Superior Form of Zinc for Oral Supplementation
Organic zinc compounds—specifically zinc glycinate, zinc gluconate, and zinc orotate—are superior to inorganic forms like zinc sulfate and zinc chloride due to significantly better tolerability and absorption. 1
Recommended Zinc Formulations (In Order of Preference)
First-Line: Organic Zinc Compounds
- Zinc glycinate (zinc bisglycinate) demonstrates 43.4% higher bioavailability compared to zinc gluconate and is the most well-absorbed form based on direct comparative studies 2, 3
- Zinc gluconate is the second-best choice, with absorption rates of approximately 61% when given without food, and serves as a well-established alternative with extensive clinical data 3, 4
- Zinc citrate shows comparable absorption to zinc gluconate (61.3% vs 60.9% fractional absorption) and represents another excellent option, particularly for liquid formulations 4
- Zinc orotate is also recommended as a well-tolerated organic form, though less comparative data exists 1
Avoid: Inorganic Zinc Salts
- Zinc sulfate and zinc chloride cause significantly more gastrointestinal side effects (nausea, vomiting, abdominal cramps) and should be avoided when organic alternatives are available 1
- Zinc oxide is poorly absorbed (only 49.9% fractional absorption vs 61% for organic forms), with some individuals showing minimal to no absorption 4
Clinical Application by Indication
For Acquired Zinc Deficiency Treatment
- Use 0.5-1 mg/kg per day of elemental zinc from organic compounds (glycinate, gluconate, or orotate) for 3-4 months 1, 5
- For a 70 kg adult, this translates to 35-70 mg elemental zinc daily 5
For Maintenance/Prevention After Bariatric Surgery
- 15 mg elemental zinc daily for RYGB and sleeve gastrectomy procedures 1, 6
- At least 30 mg elemental zinc daily for malabsorptive procedures (BPD/DS) 1, 6
- These doses can be provided within a complete multivitamin formulation 1
For General Supplementation
- 15 mg elemental zinc daily as part of a complete multivitamin and mineral supplement meets government recommended daily allowances 6
Critical Absorption Considerations
Timing with Food
- Taking zinc with food significantly delays absorption (lag time increases by 180%, time to peak concentration increases by 57%) but only moderately reduces total bioavailability (28% reduction) 7
- Zinc glycinate/bisglycinate formed in the presence of citric acid shows improved absorption over other forms, even when comparing similar organic salts 8
- If gastrointestinal side effects occur, taking zinc with food may be necessary to ensure compliance, accepting the modest reduction in absorption 6
Copper Co-Supplementation
- Always maintain a zinc-to-copper ratio of 8-15 mg zinc to 1 mg copper when providing both supplements, as high zinc intake can induce copper deficiency 6
- Include 2 mg copper in multivitamin formulations when providing zinc supplementation 1
Safety Thresholds
- Toxicity symptoms appear when zinc ingestion exceeds 1-2 grams (1000-2000 mg), far above therapeutic doses 1, 5
- Chronic high-dose zinc supplementation can cause copper deficiency, anemia, leukopenia, and neutropenia 1
Common Pitfall to Avoid
The most critical error is prescribing zinc sulfate or zinc oxide when organic forms are available—this results in unnecessary gastrointestinal side effects and reduced absorption that may compromise treatment adherence and efficacy 1, 3, 4.