Diet & Supplements for Prostate Cancer Prevention and Treatment
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Eating well is important before, during, and after treatment for prostate cancer. It can help you feel better, have more energy, keep up your strength, and lower your risk of infection. It can also help you prepare for surgery and speed your recovery after cancer treatment, and it may help keep your cancer from coming back.
Seattle Cancer Care Alliance (SCCA) offers consultation with a nutritionist for all of our patients undergoing treatment. A nutritionist can recommend food choices to help with treatment side effects (like fatigue, nausea, and changes in sense of smell or taste); discuss diet variations (like plant-based diets, anti-inflammatory diets, and whole-food diets); and work with you on an individualized plan that optimizes your health and addresses specific goals (like bone health, blood-sugar control, and weight loss or gain).
While the exact role of diet in prostate cancer is not clear, researchers have studied several factors, and they continue to look for more specific associations between diet and prostate cancer. Many of the foods thought to lower the risk for and improve survival after prostate cancer are foods of plant origin. Men who eat a lot of red meat or high-fat dairy products and fewer fruits and vegetables appear to have a slightly higher risk of prostate cancer. Some studies have suggested that men who consume a lot of calcium (through food or supplements) may have a higher risk of developing prostate cancer; however, most studies have not found such a link with the levels of calcium found in the average diet, and it's important to note that calcium is known to have other important health benefits.
For optimal health, nutritionists at SCCA recommend eating a mostly plant-based diet and including moderate amounts of foods of animal origin. Some of the many foods and nutrients showing associations with prostate cancer risk and survival are listed below.
- Dietary Fat
- Fruits & Vegetables
- Vitamin D
- Vitamin E & Selenium
- Green Tea, Coffee, & Red Wine
Protein is important to help keep up your strength and rebuild tissues that may be harmed by cancer treatment. The best choices are beans (legumes), nuts, fish, eggs, and chicken without the skin.
Everyone needs some fat as part of a healthy diet. Fat contains important nutrients, including vitamins A, D, E, and K, and is an important part of the cells in your body.
More research is needed to determine the effect fat has on prostate cancer. In any case, it is probably a good idea to choose healthy fats, limit your intake of saturated fats, and avoid trans fats. Healthy fats, such as monounsaturated and polyunsaturated fats, can lower LDL (“bad”) cholesterol and increase HDL (“good”) cholesterol, while saturated fats and trans fats can increase LDL cholesterol.
We recommend using olive and canola oils and eating avocado and a handful of nuts daily. Limit dairy to one to two servings daily. Limit your intake of red meats and chicken skin. It also is a good idea to eat foods containing omega-3 fatty acids, such as those found in fish, two to three times weekly. The omega-3 fatty acids in fish (EPA and DHA) appear to provide protection against prostate cancer and heart disease.
Increased consumption of omega-6 fatty acids, such as safflower, soybean, and corn oils, has been shown to double the risk of prostate cancer in men with a family history of the disease. In addition, regular consumption of deep-fried foods (once a week or more) is associated with increased risk for prostate cancer, and the effect appears to be slightly stronger for more aggressive forms of the disease.
Some research studies have found a significant association between eating vegetables—in particular, yellow or orange vegetables and cruciferous vegetables—and a lower risk of prostate cancer.
Fruits and vegetables provide the vitamins, minerals, and fiber that your body needs. Different colored fruits and vegetables contain unique varieties of disease-fighting phytochemicals. Only fruits and vegetables, not pills or supplements, provide all of these nutrients together.
Phytochemicals are natural antioxidants. Antioxidants are substances that may protect your cells against the effects of free radicals. Free radicals can damage cells and play a role in cancer and other diseases.
Try to eat a variety of colors of fruits and vegetables each day. Here are examples of colorful plant foods to work into your diet regularly, along with the phytochemicals they provide.
