Prostate Cancer, Nutrition, and Dietary Supplements (PDQ®): Integrative, alternative, and complementary therapies - Patient Information [NCI]

What is calcium?

Calcium is a common mineral in the body that is needed to help blood vessel s, muscles, and nerve s work to send signals from cell to cell, and to release hormones. The body stores most calcium in bones and teeth.

How is calcium given or taken?

The main sources of calcium are in foods and dietary supplements. About one-third of dietary calcium comes from milk and milk products like cheese and yogurt. Vegetable sources include Chinese cabbage, kale, and broccoli. Foods may have calcium added, such as fruit juices and drinks, tofu, and cereals.

Most research about calcium and prostate cancer risk has studied calcium in the diet and not calcium in supplements.

Have any laboratory or animal studies been done using calcium?

For information on laboratory and animal studies done using calcium, see the Laboratory/Animal/Preclinical Studies section of the health professional version of Prostate Cancer, Nutrition, and Dietary Supplements.

Have any studies of calcium been done in people?

Studies of people in many parts of the world have been done to find out if there is a link between dairy products, calcium, and prostate cancer risk. The results of these studies have been mixed. Some studies have shown that calcium has an effect on the overall risk of developing prostate cancer or on stopping cancer from coming back after treatment, and others have not. Several studies have suggested that eating a large amount of calcium may increase the risk of advanced and metastatic prostate cancer.

Combined studies

• A 2005 review found a possible link between an increased risk of prostate cancer and a diet high in dairy products and calcium.
• A review of studies published between 1996 and 2006 found that milk and dairy products in the diet increased the risk of prostate cancer.
• A 2008 review of 45 studies found no link between dairy products and the risk of prostate cancer.
• A 2013 review for the U.S. Preventive Services Task Force found that taking vitamin D and/or calcium supplements showed no overall effect on rates of cancer or deaths from cancer, including prostate cancer.
• A 2015 review of 32 studies found that high amounts of milk, low-fat milk, cheese, total dietary calcium, and dairy calcium in the diet may increase the risk of prostate cancer. Calcium supplements and non-dairy calcium were not linked with an increased risk of prostate cancer.

Population studies

• Population studies of dairy products, dietary calcium, and prostate cancer risk have shown mixed results. Age, body mass index (BMI), and other nutrients in dairy products may affect study results.

Clinical trials

• In a randomized clinical trial reported in 2005, men were given calcium or a placebo for 4 years and were followed for 12 years. During the first 6 years of the study, there were fewer cases of prostate cancer in the calcium group than in the placebo group. But after 10 years, there was no difference in the number of prostate cancers between the two groups.

Is calcium approved by the U.S. Food and Drug Administration (FDA) for use as a cancer treatment in the United States?

The FDA has not approved the use of calcium as a treatment for cancer.

The FDA does not approve dietary supplements as safe or effective. The company that makes the dietary supplements is responsible for making sure that they are safe and that the claims on the label are true and do not mislead the consumer. The way that supplements are made is not regulated by the FDA, so all batches and brands of calcium supplements may not be the same.

What is green tea?

Tea comes from the Camellia sinensis plant. The way tea leaves are processed determines whether green tea, black tea, or oolong tea is made. Green tea is made by steaming and drying the leaves.

The health benefits studied in green tea are thought to be from compounds called polyphenols. Polyphenols are a group of plant chemicals that include catechins (antioxidants that help protect cells from damage). Catechins make up most of the polyphenols in green tea and vary based on the source of the tea leaves and how they are processed. This makes it hard to identify most of the chemical factors linked to the health benefits of green tea.

Some studies have suggested that green tea may protect against heart and blood vessel disease.

How is green tea given or taken?

People usually drink green tea or take it as a dietary supplement.

Have any laboratory or animal studies been done using green tea?

For information on laboratory and animal studies done using green tea, see the Laboratory/Animal/Preclinical Studies section of the health professional version of Prostate Cancer, Nutrition, and Dietary Supplements.

Have any studies of green tea been done in people?

Population studies and clinical trials have been done to find out if green tea can prevent or treat prostate cancer. Results have been mixed; some studies have shown a short-term decrease in prostate-specific antigen (PSA) level or a lower risk of having prostate cancer, and others have not. There is not enough evidence to know whether green tea can prevent or treat prostate cancer.

