What is the recommended treatment for vitamin C deficiency?

Treatment of Vitamin C Deficiency

For symptomatic vitamin C deficiency (scurvy), initiate oral vitamin C 100 mg three times daily (300-500 mg/day total) for at least one month, and do not delay treatment while awaiting laboratory confirmation if clinical symptoms are present. 1

Initial Treatment Approach

Oral Therapy (First-Line)

• Standard repletion dose: 100 mg three times daily OR 500 mg once daily for 1 month 1
• Alternative regimen for severe cases: 250 mg twice daily for 3 weeks 1
• Treatment should begin immediately when clinical symptoms suggest scurvy (bleeding gums, petechiae, ecchymosis, poor wound healing, perifollicular hemorrhages) 1, 2
• Do not wait for plasma vitamin C measurement results, as clinical trial of vitamin C should not be delayed in the presence of clinical symptoms 1

When Intravenous Therapy is Required

• IV administration is necessary when oral therapy fails to normalize levels or resolve symptoms despite adequate dosing 3
• Critical illness/acute inflammation: 2-3 g/day IV during the acute phase 1, 2
• Malabsorption syndromes: Consider IV route if enteral absorption is compromised (Crohn's disease, bariatric surgery, chronic diarrhea) 3, 4
• Oral absorption is limited at higher doses due to saturable intestinal transporters, making IV necessary in some refractory cases 2, 3

Maintenance Therapy After Repletion

Standard Maintenance

• Healthy adults: 75-90 mg/day (women 75 mg, men 90 mg) to prevent recurrence 2, 5
• Post-bariatric surgery: 200-500 mg/day may be required long-term 1

High-Risk Populations Requiring Higher Maintenance Doses

• Chronic oxidative stress conditions (diabetes, heart failure, smoking, alcoholism, severe COPD, chronic dialysis): 200-500 mg/day 1, 2
• Chronic malabsorption: Individualized dosing based on plasma levels and clinical response 1
• Continuous renal replacement therapy: 2-3 g/day IV 1, 2

Monitoring and Duration

Laboratory Testing

• Measure plasma vitamin C only in patients with clinical suspicion of scurvy or chronic low intake 1, 2
• Do NOT measure during critical illness or severe inflammation (CRP >10 mg/L), as results are unreliable and difficult to interpret 1, 2, 6
• Normal plasma vitamin C levels are typically not detected if CRP >40 mg/L 2

Treatment Duration

• Minimum 1 month for symptomatic deficiency 1
• 3 weeks for clinical scurvy with the 250 mg twice-daily regimen 1
• Continue until clinical symptoms resolve and adequate dietary intake is established 1, 4

Safety Considerations and Contraindications

Absolute Contraindications

• Hemochromatosis or iron overload: Vitamin C enhances iron absorption 2, 7
• G6PD deficiency: Risk of hemolysis with high doses 2, 6
• Active oxalate kidney stones: High doses increase oxalate excretion 2, 6
• Severe renal dysfunction: Risk of oxalate accumulation 2, 6

Adverse Effects

• Gastrointestinal upset: Doses >2 g/day may cause diarrhea and abdominal discomfort 5, 8
• Tolerable upper limit: 2 g/day based on GI side effects 5, 8
• High doses (>1 g/day) are generally safe but require monitoring for edema 6

Common Pitfalls to Avoid

• Delaying treatment: Do not wait for laboratory confirmation when clinical scurvy is suspected—start empiric therapy immediately 1, 2
• Inadequate dosing: The 40-45 mg/day threshold prevents scurvy but does not achieve tissue adequacy or optimal repletion 2
• Ignoring malabsorption: Patients with inflammatory bowel disease, bariatric surgery, or chronic diarrhea may require IV therapy despite adequate oral dosing 3, 4
• Single high-dose strategy: Dividing total daily dose into multiple administrations (e.g., 100 mg TID rather than 300 mg once daily) maximizes absorption due to saturable intestinal transporters 2, 7
• Measuring levels during inflammation: Plasma vitamin C declines rapidly with inflammation, making interpretation unreliable in acute illness 1, 2, 6
• Assuming dietary intake is sufficient: Modern food production, transport, and storage severely impair vitamin C content, making supplementation often necessary even with adequate fruit/vegetable intake 9