Food and Cancer Prevention

Approved by the Cancer.Net Editorial Board, 09/2017

Some foods and parts of foods may increase cancer risk or help prevent cancer.

Researchers have studied how these types of food and parts of foods could affect cancer growth:

Plant-based foods. These include naturally-occurring chemicals called phytochemicals:

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

  • Polyphenols, found in herbs, spices, vegetables, green tea, apples, and berries

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

Antioxidants. These include beta carotene, selenium, and vitamins C and E. Antioxidants reduce the risk of damage from oxidants. Oxidants are substances that can lead to cell damage.

Other vitamins and minerals. These include calcium, vitamin D, and B vitamins.

Dietary fiber. Fiber helps add bulk to stool. It moves food more quickly through the digestive system.

Foods containing fiber:

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

  • Whole grain bread and pasta

  • Legumes and pulses, including black 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. This includes pork, beef, veal, and lamb. Red and processed meats are most often studied as risk factors for cancer.

Alcoholic beverages. Learn about alcohol and cancer risk.

Foods’ cancer connections

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

  • Foods contain many parts 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.

  • Sometimes, effects 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 probably protect against several cancers:

  • Head and neck cancers

  • Esophageal cancer

  • Stomach cancer

  • Lung cancer

  • Pancreatic cancer

  • Prostate cancer

These findings come from the Continuous Update Project. It is funded by the American Institute of Cancer Research (AICR) and World Cancer Research Fund (WCRF).

Phytochemicals in fruits and vegetables probably work together to lower cancer 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 that researchers have studied for cancer prevention are:

Cruciferous vegetables. These foods likely protect against some types of cancers. They include broccoli, cauliflower, cabbage, Brussels sprouts, bok choy, and kale.

Studies show that cruciferous vegetables protect against these cancers: 

  • Head and neck cancers

  • Esophageal cancer

  • Stomach cancer 

Several laboratory studies suggest that cruciferous vegetables help regulate enzymes. The body's complex system of enzymes defend against cancer. Studies also show that cruciferous vegetables may stop cancer cell growth. But these effects may differ in studies with 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 several cancers: 

  • Lung cancer

  • Stomach cancer

  • Prostate cancer

  • Colon cancer

  • Oral cancer

  • Esophageal cancer 

However, researchers have not yet found a direct link between lycopene and lowering cancer risk.

Soy. Soy contains phytochemicals. And laboratory studies suggest it helps protect against some cancer types. But clinical studies are more clearly defining soy’s role in cancer prevention. 

The relationship between soy and breast cancer risk is especially complex. Research study results are conflicting and confusing. 

Current evidence suggests it is fine to eat limited amounts of soy. This likely will not increase the risk of breast cancer. Three servings of soy products daily may be a safe amount. However, doctors 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

And 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 supplements with beta carotene don’t seem to prevent cancer. Researchers found the opposite in studies of people who currently smoke and people who have quit smoking. High-dose beta carotene supplements actually raised lung cancer risk.

Calcium and vitamin D. The Women’s Health Initiative (WHI) was a large study of women. Participants had been through menopause and were generally well nourished. Researchers studied the effects of supplemental calcium and vitamin D. The supplements did not affect the number of new colon cancer diagnoses.

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

  • Leafy, green vegetables

  • Fruits and fruit juices

  • Dried beans and peas 

One form, folic acid, is made in the laboratory. It is found in supplements. And some products are fortified with it, like breads and cereals. 

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

  • Breast cancer

  • Colon cancer

  • Pancreatic cancer 

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

Multivitamins. Currently, there is not strong enough evidence that multivitamins reduce cancer risk. But one study showed a potential benefit. People who took multivitamins for more than 10 years had reduced polyp formation. Polyps are linked to colorectal cancer risk. Thus, this study suggests multivitamins might reduce colorectal cancer risk. But these are difficult data to interpret. Usually, the healthiest people get regular cancer screening. And those people commonly take multivitamins. 

Selenium. A laboratory study evaluated whether selenium prevents cancer. Supplements did not prevent people with skin cancer from getting a second one. But it did lower the new cases of these types of cancer: 

  • Prostate cancer

  • Lung cancer

  • Colorectal cancers 

Some studies link selenium to an increased 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 not been consistent.

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

Dietary fiber

The AICR/WCRF study found connections between foods containing fiber and reduced cancer risk. Particularly a reduced risk of colorectal cancer.


Most studies suggest a link between red meat and increased colorectal cancer risk. But avoiding processed meats is even more important. These include hot dogs, bacon, and salami. The AICR/WCRF study found these meats increase colorectal cancer risk. The study found that people can eat up to 18 ounces (oz) of red meat a week without raising cancer risk.


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

  • Sugary drinks, which can include hot and cold drinks

  • 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 increased risk of many cancers. Check with your health care team for more information. And ask whether your weight is affecting your health and cancer risk.

Related Resources

Obesity, Weight, and Cancer Risk

Physical Activity and Cancer Risk

More Information

American Institute for Cancer Research: Diet

National Cancer Institute: Cancer Prevention Overview