Population studies

• Overall, population studies suggest that green tea may help protect against prostate cancer in Asian populations. Prostate cancer deaths in Asia are among the lowest in the world.

Clinical trials

• In two randomized clinical trials in men at high risk of prostate cancer (high-grade prostatic intraepithelial neoplasia [HGPIN]), those treated with green tea catechins had lower rates of prostate cancer than those treated with a placebo. A 2017 randomized clinical trial in men with HGPIN found that those treated with green tea catechins for 1 year had decreased PSA levels, though no decrease in rates of prostate cancer, compared with the placebo group. Overall, findings suggest that green tea catechins lower PSA levels and may lower the risk of prostate cancer in men at high risk for the disease. However, these clinical trials were limited to small numbers of people, and it is not clear if the benefits reported were from green tea.

Have any side effects or risks been reported from green tea?

A trial of oral green tea extract in patients with solid tumors reported that drinking 7 to 8 Japanese-style cups (equal to 3 ½ to 4 cups U.S.) of tea 3 times a day for 6 months was a safe dose.

Clinical trials have reported on the safety of long-term use of green tea to prevent prostate cancer. In a United States trial, men at risk of prostate cancer were given green tea extract or a placebo for 1 year. There were more side effects in the group who received the green tea extract than in the group who received the placebo.

In safety studies of green tea for men with prostate cancer, short-term green tea use for up to 90 days was well tolerated. One study found that the most reported side effects of green tea were headache, chest pain, or gastrointestinal symptoms, such as nausea and diarrhea. These were mild except for two reports of trouble breathing and severe anorexia. In men with advanced prostate cancer, side effects reported include insomnia, confusion, and fatigue. In rare cases, liver problems have occurred.

Is green tea approved by the U.S. Food and Drug Administration (FDA) for use as a cancer treatment in the United States?

The FDA has not approved the use of green tea as a treatment for cancer or any other medical condition.

The FDA Division of Drug Oncology Products recommends that green tea extract be taken with food by participants in clinical trials and that frequent liver function tests be considered during treatment, especially in the first few months of starting a clinical trial.

Green tea is available in the United States in food products and dietary supplements. The FDA does not approve dietary supplements as safe or effective. The company that makes the dietary supplements is responsible for making sure that they are safe and that the claims on the label are true and do not mislead the consumer. The way that supplements are made is not regulated by the FDA, so all batches and brands of green tea supplements may not be the same.

What is lycopene?

Lycopene is a carotenoid (a natural red color made by plants). It mixes with or dissolves in fats. Lycopene protects plants from light-related stress and helps them use the energy of the sun to make nutrients. Lycopene is found in fruits and vegetables like tomatoes, apricots, guavas, and watermelons.

The main source of lycopene in the United States is tomato-based products. Lycopene is easier for the body to use when it is eaten in processed tomato products like tomato paste and tomato puree than in raw tomatoes.

Lycopene has been studied for its role in the prevention of heart and blood vessel disease.

How is lycopene given or taken?

Lycopene may be eaten in food or taken in dietary supplements.

Have any laboratory or animal studies been done using lycopene?

For information on laboratory and animal studies done using lycopene, see the Laboratory/Animal/Preclinical Studies section of the health professional version of Prostate Cancer, Nutrition, and Dietary Supplements.

Have any studies of lycopene been done in people?

Population studies and clinical trials have been done to find out if lycopene can prevent or treat prostate cancer. Clinical trials have shown mixed results; some studies have shown a lower risk of prostate cancer or a decrease in prostate-specific antigen (PSA) level, and others have not. There is not enough evidence to know whether lycopene can prevent or treat prostate cancer.

Population and combined studies

• Some population studies in men have found that high amounts of lycopene in the diet are linked with a lower risk of prostate cancer.
• Some studies have shown that lycopene levels in the blood and tissue of people with cancer are lower than in those who do not have cancer. However, other studies have not shown this.
• Reviews done in 2015 and 2017 of combined studies analyzed lycopene in the diet and lycopene levels in the blood. Both reviews found that higher lycopene intake and higher blood levels of lycopene were linked with lower prostate cancer risk.
• A 2006 study done in men who took part in the National Cancer Institute's Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial found no link between lycopene and tomatoes in the diet and prostate cancer risk in men with no family history of prostate cancer. However, in men with a family history of the disease, higher amounts of lycopene in the diet were linked with a lower risk of prostate cancer.

