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Prostate cancer

Prostate cancer is the most common cancer among American men and, behind lung cancer, is the #2 cause of cancer death among men. The prostate is a walnut-sized muscular gland that secretes a thin, milky, fluid that lubricates the urethra (duct for urine and ejaculatory fluids) and helps sperm survive after ejaculation. It surrounds the urethra and for this reason, conditions affecting the size or shape of the prostate directly affect urinary and sexual function.

Like breast cancer, prostate cancer is a "hormone-sensitive" disease. Its development and progress is strongly influenced by the various natural (made by the body) and artificial (from food and environment) hormones in the body. The relative balance of these hormones is influenced by aging, dietary intake, detoxification function of the liver and intestines, exercise, smoking, and exposure to hormone-like chemicals from food and the environment.

Eat more

  • Cold water fish such as salmon, tuna, herring, mackerel and halibut for their beneficial omega 3 fatty acids
  • Flaxseeds
  • Tomatoes and tomato products (June 3, 2004)
  • Organically grown fruits and vegetables, especially the Brassica vegetables which includes broccoli, kale, mustard greens and Brussesl sprouts
  • Greens rich in vitamin E such as mustard greens, Swiss chard, turnip greens, collard greens, kale and spinach. (May 6, 2004)
  • Legumes
  • Nuts and seeds
  • Whole cranberries (October 19, 2004)

Avoid dairy; excess fat,especially the omega 6 polyunsaturated fats found in high amounts in most vegetable oils (except for olive oil, which is low in omega 6) (March 25, 2004); , canola, soy and flaxseed oils, which are high in alpha linolenic acid (June 30, 2004); excess calcium, and well done meat.

Description

Prostate cancer is the most common cancer among American men and, behind lung cancer, is the #2 cause of cancer death among men. Though the risk for prostate cancer and other prostate problems is strongly related to genetics, other controllable lifestyle factors seem to be even more important. Factors associated with a higher risk for prostate disease and cancer include:

  • High blood pressure (hypertension)
  • Diabetes (Type 2 or adult-onset diabetes)
  • High insulin levels in the blood
  • High levels of high-density lipoproteins (HDLs)
  • Having a “spare tire” or “beer belly”
  • Sedentary lifestyle
  • Diet high in fat, especially animal fat
  • Excessive intake of calcium, especially from dairy sources
  • Diet high in red meat
  • History of kidney stones
  • History of sexually transmitted disease
  • Exposure to the heavy metal cadmium
  • Exposure to agricultural chemicals
  • Allergies
  • Aging

Like breast cancer, prostate cancer is a “hormone-sensitive” disease. Its development and progress is strongly influenced by the various natural (made by the body) and artificial (from food and environment) hormones in the body. Many lifestyle factors such as diet, physical activity, and stress management address how the body metabolizes these important and influential hormones.

The prostate is a walnut-sized muscular gland that secretes a thin, milky, fluid that lubricates the urethra (duct for urine and ejaculatory fluids) and helps sperm survive after ejaculation. It surrounds the urethra and for this reason, conditions affecting the size or shape of the prostate directly affect urinary and sexual function.

The prostate is sensitive both to “male” hormones (androgens such as testosterone and androstenedione) and to “female” hormones (prolactin or estrogens such as estradiol and estrone). Though these are called “male” and “female” hormones, they all naturally occur in both men and women. It is their relative balance that results in good health or in discomfort.

The relative balance of these hormones is influenced by aging, dietary intake, detoxification function of the liver and intestines, exercise, smoking, and exposure to hormone-like chemicals from food and the environment.

Prostate cancer is a hormone-sensitive cancer (as is breast cancer) that will probably affect one in six American men. Each year roughly 200,000 American men are diagnosed with it, and over 30,000 die from it. However, because prostate cancer tends to progress slowly, it is not always life-threatening. Many men wait rather than having medical intervention immediately after their diagnosis, or opt for lifestyle changes.

In its early stages, prostate cancer does not usually cause symptoms. When symptoms do occur, they can include any or all of the following:

  • Needing to urinate frequently, especially at night
  • Difficulty starting urination or holding back urine
  • Inability to urinate
  • Weak or interrupted flow of urine
  • Painful or burning urination
  • Difficulty having an erection
  • Painful ejaculation
  • Blood in the urine or semen
  • Frequent pain or stiffness in the lower back, hips, or upper thighs

These symptoms are not specific for prostate cancer. The first four, especially, are also typically seen in cases of prostate enlargement, a benign condition. The other symptoms may also be caused by infections or prostatitis. If you are experiencing any of these symptoms, it is important to see a doctor immediately.

Dietary Causes

There is so much convincing evidence on the role of diet in prostate cancer that Dr. William Fair and his colleagues from the Memorial Sloan Kettering Cancer Center suggest that prostate cancer may be considered a “nutritional disease.”

