Zinc Citrate or Zinc Gluconate: Which is more effective?

Zinc citrate is a form of zinc typically found in dietary supplements or toothpastes. Generally synthesised from zinc oxide and citric acid, zinc citrate is a versatile active ingredient presented as a white powder. Its chemical formula is C12H10O14Zn3. When present in dietary supplements, zinc citrate is particularly praised for its effects on the radiance of the skin and its sebum-regulating properties. However, the scientific evidence supporting these claims is relatively weak.

On the other hand, zinc citrate proves to be a remarkable active ingredient in dental care. Studies have shown that zinc citrate has positive effects on dental plaque and that it possesses antimicrobial properties against certain anaerobic bacteria and streptococci that contribute to gum problems, particularly gingivitis. It has also been found that zinc gluconate has a soothing effect on dental hypersensitivity. Finally, authorised at 1% in care products, this active ingredient is considered safe for use in adults and children over the age of 6.

Zinc gluconate is predominantly found in cosmetic treatments aimed at improving the condition of the skin and hair , or in dietary supplements with a similar purpose. With the chemical formula C12H22O14Zn, this active ingredient is highly favoured by individuals with oily skin due to its sebum-regulating properties. Biologically, 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 true ally against blemishes.

Zinc gluconate also has healing properties and supports damaged skin by stimulating the production of scar tissue. Moreover, its anti-inflammatory effects , derived from its ability to inhibit the release of TNF-α, a pro-inflammatory cytokine, make it relevant for use in cases of irritation. 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 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.

Although zinc citrate and zinc gluconate are both derivatives of zinc, they have quite different properties and are not used in the same context. Thus, you will typically find the former in toothpastes, while the latter is more naturally suited to skin or hair care products.

It is therefore challenging to compare the efficacy of zinc gluconate with that of zinc citrate, as these two active ingredients are used in completely different areas of cosmetics. We can simply conclude that zinc citrate is highly effective in addressing dental concerns, while zinc gluconate is a highly favoured active ingredient for taking care of one's skin and hair.

• FINE D. & al. Clinical anti-microbial efficacy of a new zinc citrate dentifrice. Clinical oral investigations (2009).

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