Vitamin C and Zinc Supplementation Guidelines

Essential Nutrient Supplementation

• The British Journal of Sports Medicine recommends correcting documented deficiencies of vitamin C, zinc, and other micronutrients to decrease immune defenses and increase infection susceptibility 1, 2
• The World Health Organization suggests therapeutic doses of 0.5-1 mg/kg per day of elemental zinc for 3-4 months for zinc deficiency in children 3
• The Clinical Nutrition society recommends zinc supplementation when plasma zinc levels are <0.75 mmol/L without abnormal losses 4

Therapeutic Use

• The British Journal of Sports Medicine recommends zinc lozenges (75 mg/day) initiated at symptom onset to reduce duration of common cold symptoms 1, 2
• This represents the strongest evidence for therapeutic supplementation in otherwise healthy individuals 1, 2

Populations at Risk

• The British Journal of Sports Medicine prioritizes supplementation for individuals with documented micronutrient deficiencies 1, 2
• The Clinical Nutrition society prioritizes supplementation for people living with HIV/AIDS, particularly those with suboptimal treatment 5, 6

Important Clinical Caveats

• The Clinical Nutrition society states that no established evidence supports routine empirical use of supraphysiologic doses of vitamin C or zinc to prevent or improve outcomes in viral infections including COVID-19 5
• The Praxis Medical Insights guideline warns that high zinc intake (≥30 mg daily) can induce copper deficiency, leading to neutropenia, anemia, and paradoxically reduced immune function 7, 8
• The Advances in Nutrition journal notes that zinc supplementation in HIV-infected infants showed increased risk of iron deficiency, though without increased anemia risk long-term 6, 9

Practical Implementation Strategy

• The British Journal of Sports Medicine recommends ensuring adequate dietary intake through at least five portions of fruits and vegetables daily on at least 5 days per week 1
• The Clinical Nutrition society recommends avoiding routine high-dose supplementation without documented deficiency 5
• The Praxis Medical Insights guideline suggests taking zinc supplements between meals for optimal absorption, avoiding foods high in phytates 3, 7

Monitoring Requirements

• The Praxis Medical Insights guideline recommends monitoring serum zinc levels and alkaline phosphatase periodically in children on long-term zinc supplementation 3
• The Praxis Medical Insights guideline suggests assessing copper status when taking ≥30 mg daily zinc 7
• The Praxis Medical Insights guideline notes that organic zinc compounds (gluconate, citrate, glycinate) have better bioavailability than zinc oxide 7