Dietary factors associated with a higher risk for prostate cancer include:

  • High level of total fat in the diet
  • High intake of saturated fats and animal fats
  • High intake of omega 6-rich polyunsaturated fats (March 25, 2004)
  • Excessive calcium intake
  • High milk consumption (milk is a source of calcium, cholesterol, and animal fat, all of which are separate risk factors for prostate cancer)
  • High intake of red meat (especially grilled, fried, and broiled meats, which contain carcinogens)
  • Low intake of fish or omega-3 essential fats
  • Low intake of fruits and vegetables
  • Low intake of mustard family vegetables, which contain especially protective nutrients
  • Low intakes of selenium, vitamin E, lycopene, and other dietary antioxidants

Dietary factors associated with a lower risk for prostate cancer include:

  • High intake of soy foods (tofu, tempeh, texturized vegetable protein or TVP, soy nuts, soy milk, soy cheese, soy dogs, soy burgers, etc.)
  • High intake of the antioxidants selenium and vitamin E
  • High intake of whole grains, nuts, and seeds
  • Vegetarian diet
  • Adequate intake of vitamin D
  • Frequent consumption of tomatoes, especially cooked tomatoes in products such as tomato paste and tomato sauce, particularly if the tomato products also contain a little oil (June 3, 2004)
A special note for African-American men:

African-American men develop prostate cancer twice as frequently as Caucasian men, and though genetics may play a role, dietary differences between these groups of men are clearly involved. In African-American men, greater consumption of foods high in animal fat is even more strongly linked to prostate cancer than it is for men in general.

One reason for this may be that African-American men, on average, consume 2 to 3 times as much of a particular group of carcinogenic substances (called heterocyclic amines) that are found in fried, broiled, and grilled meats. It is therefore particularly important for African-American men to limit their intakes of these foods.

Nutrient Needs

Soyfoods

Soyfoods (such as soymilk, tofu, tempeh, texturized vegetable protein or TVP, soy burgers, and soy dogs) can play an important protective role against prostate cancer. A major study of diet and prostate cancer among men in 42 countries found that soyfoods were the single most significant dietary influence reducing the number of deaths from prostate cancer.

Soyfoods contain “isoflavones,” natural substances with weak estrogen-like activity that seem to modulate how the body responds to the estrogens naturally produced by men and women. Consumption of soyfoods is associated with lower rates of numerous hormone-related diseases, including prostate and breast cancer.

Among Japanese men, the lower incidence of prostate disease and lower rate of death from prostate cancer are thought to be related to their lifelong intake of isoflavones, and in American Adventist men, a high intake of soymilk is associated with a 70 percent reduction in prostate cancer risk. The isoflavones in these simple but remarkable foods show a wide variety of protective effects in laboratory studies, inhibiting the responses of normal prostate cells and of cancer cells to many stimuli that would usually cause them to grow abnormally.

A study published in the July 2003 issue of Cancer Epidemiological Markers supports the substantial protective benefit to be derived from eating soy foods. In this study of 398 Chinese men (133 men with prostate cancer and 265 age and residential community matched controls between the ages of 50 and 89), those consuming the most tofu had a 42% lower risk of developing prostate cancer compared to those consuming the least. When researchers checked the relationship between the soy isoflavones, genistein and daidzen, which are found not only in tofu, but in soy beans and other foods made from them, those consuming the most genistein were found to have a 47% lower risk for prostate cancer, while those consuming the most daidzen had a 44% lower risk.(September 8, 2003)

Soyfoods Shown to Stop the Form of Testosterone that Promotes Prostate Cancer

A molecule formed in the intestine when soy is digested can attach to and completely stop DHT, the potent form of testosterone that stimulates prostate cancer, acne and male pattern baldness, suggests an animal study published in the April 2004 issue of Biological Reproduction.

The molecule, named equol, is formed from one of the main isoflavones abundant in soy, the phytoestrogen daidzein. Equol promotes the best of all male worlds as it prevents only the dangerous DHT, but not beneficial testosterone, from binding to the androgen (male hormone) receptor.

According to Kenneth Setchell, the researcher who first identified equol in humans 20 years ago, "These findings are of immense clinical importance because blocking the action of the potent androgen DHT has been one of the holy grails of the pharmaceutical industry as a strategy for treating prostate cancer and other related diseases.”

While the pharmaceutical industry has developed drugs that inhibit the enzyme that converts testosterone to DHT, the drugs are costly and have unpleasant side effects. Equol doesn’t prevent DHT from being produced, but completely inactivates it, achieving the same goal without affecting normal testosterone metabolism and without negative side effects." Directly binding and inactivating DHT without influencing testosterone gives equol the ability to reduce many of the harmful effects of androgens without affecting the beneficial ones," said Robert J. Handa, senior author of the study.