- Red: tomato-based foods (tomato sauce, tomato juice, tomato paste, salsa, tomato soup), watermelon, pink grapefruit, papaya, and apricots, which provide lycopene
- Red/purple: pomegranates, grapes, plums, cherries, and berries, which provide anthocyanins
- Orange: carrots, sweet potatoes, mangoes, apricots, oranges, and cantaloupes, which provide carotenoids
- Orange/yellow: oranges, peaches, papaya, and nectarines, which provide cryptoxanthin
- Yellow/green: spinach, peas, corn, avocado, romaine lettuce, and honeydew melons, which provide lutein and zeaxanthin
- Green/cruciferous: broccoli, cauliflower, radishes, cabbage, Brussels sprouts, kale, chard, collards, and mustard greens, which provide sulforaphane, isothiocyanates, and indoles
- White/green: garlic, onions, asparagus, leeks, shallots, and chives, which provide allyl sulfides
In addition, some fruits and vegetables that don’t fit into the color system also have benefits. For example, celery contains salicylic acid, the active ingredient in aspirin, which has anti-inflammatory properties.
Lycopene, from red fruits and vegetables or from supplements, is a phytochemical of particular interest because it may affect antioxidant activity and lower the risk of prostate cancer. Laboratory and preclinical studies show less cancer cell growth in the presence of lycopene; however, clinical studies have had mixed results. Several issues—including prostate cancer stage, genetic risk factors, sources and types of lycopene, other dietary differences, and obesity—may impact whether lycopene helps prevent prostate cancer or is useful in treating prostate cancer.
Fiber may bind to toxic compounds and carcinogens in the body; and a high-fiber diet may reduce levels of hormones that are involved in the progression of prostate cancer. Dietary fiber comes from the parts of plants your body can’t digest. There are two types, soluble fiber and insoluble fiber.
When eaten regularly as part of a low-fat, low-cholesterol diet, soluble fiber can help lower blood cholesterol. Oats have the highest proportion of soluble fiber of any grain. Foods high in soluble fiber include oat bran, oatmeal, beans (legumes), peas, rice bran, barley, citrus fruits, strawberries, and apples.
Insoluble fiber doesn’t seem to help lower blood cholesterol. However, it’s an important aid in normal bowel function. Foods high in insoluble fiber include whole wheat breads, wheat cereals, wheat bran, rye, rice, barley, most other grains, cabbage, beets, carrots, Brussels sprouts, turnips, cauliflower, and apple peels.
There is some evidence that soy may help prevent prostate cancer (and more evidence that it can help reduce risk for heart disease). Soy contains phytochemicals called isoflavones, which have antioxidant, antimicrobial, and antifungal properties. Isoflavones are also antiangiogenic (they block formation of new blood vessels that nourish tumors) and may block growth of cancer cells.
Soynuts, edamame, tempeh, tofu, and soy milk are sources of soy. Soy may cause some gastrointestinal upset, such as gas, so if you do not eat soy foods regularly now, it may be better to introduce soy to your diet gradually over several weeks.
The role of calcium in prostate cancer is unclear. Too much may increase the risk of prostate cancer (and lead to other harmful side effects), while too little may increase the risk of colon cancer. In a study reported in the Journal of Nutrition in 2007, increased dairy intake cut the risk of smokers developing prostate cancer by about 40 percent.
Since prostate cancer treatment may result in a loss of bone density, it is important to consume adequate calcium and vitamin D to help keep your bones strong. Exercise is also important in preventing bone loss. Your calcium requirements depend on whether or not you are receiving hormone therapy and whether or not you have osteoporosis.
- If you have had a normal DEXA scan and you are not receiving androgen-deprivation therapy, you need between 1,000 and 1,200 mg of calcium a day.
- If you have osteoporosis or osteopenia or are receiving androgen-deprivation therapy, you need 1,500 mg of calcium per day.
Calcium is found in many foods, including dark green vegetables, soy products, fish, nuts, and beans (legumes). While dairy products are a good source of calcium, research indicates dairy should be limited for prostate cancer survival and prevention. We recommend eating mostly plant-based sources of calcium and limiting intake of dairy to one to two servings daily.
If you do not consume enough calcium in food, you should take a supplement. Calcium carbonate supplements should be taken with meals for best absorption. Calcium citrate can be taken between or with meals. Avoid consuming more than 2,000 mg of calcium daily from food and supplements.