Sources and types of lycopene, types of diets, genetic risk factors, obesity, tobacco and alcohol use, and other factors, may play a part in mixed study results. Most research has studied the effects of lycopene on the risk of all prostate cancers, and has not studied effects of lycopene on low-grade prostate cancer compared with high-grade prostate cancer.

There are other trials of combination therapies that include lycopene in the Combination Therapies section of this summary.

Have any side effects or risks been reported from lycopene?

Lycopene has been given in many clinical trials with very few side effects. Side effects, such as diarrhea, nausea and vomiting, bloating, increased gas, and stomach irritation have been reported. In one study, symptoms went away when lycopene was taken with meals.

Is lycopene approved by the U.S. Food and Drug Administration (FDA) for use to prevent or treat cancer in the United States?

The FDA has not approved the use of lycopene as a treatment for cancer or any other medical condition.

Lycopene is deemed Generally Recognized as Safe by the FDA.

Lycopene is available in the United States in food products and dietary supplements. The FDA does not approve dietary supplements as safe or effective. The company that makes the dietary supplements is responsible for making sure that they are safe and that the claims on the label are true and do not mislead the consumer. The way that supplements are made is not regulated by the FDA, so all batches and brands of lycopene supplements may not be the same.

What is modified citrus pectin?

Pectin is a substance made of small sugar molecules that are linked together. Pectin is found in the cell wall of most plants and has gel-like qualities that are useful in making many types of food and medicine.

Citrus pectin is found in the peel and pulp of citrus fruits such as oranges, grapefruit, lemons, and limes. Citrus pectin can be modified (changed) during manufacturing so that it can be dissolved in water and absorbed by the body. This changed citrus pectin is called modified citrus pectin (MCP).

How is MCP given or taken?

MCP may be taken by mouth in powder or capsule form.

Have any laboratory or animal studies been done using MCP?

For information on laboratory and animal studies done using MCP, see the Laboratory/Animal/Preclinical Studies section of the health professional version of Prostate Cancer, Nutrition, and Dietary Supplements.

Have any studies of MCP been done in people?

Few studies have been done in men with prostate cancer. There is not enough evidence to know whether MCP has any effect on prostate cancer.

Have any side effects or risks been reported from MCP?

Side effects that have been reported include itching, stomach upset, abdominal cramps, increased gas, and diarrhea.

Is MCP approved by the U.S. Food and Drug Administration (FDA) for use to prevent or treat cancer in the United States?

The FDA has not approved the use of MCP as a treatment for cancer or any other medical condition.

MCP is available in the United States in food products and dietary supplements. The FDA does not approve dietary supplements as safe or effective. The company that makes the dietary supplements is responsible for making sure that they are safe and that the claims on the label are true and do not mislead the consumer. The way that supplements are made is not regulated by the FDA, so all batches and brands of MCP supplements may not be the same.

What is pomegranate?

The pomegranate is a fruit grown in Asia and in the Mediterranean, East Indies, Africa, and the United States. Pomegranate has been used as medicine for hundreds of years.

The pomegranate is made up of the following:

• The peel, which makes up half the fruit and contains polyphenols and minerals.
• The seeds.
• The aril (the layer between the peel and the seeds), which contains phenolics and flavonoids including anthocyanins, which give the pomegranate fruit and juice a red color.

How is pomegranate given or taken?

Pomegranate fruit and juice may be taken as food, drink, or a dietary supplement.

Have any laboratory or animal studies been done using pomegranate?

For information on laboratory and animal studies done using pomegranate, see the Laboratory/Animal/Preclinical Studies section of the health professional version of Prostate Cancer, Nutrition, and Dietary Supplements.

Have any studies of pomegranate been done in people?

In a 2015 study, 183 men with recurrent prostate cancer were randomly assigned to receive either pomegranate juice, pomegranate extract, or a placebo. The study found no difference in how fast the prostate-specific antigen (PSA) level rose between the 3 groups. There is not enough evidence to know whether pomegranate can prevent or treat prostate cancer.