The researchers demonstrated that in male rats, injections of equol reduced the size of the prostate. The rats’ testes were removed to eliminate all DHT production. When investigators injected these rats with equol, nothing happened; when they DHT into the rats, their prostates grew, but when the rats were given equol along with the DHT, no prostate growth occurred—the equol prevented the DHT from stimulating prostate growth.

The researchers think equol’s protective action may explain why men in Japan, who typically and regularly eat soy, rarely develop prostate cancer despite the fact that, like men in the Western world, as they age, Japanese men suffer equally from BPH (benign prostatic hyperplasia). The researchers, hopeful that, because of DHT’s importance in both acne and male pattern baldness, equol may offer a means of promoting healthy skin and preventing hair loss, have begun further studies to evaluate equol’s potential in the treatment of these and other androgen-influenced conditions.(May 6, 2004)

Cranberries

Enjoy whole cranberries, not just cranberry juice. Cranberry presscake (the material remaining after squeezing juice from the berries), when fed to mice bearing human breast cancer cells, has previously been shown to decrease the growth and metastasis of tumors, and a new study published in the June 2004 issue of the Journal of Nutrition suggests compounds in whole cranberries also inhibit prostate, skin, lung and brain cancer cells as well.

Androgen-dependent prostate cancer cells were inhibited the most (just 10 mg of a warm water extract of cranberry presscake inhibited their growth by 50%). With androgen-independent prostate cancer cells and estrogen-independent breast cancer cells, a larger amount was needed but produced the same beneficial effect (250 mg of cranberry presscake extract inhibited their growth by 50%). Researchers concluded that the active compounds in whole cranberry prevent cancer by blocking cell cycle progression and inducing cells to undergo apoptosis (programmed cell death).(October 19, 2004)

Lycopene

Lycopene is a “carotenoid,” a natural antioxidant coloring found in fruits and vegetables that helps protect them from damage. In the body it is normally concentrated in the prostate and testes, and its consumption is associated with a lower prostate cancer risk. Interestingly, lycopene is the only carotenoid not found to be naturally lower in the blood of men versus women.

Low blood levels of lycopene are strongly associated with a higher risk for prostate cancer. These observations all seem to indicate a special protective role for lycopene in the hormone-sensitive prostate gland. Smoking, alcohol consumption, and lipid-lowering drugs decrease blood lycopene levels. But heating tomato foods before consumption and consuming tomato foods with moderate amounts of fat increases the bioavailability of lycopene. More than 80 percent of lycopene consumed in the United States comes from tomatoes, although apricots, papaya, pink grapefruit, guava, and watermelon also provide lycopene.

Tomatoes have been shown to be helpful in reducing the risk of prostate cancer in men, and it was thought that their protective effect was primarily due to their lycopene content. However, a 14-month study published in the November 2003 issue of the Journal of the National Cancer Institute has underscored the importance of whole tomatoes, not lycopene alone, in the prevention of prostate cancer. In this study, rats fed a lycopene-rich diet and treated with N-methyl-N-nitrosourea (a carcinogen) and testosterone to induce prostate cancer had a similar risk of death from prostate cancer as rats fed a control diet. In contrast, rats fed whole tomato powder were 26% less likely to die of prostate cancer. By the end of the study, 80% of the control group and 72% of the rats fed lycopene had succumbed to prostate cancer, while only 62% of the rats fed whole tomato powder had died.

In addition to the controls and those rats receiving lycopene or tomato powder, each group was also divided into two sub-groups, one of which was given 20% less food than the other sub-group. Rats on the energy-restricted, tomato-based diet fared best of all, showing a 32% drop in their risk of dying from prostate cancer.

Researchers concluded this was due to the fact that tomatoes contain not merely lycopene, but a variety of protective phytochemicals and suggest that the lycopene found in human prostate tissue and the blood of animals and humans who remain free of prostate cancer may indicate exposure to higher amounts of not just lycopene but other compounds working in synergy with it. Study leader, Dr. Steven Clinton, Ohio State University, commented, “Our findings strongly suggest that risks of poor dietary habits cannot be reversed simply by taking a pill…if we want the health benefits of tomatoes, we should eat tomatoes or tomato products and not rely on lycopene supplements alone.” In an accompanying editorial, Peter H. Gann, of the Robert H. Lurie Comprehensive Cancer Center at Northwestern University in Chicago, and Frederick Khachik, of the University of Maryland, College Park, remarked that this study supports those who advocate whole foods in the debate about whether cancer prevention is best achieved with whole foods or concentrated single compounds. They point out that carotenoids and other phytochemicals evolved as sets of interacting compounds, and that this complexity limits the usefulness of reductionist approaches that seek to identify single protective compounds. (December 8, 2003)



