Introduction
Zinc is an essential trace element for which EFSA has approved several health claims: zinc contributes to the normal function of the immune system, normal DNA synthesis, protection of cells from oxidative stress, and maintenance of normal skin. But zinc supplements vary significantly in form — and this affects absorption and price.
In this article, we compare the five most common zinc forms.
Zinc picolinate
Zinc bonded to picolinic acid, a tryptophan metabolite that helps transport minerals across the intestinal wall.
- Absorption: Generally very good — some studies show picolinate absorbs better than gluconate and citrate (Barrie et al., 1987)
- Price: Medium to higher
- Best for: General daily zinc supplementation, especially when absorption is a priority
Zinc bisglycinate
Zinc bonded to two glycine amino acids (chelated form). One of the newer and increasingly popular forms.
- Absorption: Very good — the chelated form is gentle on the digestive tract and absorbs well (Gandia et al., 2007)
- Price: Medium to higher
- Best for: People with sensitive digestive systems who experience nausea with other zinc forms
Zinc citrate
Zinc bonded to citric acid. Widely used and well-studied form.
- Absorption: Good — better than oxide, similar to gluconate (Wegmuller et al., 2014)
- Price: Affordable to medium
- Best for: Good value for money, everyday use
Zinc gluconate
Zinc bonded to gluconic acid. One of the most common and affordable forms.
- Absorption: Good — well-studied and effective (Prasad et al., 2008)
- Price: Affordable
- Best for: Budget-conscious choice, widely used in lozenges (for sore throat)
Zinc oxide
Zinc bonded to oxygen. The simplest and cheapest form. Contains the highest percentage of elemental zinc.
- Absorption: Poorer — less bioavailable than other forms (Wegmuller et al., 2014)
- Price: Most affordable
- Best for: Topical use (creams, ointments). For oral supplementation, other forms are preferred
Comparison table
| Feature | Picolinate | Bisglycinate | Citrate | Gluconate | Oxide |
|---|---|---|---|---|---|
| Absorption | Very good | Very good | Good | Good | Poorer |
| Digestive tolerance | Good | Best | Good | Good | Moderate |
| Elemental zinc | ~21% | ~14% | ~34% | ~14% | ~80% |
| Price/dose | medium | medium | low | low | lowest |
| Research volume | Moderate | Growing | Good | Extensive | Extensive |
When to choose picolinate
- You want the best absorption and are willing to pay slightly more
- You use zinc for general health support on a daily basis
When to choose bisglycinate
- You have a sensitive digestive system — bisglycinate is one of the gentlest forms
- Other zinc forms cause nausea (especially on an empty stomach)
- You value the advantages of chelated minerals
When to choose citrate or gluconate
- You are looking for good value for money — both are effective and affordable
- Gluconate is a good choice as lozenges during cold season
When to avoid oxide
- For oral supplementation, other forms are preferable due to better bioavailability
- Oxide is a good choice in creams and ointments, but not the best option in a capsule
Frequently asked questions
Which zinc form absorbs best?
Picolinate and bisglycinate generally show the best absorption in studies (Barrie et al., 1987; Gandia et al., 2007). However, the difference with citrate and gluconate is not always significant.
How much zinc should I take daily?
The EFSA recommendation is 10 mg of elemental zinc per day for adults (EFSA Panel, 2014). The tolerable upper intake level is 25 mg per day. Do not exceed this without medical guidance.
Should zinc be taken on an empty stomach?
Zinc can be taken with food to reduce nausea. Bisglycinate tolerates an empty stomach better than most forms.
Does zinc affect copper absorption?
Yes, long-term high-dose zinc supplementation can reduce copper absorption (Fischer et al., 1984). For maintaining balance, see our article on copper-zinc balance.
Can you overdose on zinc?
Yes. Long-term overdosing can cause nausea, copper deficiency, and immune suppression. Follow recommended doses.
References
1. Barrie SA, Wright JV, Pizzorno JE, et al. (1987). Comparative absorption of zinc picolinate, zinc citrate and zinc gluconate in humans. Agents and Actions, 21(1-2), 223-228.
2. Gandia P, Bour D, Maurette JM, et al. (2007). A bioavailability study comparing two oral formulations containing zinc (Zn bis-glycinate vs. Zn gluconate) after a single administration to twelve healthy female volunteers. International Journal for Vitamin and Nutrition Research, 77(4), 243-248.
3. Wegmuller R, Tay F, Zeder C, et al. (2014). Zinc absorption by young adults from supplemental zinc citrate is comparable with that from zinc gluconate and higher than from zinc oxide. Journal of Nutrition, 144(2), 132-136.
4. Prasad AS, Beck FW, Bao B, et al. (2008). Duration and severity of symptoms and levels of plasma interleukin-1 receptor antagonist, soluble tumor necrosis factor receptor, and adhesion molecules in patients with common cold treated with zinc acetate. Journal of Infectious Diseases, 197(6), 795-802.
5. Fischer PW, Giroux A, L'Abbe MR. (1984). Effect of zinc supplementation on copper status in adult man. American Journal of Clinical Nutrition, 40(4), 743-746.
6. EFSA Panel on Dietetic Products, Nutrition and Allergies. (2014). Scientific opinion on dietary reference values for zinc. EFSA Journal, 12(10), 3844.
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Disclaimer
A food supplement is not a substitute for a varied and balanced diet and a healthy lifestyle.
