Nutrition to Reduce Cancer Risk

Research continues to be done on how diet may affect the development of cancer. It has shown that eating fruits, vegetables, and cereal grains may lower your risk of getting certain cancers. In addition, eating more fruits and vegetables can also reduce your risk for:

  • Diabetes

  • Heart disease

  • High blood pressure

  • Obesity

  • Other chronic diseases

This article is about nutrition and its role in cancer prevention. If you have cancer or are on chemotherapy, different nutritional approaches may be needed.

Early research suggests that some components of food may play a role in decreasing the risk of developing cancer. This includes: phytochemicals, antioxidants, and omega-3 fatty acids.

Phytochemicals

Phytochemicals are chemicals found in plants. They protect plants from bacteria, viruses, and fungi. Eating foods high in phytochemicals may lower your risk for certain cancers. It will also lower your risk for diabetes, high blood pressure, and heart disease. To get enough phytochemicals, eat large amounts of brightly colored fruits and vegetables, whole grains and cereals, and beans. The way that phytochemicals work varies by color and type of food. They may act as antioxidants or nutrient protectors, or prevent cancer-causing agents from forming.

Some phytochemicals found in foods include:

  • Allicin is found in onions and garlic.

  • Anthocyanins are found in vegetables and red and blue fruits, such as raspberries and blueberries.

  • Biflavonoids are found in citrus fruits.

  • Carotenoids are found in dark yellow, orange, red, and deep green fruits and vegetables. These include tomatoes, parsley, oranges, pink grapefruit, and spinach.

  • Flavonoids are found in fruits, vegetables, wine, green tea, onions, apples, kale, and beans.

  • Indoles are found in broccoli, bok choy, cabbage, kale, Brussels sprouts, and turnips. They are also known as cruciferous vegetables.

  • Isoflavones are found in soybeans and soybean products.

  • Lignans are found in flaxseed and whole grain products.

  • Lutein is found in leafy green vegetables.

  • Lycopene is found mainly in tomato products.

  • Phenolics are found in citrus fruits, fruit juices, dried and fresh plums, raisins, eggplant, cereals, legumes, and oilseeds.

Phytochemicals generally can’t be found in supplements. They are only present in food. Foods high in phytochemicals include:

  • Apples

  • Apricots

  • Berries

  • Bok choy

  • Broccoli

  • Brussels sprouts

  • Cabbage

  • Cantaloupe

  • Carrots

  • Celery

  • Garlic

  • Green tea

  • Kale

  • Lentils

  • Olives

  • Onions

  • Pears

  • Seeds

  • Soybeans

  • Soy nuts

  • Spinach

  • Tomatoes

  • Turnips

  • Red wine

There is no recommended dietary allowance for phytochemicals. Eat a variety of foods, including plenty of fruits and vegetables. This is the best way to make sure you are getting enough phytochemicals in your diet.

Antioxidants

Antioxidants are substances that prevent the oxidation process and act as protective agents. They protect the body from the damaging effects of free radicals. These are by-products of the body’s normal chemical processes. Free radicals attack healthy cells. This changes the cells’ DNA and allows tumors to grow. Researchers are looking at how antioxidants may lower the risk of developing cancer.

Antioxidants include:

  • Vitamin C (ascorbic acid). The following foods are good sources of vitamin C:

    • One medium orange – 70 mg

    • 3/4 cup orange juice – 61 to 93 mg

    • 1/2 cup raw green pepper – 60 mg

    • 1 /2 cup raw strawberries – 49 mg

    • 1/4 medium, raw, cubed papaya – 47 mg

    • 1/2 cup raw red pepper – 142 mg

    • 1/2 cup raw broccoli – 39 mg

The recommended dietary allowance for vitamin C is 75 mg per day for women and 90 mg per day for men.

  • Beta carotene. Beta carotene, also known as provitamin A, may help lower the risk of getting cancer. This nutrient may help prevent normal cells from becoming cancerous. But it's not yet clear if it can actually help prevent cancer in people. There is no recommended dietary allowance for beta carotene. Examples of some foods high in beta carotene include the following:

    • Carrots

    • Collards

    • Spinach

    • Squash

    • Sweet potatoes

  • Vitamin E. Our bodies need Vitamin E in order to work properly. It helps to build normal and red blood cells. It also works 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 mg per day. The adult upper limit for vitamin E is 1,000 mg per day. Good sources of vitamin E include:

    • 1 tbsp sunflower oil - 5.6 mg

    • 1 ounce dry, roasted sunflower seeds - 7.4 mg

    • 1 ounce almonds - 7.3 mg

    • 1 ounce hazelnuts - 4.3 mg

    • 1 ounce peanuts - 2.2 mg

    • 1/2 cup tomato sauce - 2.5 mg

    • 1 tbsp olive oil - 1.9 mg

    • 2 tbsp toasted, plain wheat germ - 2.3 mg

There is no recommended dietary allowance for antioxidants overall. Eat a variety of foods, including plenty of fruits and vegetables, to make sure you are getting enough in your diet.

Omega-3 fatty acids

Researchers are studying the effects omega-3 fatty acids may have on delaying or reducing tumor development. Since our bodies can’t make omega-3s, we must get them from food or supplements. The omega-3s include:

  • Alpha-linolenic acid

  • Docosahexaenoic acid

  • Eicosapentaenoic acid

Sources of foods high in omega-3s include:

  • Seafood, especially cold-water fish like salmon, mackerel, sardines, herring, halibut, striped bass, tuna, and lake trout

  • Flaxseed oil and beans, such as kidney, great northern, navy, and soybeans

You should avoid omega-3s if you:

  • Take aspirin or medicines to prevent blood clots (anticoagulants). Omega-3 supplements may increase the risk of excessive bleeding.

  • Are pregnant or breastfeeding. Talk with your healthcare provider before eating fish that are likely to be high in omega-3s or taking omega-3 supplements.

There is no recommended dietary allowance for omega-3s. Eat a variety of foods, including plenty of fish and beans, to make sure you are getting enough in your diet.

Nutritional information can seem complex and overwhelming. If you have questions about your diet, ask your healthcare provider for referral to a registered dietitian. A dietitian can evaluate your nutritional needs and give you up-to-date information. He or she can also help you decide what type of diet is best for your personal health.