More Studies Show Tomatoes Protective agasint Prostate Cancer

In animal studies, published in the April 14 on-line edition of the FASEB Journal (the official publication of the Federation of American Societies for Experimental Biology) lycopene and vitamin E were also found to reduce prostate cancer risk. Vitamin E reduced androgen (male hormone) signaling without affecting normal androgen metabolism, and lycopene down-regulated 5-alpha reductase, the enzyme that converts testosterone to the much more potent, and prostate cancer-promoting DHT. In addition, lycopene down-regulated the production in the prostate of two inflammatory chemicals, the cytokines IGF-I and IL-6, both of which are risk factors for prostate cancer. (May 6, 2004)

A meta-analysis of 21 studies published in the March 2004 issue of Cancer Epidemiology Biomarkers and Prevention confirms that eating tomatoes, especially cooked tomatoes, provides protection against prostate cancer. (Meta-analyses are considered the gold standard in medical research since, by combining the results of numerous studies, they integrate the results that occurred in different settings and include a much larger group of people, so they are thought to provide a more accurate assessment.) When the data from all 21 studies was combined, men who ate the highest amounts of raw tomatoes were found to have an 11% reduction in risk for prostate cancer. Those eating the most cooked tomato products fared even better with a 19% reduction in prostate cancer risk. Even eating just one 6-ounce serving a day of raw tomato provided some benefit—a reduction in prostate cancer risk of 3%.(June 3, 2004)

How Tomatoes Protect against Cancer

New research by Dr. Joseph Levy and colleagues from Ben-Gurion University of the Negev, Beer-Sheva, Israel, may have identified the unique mechanism through which lycopene protects against cancer: activating cancer-preventive phase II enzymes.

When the researchers incubated breast and liver cancer cells with lycopene, the carotenoid triggered the production and activity of the phase II detoxification enzymes (NAD(P)H:quinone oxidoreductase (NQ01) and glutamylcysteine synthetase (GCS). Lycopene ramped up production and activity of these protective enzymes by causing the expression of a reporter gene called luciferase that then activated the “antioxidant response element” in other genes that encode the enzymes, thus causing the genes to direct increased enzyme production. In contrast, other carotenoids including beta-carotene, astaxanthin and phytoene did not have this effect. Since much epidemiological evidence indicates that lycopene acts synergistically with other phytochemicals to give tomatoes their protective effects, and recent studies have shown that eating tomato products prevents cancer more effectively than taking lycopene alone, the researchers concluded that other carotenoids stimulate phase II enzymes via different pathways from that used by lycopene. (May 6, 2004)

The Right Amount of Vitamin D

A study published in the January 2004 issue of the International Journal of Cancer involving more than 2,000 men in Norway, Finland and Sweden, found that those whose blood levels of vitamin D were either too low (>19nmol/l) or too high (<80nmol/l) had an increased prostate cancer risk. Men whose average serum concentration of vitamin D ranged from 40-60 nmol/l had the lowest risk of prostate cancer. The researchers theorize that when vitamin D serum concentration is too low, this leads to low tissue concentration of vitamin D and weakened control of cell division in prostate cells. When vitamin D levels are too high, however, this may lead to an increase in the production of the enzyme 24-hyrdoxylase, which inactivates vitamin D.

So what does this mean in terms of how much vitamin D-rich food a man should eat? It depends upon where he lives and how old he is. Since the process through which our bodies make vitamin D begins when our skin is exposed to sunlight, regular consumption of foods rich in vitamin D is especially important for men who live in northern latitudes, are homebound, or wear sunscreen or clothing that completely covers the body. Regular consumption of vitamin D-rich foods is especially important for older men who live in northern latitudes since the production of vitamin D precursors in the skin, and thus our ability to make the vitamin, decreases with age. Foods rich in vitamin D include sardines, salmon, tuna, shrimp, cod, snapper, halibut, eggs and vitamin D-fortified milk products. If these are all staples in your diet and you live in an area where sunshine is the norm year round, it might be wise to ask your doctor to check your serum concentration of 25(OH)-vitamin D to be sure it is not excessive. If you eat few of these foods and live in the sun-sparse north, you might also consider having your physician check to be sure your serum level of 25(OH)-vitamin D is not too low and adding a serving of vitamin D-rich food to your daily menu. (February 26, 2004)

Vitamin E

In addition to its well-known protective effects on cardiovascular function, vitamin E may provide specific antioxidant protection for prostate health. Especially among smokers, low blood levels of vitamin E relate to a higher risk of death from prostate cancer, and higher blood levels correlate to a lower incidence of prostate cancer as well as a reduced risk of death from prostate cancer. In the laboratory, prostate and breast cancer cells exposed to higher levels of vitamin E grow more slowly and are more likely to die than those exposed to lower levels. This fat-soluble vitamin is another important link in the nutritional chain of prostate protection.

