What role does zinc play in prostate health?

More and more research is demonstrating the role of zinc (Zn) in the function of the prostate.

The prostate is a gland that is part of the urinary and reproductive systems. Its primary function as a male accessory sexual organ lies in the secretion of prostatic fluid, a component of sperm that contributes between 15 and 30% of the total seminal fluid volume.

The prostate possesses a muscular layer that during the ejaculatory stimulus ensures that seminal fluid is pressed into the’urethra. To prevent seminal fluid from going in the direction of the bladder during ejaculation, the prostate muscles and urethral sphincter contract effectively, closing the urethra towards the bladder.

Prostatic fluid contains various enzymes, citric acid, and high amounts of monovalent and divalent metal ions such as zinc.

The role of zinc in normal prostate function and metabolism

The function of citric acid in prostatic fluid is not yet completely clear. It is known that by binding with calcium ions, it regulates the concentration of these in the sperm, influencing the fluidification of the ejaculate and maintaining its pH stable.

To produce and secrete high levels of citric acid, the prostate accumulates high levels of zinc in specialized cells in the peripheral area. Zinc levels and citrate metabolism are closely linked at the prostate level: zinc directly inhibits the enzyme that metabolizes citric acid, causing its accumulation for subsequent secretion into the prostatic fluid.

The prostate therefore needs to absorb zinc and can do so thanks to the large presence of particular transporter channels at cellular level, called ZIP1, which are regulated by molecules such as testosterone and prolactin.

The accumulation of zinc in prostate cells, in addition to inhibiting citrate metabolism and therefore energy production, can be an inducer of programmed mitochondrial death (apoptosis), thus effectively inhibiting tissue proliferation and growth.

Interestingly, both zinc and citrate were decreased in cells prostate cancer, suggesting an essential role of high zinc levels in maintaining a non-malignant prostate.

Zinc deficiency in prostate disease

More than 16 studies have reported that zinc levels are significantly decreased in prostate cancer tissue (up to 80%), but also in situations of benign hyperplasia (around 50%).

From a study conducted by a research group at the University of Turin and published in the journal Cancers [source] which involved more than 600 men undergoing prostate biopsy for suspected prostate cancer, it was seen that the levels of zinc detectable in the urine gradually decrease as the aggressiveness of the tumor increases.

This evidence has led to the idea that zinc deficiency could play a key role in the transformation process, suggesting that restoring normal zinc levels could be a promising approach in the prevention and treatment of prostate cancer.

Decreased levels of zinc and, consequently, citrate are one of the most characteristic signs of prostate cancer. The important role of zinc as a regulator of apoptosis in prostate cells makes the decrease a probable cause rather than a consequence of the tumor. Therefore, an adequate dietary intake of zinc is essential, especially for older adults.

The consequences of a mild zinc deficiency, such as reduced immune system function, are particularly relevant for maintaining health and may be critical in the prevention of age-related diseases.

Especially in the prostate, an adequate supply of zinc will help maintain health and physiological function and prevent the development or further progression of prostate disease, thus acting as an anti-hyperplasia and anti-tumor agent.

Therefore, targeted zinc supplementation should be considered with supplements adapted to the needs of the individual man.

Is it therefore necessary to supplement zinc?

In most cases, Zn supplementation in addition to food sources is a convenient option to compensate for insufficient intake, malabsorption or increased loss due to intestinal diseases.

Ionic zinc (Zn2+), or bivalent, from food sources is absorbed in the intestine by the family of ZIP zinc transporters, transporting zinc from the intestinal lumen to the intestinal enterocytes. From enterocytes, zinc is further transported into the bloodstream by another family of zinc transporters.

But not all sources of zinc are created equal.

Zinc occurs naturally in different forms, with different chemical properties. For example, if zinc is in a form that dissociates due to low pH in the stomach, it will be easily absorbed from the intestine, otherwise it will not be bioavailable.

The most common forms in which zinc is found are zinc bisglycinate, picolinate, gluconate (high bioavailability), citrate, sulfate (moderate bioavailability), zinc oxide and chloride (low bioavailability) (source).

What clinical studies say about zinc and prostate cancer

Several studies indicate Zinc as a parameter for evaluating the presence and progression of prostate cancer.

In a prospective cohort of 633 men scheduled for prostate biopsy (AOU Città della Salute e della Scienza, Turin), post-prostatic massage urinary zinc levels were significantly lower in cancer patients compared to healthy subjects and decreased with increasing stage/aggressiveness.

The addition of urinary zinc value to the standard parameters (age, PSA, digital rectal examination, MRI) improves the diagnostic performance (source).

A second prospective study tested urinary Zinc levels, combined with urinary PSA levels, to identify men with prostate cancer more correctly than standard parameters, suggesting a 50% reduction in biopsies in healthy men (source).

A systematic meta-analysis (52 studies, 163,909 participants) confirmed that zinc levels in blood, tissue, prostatic fluid, and hair are lower in prostate cancer patients, even when dietary zinc intake did not differ significantly from that of controls. The authors conclude that high zinc levels may have a protective role, but high-quality prospective studies are needed (source).

Conversely, large prospective cohorts suggest caution with high doses of supplements: in the Health Professionals Follow-up Study (47,240 men, 30 years of follow-up) >75 mg/day of zinc or >15 years of use were associated with increased risk of aggressive or lethal cancer (source).

In terms of safety, the maximum tolerable limits differ according to the geographical area: EFSA in Europe indicates 25 mg/day for adults, while in the USA the Food and Nutrition Board/NIH ODS indicates 40 mg/day; a chronic excess can lead to copper deficiency and other toxicities ( (fonte).