Vitamin C Needs Calculator
Estimate your recommended daily vitamin C from sex and smoking status, with the extra allowance smokers need and the safe upper limit.
How it works
target = RDA (90 mg men, 75 mg women) + 35 mg if a smoker · stay under the tolerable upper limit
Vitamin C is a water-soluble antioxidant the body cannot store, so a steady daily intake matters. Smokers are advised to add 35 mg because tobacco raises oxidative stress and lowers circulating levels. Very high doses are not more helpful — anything above about 200 mg is absorbed less efficiently and the excess is simply excreted, while grams-per-day megadoses can cause diarrhea and raise kidney-stone risk.
Worked example
A 30-year-old woman who smokes needs 75 + 35 = 110 mg/day. Since a medium orange has about 70 mg, roughly one and a half oranges — or an orange plus a serving of peppers — covers it.
Frequently asked questions
Does vitamin C prevent colds?
For most people, regular supplements do not prevent colds, though they may slightly shorten one. Getting enough from food is the sensible goal rather than megadosing.
Can I take too much vitamin C?
Yes. Above the tolerable upper limit (2000 mg/day for adults) it commonly causes stomach upset and diarrhea, and can increase the risk of kidney stones in susceptible people.
Which foods are highest in vitamin C?
Bell peppers, citrus fruit, kiwi, strawberries, broccoli and tomatoes are all rich sources. A varied diet with fruit and vegetables usually exceeds the RDA easily.
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Educational estimate only — not medical or dietary advice. Nutrient reference values are population averages; your individual needs may differ with medical conditions, medications, pregnancy or activity. Talk to a doctor or registered dietitian before making changes.