Research continues to be done on how diet might affect cancer risk. But it's already shown that a diet with a lot of fruits, vegetables, and cereal grains may help lower your risk of getting certain cancers. Eating more fruits and vegetables can also reduce your risk for:
High blood pressure
Too much weight gain, including obesity
Other chronic diseases
Experts also say that some foods and drinks should be limited or not eaten. These include:
Red and processed meats
Highly processed foods
Refined grain products
Here, you can learn more about nutrition and its role in cancer prevention. If you have cancer or are getting cancer treatment, you may need a different kind of diet. Talk with your healthcare provider or a dietitian to find out what's best for you.
Early research suggests that some parts of food might play a role in lowering cancer risk. This includes phytochemicals, antioxidants, and omega-3 fatty acids.
Phytochemicals are compounds found in plants. Studies around the world have shown that eating foods high in phytochemicals may lower your risk for certain diseases, like cancer, 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 kinds of phytochemicals varies by color and type of food. These compounds may act as antioxidants or nutrient protectors. They can help keep cancer-causing agents from forming.
Here are some examples of phytochemicals found in food:
Allicin is found in onions, leeks, chives, and garlic.
Anthocyanins are found in vegetables, like red potatoes, and red and blue fruits, such as raspberries, strawberries, blueberries, and the skin of red apples.
Carotenoids are found in dark yellow, orange, red, and deep green fruits and vegetables. These include tomatoes, parsley, oranges, pink grapefruit, spinach, and other dark leafy green vegetables.
Flavonoids are found in fruits, vegetables, wine, green tea, onions, apples, kale, and beans.
Isoflavones are found in soybeans and soy products, like tofu and soy milk.
Lignans are found in flaxseed and whole grain products. They're also in apricots, strawberries, nuts, and seeds .
Phenolic acids are found in citrus fruits, fruit juices, dried and fresh plums, raisins, eggplant, cereals, legumes, oilseeds, tea, and coffee.
Phytochemicals generally can’t be found in supplements. They are only in plant-based food. Foods high in phytochemicals include:
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.
Oxidation is a process that's a normal part of metabolism. It makes free radicals, which can attack healthy cells. This changes the DNA of cells and allows tumors to grow. Antioxidants protect the body from the damaging effects of free radicals. Researchers are looking at how antioxidants may help lower cancer risk.
Antioxidant supplements are being studied. Most experts don't advise them. Instead, they prefer you get antioxidants from food. Antioxidants can be found in many kinds of food. But vegetables and fruits are rich sources of them.
Here are a few antioxidants with examples of good sources for them:
Experts advise that you should get at least75 mg of vitamin C per day if you are a woman and 90 mg per day if you are a man. The adult upper limit for vitamin C is 2,000 mg per day.
The following foods are good sources of vitamin C:
1 large orange – 98 mg
1 cup orange juice – 124 mg
1 cup raw, red sweet pepper – 190 mg
1 cup sliced, raw strawberries – 98 mg
1 small, raw, cubed papaya – 96 mg
1 cup canned tomato juice – 170 mg
1 cup raw broccoli – 81 mg
Beta carotene is also known as provitamin A. It may help lower the risk of getting cancer. But it's not yet clear if it can actually help prevent cancer. There is no recommended dietary allowance for beta carotene.
Foods high in beta carotene include:
Carrots (raw, cooked, or juiced)
Our bodies need vitamin E to work properly. It helps to build normal blood cells. It also works as an antioxidant. 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 wheat germ oil – 20.3 mg
1 tbsp sunflower oil – 5.6 mg
1 ounce dry, roasted sunflower seeds – 7.4 mg
1 ounce dry, roasted almonds – 6.8 mg
1 ounce dry, roasted hazelnuts – 4.3 mg
1 ounce dry, roasted peanuts – 2.2 mg
1/2 cup boiled spinach – 1.9 mg
1/2 cup boiled, chopped broccoli – 1.2 mg
1 medium kiwi fruit – 1.1 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 are key to cell structure and function. The body can also use them for energy. Researchers are studying the effects omega-3s may have on delaying or reducing tumor growth. Since our bodies can’t make omega-3s, we must get them from food or supplements. The omega-3s include:
Alpha-linolenic acid (ALA)
Docosahexaenoic acid (DHA)
Eicosapentaenoic acid (EPA)
Sources of foods high in omega-3s include:
Seafood, especially cold-water fish like salmon, mackerel, sardines, herring, and tuna, as well as oysters, mussels, and crab
Flaxseed, soybean, and canola oils
Nuts and seeds, like flaxseed, walnuts, and chia seeds
Beans, such as kidney, great northern, pinto, navy, and soybeans
You should not eat omega-3s if you:
Take aspirin or medicines to prevent blood clots (anticoagulants). Omega-3 supplements may increase the risk of bleeding if you take a blood thinner.
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. These fish may also be high in mercury.
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 a referral to a registered dietitian. A dietitian can review your nutritional needs and give you up-to-date information. The dietitian can also help you decide what type of diet is best for you.