Zinc Bisglycinate

Zinc bisglycinate is elemental zinc chelated to two molecules of the amino acid glycine (Zn(C₂H₄NO₂)₂). Wrapping the zinc ion inside two glycine “claws” is thought to shield it from dietary antagonists such as phytate and to make it gentler on the gut lining than ionic salts. In the limited head-to-head human data it absorbs at or near the top of the common oral forms and it is the best tolerated of them — which is why it is the usual choice for people who get nausea or stomach upset on other zinc salts. Its advantage is absorption and tolerability, not a distinct clinical benefit: nearly all outcome trials (immunity, colds, diarrhoea, taste, skin) were run with other salts, and their conclusions transfer to bisglycinate through zinc itself. For zinc’s full evidence base, dietary sources and intake references, see the Zinc hub; this page covers only what is specific to the bisglycinate form.

Absorption & Tolerability

The bisglycinate form’s reputation rests on a small but consistent body of comparative data, weighted toward mechanism and short-term pharmacokinetics rather than large trials.

• Human PK (the headline study). In a randomised, cross-over trial in 12 healthy women, a single 15 mg dose (7.5 mg × 2) of zinc bis-glycinate raised serum-zinc bioavailability by +43.4% versus zinc gluconate, and was safe and well tolerated ^{1Reference 1Gandia et al. · 2007RCTA bioavailability study comparing two oral formulations containing zinc (Zn bis-glycinate vsView study →}. This is the primary human evidence for the form’s absorption edge — but it is a single, small, single-dose study against one comparator (gluconate), not a broad ranking.
• Human narrative review. A 2024 review of clinical comparisons concluded that zinc glycinate and zinc gluconate are better absorbed than other forms of zinc ^{2Reference 2Devarshi et al. · 2024ReviewComparative Absorption and Bioavailability of Various Chemical Forms of Zinc in Humans: A Narrative Review (industry-authored)View study →}. Useful context, but the authors are employees of a supplement manufacturer (declared conflict of interest), so read the “top of the class” framing with that in mind.
• Resistance to phytate (mechanism). In a standardised in-vitro digestion + intestinal-cell model, chelated zinc sources were less susceptible to phytic-acid antagonism than inorganic zinc sulphate: ZnSO₄ solubility dropped from a 2:100 phytate:zinc ratio, whereas bisglycinate held out until 4:100. Notably, bisglycinate’s bioaccessibility without phytate (27%) was only marginally above ZnSO₄ (24%) and below zinc proteinate (42%), and cellular uptake was unaffected by phytate — so the chelate’s benefit is mainly protection in a phytate-rich (plant-based) meal, not a large intrinsic uptake advantage ^{3Reference 3Rock et al. · 2025In vitroThe Antagonistic Influence of Phytic Acid on Zinc Absorption: An In Vitro Comparison of Inorganic and Chelated Trace Mineral SourcesView study →}.
• Animal confirmation. In phytate-fed rats, true zinc absorption was higher from glycinate than sulphate (51% vs 44%), giving ~16% greater overall bioavailability — again, the edge appeared specifically in the presence of the anti-nutrient ^{4Reference 4Schlegel et al. · 2006AnimalBioavailability of zinc glycinate in comparison with zinc sulphate in the presence of dietary phytate in an animal model with ⁶⁵Zn-labelled ratsView study →}.
• The honest null. In weaning pigs fed a wheat/barley/soy diet, glycinate and an amino-acid chelate did not out-perform zinc sulphate on digestibility or plasma zinc ^{5Reference 5Paulicks et al. · 2011Bioavailability of two organic forms of zinc in comparison to zinc sulphate for weaning pigs — no difference vs sulphateView study →}. Where the diet or dose is already adequate, the chelate’s advantage can disappear.
• Tolerability. Direct comparative tolerability trials are sparse, but the rationale is well established: an ADHD trial deliberately chose zinc glycinate “as having less gastrointestinal discomfort than sulfate,” and reported no excess adverse events at up to 30 mg/day for 8 weeks ^{6Reference 6Arnold et al. · 2011RCTZinc for attention-deficit/hyperactivity disorder: placebo-controlled double-blind pilot trial (zinc glycinate chosen for less GI discomfort than sulfate; safe to 30 mg/day × 8 wk)View study →}; a paediatric diarrhoea RCT using 15 mg bisglycinate reported good compliance in all participants ^{7Reference 7Rerksuppaphol et al. · 2020RCTEfficacy of zinc supplementation in the management of acute diarrhoea: a randomised controlled trial (15 mg elemental as bisglycinate)View study →}.