Have any side effects or risks been reported from pomegranate?

No serious side effects have been reported from the use of pomegranate.

Is pomegranate approved by the U.S. Food and Drug Administration (FDA) for use to prevent or treat cancer in the United States?

The FDA has not approved the use of pomegranate as a treatment for cancer or any other medical condition.

Pomegranate is available in the United States in food products and dietary supplements. The FDA does not approve dietary supplements as safe or effective. The company that makes the dietary supplements is responsible for making sure that they are safe and that the claims on the label are true and do not mislead the consumer. The way that supplements are made is not regulated by the FDA, so all batches and brands of pomegranate supplements may not be the same.

What is selenium?

Selenium is a mineral that is essential to people in tiny amounts. Selenium is needed for many body functions, including reproduction and immunity. Food sources of selenium include meat, vegetables, and nuts. The amount of selenium found in the food depends on the amount of selenium in the soil where the food grows. Selenium is stored in the thyroid gland, liver, pancreas, pituitary gland, and kidneys.

Selenium may play a role in many diseases, including cancer. Results of the large National Cancer Institute -sponsored Selenium and Vitamin E Cancer Prevention Trial (SELECT) suggest that men with prostate cancer should not take selenium supplements.

How is selenium given or taken?

Selenium may be eaten in food or taken in dietary supplements.

Have any laboratory or animal studies been done using selenium?

For information on laboratory and animal studies done using selenium, see the Laboratory/Animal/Preclinical Studies section of the health professional version of Prostate Cancer, Nutrition, and Dietary Supplements.

Have any studies of selenium been done in people?

Population studies and clinical trials have been done to find out if selenium can prevent or treat prostate cancer. The results of these studies have been mixed, but the results of a large, randomized clinical trial showed selenium had no effect on preventing prostate cancer.

Combined studies

• A review of 15 studies found that blood selenium levels and levels of selenium measured in toenail clippings were linked to a decreased risk of prostate cancer.

Population studies

• One study tracking men for up to 10 years found that those who had high levels of selenium in their blood had a lower risk of prostate cancer. However, a 2009 study found that men with high selenium levels were at greater risk of being diagnosed with aggressive prostate cancer. These differences may be due to genetic factors.
• The Health Professionals Follow-Up Study included 4,459 men with prostate cancer that had not spread to other parts of the body. The study found that taking selenium supplements after diagnosis may increase the risk of death from prostate cancer. The study investigators recommended that men with prostate cancer use caution in taking selenium supplements.

The Selenium and Vitamin E Cancer Prevention Trial (SELECT)

SELECT was a large clinical trial begun by the National Cancer Institute in 2001 to find out whether selenium and/or vitamin E could help prevent prostate cancer when taken as dietary supplements. Over 35,000 men, aged 50 years and older, were randomly assigned to receive one of the following combinations daily for 7 to 12 years:

• Vitamin E and a placebo.
• Selenium and a placebo.
• Vitamin E and selenium.
• Two placebos.

Early results of SELECT reported in 2009 found no difference in the rate of prostate cancer among the 4 groups. In the selenium alone group, there was a slight increase in the rate of diabetes mellitus. Even though this change was not clearly shown to be due to the supplement, the men in the study were advised to stop taking the study supplements.

Updated results of SELECT in 2011 showed that selenium supplements had no effect on prostate cancer risk.

In 2014, further results of SELECT showed that selenium supplements in men with low selenium levels at the start of the trial had no effect on prostate cancer risk. However, selenium supplements in men who had high levels of selenium at the start of the trial increased the risk of aggressive prostate cancer.

A study of 1,434 men in SELECT suggested that changes in certain genes which control the way selenium is used by the body may have an effect on the risk of prostate cancer.

Several factors may have affected study results, including the dose of vitamin E and the form of selenium used. The authors concluded that men should avoid selenium at doses that are higher than the recommended dietary intake.

Have any side effects or risks of selenium supplements been reported?

Selenium supplements have been well tolerated in many clinical trials. But, in the SELECT trial, the use of selenium supplements was linked with a slight increase in the rate of diabetes mellitus.

In several large studies, men with high selenium levels were at greater risk of being diagnosed with aggressive prostate cancer or dying from prostate cancer.

