Zinc (Bisglycinate)

Why Zinc Deficiency Is So Common

Approximately 17% of the global population is zinc-deficient, with estimates reaching 35-45% in Western countries when accounting for subclinical deficiency. Primary causes include:

• Soil depletion reducing zinc content in plant foods
• Low consumption of the richest dietary sources (oysters, red meat, shellfish)
• Poor absorption from phytate-rich plant-based diets
• Increased demands from intense exercise, chronic stress, and alcohol consumption

Role in Testosterone Synthesis

Zinc is an essential cofactor for 5-alpha reductase and several enzymes in the testosterone biosynthesis pathway in Leydig cells. Zinc deficiency directly suppresses LH release from the pituitary and reduces gonadal responsiveness to LH stimulation.

The landmark 1996 study by Prasad et al. (Wayne State University) demonstrated that dietary zinc restriction in healthy young men reduced serum testosterone by 75% over 20 weeks. Zinc supplementation in zinc-deficient older men restored testosterone to levels comparable to younger controls.

Why Bisglycinate?

Zinc bisglycinate (zinc chelated to two glycine molecules) demonstrates 40-50% greater bioavailability than zinc oxide and produces significantly less gastrointestinal irritation than zinc sulphate. For supplementation purposes, bisglycinate or zinc picolinate are the preferred forms.

The Copper Balance Rule

At doses above 30-40mg/day, zinc competes with copper absorption in the small intestine. Long-term high-dose zinc supplementation without copper supplementation can cause frank copper deficiency, leading to anaemia and neurological symptoms. Standard guidance: supplement 1-2mg copper for every 15-30mg zinc above dietary baseline.