Consuming Certain Plants Increases Risk of a Man Developing Advanced Prostate Cancer, Study Finds

Consuming Certain Plants Increases Risk of a Man Developing Advanced Prostate Cancer, Study Finds

A diet rich in soybeans, flaxseed, green tea, strawberries and other plants doubles a man’s risk of developing an aggressive form of prostate cancer, a study indicates.

Researchers found no link between the foods — which nutritionists consider healthy — and the development of non-aggressive forms of the cancer.

The Indiana University study, which appeared in the International Journal of Cancer, was titled “Dietary intake of isoflavones and coumestrol and the risk of prostate cancer in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial.

It covered three categories of plant-derived compounds called phytoestrogens that have properties similar to those in the female hormone estrogen.

One category is Isoflavones, which includes compounds such as genistein, daidzein, glycitein, formononetin, and biochanin A. They are mainly found in soybeans, kudzu root, and American groundnuts.

A second category is lignins, which includes the compounds matairesinol and seco-isolariciresinol. They are found in flaxseed, green tea, and strawberries. The third category of compounds, coumestans, is found in legumes, clover, and soybean sprouts.

Previous studies have suggested that consuming phytoestrogens could increase the risk of a woman  developing certain types of cancer — breast cancer, for example. Phytoestrogens have a chemical structure similar to estradiol, an estrogen that is the primary female sex hormone.

Some research in animals has suggested that a diet rich in these compounds can reduce levels of the male horomone testosterone, and consequently the risk of prostate cancer. But in another study, researchers found that the prostate cancer of mice that were fed genistein not only increased but also  spread to other parts of the body.

To obtain a better grasp of the compounds’ role in prostate cancer, the Indiana researchers studied thousands of patients’ consumption of plants containing the compounds. They did this with questionnaires that asked patients to report their consumption of the plants — except for lignans-producing plants.

The study covered 27,004 men for a median of 11 1/2 years. The team drew the patients from the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial (NCT00002540)

During the study, doctors diagnosed 2,598 cases of prostate cancer, 287 of which were advanced cases.

Matching the questionnaire results to the diagnoses, researcher determined that the top contributors to isoflavones consumption were tofu and soybeans, peas, and tea. The main sources of coumestrol were tea, beans, and soups.

High consumption of isoflavones doubled the risk that a man would develop an advanced prostate cancer, researchers found. Looking at the results by category, the team discovered that genistein increased the rise of advanced prostate cancer by 50 percent, daidzein by 80 percent, and glycitein by 67 percent.

The team failed to find significant associations between isoflavones and the development of non-advanced prostate cancer.

“Our study offers novel evidence that dietary intake of isoflavones has different effects on advanced and non-advanced prostate cancer,” said Dr. Jianjun Zhang, an associate professor at Indiana University’s Fairbanks School of Public Health, said in a news release. He was the senior author of the study.

“This observation is important for understanding the etiology [the causes of] and prevention of prostate cancer, but needs to be confirmed in more epidemiologic studies among populations with diverse dietary habits,” he added.

Epidemiology is the study of the patterns, causes, and effects of diseases in particular populations.

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8 comments

  1. William Logan says:

    It would seem that many food items once thought of as protective are now complicit in exacerbating the cancer. Where to go from here must be the frustration prostate cancer patients and survivors face. Remaining dietary options suggest limited to no sugar, alcohol, red meat, saturated fats, or highly digestible carbohydrates (no fun)! A very modified Mediterranean diet based on fish chicken, fruits, and vegetables seems the best choice.

  2. Mike says:

    I find this hard to believe, Japan has one of the lowest rates of prostate cancer and they drink lots of green tea and eat plenty of soy products. If this is true then maybe I should convert back to my steak and beer diet.

  3. Mark Walz says:

    I’m running out of things that are safe to eat! There is so much contradictory information being disseminated out there. No wonder we patients are confused, and don’t know what to do, take, or consume. It’s hard to know who to believe anymore.

  4. As mentioned above, it’s very strange how cultures with the highest soya intake have the lowest prostate cancer risk.

    In this blog, you generalised the dietary concerns in the study to include flaxseed and green tea – actually they specially stated in the research that there was no link with lignans (i.e. Flaxseed) and did not even mention green tea which has little or no isoflavones. In my opinion flaxseeds remain a very healthy food for men for a wide range of reasons (good fats, fibre, other polyphenols)

    In addition As the chief investigator of the World’s Largest double blind double blind randomised trial of a polyphenol rich oral nutritional supplement (the NCRN Pomi-t trial). In order to avoid any possible confusion, foods such as pomegranate, green tea, broccoli and turmeric are rich is polyphenols but not isoflavones have been shown to have a significant anti-prostate cancer effect and the intake of these foods should be encouraged.

    • Mark Good says:

      Thank you for your answer. The article was a bit confusing, good to know green tea is ok for prostate cancer patients. The Pomi-T-study seems to be interesting, I found it actually on Natures website nature.com/pcan/journal/v17/n2/full/pcan20146a.html

  5. DAVID WALLER says:

    Confusing to say the least – my Soy milk smoothies with strawberries etc; vegetarian choices with tofu; peanut snacks with chilli suppers will do me in; as quickly as my previous cow milk, full English breakfasts and fatty lamb chops with chips and peas? Who knows.
    Not much left apart from salads.
    DW

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