Food and Cancer Prevention

Approved by the Cancer.Net Editorial Board, 04/2016

Many foods have long been studied to find out if they increase cancer risk or can help prevent cancer. This includes several types of food and parts of foods:

  • Plant-based foods, including naturally-occurring chemicals called phytochemicals such as:

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

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

    • Allium compounds, which are in  chives, garlic, leeks, and onions

  • Antioxidants, such as beta carotene, selenium, and vitamins C and E

  • Other vitamins and minerals, such as calcium, vitamin D, and B vitamins

  • Dietary fiber

  • Protein

  • Alcoholic Beverages. Find out about alcohol and cancer risk.

Foods and their cancer connection

Finding a specific link between a food or part of a food and cancer is difficult. There are many challenges:

  • Foods contain many things that may contribute to cancer prevention.

  • Most people eat and drink a variety of foods, creating interactions that are challenging to study.

  • Sometimes foods have different effects on the body 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, including mouth, throat, voice box, esophagus, stomach, lung, pancreas, and prostate. These findings come from the American Institute of Cancer Research (AICR) and World Cancer Research Fund (WCRF).

It is likely that the various phytochemicals in fruits and vegetables 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, such as tobacco or ozone.

Here is some information about specific plant-based foods that have been researched as way to prevent cancer:

  • Cruciferous vegetables. These foods are likely to protect against some types of cancers. They include broccoli, cauliflower, cabbage, Brussels sprouts, bok choy, and kale. A protective effect has been shown for cancers of the mouth, pharynx, voice box, esophagus, and stomach. Several laboratory studies suggest that cruciferous vegetables help regulate the body's complex system of enzymes that defend against cancer. They also show that parts of the vegetables can stop cancer cell growth. However, these may not work the same or as well in people as in laboratory studies.

  • Lycopene. This carotenoid is found in tomato products, such as tomato sauce. Other important sources of lycopene include pink grapefruit, watermelon, and apricots. Studies show that it may protect against several cancers. These include lung, stomach, prostate, colon, oral, and esophageal cancers. But researchers have not yet found a direct link between eating lycopene and lowering cancer risk.

  • Soy and breast cancer. Some laboratory studies show that soybean products may help protect against some cancer types. But clinical studies have since more clearly determined their role in cancer prevention.

    The relationship between soy, which contains phytochemicals, and breast cancer risk is especially complex, and research study results are conflicting. Some studies suggest that soy may act like the hormone estrogen. This may be a concern for women with estrogen receptor–positive breast cancer, which is fueled by estrogen.

    Current evidence suggests that eating normal amounts, such as three servings each day, of soy foods such as soy milk and tofu is unlikely to increase the risk of breast cancer growing and spreading. However, taking concentrated isoflavone pills and powders is not recommended.

Vitamins, minerals, and antioxidants

Your body needs vitamins and minerals to perform essential functions, grow and develop, and repair itself. Research on whether they prevent cancer continues, with mixed results. Some vitamins, minerals, and other nutrients help protect your body against damage from oxidants. They are called antioxidants.

A review of clinical trials in people shows the following:

  • Beta carotene. High-dose supplements with beta carotene do not seem to prevent cancer. In studies of current and former smokers, 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 who had been through menopause and were generally well nourished. Researchers found that supplemental calcium and vitamin D had no effect on the number of new diagnoses of colorectal cancer.

  • Folate. Folate is a generic description of a B vitamin that is found in foods such as leafy, green vegetables, fruit, and dried beans and peas. One form, folic acid, is made in the laboratory. It is found in supplements and fortified foods, such as breads and cereals. Studies show that people with low levels of folate have an increased risk of breast, colon, and pancreas cancers. So far, studies in people have not shown a relationship between folic acid and cancer prevention.

  • Multivitamins. A few studies have tested whether taking a multivitamin reduces your risk of cancer. Generally the studies have not shown a protection. But one study showed that people who took multivitamins for more than 10 years had reduced polyp formation. Because polyps are linked to colorectal cancer risk, this study suggests a multivitamin might reduce colorectal cancer risk. But these are difficult data to interpret. Usually the healthiest people who get regular cancer screening are also the people taking multivitamins.

  • Selenium. In a laboratory study, selenium supplements did not prevent a second skin cancer in people who already had the disease. But it did lower the new cases of prostate, lung, and colorectal cancers. In some studies, selenium has been linked to an increased risk for diabetes. So be cautious about considering supplements that contain selenium.

  • Vitamin C. Some research studies show that higher amounts of vitamin C in the diet can lower the risk of stomach cancer. But the results have not been consistent.

  • Vitamin E. A large clinical trial called the Selenium and Vitamin E Cancer Prevention Trial (SELECT) tested the relationship between vitamin E and prostate cancer. Updated results showed that participants who took vitamin E had an increased risk for prostate cancer.

Dietary fiber

It comes from the outer layer of grains and is found in fruits, vegetables, legumes, and nuts. Fiber helps add bulk to stool and move food more quickly through the digestive system. Fiber is in certain foods, such as:

  • Whole grains, including barley, oats, kamut, spelt, bulgur, corn

  • Whole grain bread and pasta

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

  • Vegetables and fruits

The AICR/WCRF study found that foods containing fiber are linked to a reduced risk of cancer, particularly colorectal cancer.


Meat, fish, poultry, shellfish, cheese, and eggs are the major sources of animal protein in most diets. Of those, red meat and processed meat are most often studied as risk factors for cancer. Most of the studies suggest that people who eat more red meat have a higher risk for developing colorectal cancer than those who eat less red meat. But avoiding processed meats is even more important. The AICR/WCRF study found that eating processed meat, such as hot dogs, bacon, and salami, increases the chances of colorectal cancer. The study found that people can eat up to 18 ounces (oz)  of red meat a week without raising cancer risk. Try meatless meals and limiting red meat intake to 18 oz a week or less.


Sugary drinks, full-fat dairy products, and high-fat meats can all add extra calories that lead to obesity. Obesity is linked to increased risk of many cancers. Check with your health care team for more information about whether your weight is affecting your health and cancer risk.

More Information

Obesity, Weight, and Cancer Risk

Physical Activity and Cancer Risk

Additional Resource

American Institute for Cancer Research