When it comes to dietary supplements, less is more. Mega-doses suggest a worse outcome or prognosis in patients with cancer. 


B12 may be needed if blood tests show a deficiency. Excess B vitamins may promote heart disease and cancer growth. Researchers have not found that Vitamin C helps prevent or treat prostate cancer. For Vitamin D, I generally recommend 1,000 IU daily if the level is below normal. Men with prostate cancer should not take an individual Vitamin E supplement. Higher doses of Multivitamin pills may feed prostate tumors. Taking a children’s multivitamin several times a week, not to exceed one pill a day, makes more sense. Folic acid and Zinc in higher amounts have been associated with a higher risk of aggressive prostate cancer in human studies. 

Fish Oil (Omega-3 fatty acids)

Pills containing EPA and DHA may reduce the risk of cardiovascular events and may have anti-arthritic and anti-depressive properties. Some new research suggests it could encourage the growth of some prostate cancers. 


500-1,000 mg per day may reduce nausea during and after chemotherapy.  

Korean Red Ginseng, MACA, L-arginine, L-citrulline and American Ginseng

Preliminary data shows they improve sexual health. Panax ginseng may help reduce fatigue in cancer patients. American ginseng from the Ginseng Board of Wisconsin is arguably the safest, least expensive, and most effective option for fatigue.   

Glucosamine, Pycnogenol, SAM-e, Lycopene and Resveratrol

Show no evidence of anti-prostate cancer activity. The few studies published to date are inconclusive and controversial. 


It has been used with some success in chronic nonbacterial prostatitis.

Saw Palmetto & Other BPH Supplements

In two major clinical trials, the most commonly used dosage was safe but did not work better than a placebo.


Supplements may increase the risk of aggressive prostate cancer!

Tea and Tea Supplements

Most forms of tea, including black, green, herbal, and oolong are healthy and have few or no calories, so enjoy drinking them. However, please keep in mind that tea-based dietary supplements or pills (not the drink) have no solid proof from human studies that they do anything against prostate cancer. A large clinical trial of high-dose green tea supplements in patients with advanced cancer showed no real benefit. 

Whey Protein or Protein Powder

This can be taken as a powdered drink supplement (never as a pill) for any man needing more high-quality protein for health, weight loss and to support muscle health.


Zinc supplements in high dosages, 80 to 100 mg per day or more, should be avoided. Recent human research has linked higher doses of zinc from dietary supplements to abnormal immune changes, a potential reduction in the impact of bone-building drugs, abnormal changes in cholesterol blood tests, increased risk of urinary tract infections, kidney stones, prostate enlargement, and an increased risk of aggressive prostate cancer. 

Marijuana Cures Everything, Dude?!  

So, let’s review: Personally, if you are healthy, I think the risks of marijuana outweigh the benefits, unless of course you win the lottery and just want to try it one time to celebrate the fact that you never again have to listen to your boss or some of your annoying coworkers. Marijuana has NOT been proven to be heart-healthy and in fact it could be heart-unhealthy. And the smoke does not make the lung tissue happy, even though you could feel temporarily happy. 

I frequently hear, “Marijuana is natural.” So, should I get excited about it? Just because it is natural is not the reason I get excited about diddly squat (aka anything). I mean, poison ivy and arsenic are natural, folks, but I usually do not recommend those things—except to my big brother when he pushed my face in the snow when we were kids…  

Do I think it’s possible that marijuana or one of its compounds can fight cancer or encourage the growth of cancer? Yes! But at this point, we have no conclusive evidence one way or the other. It’s dangerous to treat humans unless studies in humans show that it works. In Europe, a laboratory study showed that a certain drug could impact a cannabinoid receptor in the brain. “Experts” were convinced that it would be a great weight-loss drug and it was marketed briefly under the trade name of Acomplia (Google that bad boy). It was removed from the market because of serious side effects such as anxiety, suicidal ideation, nausea, and, in some cases, the development of multiple sclerosis. 

Final Thoughts

Always talk to your doctor about any pill or supplement. Use the same approach to taking a dietary supplement as you would use for starting a prescription medication.



Mark A. Moyad, MD, MPH is arguably one of the world’s leading medical experts on diet and dietary supplements. He is the Jenkins/Pokempner Director of Preventative and Alternative Medicine at the University of Michigan Medical Center-Department of Urology.  He graduated from the University of South Florida College of Public Health and the Wayne State University School of Medicine.  He is the primary author of over 150 published medical journal articles, the past editor-in-chief of the medical journal Seminars in Preventive & Alternative Medicine (Elsevier Publishing), and has given over 5,000 lectures around the world to the public and health care professionals in virtually every medical specialty and major medical center.  He is co-author or author of 14 academic and consumer books including The Supplement Handbook: A Trusted Expert’s Guide to What Works & What’s Worthless for more than 100 conditions.  He has been a consultant and/or interviewed for most major magazines, websites, radio, and television shows devoted to health in the U.S., and appears regularly on a variety of network news/programs.