Ask the Doctors: Link between zinc and prostate enlargement needs more study
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Dear Doctor: I developed acute prostate problems at the early age of 29. My doctor’s prescriptions didn’t work, so when a neighbor recommended 50 milligrams of zinc a day for at least 30 days, I gave it a shot. I haven’t had any problems since — and that was more than 30 years ago. Why don’t more people use this miracle mineral for an enlarged prostate?
Dear Reader: Before you posed this question, I had never heard of any relationship between zinc and the prostate. Like most people, I thought of zinc simply as an important element in the body — necessary for multiple enzymatic processes involved in human metabolism. I also knew that zinc concentrates in the liver, kidney, muscle and retina and is found at very high levels in the prostate.
After some research, I also found that the content of zinc in the prostate is about 100 times that found in the bloodstream. At high tissue concentrations, zinc can inhibit the formation of dihydrotestosterone, the main hormone that leads to prostate enlargement. It has also been shown to help preserve the normal tissue structure of the prostate and to help maintain prostate function. Zinc may also increase the ability to kill bacteria that lead to infections of the prostate.
A 2016 analysis of 10 studies assessed blood levels of zinc in men with prostate cancer. Seven of the studies found low concentrations. This is notable because multiple lab studies have shown that zinc can inhibit prostate cancer growth by hindering the function of prostate cancer cells and by turning on mechanisms that lead to the death of prostate cancer cells. In Japan and China, where zinc intake is high, the rates of prostate cancer are low. But after one generation in the United States, ethnic Japanese, for example, have the same rates of prostate cancer as Caucasians in the U.S.
As for prostate enlargement, this same analysis evaluated five studies assessing a potential link between blood levels of zinc and decreased risk of prostate enlargement — and found none. In fact, three of the five studies showed a link between higher zinc concentrations and prostate enlargement, countering the notion that zinc could decrease the enlargement of the prostate.
So, although low zinc may be linked to an increased risk of prostate cancer, the same does not hold true for a decreased risk of prostate enlargement. A laboratory study of prostate tissue did show that zinc at high doses decreases smooth muscle proliferation in the prostate and thus possibly could decrease prostate size. Further, in a 2017 Italian study, 62 patients with symptoms related to prostate enlargement were given 10 milligrams of zinc in addition to herbal extracts. After six months, a majority of men reported decreased urinary frequency, increased flow rates and less urine retained in the bladder. Note that because zinc was administered with other therapies, it is difficult to know what effect the mineral alone had.
Because you had prostate problems early in life, I suspect your prostate issues may have been related to infection, rather than the more typical prostate problems of older men. It’s possible that zinc may have had an antibacterial effect of preventing further infections of the prostate. Because of decreased infections, your prostate didn’t enlarge and cause future problems. Perhaps this is why zinc helped you — and why it may be helpful to others who have early prostate infection or inflammation.
Thanks for your question. Clearly, zinc therapy for the prostate should be studied further.
Robert Ashley, M.D., is an internist and assistant professor of medicine at the University of California, Los Angeles.