Vitamin D helps the body utilize calcium and phosphorus to build bones and teeth. Since prostate cancer treatment may result in loss of bone density, it is important to get enough vitamin D to keep your bones strong. Research has found that men with high levels of vitamin D have a lower risk of developing the more lethal forms of prostate cancer.
With adequate sun exposure, your body can manufacture vitamin D. But as you grow older your ability to manufacture vitamin D declines. Risk factors for developing a vitamin D deficiency are living in a less sunny climate (such as the Pacific Northwest), being obese, being over 60, and not getting adequate dietary vitamin D.
It is best to get vitamin D from food, a multivitamin supplement, or a calcium supplement that includes vitamin D. Food sources of vitamin D are limited and generally include fortified sources, such as milk, soy milk, yogurt, orange juice, and cereal.
To determine how much vitamin D you need to get from your diet and possibly supplements, get a blood test to measure your current vitamin D level. Discuss checking your vitamin D level with your medical team.
In a clinical study known as the SELECT trial, researchers studied whether selenium and vitamin E, taken together or alone, could help prevent prostate cancer.
As reported in the 2011 results, men who took vitamin E supplements alone had a 17 percent relative increase in prostate cancer. For this reason, we suggest you avoid taking vitamin E supplements and focus instead on consuming foods rich in vitamin E. These include nuts (such as almonds, hazelnuts, and peanuts), vegetable oils (such as olive and canola), seeds, wheat germ, whole grain products, and spinach and other dark, green leafy vegetables.
As reported in the study’s 2008 and 2011 results, there were more cases of diabetes in men taking only selenium, and men taking selenium alone or in combination with vitamin E were more likely to develop prostate cancer. The findings were not statistically significant and cannot be definitely linked to selenium. However, we recommend against taking selenium supplements. The best source of selenium is food. Foods rich in selenium include Brazil nuts, wheat germ, bran, brown rice, whole wheat bread, barley, onions, garlic, turnips, soybeans, mushrooms, fish, and eggs.
The health benefits of green tea are thought to come from polyphenols, which include catechins—powerful antioxidants. Laboratory and preclinical studies have shown catechins slow the spread of prostate cancer by blocking the stimulating effect of androgen (male hormones, such as testosterone), and they may block a protein involved in the growth of prostate cancer. Catechins also make prostate cancer cells more susceptible to radiation and hormone therapy.
Coffee consumption has been associated with a lower risk of prostate cancer recurrence and progression. In a study reported by Fred Hutchinson Cancer Research Center in August 2013, men who drank four or more cups of coffee a day experienced a 59 percent reduced risk of prostate cancer recurrence and progression compared with men who drank only one or fewer cups of coffee per week. While more studies are needed to determine the mechanisms for this effect, researchers believe that the phytochemical compounds found in coffee have anti-inflammatory and antioxidant effects and modulate glucose metabolism.
Also, according to a study by researchers at the Hutch, men who drank four or more glasses of red wine per week reduced their risk of prostate cancer by half and had a 60 percent lower incidence of more aggressive types of the disease. This may be due to the anti-inflammatory and antioxidant properties of resveratrol, found in red grape skins, peanuts, and raspberries. Resveratrol is also available as a dietary supplement.
It is important to note that increased consumption of coffee may be harmful for some men, and heavy alcohol use has health risks that are well documented.
Most research suggests that food is the best source of nutrients—a balanced diet, including fruits and vegetables, is of greater benefit than taking dietary supplements. Supplements can have both risks and benefits. Some studies indicate taking certain nutrient supplements in high doses may have negative health outcomes. In fact, as a result of a large clinical study known as SELECT, we recommend prostate cancer patients do not take vitamin E or selenium supplements. More information about vitamin E and selenium is included in the section on diet above.
Multivitamins and mineral supplements offer no known health benefits and are generally not needed if you eat a balanced diet. However, if you avoid specific groups of foods, such as meat, milk, cheese, eggs, or fruit, you may need to take a multivitamin or mineral supplement in order to get some of the nutrients these foods supply.
Before starting vitamins or other supplements, consult a nutritionist and your medical team.