Another extensive review shows that exercise is associated with a lowered risk for prostate cancer and its recurrence (Cancer Epidemiology, Biomarkers & Prevention, January 28, 2015). The literature overwhelmingly shows that to reduce your chances of developing prostate cancer, avoid being overweight and do not use tobacco or excessive alcohol.
Elevated Blood Sugar a Risk Factor for Prostate Cancer
Prostate cancer is associated with everything that raises blood sugar levels: metabolic syndrome (pre-diabetes), diabetes, inflammation, obesity and weight gain (Cancer Causes and Control, 05/14/2014), lack of exercise (Cancer Epidemiology, Biomarkers & Prevention, 04/02/2014), and lack of vitamin D. Vitamin D deficiency blocks insulin receptors to raise blood sugar levels and increase risk for diabetes. Scientists have not shown that high blood sugar levels cause prostate cancer, but they have shown that having high blood sugar levels is associated with increased prostate cancer risk.
A high rise in blood sugar causes a marked increase in insulin and IGF-1, hormones that cause cells to multiply and grow to increase cancer risk. People who take in a lot of refined carbohydrates have high insulin and IGF-1 levels and are at increased risk for prostate cancer (Prostate, 2008, 68:11-19).
This year, the Annual Scientific Meeting of the American Urological Association had several papers associating prostate cancer with factors that raise blood sugar levels:
* Men who eat lots of high complex carbohydrate foods (fiber, whole grains) that are associated with low blood sugar levels are at reduced risk for prostate cancer. Diets rich in sugar-added foods and drinks are associated with increased prostate cancer risk (#PD31-11).
* High milk intake is associated with increased risk for rapidly progressive advanced prostate cancer. Yogurt, ice cream and cheese consumption were not associated with either advanced or localized cancer (#PD31-06).
* Having two or more metabolic syndrome components was associated with an increased risk of high-grade prostate cancer (obesity, high blood pressure, elevated fasting blood sugar (>100), high fasting insulin (>5), low HDL cholesterol (150), or fatty liver and storing fat primarily in the belly (#PD31-01).
We do not know if metformin helps to prevent prostate cancer. Metformin is a drug that is used to treat diabetes because it lowers high blood sugar levels. In some studies, it reduces prostate cancer risk and death from prostate cancer in humans (J Clin Oncol. 2013, 31:3069-3075), while in other studies, it offers no protection at all (Prostate Cancer Prostatic Dis, 2013, 16:391-397).
Lack of Vitamin D
Men who have low blood levels of vitamin D are at increased risk for prostate cancer and specifically for the type of prostate cancer that kills (Clinical Cancer Research, May 1, 2014). Vitamin D plays several critical roles in how cells develop and grow. Vitamin D helps to regulate how stem cells change into prostate cells and the rate that normal cells turn into cancer cells. Adding vitamin D to prostate cells in a petri dish slows their rate of growth.
Perhaps not having enough vitamin D can cause normal cells to become cancerous. Researchers found that almost all of 667 men referred for prostate biopsies because of high blood PSA tests or abnormal prostate exams had low levels of vitamin D. Their levels of hydroxy vitamin D were usually below 20ng/ml. Normal is 30 to 80. Furthermore, 44 percent of the men with prostate cancer had very low levels of vitamin D compared to 38 percent of those who tested negative. The lower the level of vitamin D, the more likely the cancer was to kill them.
No good data determines whether the amount of protein you eat affects prostate cancer risk. One recent study reported that low protein intake is associated with lower risk for prostate cancer in men 65 and younger, while in men older than 65, low protein intake was associated with a higher risk for cancer and death (Cell Metab, 2014, 19:407-417).
Red meat has been associated with increased advanced prostate cancer risk (Am J Clin Nutr, 2010, 91:712-721). Fish may be associated with reduced death from prostate cancer. Cooking protein without water (grilling, broiling, frying and so forth) increases cancer risk because it causes carcinogens called Advanced Glycation Endproducts (AGEs) to form. When you cook with water, sugar binds to the water and is harmless. When you cook without water, sugar binds to protein and nucleic acids to form AGEs that are known carcinogens (Cancer Causes Control, 2012, 23:405-420).
Fruits and Vegetables
Eating a diet rich in fruits and vegetables is associated with reduced risk for suffering prostate cancer (Int J Urol, 2012, 19:134-141 and Asian Pac J Cancer Prev, 2014, 15:5223-5227) and reduced risk for recurrence in men already diagnosed with prostate cancer (Int J Cancer, 2012, 131:201-210).
I think the data is strong enough to recommend that you follow a prostate-healthy (and heart-healthy) diet as much as you can:
* Eat plenty of fruits and vegetables,
* Restrict sugared drinks and sugar-added foods,
* Replace refined carbohydrates with whole grains, beans, nuts and other seeds,
* Restrict red meat,
* Restrict cooking meat at high temperatures,
* Restrict fried foods
Gabe Mirkin, M.D., is a sports medicine doctor and fitness guru. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin has run more than 40 marathons and is now a serious tandem bike rider with his wife, Diana. His website is http://drmirkin.com/. Click to read Gabe’s full bio.