New research presented at the annual meeting of the American Association for Cancer Research, held March 27-31, 2004, in Orlando, FL, found that people who eat the most vitamin E-containing foods are the least likely to have bladder or prostate cancer.

Bladder cancer, the fourth leading cause of death in men in the U.S. is also a leading cause of death in other industrialized countries such as Canada, France, Denmark, Italy, and Spain.

Reporting on the results of a study conducted at the University of Texas M.D. Anderson Cancer Center and Texas Woman's University, researcher Ladia M. Hernandez noted that "High intake of vitamin E from dietary sources alone was associated with a 42% reduced risk of bladder cancer, whereas high intake of vitamin E from dietary sources and supplements combined reduced the risk by 44%."

In the case control study from which these statistics were derived, Hernandez and colleagues developed a database based on published values of the tocopherol (vitamin E) content of foods and interviewed 468 bladder cancer patients and 534 healthy, cancer-free controls about their dietary and supplemental intake of the vitamin.

In a second study, data collected by researchers from the U.S. National Cancer Institute, the Fred Hutchinson Cancer Research Center and the National Public Health Institute of Finland showed that two vitamin E fractions, alpha- and gamma-tocopherol, lowered the risk of prostate cancer, alpha tocopherol by up to 53% and gamma-tocopherol by as much as 39%.

In this study, 100 men with prostate cancer and 200 without were selected from the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study cohort of 29,133 Finnish men, aged between 50 and 69 years.

Prior to this, the ATBC study had already demonstrated a 32% reduction in the rate of prostate cancer in men who took 50 mg of the alpha-tocopherol fraction of vitamin E daily for a period of five to eight years.

In the new study, men not taking supplements were included to evaluate serum levels of alpha- and gamma-tocopherol derived from their diets. The men who were randomized to receive a vitamin E supplement as part of the ATBC trial and who also had the highest serum vitamin E levels at baseline, indicating their diets supplied the most vitamin E, were found to have the lowest risk of prostate cancer.

Taken together, the two studies appear to support an increase in dietary alpha-tocopherol, but it should be noted that this form of the vitamin is typically found in greater concentrations in the blood than the gamma form largely because a protein in the liver called “alpha-tocopherol transfer protein” binds alpha-tocopherol and transfers it into the plasma. Our thought at the World’s Healthiest Foods is “Why limit yourself to one fraction of vitamin E when Mother Nature supplies them all, perfectly balanced in delicious foods?”

The best food sources of vitamin E include: greens (mustard greens, Swiss chard, turnip greens, collard greens, kale, spinach) sunflower seeds, broccoli, almonds, papaya, and olives. For an outstanding, vitamin E-rich dish you can prepare in less than 10 minutes, try steaming some whole kale leaves (5 minutes), transfer to a bowl, drizzle generously with olive oil, cut into bite-sized pieces, and toss with salt, pepper and almonds or sunflower seeds. If desired, top with a splash of lemon juice or balsamic vinegar (3-4 minutes). (May 6, 2004)

Selenium

Selenium is a crucial antioxidant in the body, and higher selenium levels in the body are associated with lower risks for numerous cancers, including prostate cancer. It works closely with vitamin E, and seems to protect prostate (and other) cells and their genetic material from damage by free radicals, heavy metals, and toxins.

Because the evidence from earlier studies with vitamin E and selenium were so promising, a number of larger studies are now in progress, including the SELECT (Selenium and Vitamin E Cancer Prevention Trial) Prostate Cancer Prevention Trial, the largest trial of its kind to date.

Brassica family vegetables

The members of the brassica family (also called cruciferous) vegetables - including broccoli, kale, cauliflower, cabbage, mustard, horseradish, and Brussels sprouts, as well as broccoli sprouts - provide unique nutrients (called glucosinolates) that support your body’s normal detoxification processes, which are necessary for maintaining healthy levels of both “male” and “female” hormones. Even within individual prostate cells, glucosinolates beneficially influence the metabolism of hormones, which may explain why a higher consumption of mustard family vegetables is associated with a lower risk for prostate cancer. In fact, a study that compared the diets of 602 men under 65 years of age without prostate cancer to 628 men newly diagnosed with prostate cancer found that the men least likely to develop prostate cancer were those who ate three or more servings of cruciferous vegetables every week. These men had a 41% decreased risk of prostate cancer compared with men who ate less than one serving per week, even after the researchers accounted for total vegetable intake.