Is selenium approved by the U.S. Food and Drug Administration (FDA) for use as a cancer treatment in the United States?

The FDA has not approved the use of selenium supplements for the treatment or prevention of cancer.

Selenium is available in the United States in food products and dietary supplements. The FDA does not approve dietary supplements as safe or effective. The company that makes the dietary supplements is responsible for making sure that they are safe and that the claims on the label are true and do not mislead the consumer. The way that supplements are made is not regulated by the FDA, so all batches and brands of selenium supplements may not be the same.

What is soy?

The soybean plant has been grown in Asia for food for hundreds of years. The soybean can be made into products, such as soy milk, miso, tofu, soy flour, and oil.

Soy foods contain phytochemicals that may have health benefits. Isoflavones are the most widely studied compounds in soy. Major isoflavones in the soybean include genistein, daidzein, and glycitein.

Isoflavones are phytoestrogens (estrogen -like substances found in plants) that attach to estrogen receptors found in prostate cancer cells. Genistein may affect some processes inside prostate cancer cells that are involved in the growth and spread of cancer.

How is soy given or taken?

Soy may be eaten in food or taken in dietary supplements.

Have any laboratory or animal studies been done using soy?

For information on laboratory and animal studies done using soy, see the Laboratory/Animal/Preclinical Studies section of the health professional version of Prostate Cancer, Nutrition, and Dietary Supplements.

Have any studies of soy been done in people?

Population studies and clinical trials have been done to find out if soy can prevent or treat prostate cancer. The results of these studies have been mixed. Some studies have shown a lower risk of prostate cancer or a change in prostate-specific antigen (PSA) level, and others have not. The results may be mixed because of the small number of men who participated in the studies and the different types and doses of soy products given.

Combined population studies

• A 2018 review showed that men eating large amounts of nonfermented soy foods (for example, tofu and soybean milk) had a lower risk of prostate cancer. Eating large amounts of fermented foods (for example, miso) was not found to affect the risk of prostate cancer. However, these results may have been affected by the way the data were collected, the types of soy taken, and genetic risk factors.

Clinical trials

Small randomized clinical trials have been done to study the effects of isoflavones or soy on prostate cancer. The results of these studies have been mixed. See Table 3, Table 4, and Table 5 of the health professional version of this summary for information on randomized, placebo-controlled clinical trials of isoflavones and soy.

Have any side effects or risks been reported from soy?

Soy products and isoflavones have been taken by prostate cancer patients with very few side effects in many clinical trials. The most commonly reported side effects were gastrointestinal symptoms, such as diarrhea.

Is soy approved by the U.S. Food and Drug Administration (FDA) for use to prevent or treat cancer in the United States?

The FDA has not approved the use of soy as a treatment for cancer or any other medical condition.

Soy is available in the United States in food products and dietary supplements. The FDA does not approve dietary supplements as safe or effective. The company that makes the dietary supplements is responsible for making sure that they are safe and that the claims on the label are true and do not mislead the consumer. The way that supplements are made is not regulated by the FDA, so all batches and brands of soy supplements may not be the same.

What is vitamin D?

Vitamin D is a fat-soluble vitamin found in fatty fish, fish liver oil, and eggs. Vitamin D may also be added to dairy products.

Vitamin D has many functions in the body, such as the following:

• Helps absorb calcium from food in the small intestine.
• Improves muscle strength and immune system function.
• Lowers inflammation.
• Maintains levels of calcium and phosphate in the blood.
• Helps with bone growth and protects against osteoporosis in adults.

A person's vitamin D level is checked by measuring the amount of 25-hydroxyvitamin D in the blood.

How is vitamin D given or taken?

Vitamin D is made by the body when exposed to sunlight. Vitamin D may also be eaten in food or taken in dietary supplements.

Have any laboratory or animal studies been done using vitamin D?

For information on laboratory and animal studies done using vitamin D, see the Laboratory/Animal/Preclinical Studies section of the health professional version of Prostate Cancer, Nutrition, and Dietary Supplements.

Have any studies of vitamin D been done in people?

Population studies and clinical trials have been done to study the effects of vitamin D on prostate cancer. The results of these studies have been mixed. Some studies have shown a link between Vitamin D levels and prostate cancer, and others have not. There is not enough evidence to know whether vitamin D can prevent prostate cancer.

