Vitamin C RDA Table
| Life stage | RDA (mg/day) |
|---|---|
| Infant 0–6 mo | 40 (AI) |
| Infant 7–12 mo | 50 (AI) |
| 1–3 years | 15 |
| 4–8 years | 25 |
| 9–13 years | 45 |
| 14–18 years | 75 (M) / 65 (F) |
| 19+ years | 90 (M) / 75 (F) |
| Pregnancy | 80 (≤18) / 85 (19+) |
| Lactation | 115 (≤18) / 120 (19+) |
| Smokers, adult | RDA + 35 |
| Food | Portion | mg | %DV |
|---|---|---|---|
| Red pepper, raw | 1/2 cup | 95 | 106% |
| Orange juice | 3/4 cup | 93 | 103% |
| Grapefruit juice | 3/4 cup | 70 | 78% |
| Orange | 1 medium | 70 | 78% |
| Kiwifruit | 1 medium | 64 | 71% |
| Green pepper, raw | 1/2 cup | 60 | 67% |
| Broccoli, cooked | 1/2 cup | 51 | 57% |
| Strawberries | 1/2 cup | 49 | 54% |
Vitamin C's table is small because the need is small: 90 mg a day for men and 75 for women - about one orange - and the body refuses to be rushed past it. Absorption runs 70-90% at ordinary intakes, but past a single 1-gram dose the gut's transport saturates and uptake falls below half, which is why the 1,000 mg effervescent tablet mostly prices as expensive urine. The tolerable upper limit is 2,000 mg, and chronic megadosing buys kidney-stone risk, not immunity.
The table's one lifestyle line is the smoker's surcharge: +35 mg a day, on the logic that cigarette smoke is an oxidative assault and vitamin C is the antioxidant that depletes fastest defending it. It is the only RDA in the entire NIH series that prices a behavior, and it applies by exposure - secondhand smoke measurably lowers plasma levels too.
The food table ends the supplement debate on its own: half a cup of raw red pepper carries 95 mg - 106% of the Daily Value - and orange juice crosses the line in three-quarters of a cup. Every historical scurvy epidemic was a winter-storage problem (grain, roots, and nothing green for months), and the Royal Navy's limes worked a century before anyone isolated the molecule. Fresh produce still solves it faster than any pill.
How to use
- Find your row: 90 mg for men and 75 for women from 19; 75 and 65 for teens; 45 from ages 9-13; pregnancy adds 10 and breastfeeding adds 45; smokers of either sex add 35 to the adult number.
- Meet it from the food table: a half cup of red pepper or three-quarters of a cup of OJ at breakfast clears the whole day; kiwi, green pepper or strawberries stack the rest without counting.
- If you supplement anyway, split it: 250 mg twice a day beats 1,000 mg once - the absorption table saturates, so smaller doses keep uptake near 80% while the mega-dose discards more than half; and stay under the 2,000 mg ceiling.
Frequently asked questions
How much vitamin C do I need per day?
The NIH RDA: 90 mg for men and 75 for women from age 19; 75 and 65 for teens 14-18; 45 from ages 9-13; 25 at 4-8 and 15 at 1-3; infants run 40-50 mg as an adequate intake. Pregnancy adds 10 mg (85 for adults) and breastfeeding adds 45 (120 for adults). Smokers add 35 mg at any adult age - the table's only lifestyle adjustment.
What foods are highest in vitamin C?
Half a cup of raw red pepper leads outright at 95 mg (106% DV); three-quarters of a cup of orange juice delivers 93; grapefruit juice and a whole orange each carry 70; a kiwifruit 64; half a cup of green pepper 60; cooked broccoli 51; half a cup of strawberries 49. The pepper-outruns-the-orange result is the standard surprise: heat destroys some vitamin C, but the raw red pepper's concentration beats cooked rows and every citrus on the list.
Can you take too much vitamin C?
The adult ceiling is 2,000 mg a day (lower for children). Chronically above it, the documented costs are GI upset and a raised oxalate-kidney-stone risk in men - not toxicity in the poisoning sense, because the vitamin is water-soluble and the kidneys shed the rest. The subtler failure is marketing math: absorption falls below 50% past single 1-gram doses, so the 1,500 mg 'immunity' tablet delivers less usable vitamin C than breakfast.
Does vitamin C actually help colds?
The honest summary of decades of trials: regular supplementation does not prevent colds in the general population, but it modestly shortens duration (about 8% in adults, 14% in children in meta-analyses). The one population with real prevention evidence is people under extreme physical stress - marathon runners and soldiers in subarctic training - roughly halving their cold incidence. Taking it after symptoms start shows little effect, which is why the orange juice at breakfast beats the emergency packet at the first sniffle.
Why does vitamin C matter for iron - and what was scurvy?
Vitamin C converts plant (non-heme) iron into the form the gut absorbs, which is why the iron RDA table pairs lentils and spinach with peppers or citrus - same plate, several times the iron uptake. Scurvy is the deficiency's endgame: collagen synthesis fails, so wounds reopen and gums bleed - the Royal Navy's lime ration fixed it in the 1790s before the molecule was isolated in 1932, and 'limey' stuck as the word. The body pools only a few weeks' reserve, which is why stored-grain winter diets were the killer.