Indole-3-carbinol (I3C), a naturally occurring component of Brassica vegetables, such as cabbage, broccoli, and Brussels sprouts, has been recognized as a promising anticancer agent against certain reproductive tumor cells. A study published in the December 2003 issue of Cancer, the journal of the American Cancer Society, looked at I3C’s effects on cell cycling progression and cancer cell proliferation in human prostate cancer cells. I3C was shown to suppress the growth of prostate cancer cells in a dose-dependent manner by blocking several important steps in cell cycling and also to inhibit the production of prostate specific antigen, a protein produced by the prostate whose rising levels may indicate prostate cancer. Researchers noted that the results of this study demonstrate that “I3C has a potent antiproliferative effect” in human prostate cancer cells, which qualifies it as “a potential chemotherapeutic agent” against human prostate cancer.(December 31,2003)

Vegetable Fiber

Not only how much fiber, but the source of the fiber a man consumes may affect his risk of prostate cancer, suggests a study published in the March 2004 issue of the International Journal of Cancer.

An Italian multi-center, case control study of 2,745 men aged 46-74 (1,294 men with prostate cancer and 1451 controls) found that while men with the highest intake of all kinds of fiber had a 7% lower risk of developing prostate cancer, those men who obtained most of their fiber from vegetables were 18% less likely to develop prostate cancer. Fiber from fruits and grains was not associated with a reduction in prostate cancer risk. These associations held regardless of age, family history of prostate cancer, body mass index and education level. (May 6, 2004)

Zinc

Zinc is used by the body in hundreds of processes, and is critical for the normal hormonal, immune system, and genetic function. It is concentrated more highly in the prostate than in any other human tissue, and low levels of zinc in the prostate relate to a higher risk for prostate cancer. Our intake of zinc usually decreases when we age, as does our absorption of zinc from food.

The Right Omega-3 Essential Fats

Omega-3 essential fats (such as occur in nuts, seeds, especially flaxseeds, and cold-water fish) are very important nutrients. A man’s risk for prostate cancer is decreased by a higher consumption of two particular essential fatty acids (called eicosapentaenoic acid or EPA and docosahexaenoic acid or DHA) that are found in cold-water fish. Laboratory studies of isolated prostate cancer cells also show that these omega-3 essential fats inhibit their growth.

Not All Omega 3 Fats Inhibit Prostate Tumor Growth

Laboratory studies have shown that omega 3 fatty acids (found in cold water fish and flaxseed) inhibit prostate tumor growth, but a study published in the June 2004 issue of the American Journal of Clinical Nutrition suggests that not all omega 3 fats have this beneficial effect.

For 14 years, this study followed a population of 47,866 American men, aged 40-75 and free of prostate cancer when the study began. Of the three types of omega 3 fats - eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and alpha linolenic acid (ALA) – the first two were linked to a lower risk of prostate cancer, but the third was associated with an increased risk of advanced prostate cancer.

EPA was found to decrease prostate cancer risk by 11% and DHA by 26%. In contrast, ALA from plant sources increased prostate cancer risk by 102%. Men at risk for prostate cancer may wish to limit the amount of ALA, and increase the amount of EPA and DHA, they consume. ALA is found in highest quantities in flax, canola and soy oils. Excellent sources for EPA and DHA are cold water fish such as salmon, sardines, cod and tuna.(June 30, 2004)

Flaxseed

Ground flaxseed is a very good source of omega-3 essential fats, dietary fiber, and lignans, which assist the body in excreting “used up” hormones. Ground flaxseed may be beneficial not only for prevention of prostate cancer, but also in men with existing prostate cancer.

A study of men with prostate cancer conducted at the Duke University Medical Center and Durham Veterans Affairs Medical Center investigated the effects of a low-fat diet (less than 20 percent of calories from fat) along with about 2 tablespoons of ground flaxseed daily.

These two relatively simple changes resulted in slower cancer cell growth, increased cancer cell death, and lower blood levels of testosterone - all beneficial effects for these men - and in only 34 days.

There is existing controversy and confusion regarding the use of flaxseed oil for prostate health, so it may be wiser for men to consume ground whole flaxseeds and fish to increase their intake of omega-3 essential fats.

Phytosterols vs. cholesterol

Phytosterols are plant analogues of animal sterols (such as cholesterol, from animal fat) and include beta-sitosterol and campesterol. They are common in beans, peas, whole grains, seeds, and nuts, and their activities modulate those of animal sterols. A very recent study from the State University of New York at Buffalo concluded that the plant sterols decrease the growth of prostate cells, whereas cholesterol increases their growth. Another study concluded that beta-sitosterol increases prostate cancer cell death four-fold.

New Research Approach Underscores the Synergistic Fffects of the World's Healthiest Foods: Tomatoes and Broccoli Team Up to Provide Greater Cancer Protection

Finally, a study has examined the effect of eating whole foods in combination instead of isolated nutrients, and guess what—the beneficial synergy among nutrients that results when we consume a variety of healthful foods has got taking single nutrients beat by a mile.

According to this research, presented July 15, 2004, at the two-day WCRF/AICR International Research Conference on Food, Nutrition and Cancer in Washington, D.C., eating broccoli along with tomatoes maximizes the cancer protection both foods provide.