Combined studies

• A 2008 review of 45 studies found no link between taking vitamin D and prostate cancer risk.
• A 2009 study found that men with low levels of sun exposure had an increased risk of prostate cancer and advanced disease.
• A 2011 review of 25 studies found no link between either vitamin D in the diet or blood levels of vitamin D and the risk of prostate cancer.
• A 2014 review of 21 studies found that high levels of vitamin D may be linked with a higher risk of prostate cancer. Many factors may have affected this finding. It has been proposed that men from higher income groups may have higher vitamin D levels and are more likely to get PSA testing, leading to higher rates of reported prostate cancer.

Population studies

• Vitamin D levels were checked every year for 5 years in men with prostate cancer that had not spread. Throughout the study, low levels of vitamin D were found in these men.
• Another study in men with prostate cancer suggested that medium or high levels of vitamin D in the blood may be linked with better outcomes than lower levels.
• One thousand men with prostate cancer and 1,000 men who did not have prostate cancer were followed for up to 20 years in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. Results suggested that men with higher blood levels of vitamin D had a greater risk of prostate cancer than men with lower vitamin D levels.
• In an analysis from the Selenium and Vitamin E Cancer Prevention Trial (SELECT), men who had moderate blood levels of 25-hydroxyvitamin D were found to have a lower risk of aggressive prostate cancer than men who had either lower or higher levels of 25-hydroxyvitamin D.
• A study of patterns of deaths in the United States from 1950 to 1994 showed that higher death rates from prostate cancer occurred in parts of the country with lower levels of UV radiation from sunlight.

Clinical trials

• In a 2018 randomized controlled trial, vitamin D3 and omega-3 fatty acid supplements were given to prevent cancer and cardiovascular disease. Those who took the vitamin D supplement did not have a lower rate of any cancer.
• A clinical trial treated patients with prostate cancer that had recurred (come back) with calcitriol (the active form of vitamin D) and naproxen for 1 year. Results showed that after taking calcitriol and naproxen the prostate-specific antigen (PSA) level rose more slowly.
• In a 2010 study, patients with prostate cancer that did not respond to hormone therapy were treated with calcitriol and dexamethasone. The results showed no effect on PSA levels.
• In a 2009 study, patients with locally advanced or metastatic prostate cancer were treated with vitamin D. The study reported that 1 in every 5 patients who took vitamin D had lower PSA levels.

Have any side effects or risks been reported from vitamin D?

Vitamin D can cause serious health problems when taken at high doses over many years. Taking high levels of Vitamin D can cause too much calcium to be absorbed in the intestines, leading to rapid increases in blood calcium levels. This condition is called hypercalcemia.

In a group of 26 studies, Vitamin D was reviewed for safety, how well it works, and whether it interacts with drugs used to treat prostate cancer and other tumors. The reviewers found the risk of side effects and interactions with other drugs to be low.

Several studies looked at the safety of high-dose vitamin D and how well it works with chemotherapy (docetaxel) to treat men with prostate cancer that did not respond to hormone therapy. The side effects that occurred after treatment with high-dose vitamin D and docetaxel were the same as the side effects noted after treatment with docetaxel alone.

Is vitamin D approved by the U.S. Food and Drug Administration (FDA) for use as a cancer treatment in the United States?

The FDA has not approved the use of vitamin D as a treatment for cancer.

Vitamin D is available in the United States in food products and dietary supplements. The FDA does not approve dietary supplements as safe or effective. The company that makes the dietary supplements is responsible for making sure that they are safe and that the claims on the label are true and do not mislead the consumer. The way that supplements are made is not regulated by the FDA, so all batches and brands of vitamin D supplements may not be the same.

What is vitamin E?

Vitamin E is an antioxidant that may help protect cells from damage. Vitamin E also affects how signals are sent within cells and how the cell makes RNA and proteins.

There are eight forms of vitamin E: four tocopherols (alpha-, beta-, gamma-, and sigma-) and four tocotrienols (alpha-, beta-, gamma-, and sigma-). Alpha-tocopherol, the form of vitamin E used in dietary supplements, is found in greater amounts in the body and is the most active form of vitamin E. Most vitamin E in the diet comes from gamma-tocopherol. Food sources of vitamin E include vegetable oils, nuts, and egg yolks.

