Healthy prostate tissue contains very high levels of zinc, which the gland uses in its normal metabolism [4]. That has led to the popular idea that zinc supplements can shrink the prostate, but research has not shown this. Most men get the 11 mg a day they need from food, and taking more than 40 mg a day can cause problems, including low copper [1][2].
Key Takeaways
- Healthy prostate tissue stores very high levels of zinc, which specialized cells use to produce and secrete large amounts of citrate [4].
- No controlled trial has shown that zinc supplements reduce prostate size; human studies are observational and their results are inconsistent [5][6].
- Men need 11 mg of zinc a day and women 8 mg. Oysters, beef, crab, fortified cereal and pumpkin seeds are top food sources [1].
- The adult upper limit is 40 mg a day from all sources. Doses of 50 mg or more for weeks can lower copper status [1][2].
- In one large cohort, men who took more than 100 mg of supplemental zinc a day had worse prostate outcomes, a reminder that more is not better [6].
- Zinc can interact with some antibiotics, penicillamine and thiazide diuretics [1].
Evidence grade: Emerging. Zinc's high concentration in prostate tissue is well documented, but human evidence linking zinc intake to prostate outcomes is observational and inconsistent, and no controlled trial has shown a change in prostate size.
What Zinc Does in the Body
Zinc is an essential mineral. It is required for the activity of hundreds of enzymes and is involved in immune function, protein and DNA synthesis, wound healing, and cell signaling and division. It also plays a role in the sense of taste [1]. For how zinc fits with other minerals the immune system relies on, see our overview of minerals and immunity.
Why the Prostate Holds So Much Zinc
The human prostate contains extremely high zinc levels. Specialized cells in the gland's outer (peripheral) zone accumulate zinc, and that zinc changes how the cells handle energy so they can produce and secrete unusually large amounts of citrate [4]. In other words, zinc is part of the prostate's everyday chemistry.
Researchers have also studied how zinc levels differ in prostate disease. A 2016 review by Costello and Franklin describes lower tissue zinc as a consistent feature of prostate cancer tissue and discusses laboratory ideas for raising zinc inside tumor cells; those ideas remain hypotheses, not something shown in people [4]. A 2016 meta-analysis of 14 studies found that blood zinc was lower in men with prostate cancer than in men without it, but higher, not lower, in men with benign prostate enlargement than in healthy controls. The authors called earlier findings inconsistent and said larger, well-designed studies are needed [5].
Does Zinc Shrink the Prostate?
The short answer is that this has not been shown. The idea comes from the observation that the prostate is rich in zinc, but a nutrient being concentrated in a tissue does not mean that taking more of it changes the tissue's size. We did not find any controlled trial in which zinc supplements reduced prostate size, and the blood-level research above does not point that way, since men with benign enlargement had higher, not lower, serum zinc in the pooled analysis [5].
The strongest caution comes from the Health Professionals Follow-Up Study, which followed 46,974 U.S. men for 14 years. Supplemental zinc up to 100 mg a day was not linked to prostate cancer risk. Men who took more than 100 mg a day, or who took zinc supplements for 10 years or more, had more than twice the risk of advanced prostate cancer [6]. This was an observational study, and the authors noted other factors could explain part of the link, but it is a good reason not to take high doses on the theory that more zinc helps the prostate.
If you have urinary symptoms or questions about your prostate, see a clinician. Those symptoms have several possible causes and deserve a proper evaluation. For background on another ingredient often studied for men's prostate health, see our monograph on saw palmetto.
How Much Zinc Do Men Need?
| Adults 19+ | RDA | Upper limit (UL) |
|---|---|---|
| Men | 11 mg | 40 mg |
| Women | 8 mg | 40 mg |
| Pregnancy / lactation | 11 mg / 12 mg | 40 mg |
The upper limit covers zinc from food, fortified foods and supplements combined, and it was set based on the amount of zinc that harms copper status [1]. It does not apply to people taking zinc under a doctor's care for a medical reason.
Food sources of zinc
| Food and serving | Zinc (mg) | % Daily Value |
|---|---|---|
| Oysters, Eastern, farmed, raw, 3 oz | 32 | 291% |
| Oysters, Pacific, cooked, 3 oz | 28.2 | 256% |
| Beef, bottom sirloin, roasted, 3 oz | 3.8 | 35% |
| Blue crab, cooked, 3 oz | 3.2 | 29% |
| Breakfast cereal, fortified with 25% DV, 1 serving | 2.8 | 25% |
| Pumpkin seeds, roasted, 1 oz | 2.2 | 20% |
| Pork loin chop, broiled, 3 oz | 1.9 | 17% |
| Cheddar cheese, 1.5 oz | 1.5 | 14% |
| Shrimp, cooked, 3 oz | 1.4 | 13% |
| Lentils, boiled, ½ cup | 1.3 | 12% |
Oysters have more zinc per serving than any other food, while beef supplies about 20% of the zinc Americans eat [1]. Beans, nuts and whole grains contain zinc too, but compounds called phytates reduce how much is absorbed. That is why vegetarians and vegans tend to have lower zinc intakes; soaking beans, grains and seeds before cooking can help [1]. Our guide to nutrients to watch on a vegan diet covers zinc alongside other common gaps.
Zinc Forms: Picolinate, Gluconate, Citrate and Others
Supplements use zinc sulfate, acetate, gluconate, citrate, oxide, picolinate and other forms. The Supplement Facts label lists elemental zinc, which is the number to compare [1]. One study found zinc citrate and zinc gluconate were absorbed at about 61% in young adults, compared with about 50% for zinc oxide [1].