In the study, which will be published in the December 2004 issue of the Journal of Nutrition, rats fed a tomato-and-broccoli combo had way less prostate tumor growth than rats given diets containing either food alone or normal rat chow diets supplemented with lycopene (a cancer-fighting carotenoid isolated from tomatoes) or finasteride (the drug commonly prescribed to men with benign prostatic hyperplasia or BPH).

When the results were analyzed, the researchers were surprised to find that all of the diets (tomato-and-broccoli, tomato, broccoli, and lycopene) were more effective in suppressing prostate tumor growth than the drug (finasteride).

At a press conference, lead researcher John W. Erdman, Ph.D., Professor of Food Science and Human Nutrition at the University of Illinois at Urbana, explained the rationale behind the new approach to nutrition research:

“We decided to look at these foods in combination because we believed it was a way to learn more about real diets eaten by real people. People don’t eat nutrients, they eat food. And they don’t eat one food; they eat many foods in combination."

Erdman also noted, "Studies that examine individual substances in isolation are simply not designed to tell us anything about the interactions that occur between those substances, much less between foods that each contains its own anti-cancer arsenal.”

Erdman and his colleagues may have been inspired to try this novel approach by research they published in the November 2003 in the Journal of the National Cancer Institute. In this study, lycopene alone offered rats little protection from prostate cancer, while diets containing freeze-dried tomato powder greatly improved their prostate cancer survival.

In the new study, Erdman chose to combine tomatoes with broccoli, another food with well-studied anti-cancer effects. Compounds in broccoli called glucosinolates are converted in the intestines into compounds that increase liver enzymes' ability to clear carcinogens before they can cause harm.

Erdman was quick to assert that the food synergy between tomatoes and broccoli is not unique, that “This interactivity is likely taking place in any diet high in a variety of plant foods – fruits, vegetables, whole grains and beans.”

His colleague, Jeff Prince, Vice-President for Education at the American Institute for Cancer Research, echoed Erdman’s belief:

“The take-home message isn’t just about tomatoes and broccoli. The inferences to be drawn are more tentative and a lot broader. A lycopene supplement may not hurt you, but the whole tomato can help you more. A whole tomato may help you, but a tomato eaten with broccoli will help you more. Tomato with broccoli may help you, but a medley of different vegetables eaten together will bolster the body’s different defenses against chronic disease.” (August 23, 2004)

Special note on Vegetarian Diet and Stress Reduction

We often hear that vegetarian eating is good and that stress management is good, but in combination, they appear to be particularly good for men who have already had prostate cancer.

A recent small study looked at men previously treated for prostate cancer (their prostates were removed) yet showed elevated levels of PSA (prostate-specific antigen), a laboratory screening marker for prostate cancer. They were considered to be in the early stages of recurrence of prostate cancer and at increased risk for the cancer spreading to other parts of the body, a fate shared by more than one-third of men treated for prostate cancer.

These men followed a low-fat, high-fiber, plant food-based diet (rich in whole grains, beans, fresh vegetables, soyfoods, and fruit, and restricted in caffeine, animal foods, and processed foods) combined with a stress reduction program. After four months, tumor growth had slowed, the men lost weight, and in some cases their PSA levels had even decreased — all beneficial results for the men.

Nutrient Excesses

Fat

Total fat in the diet has one of the strongest links to hormone-related diseases like prostate cancer and breast cancer. This may be for a number of related reasons. Obviously, fats are energy-rich and are easy for the body to store as excess body fat, which is related to a wide range of health problems. Additionally, these stored fats send biochemical messages throughout your body that influence your hormone status and balance, the way you use food energy, and even how your immune system works.

Lower your intake of polyunsaturated fats high in omega 6 fatty acids

A diet low in polyunsaturated fats, which are high in omega 6 fatty acids, (most salad oils, e.g., corn, safflower, canola, soy, peanut, sesame oils), may help men with aggressive prostate cancer, suggests a new study published in the February 2004 issue of Cancer Research. In this study, mice with advanced human prostate cancer that were deprived of testosterone and fed a diet low in polyunsaturated fats remained in remission and lived nearly twice as long as mice given a diet high in polyunsaturated fat. In addition, levels of PSA (prostate specific antigen), a measure of the level of prostate cancer present, were much lower in the mice on the low polyunsaturated fat diet.

In humans, the standard treatment for advanced prostate cancer is androgen deprivation therapy, which inhibits the body’s production of testosterone, the hormone thought to drive cancer growth. Unfortunately, this treatment usually only works for a time, after which many men develop androgen independent cancers—cancers that grow despite low levels of testosterone. Once this happens, androgen therapy is no longer effective, and few other treatment options are available, which is why this new study offers new hope.