Vitamin E may protect against chronic diseases, such as heart and blood vessel disease.

How is vitamin E given or taken?

Vitamin E may be eaten in food or taken in dietary supplements.

Have any studies of vitamin E been done in people?

Population studies and clinical trials have been done to find out if vitamin E may prevent prostate cancer. The results of these studies have been mixed; some studies have shown no change in the overall risk of prostate cancer, and others have shown an increased risk of prostate cancer. There is not enough evidence to know whether vitamin E affects the risk of prostate cancer.

Combined population studies

• In a review of combined studies with about 370,000 men from several countries, higher blood levels of alpha-tocopherol were linked with a lower risk of prostate cancer.

Population studies

• The National Institutes of Health –American Association of Retired Persons (NIH-AARP) Diet and Healthy Study studied whether taking increased amounts of vitamin E in the diet and in dietary supplements could prevent prostate cancer. After 5 years, no link between vitamin E supplements and prostate cancer risk was found. However, a lower risk of advanced prostate cancer was found in men who took high amounts of gamma-tocopherol.
• In a 2010 study that measured blood levels of vitamin E, the men who had prostate cancer had lower blood levels of vitamin E than those who did not have prostate cancer. In addition, those who had higher PSA levels had lower levels of vitamin E in their blood.
• The Alpha-Tocopherol, Beta Carotene Cancer Prevention Study (ATBC) trial measured blood levels of alpha-tocopherol and dietary intake of vitamin E in men who were followed for up to 19 years. Results showed no link between vitamin E in the diet and prostate cancer risk. However, higher levels of alpha-tocopherol in the blood may be linked with a lower risk of advanced prostate cancer.

  Men in the ATBC trial who developed prostate cancer were studied to find out if blood levels of alpha-tocopherol affected survival time. Higher blood levels of alpha-tocopherol, at both time of diagnosis and at the 3-year time point, were linked with improved prostate cancer survival.

The Selenium and Vitamin E Cancer Prevention Trial (SELECT)

SELECT was a large clinical trial begun by the National Cancer Institute in 2001 to find out whether selenium and/or vitamin E could help prevent prostate cancer when taken as dietary supplements. Over 35,000 men, aged 50 years and older, were randomly assigned to receive one of the following combinations daily for 7 to12 years:

• Vitamin E and a placebo.
• Selenium and a placebo.
• Vitamin E and selenium.
• Two placebos.

SELECT results published in 2011 showed that men taking vitamin E alone had a 17% increase in prostate cancer risk compared with men who did not take vitamin E.

Several factors may have affected study results, including the dose of vitamin E.

Clinical trials

• In the Physicians' Health Study II, men took either vitamin E supplements, vitamin C supplements, or both and were followed for about 8 years. The overall rates of prostate cancer were similar in the men who took vitamin E supplements and in those who did not. Vitamin E did not affect the number of new cases of cancer or the number of deaths from cancer.
• A 2011 study of men who took part in The Carotene and Retinol Efficacy Trial (CARET) found that, among those who were current smokers, higher blood levels of alpha-tocopherols and gamma-tocopherols were linked with lower risk of aggressive prostate cancer. In another study of men who were current smokers or who recently stopped smoking, higher blood levels of alpha-tocopherol were linked to a lower risk of prostate cancer.

Have any side effects or risks been reported from vitamin E?

In the Physicians' Health Study II and the Alpha-Tocopherol, Beta Carotene Cancer Prevention Study Group, there was a higher number of strokes caused by a broken blood vessel in the brain in men who took vitamin E than in men who took a placebo.

Is vitamin E approved by the U.S. Food and Drug Administration (FDA) for use as a cancer treatment in the United States?

The FDA has not approved the use of vitamin E as a treatment for cancer.

Alpha-tocopherols are deemed Generally Recognized as Safe by the FDA.

Vitamin E is available in the United States in food products and dietary supplements. The FDA does not approve dietary supplements as safe or effective. The company that makes the dietary supplements is responsible for making sure that they are safe and that the claims on the label are true and do not mislead the consumer. The way that supplements are made is not regulated by the FDA, so all batches and brands of vitamin E supplements may not be the same.