What are phytochemicals (or phytonutrients)?

Eating large amounts of brightly colored fruits and vegetables (yellow, orange, red, green, white, blue, purple), whole grains/cereals, and beans containing phytochemicals may decrease the risk of developing certain cancers as well as diabetes, hypertension, and heart disease.

What are specific sources of phytochemicals?

Phytochemicals generally cannot be found in supplements and are only present in food. Foods high in phytochemicals include the following:

• broccoli
• berries
• soy nuts
• pears
• turnips
• celery
• carrots
• spinach
• olives
• tomatoes
• lentils
• cantaloupe
• garlic
• apricots
• onions
• seeds
• soybeans
• green tea
• apples
• cabbage
• Brussels sprouts
• bok choy
• kale
• ed wine

There is no recommended dietary allowance for phytochemicals. Eat a variety of foods, including plenty of fruits and vegetables, to ensure you are getting adequate amounts in your diet.

What are antioxidants?

Antioxidants are substances that inhibit the oxidation process and act as protective agents. They protect the body from the damaging effects of free radicals (by-products of the body’s normal chemical processes). Free radicals attack healthy cells, which changes their DNA, allowing tumors to grow. Research is underway to investigate the role of antioxidants in decreasing the risk of developing cancer.

Antioxidants include:

Vitamin C (ascorbic acid)

According to the National Cancer Institute (NCI), vitamin C may protect against cancer of the oral cavity, stomach and esophagus and may also reduce the risk of developing cancers of the rectum, pancreas and cervix. Also known as ascorbic acid, vitamin C may provide protection against breast and lung cancer.

According to the American Dietetic Association and USDA Nutrient Database for Standard Reference, the following foods are good sources of vitamin C:

• one medium orange - 69 mg
• 1 cup orange juice - 124 mg
• 1 medium raw green pepper - 106 mg
• 1 cup raw strawberries - 81 mg
• 1 cup cubed papaya - 86 mg
• 1 medium raw red pepper - 226 mg
• 1/2 cup cooked broccoli - 58 mg

The recommended dietary allowance (RDA) for vitamin C has recently been increased to 75 milligrams per day for women and 90 milligrams per day for men. If you smoke cigarettes, it is recommended to increase your intake of vitamin C to 100 milligrams per day.

Beta Carotene

Beta carotene, also known as provitamin A, may help decrease the risk of developing cancer. According to the American Cancer Society, this nutrient may prevent certain cancers by enhancing the white blood cells in your immune system. White blood cells work to block cell-damaging free radicals.
Good sources of beta carotene are dark green leafy and yellow-orange fruits and vegetables. In the body, beta carotene is converted to vitamin A. Eating foods rich in beta carotene is recommended to possibly decrease the risk of developing stomach, lung, prostate, breast, and head and neck cancer. However, more research is needed before a definite recommendation on beta carotene consumption can be made. Overdosing on beta carotene is not recommended. Large doses can cause the skin to turn a yellow-orange color, a condition called carotenosis. High intakes of beta carotene in supplement form may actually cause lung cancer in people at risk, such as smokers.

While there is a recommended dietary allowance for vitamin A, there is not one for beta carotene. Examples of some foods high in beta carotene include the following:

• carrots
• squash
• collards
• spinach
• sweet potatoes

Vitamin E

Vitamin E is essential for our bodies to work properly. Vitamin E helps to build normal and red blood cells, as well as working as an antioxidant. Research is finding evidence that vitamin E may protect against prostate and colorectal cancer. The recommended dietary allowance for vitamin E is 15 milligrams per day. The adult upper limit for vitamin E is 1,000 milligrams per day. Good sources of vitamin E (and the amount each serving contains) include the following:

• 1 tablespoon sunflower oil - 6.9 mg
• 1 ounce sunflower seeds - 14 mg
• 1 ounce almonds - 7.4 mg
• 1 ounce hazelnuts - 4.3 mg
• 1 ounce peanuts - 2.1 mg
• 3/4 cup bran cereal - 5.1 mg
• 1 slice whole wheat bread - .23 mg
• 1 ounce wheat germ - 5.1 mg

Since some sources of vitamin E are high in fat. A synthetic form of a vitamin E is available as a supplement. Vitamin E supplementation is probably not needed for most individuals because vitamin E is a fat-soluble vitamin and is stored in our bodies. Very high doses of vitamin E can also interfere with the way other fat-soluble vitamins work. Also, large doses of vitamin E from supplements are not recommended for people taking blood thinners and some other medications, as the vitamin can interfere with the action of the medication. To make sure you are meeting your needs, eat a varied diet that includes whole-wheat breads and cereals.

There is no recommended dietary allowance for antioxidants. Eat a variety of foods, including plenty of fruits and vegetables, to ensure you are getting adequate amounts in your diet.

 

Information on this page is provided collaboratively by the team at the Prostate Cancer Center at Saint Joseph's and has been medically reviewed by Rajesh G. Laungani, MD, 2010.

Last Updated: October 14, 2010 (RSH)