In the study, lab mice with human prostate cancer were divided into three groups. One group was fed a high-fat diet containing about 42% of calories from polyunsaturated fat. The second group was castrated, to mimic men on androgen deprivation therapy, and also fed a diet containing 42% of calories from polyunsaturated fat. The third group, also castrated, were given a diet in which only 12% of calories came from fat.

In the first group, uncastrated mice on the high-fat diet, tumors grew rapidly, and the animals soon died. In the castrated mice on the high-fat diet, tumor growth stabilized for a time, but then began to grow again—mirroring what happens in men with advanced prostate cancer on androgen deprivation therapy. The third group, the castrated mice on the low-fat diet, went twice as long before their cancers became androgen indepdent, and even then, their tumors were much smaller and their survival times significantly longer than either of the other groups.

Numerous studies have shown that the omega 6 fats, which are found in significant amounts in meats and most vegetable oils (olive and flaxseed oils are the exception), are pro-inflammatory. Excessive consumption of these fats, particularly when their intake is not balanced by eating foods rich in the anti-inflammatory omega 3 fats most abundant in cold water fish and flaxseed, has been linked not only to cancer but to cardiovascular disease. According to Dr. William Aronson, a Jonsson Cancer Center researcher and the study’s lead author, “This study may help us solve a clinical problem, how to prevent or delay androgen independence. I think dietary fat reduction, coupled with high fiber intake from fruits and vegetables in a variety of colors, can truly have an impact on prostate cancer prevention, and in combination with existing treatments, perhaps increase survival times for patients.” (March 25, 2004)

It is also important to remember that the biochemical messages sent by fat throughout the body can be modified by other aspects of your diet, such as your consumption of dietary fiber, soyfoods, mustard family vegetables, omega-3 essential fats, selenium, and other essential or antioxidant nutrients. A “lifestyle approach” to eating is what is needed, not just a single dietary change.

Animal foods

Animal foods (meat in particular, but also milk, eggs, and cheese) are key dietary sources of saturated fats and cholesterol, both of which are strongly implicated in the development of prostate and cardiovascular diseases.

Additionally, animals raised for meat are sometimes given hormones to stimulate their growth or are exposed to other agricultural chemicals whose residues may be stored in their flesh. Non-organic milk can also be a potential dietary source of cadmium stemming from environmental pollution. Intake of this heavy metal is also associated with prostate disease.

While organic animal foods are preferable to non-organic, they still contain saturated fats and cholesterol. For prevention of prostate conditions, it is best to limit your intake of animal foods and to instead base your diet on plant foods.

Dairy products

Dairy products like milk and cheese supply saturated animal fats, cholesterol, and calcium. Excesses of any of these increase men’s risk of prostate cancer.

Research has found that men consuming 2.5 servings of dairy products daily increase their risk of prostate cancer by 50 percent! Though it is necessary to get enough calcium, regular consumption of dairy products supplies so much calcium that it may upset the body’s balance between calcium and vitamin D (excess calcium reduces vitamin D levels), which can increase the risk for prostate and other cancers.

Fried, broiled, and grilled meats

Carcinogenic compounds from fried, broiled, and grilled meats have been shown in the laboratory to cause prostatic DNA mutations as well as prostate tumors. African-American men ingest more of these meats and their carcinogens than do Caucasian American men, which may partly explain why prostate cancer mortality in African-American men is double that of Caucasian American men.

Recommended Diet

Dietary guidelines for prostate health and function include:

  • Eat fresh and organic foods whenever possible
  • Eat legumes regularly, especially soyfoods (tofu, tempeh, TVP-texturized vegetable protein, etc)
  • Eat fresh vegetables every day, especially mustard family vegetables (broccoli, cauliflower, kale, cabbage, Brussels sprouts, etc.) Men eating 4 servings of vegetables daily have almost half the risk for prostate cancer as men eating less than 2 servings of vegetables daily
  • Limit your intakes of animal foods, especially animal fat, dairy foods, and red meat
  • Do eat fish, especially cold-water fish
  • Eat tomato products frequently (excellent source of lycopene)
  • Eat whole-grain rice, pasta, cereals, breads, and crackers; suggestion: have whole-grains (like rice, quinoa, or pasta) with tomato sauce, olive oil, garlic, onions, spices, and tofu (or other soyfood) a few times weekly
  • Eat nuts and seeds regularly, especially ground flaxseed—for essential fats, selenium, zinc, vitamin E, dietary fiber, and phytosterols
  • Enjoy fresh or dried fruit for dessert, especially whole cranberries (October 19, 2004)
  • If you eat meat, focus on fish and organic game and poultry rather than red meats
  • Use spices every day, especially rosemary, ginger, garlic, turmeric, basil, sage, thyme, oregano, and curry spice (spices like these support hormone metabolism and excretion)

The Condition Specific Meal Planner for Prostate Cancer has menus that cover the nutritional needs of this condition over a four day period.

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This page was updated on: 2004-11-21 15:56:11

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