Vitamin C Daily Need Calculator

Vitamin C (ascorbic acid) is an essential water-soluble vitamin that the human body cannot synthesize on its own — it must come entirely from diet or supplements. It plays critical roles in collagen synthesis, immune function, iron absorption, and antioxidant defense.

Recommended Dietary Allowances (RDA) by age and group:

• Infants 0–6 months: 40 mg/day (AI)
• Infants 7–12 months: 50 mg/day (AI)
• Children 1–3 years: 15 mg/day
• Children 4–8 years: 25 mg/day
• Children 9–13 years: 45 mg/day
• Teens 14–18 (male): 75 mg/day
• Teens 14–18 (female): 65 mg/day
• Adult males: 90 mg/day
• Adult females: 75 mg/day
• Pregnant women: 85 mg/day
• Breastfeeding women: 120 mg/day
• Smokers: add 35 mg/day to all above (smoking depletes vitamin C)

Tolerable Upper Intake Level (UL): 2,000 mg/day for adults Exceeding the UL may cause: nausea, diarrhea, abdominal cramps, kidney stones (oxalate pathway).

Bioavailability formula (absorption efficiency):

• At doses ≤200 mg: ~90% absorbed
• At 500 mg: ~73% absorbed
• At 1,000 mg: ~50% absorbed
• At 2,000 mg: ~20% absorbed: higher doses yield diminishing returns

Worked example: Adult male smoker: RDA = 90 + 35 = 125 mg/day. Takes a 500 mg supplement. Absorption ≈ 73%. Absorbed dose = 500 × 0.73 = 365 mg — well above the RDA with comfortable margin below the 2,000 mg UL.

Top dietary sources of vitamin C:

• Bell peppers (red): 190 mg per 100g
• Kiwi: 93 mg per 100g
• Broccoli: 89 mg per 100g
• Strawberries: 59 mg per 100g
• Orange juice: 50 mg per 100g
• One medium orange: ~70 mg

Vitamin C is heat-sensitive — cooking can destroy 15–55% of content. Raw or lightly steamed vegetables retain the most.