Most adults need between 75 and 90 mg of vitamin C per day. Women need 75 mg, and men need 90 mg. These are the recommended dietary allowances set by the National Institutes of Health, and most people can hit these targets through food alone. But your specific needs shift based on age, smoking status, pregnancy, and whether you’re supplementing on top of your diet.
Daily Recommendations by Age and Sex
Children need less vitamin C than adults, and the recommendation gradually increases with age. Toddlers aged 1 to 3 need about 15 mg per day, while children aged 4 to 8 need 25 mg. From ages 9 to 13, the recommendation rises to 45 mg for both boys and girls. Teen boys (14 to 18) need 75 mg, while teen girls in the same age range need 65 mg.
For adults 19 and older, the numbers are straightforward: 90 mg per day for men and 75 mg for women. These amounts are enough to maintain healthy tissue repair, immune function, and the antioxidant protection vitamin C provides throughout the body. A single medium orange contains roughly 70 mg, so one piece of fruit gets you most of the way there.
Adjustments for Smokers
If you smoke, you need 35 mg more vitamin C per day than the standard recommendation. That puts the target at 125 mg for men and 110 mg for women. Smoking generates more oxidative stress in the body, which depletes vitamin C faster. People regularly exposed to secondhand smoke also tend to have lower levels, though no separate official recommendation exists for them.
Pregnancy and Breastfeeding
Pregnant women aged 19 to 50 need 85 mg per day, a modest increase over the standard 75 mg. For pregnant teens (14 to 18), the recommendation is 80 mg. The increase supports fetal development and the higher metabolic demands of pregnancy.
Breastfeeding raises the requirement more significantly. Women aged 19 to 50 who are nursing need 120 mg per day, while breastfeeding teens need 115 mg. The additional vitamin C helps maintain adequate levels in breast milk for the infant.
How Much Your Body Actually Absorbs
Your body doesn’t absorb vitamin C equally at every dose. At intakes between 15 and 100 mg, absorption rates are 80% or higher. As the dose climbs, your intestines become less efficient at pulling it in. At 1,250 mg per day or more, less than 50% actually gets absorbed. The rest passes through your system unused.
This means there are diminishing returns to megadosing. Taking 200 mg gives you nearly twice the usable vitamin C of a 1,000 mg supplement when you account for the absorption difference. Your body also can’t store large amounts of vitamin C. Excess is filtered out through urine, so spreading your intake across meals is more effective than taking one large dose.
What High Doses Actually Do for Colds
The idea that massive vitamin C doses can prevent or cure colds is one of the most persistent beliefs in nutrition, and the evidence is more nuanced than most people expect. Taking 250 mg to 2 grams daily on a routine basis does not reduce how often the average person catches a cold. The one exception: people under heavy physical stress, like marathon runners, skiers, or soldiers in extreme cold, do see fewer colds with regular supplementation.
Where vitamin C supplementation does show a consistent effect is in shortening colds you’ve already caught, but only if you were taking it regularly before symptoms started. Adults who supplement daily experience colds that are about 8% shorter, while children see a 14% reduction. That translates to roughly half a day less of symptoms for an adult cold that would normally last a week. Severity also drops slightly. However, starting vitamin C after you already feel sick doesn’t appear to help.
The Upper Limit and Risks of Too Much
The tolerable upper intake level for adults is 2,000 mg per day. Going above this regularly increases the risk of digestive problems like diarrhea, nausea, and stomach cramps. Your body converts excess vitamin C into oxalate, which is filtered through the kidneys. In some people, particularly men, high-dose supplements have been linked to a greater risk of calcium oxalate kidney stones.
Since many vitamin C supplements contain 500 to 1,000 mg per tablet (sometimes more than 10 times the daily requirement), it’s easy to overshoot without realizing it. If you have a history of kidney stones, high-dose supplementation is worth avoiding entirely. For everyone else, staying at or below 2,000 mg keeps you well within safe territory, though there’s little evidence that anything above 200 to 400 mg per day offers additional health benefits for most people.
Getting Enough From Food
Most people in developed countries get enough vitamin C from diet alone. A cup of strawberries has about 90 mg. A medium red bell pepper has over 150 mg. Broccoli, kiwi, tomatoes, and citrus fruits are all strong sources. Even a baked potato contributes around 17 mg.
Cooking reduces vitamin C content because it’s sensitive to heat and water. Raw or lightly steamed vegetables retain more than boiled or heavily cooked ones. If your diet regularly includes a few servings of fruits and vegetables, you’re likely meeting the recommendation without supplements. People at higher risk of falling short include those with very limited diets, heavy smokers, and individuals with conditions that impair nutrient absorption.