Zinc Gluconate versus Zinc Picolinate.

Zinc gluconate is an active ingredient with the chemical formula C12H22O14Zn. It is particularly renowned for its sebum-regulating properties, making it a friend to oily skin. From a biological perspective, zinc gluconate inhibits 5-α-reductase, the enzyme that catalyses the conversion of testosterone into dihydrotestosterone (DHT). The binding of DHT to a receptor in the sebaceous glands increases their activity and the synthesis of sebum. The zinc gluconate also inhibits the growth of Cutibacterium acnes, a bacterium involved in acne, making it a good complement to anti-acne treatments.

Zinc gluconate is also recognised for its healing virtues and its ability to stimulate the production of scar tissue. Furthermore, its anti-inflammatory activity, resulting from its ability to inhibit the release of TNF-α, a pro-inflammatory cytokine, makes it a valuable asset for soothing skin irritations. Finally, studies have shown that zinc gluconate also finds utility in hair application and it helps to reduce dandruff by eliminating the fungi Malassezia, partly responsible for dandruff, and to prevent hair loss. This latter property is explained by its ability to inhibit 5-α-reductase and thus limit the production of DHT, a hormone that accelerates the entry of hair follicles into the telogen phase, also known as the shedding phase.

Zinc picolinate is another derivative of zinc, obtained from the chelation of picolinic acid by metallic zinc. Its chemical formula is C12H8N2O4Zn. Zinc picolinate is rarely found in cosmetic care, although it can be found in some shampoos, and is more commonly used as a dietary supplement. In this form, it helps to compensate for zinc deficiencies and stimulate the immune system. Zinc picolinate is also found in dietary supplements designed to alleviate acne and skin inflammation and take care of one's hair. The oral properties of zinc picolinate are quite similar to those of zinc gluconate.

If zinc picolinate is most commonly used in oral form, it is due to its high absorption by the body. Indeed, a comparative study was conducted on the absorption of zinc in different forms by about fifteen participants. This showed that oral intake of zinc picolinate allowed for a greater absorption of zinc than the intake of zinc gluconate or zinc citrate. After four weeks, the serum of the various participants was collected and the concentration of zinc was measured. Those who had taken zinc picolinate had zinc levels of about 0.57 ppm compared to 0.56 ppm for those who had taken zinc citrate and 0.54 ppm for those who had taken zinc gluconate. However, it should be noted that this is a single study and the number of participants was limited, which urges caution in considering the results.

Zinc gluconate and zinc picolinate are two derivatives of zinc with similar properties. Both are effective in combating acne and caring for one's skin and hair. However, zinc picolinate is almost exclusively found in dietary supplements, while zinc gluconate can be found in certain masks, creams, or even medications.

It is challenging to explain why the use of zinc gluconate is more widespread, even though the oral absorption of zinc picolinate appears to be higher. However, there are fewer scientific studies focused on the effectiveness of zinc picolinate compared to those about zinc gluconate, which could provide some explanation. This situation may change in the future but, for now, it would seem that zinc gluconate is the active ingredient gaining popularity.

• BARRON P. & al. Comparative absorption of zinc picolinate, zinc citrate and zinc gluconate in humans. Agents and actions (1987).

• KALINOWSKA-LIS U. & al. Zinc-containing compounds for personal care applications. International Journal of Cosmetic Science (2018).