants

Your body needs vitamins and minerals. They help the body:

  • Perform essential functions

  • Grow and develop

  • Repair itself

Some vitamins, minerals and other nutrients are antioxidants. Research on their role in cancer prevention continues because studies show mixed results.

A review of clinical trials in people shows the following:

Beta carotene. High-dose beta carotene supplements do not seem to prevent cancer. Two large clinical trials have found that people at high risk for lung cancer, including smokers, former smokers, and people exposed to asbestos, have a higher risk of lung cancer if they take high-dose beta carotene supplements.

Calcium and vitamin D. The Women’s Health Initiative (WHI) was a large study of women who had been through menopause and were generally well nourished. Researchers studied the effects of supplemental calcium and vitamin D. They found that supplements did not affect colorectal cancer risk.

Folate. Folate is a type of B vitamin found in:

  • Leafy, green vegetables

  • Fruits and fruit juices

  • Dried beans and peas

One form, folic acid, is made in the laboratory and found in dietary supplements. Enriched, white flour is fortified with it. This means that foods made with flour, including breads and cereals, contain folic acid.

Studies show a link between folate and cancer risk. People with low folate levels have a higher risk of:

  • Breast cancer

  • Colon cancer

  • Pancreatic cancer

But clinical studies have not yet shown a relationship between taking extra folic acid and cancer prevention.

Multivitamins. Currently, there is no strong enough evidence that multivitamins reduce cancer risk. But 1 study showed a potential benefit. People who took multivitamins for more than 10 years had reduced colon polyp formation. Some polyps can develop into colorectal cancer if not removed during colonoscopy cancer screening. By reducing polyps, the study suggests multivitamins might reduce colorectal cancer risk, too. But this research can be difficult to interpret. Usually, the healthiest people get regular cancer screening. And those people also commonly take multivitamins.

Selenium. One study evaluated whether selenium prevents cancer. Supplements did not prevent people with skin cancer from getting a second one. But it did reduce new cases of:

  • Prostate cancer

  • Lung cancer

  • Colorectal cancer

Some studies link selenium to a higher risk of diabetes. So use caution when considering supplements that contain selenium.

Vitamin C. Some studies show diets with higher amounts of vitamin C can lower stomach cancer risk. But results have been inconsistent.

Vitamin E. A large clinical trial called the Selenium and Vitamin E Cancer Prevention Trial (SELECT) found that participants who took vitamin E had a higher risk of prostate cancer.

High-dose vitamin C and E supplements have been shown to raise the risk of a head and neck cancer recurrence. A recurrence is when the cancer comes back after treatment.

Dietary fiber

The AICR/WCRF study found connections between fiber-rich foods and reduced cancer risk. This relationship is strongest for colorectal cancer.

Protein

Most studies suggest a link between red meat and a higher risk for colorectal cancer. But avoiding processed meats is even more important. This includes bacon, ham, lunch meats, meat jerky, hot dogs, salami, and other cured meat products. The AICR/WCRF study found these meats increase colorectal cancer risk. The study also found that people can eat up to 18 ounces (510 grams) of unprocessed red meat a week without raising cancer risk.

Obesity

Eating more calories than your body needs can cause weight gain. Many people eat too much food with added sugar and fat. The following foods add extra calories that can contribute to obesity:

  • Sugar sweetened beverages, including soda and fruit-flavored drinks. Sugary drinks can be hot or cold.

  • Full-fat dairy products, such as whole milk cheese

  • High-fat meats, including fried chicken with skin, duck, hamburgers, bacon, ham, sausage, hot dogs, and many deli meats

Obesity is linked to a higher risk of many cancers. Talk with your health care team about whether your weight is affecting your health and cancer risk.

Related Resources

Foods to Avoid During Cancer Treatment

Obesity, Weight, and Cancer Risk

Physical Activity and Cancer Risk

More Information

American Institute for Cancer Research: Diet -What to Eat for Lower Cancer Risk

National Cancer Institute: Cancer Prevention Overview