Editorial NexoScience
Ten times. That’s roughly how much more zinc a healthy prostate gland packs in compared with almost any other tissue in the human body, a peculiarity researchers have known about for decades. A systematic review and meta-analysis pooling data from 52 studies and more than 163,000 people has now put numbers on what happens to that stockpile once prostate cancer appears.
The pattern holds across almost every kind of sample researchers checked. Men with prostate cancer had significantly lower zinc in their blood serum, in their hair, and directly in prostatic fluid or tissue, which showed the steepest drop of all. Nail zinc levels, by contrast, showed no meaningful difference between men with the disease and healthy controls, and neither did how much zinc people reported eating or taking as supplements.
That last detail complicates the obvious takeaway. If zinc intake looked essentially identical between the two groups while tissue zinc diverged so sharply, the missing mineral is unlikely to be something people are simply failing to eat enough of. The researchers point to a more specific biological story instead: healthy prostate cells produce citrate and hold onto zinc to do it, while cells that turn malignant switch to oxidizing citrate, apparently losing their grip on zinc along the way.
Zinc’s job inside a healthy prostate goes well beyond storage. In cells that still retain it, zinc has been linked to blocking uncontrolled proliferation, triggering programmed cell death through pathways involving caspase enzymes, and interfering with signals tumors use to grow new blood vessels and spread. Once a cell loses the ability to hold onto zinc, several of those protective mechanisms appear to switch off with it.
None of this settles whether supplements would help. The picture from dosing studies is genuinely mixed. One large cohort that tracked health professionals for 14 years found men taking 100 milligrams or more of supplemental zinc daily had more than double the risk of prostate cancer compared with non-users, while other long-term data linked very high, prolonged zinc supplementation to a heightened risk specifically of lethal disease. The researchers behind this review are explicit that their findings describe an association observed in tissue, not proof that boosting zinc intake prevents or treats the disease.
The heterogeneity between the 52 pooled studies was substantial, and the authors flag it themselves. Sampling methods varied widely, from blood draws to hair clippings to laser-based imaging of prostate tissue, and the team could not fully explain why results differed as much as they did between studies, nor fully rule out publication bias in the serum and hair results specifically.
The study, “The Association Between Zinc and Prostate Cancer Development: A Systematic Review and Meta-Analysis,” was conducted by Shahrzad Shahrokhi Nejad, Zahra Golzari, Moein Zangiabadian, Amir Abbas Salehi Amniyeh Khozani, Rasoul Ebrahimi, Seyed Aria Nejadghaderi and Azadeh Aletaha, and published in PLOS ONE in March 2024. DOI: 10.1371/journal.pone.0299398.