Zinc picolinate is often marketed as better absorbed. The main human evidence is a 1987 crossover study in 15 healthy volunteers: at 50 mg of zinc a day for four weeks, zinc levels in hair, urine and red blood cells rose with picolinate but not with citrate or gluconate [7]. That is a small, old study, and its dose was above today's upper limit. It did not measure any prostate outcome. Taking zinc at the same time as 25 mg or more of supplemental iron can lower zinc absorption [1].
Zinc, Magnesium and Testosterone
Zinc and magnesium are often sold together. Both are essential minerals, but we did not find controlled trials of the combination for prostate outcomes. One point is clear: very high zinc intakes (142 mg a day in one study) interfered with magnesium absorption and balance, another reason to stay within the upper limit [3].
Zinc is also involved in testosterone production. In a small 1996 study, cellular zinc levels tracked with testosterone in 40 healthy men; restricting dietary zinc in four young men lowered testosterone, and zinc supplements raised it in nine older men who were marginally low in zinc [8]. That suggests adequate zinc supports normal testosterone levels. It does not show that extra zinc raises testosterone in men who already get enough.
Where a Prostate Formula Fits
Men who want a daily formula sometimes look for zinc alongside botanicals. OPA's Prostate Formula lists 12.5 mg of zinc per two-capsule serving, together with saw palmetto extract (200 mg), pygeum (100 mg), a plant sterol complex (50 mg), selenium (55 mcg), vitamin E, vitamin B6, copper (4 mg) and a botanical blend. For context, 12.5 mg of zinc is a little above the 11 mg RDA for men and well under the 40 mg upper limit, far below the more-than-100 mg a day linked to concern in the cohort study above [1][6]. The 4 mg of copper is under the 10 mg adult upper limit for copper [2]. If you also take a multivitamin or a separate zinc supplement, add up the zinc from all of them. The formula contains soy. No study has tested this specific formula.
Safety and Interactions
Too much zinc can cause nausea, vomiting, dizziness, headaches, stomach upset and loss of appetite [1]. Taking 50 mg or more a day for weeks can reduce copper absorption, lower immune function and lower HDL ("good") cholesterol [1]. Reductions in a marker of copper status have been seen at about 60 mg a day for up to 10 weeks [2]. Low copper can be serious; excessive use of zinc-containing denture creams over years has caused copper deficiency and nerve problems [1].
Talk to your doctor or pharmacist before taking zinc if you take:
- Quinolone or tetracycline antibiotics, such as ciprofloxacin. Zinc and these antibiotics can block each other's absorption; take the antibiotic at least 2 hours before or 4 to 6 hours after zinc [1].
- Penicillamine. Zinc can reduce its absorption and action; take them at least 1 hour apart [1].
- Thiazide diuretics, such as hydrochlorothiazide or chlorthalidone, which increase zinc loss in urine [1].
Also check with your clinician first if you have a digestive condition that affects absorption, have had bariatric surgery, or are being evaluated for prostate or urinary symptoms.
Frequently Asked Questions
Does zinc shrink the prostate?
This has not been shown. The prostate naturally holds a lot of zinc [4], but we found no controlled trial in which zinc supplements reduced prostate size, and a pooled analysis found men with benign enlargement had higher blood zinc than healthy men [5].
What does zinc do for the prostate?
Zinc-accumulating cells in the prostate use it to produce and secrete large amounts of citrate, so zinc is part of the gland's normal metabolism [4]. Research on zinc and prostate conditions is ongoing and mixed [5][6].
Is it OK to take zinc every day?
Daily zinc within the RDA (11 mg for men, 8 mg for women) is normal, and many people meet it with food. Keep total intake from food and supplements at or below 40 mg a day unless a doctor advises otherwise, since higher amounts over time can lower copper [1][2].
How much zinc should a man take for prostate health?
There is no established prostate-specific dose. The RDA for men is 11 mg a day and the upper limit is 40 mg [1]. Very high supplemental intakes, above 100 mg a day, were linked to worse outcomes in one large study [6].
What does zinc do for a man?
Zinc supports normal immune function, wound healing, protein and DNA synthesis and cell growth [1], and adequate zinc is associated with normal testosterone levels [8].
Does zinc increase testosterone?
In men who are low in zinc, restoring zinc raised testosterone in a small study [8]. There is no good evidence that extra zinc raises testosterone in men who already get enough.
Sources
- NIH Office of Dietary Supplements. Zinc: Fact Sheet for Health Professionals.
- NIH Office of Dietary Supplements. Copper: Fact Sheet for Health Professionals.
- NIH Office of Dietary Supplements. Magnesium: Fact Sheet for Health Professionals.
- Costello LC, Franklin RB. A comprehensive review of the role of zinc in normal prostate function and metabolism; and its implications in prostate cancer. Archives of Biochemistry and Biophysics. 2016.
- Zhao J, Wu Q, Hu X, et al. Comparative study of serum zinc concentrations in benign and malignant prostate disease: a systematic review and meta-analysis. Scientific Reports. 2016.
- Leitzmann MF, Stampfer MJ, Wu K, et al. Zinc supplement use and risk of prostate cancer. Journal of the National Cancer Institute. 2003.
- Barrie SA, Wright JV, Pizzorno JE, Kutter E, Barron PC. Comparative absorption of zinc picolinate, zinc citrate and zinc gluconate in humans. Agents and Actions. 1987.
- Prasad AS, Mantzoros CS, Beck FW, Hess JW, Brewer GJ. Zinc status and serum testosterone levels of healthy adults. Nutrition. 1996.
Disclosure: OPA Nutrition sells supplements, including products mentioned in this article. This content is for education only and is not medical advice. Statements about dietary supplements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease. Talk to your healthcare provider before using any supplement, especially if you take medication or have a medical condition.
Written and reviewed by Michael Gonzales, Founder, OPA Nutrition · Last reviewed: · How OPA researches and writes