Bottom line: roughly 20% elemental zinc as commonly sold (buffered/blended products; the pure anhydrous or dihydrate chelate is nearer 26–31% by formula weight — check the label). It sits at the top of the common oral forms for absorption and is the easiest on the stomach. But the human comparative evidence is one small PK study plus an industry review, the biggest measured gains are against poorly absorbed salts (sulphate/oxide) in phytate-rich meals, and head-to-head data against the other well-absorbed forms (gluconate, citrate, picolinate, acetate) are thin. Choose it for tolerance and plant-based diets, not for a dramatic absorption leap over every alternative.

What the Evidence Says

Form-specific clinical outcome data are limited. Most zinc outcome trials (immune support, common cold, acute diarrhoea, taste disorders, acne) used sulphate, gluconate or acetate, so the bisglycinate form’s edge is delivery — how much zinc gets in and how well the dose is tolerated — not a separate therapeutic effect. Where bisglycinate itself was the study form, it performed as an effective zinc vehicle: in a double-blind paediatric RCT, 15 mg elemental zinc as bisglycinate shortened acute-diarrhoea recovery (44 vs 52 h to resolution) and reduced stool frequency and hospital stay versus placebo ^{7Reference 7Rerksuppaphol et al. · 2020RCTEfficacy of zinc supplementation in the management of acute diarrhoea: a randomised controlled trial (15 mg elemental as bisglycinate)View study →} — a zinc effect delivered through this form, with good compliance.

For the mineral’s full, form-agnostic evidence base — immune function, common cold, deficiency correction, skin, taste, and the repletion-vs-extra-on-top distinction — see the Zinc hub.

Dosage

Dosed as elemental zinc, so read labels carefully — a “25 mg zinc bisglycinate” capsule may supply anywhere from ~5 mg (if the number is chelate weight at ~20%) up to the full 25 mg (if it is the elemental figure). Typical supplemental range is 15–30 mg elemental/day, within zinc’s intake references (RDA 8–11 mg/day; UL 40 mg/day — see the Zinc hub). Because fractional zinc absorption falls as the dose rises, splitting larger doses and taking it away from high-phytate meals, calcium and iron improves uptake — though the chelate is specifically more phytate-resistant than the inorganic salts ^{3,4Reference 3Rock et al. · 2025In vitroThe Antagonistic Influence of Phytic Acid on Zinc Absorption: An In Vitro Comparison of Inorganic and Chelated Trace Mineral SourcesView study →Reference 4Schlegel et al. · 2006AnimalBioavailability of zinc glycinate in comparison with zinc sulphate in the presence of dietary phytate in an animal model with ⁶⁵Zn-labelled ratsView study →}. These are doses studied in research, not a personal recommendation.

Safety

The form does not change zinc’s safety ceiling. General zinc cautions apply: sustained intake at or above ~40 mg/day elemental (the UL) can induce copper deficiency (anaemia, neutropenia, and — with chronic excess — neurological problems); pair higher chronic doses with copper. Zinc also competes with iron and calcium for absorption and can reduce absorption of tetracycline and fluoroquinolone antibiotics (separate by ~2 hours). What is specific to bisglycinate is on the favourable side: it is the best-tolerated common oral form, chosen in trials precisely to avoid the nausea and gastric upset associated with zinc sulphate ^{6Reference 6Arnold et al. · 2011RCTZinc for attention-deficit/hyperactivity disorder: placebo-controlled double-blind pilot trial (zinc glycinate chosen for less GI discomfort than sulfate; safe to 30 mg/day × 8 wk)View study →}, with no excess adverse events at ≤30 mg/day over 8 weeks ^{6Reference 6Arnold et al. · 2011RCTZinc for attention-deficit/hyperactivity disorder: placebo-controlled double-blind pilot trial (zinc glycinate chosen for less GI discomfort than sulfate; safe to 30 mg/day × 8 wk)View study →} and good compliance in paediatric use ^{7Reference 7Rerksuppaphol et al. · 2020RCTEfficacy of zinc supplementation in the management of acute diarrhoea: a randomised controlled trial (15 mg elemental as bisglycinate)View study →}. Never infer safety from an absence of form-specific reports: bisglycinate’s clean tolerability record reflects short trials at ≤30 mg/day and does not license open-ended high-dose use. See the Zinc hub for the complete safety and interaction detail.

Pregnancy & lactation

Zinc’s pregnancy and lactation profile is a property of the nutrient, not this form: the bisglycinate chelate raises no additional pregnancy-specific concern beyond zinc’s own, and this page does not add a separate assessment — see the Zinc hub.

Related compounds / cross-links

• Nutrient hub: Zinc — full evidence, dietary sources, intake references.
• Sibling forms: Zinc citrate, Zinc gluconate, Zinc picolinate, Zinc acetate, Zinc oxide (the poorly absorbed low-cost form).
• Chelating ligand: Glycine.

References