Most adults need between 75 and 90 milligrams of vitamin C per day. Women should aim for 75 mg, and men should aim for 90 mg. These are the recommended dietary allowances set by the National Institutes of Health, and most people can hit these numbers through food alone without supplements.
Daily Recommendations by Age and Sex
Children need less vitamin C than adults, with requirements increasing as they grow. Toddlers ages 1 to 3 need about 15 mg per day, children ages 4 to 8 need 25 mg, and kids ages 9 to 13 need 45 mg. Teenagers start to see a split by sex: boys ages 14 to 18 need 75 mg, while girls in that range need 65 mg.
For adults 19 and older, the recommendation is 90 mg for men and 75 mg for women. During pregnancy, the target rises to 85 mg per day, though research has found that roughly 40% of pregnant individuals don’t reach even that modest amount. During breastfeeding, the recommendation increases further to 120 mg per day to account for the vitamin C passed through breast milk.
Who Needs More Than the Standard Amount
Smokers need an extra 35 mg of vitamin C per day on top of the standard recommendation, putting the target at 125 mg for men and 110 mg for women who smoke. This isn’t a soft suggestion. Smoking increases oxidative stress in the body, and studies consistently show that smokers have significantly lower vitamin C levels in their blood and immune cells compared to nonsmokers. People regularly exposed to secondhand smoke should also aim higher, though there’s no specific number set for them.
People under heavy physical stress may also benefit from more than the baseline. Research on marathon runners, skiers, and soldiers training in subarctic conditions has found that routine vitamin C supplementation (ranging from 250 mg to 2 grams per day) reduced the occurrence of common colds in these groups. For the general population, that same supplementation didn’t prevent colds, but it did slightly shorten them: about an 8% reduction in duration for adults and 14% for children.
How Much Your Body Actually Absorbs
Your body doesn’t absorb vitamin C in a straight line. At lower doses, absorption is highly efficient. When you take around 200 mg or less, your body absorbs the vast majority of it. But as the dose climbs, absorption drops off sharply. At 1,000 mg, your body absorbs less than half of what you take in, and the rest is excreted through urine. This is why taking mega-doses doesn’t proportionally raise your blood levels of vitamin C. You’re mostly paying for expensive urine.
This absorption curve is one reason many nutrition researchers suggest that 200 mg per day is a practical sweet spot for people who want to go above the baseline RDA. It’s enough to fully saturate your blood levels without waste, and it’s easily achievable through diet.
Foods That Cover Your Needs
Vitamin C is abundant in fruits and vegetables, and you don’t need to eat oranges all day to get enough. A single medium red bell pepper provides well over 100 mg. A cup of strawberries delivers about 85 mg. One medium orange contains roughly 70 mg. Kiwifruit, broccoli, Brussels sprouts, and tomatoes are all solid sources as well. A guava is one of the most concentrated sources available, packing over 125 mg in a single fruit.
The key detail with food sources is that vitamin C breaks down with heat and prolonged storage. Raw or lightly cooked vegetables retain the most. Boiling vegetables for a long time can destroy a significant portion of their vitamin C content, so steaming or eating them raw preserves more of what you need.
The Upper Limit and Risks of High Doses
The tolerable upper intake level for adults is 2,000 mg per day. This is the ceiling, not a target. Going above it raises the risk of digestive problems like diarrhea, nausea, and stomach cramps. But problems can emerge at lower mega-doses too.
The most notable risk of high-dose vitamin C supplementation is kidney stones. Your body converts excess vitamin C into oxalate, which can combine with calcium in the kidneys to form calcium oxalate stones. Harvard Health has specifically flagged this connection in men, noting that high-dose supplements should be avoided entirely by anyone with a history of calcium oxalate stones. Many supplements on the market deliver 500 to 1,000 mg per tablet, which is 5 to 10 times the daily requirement, and that level of intake over time can meaningfully increase stone risk in susceptible people.
Iron overload is another concern at very high doses. Vitamin C enhances iron absorption, which is helpful for most people but potentially dangerous for those with conditions that cause iron buildup, such as hemochromatosis.
Do You Need a Supplement?
Most people eating a reasonably varied diet that includes fruits and vegetables do not need a vitamin C supplement. A single serving of bell peppers or a couple of pieces of fruit can cover the entire day’s requirement. Supplements make the most sense for people with highly restricted diets, smokers who struggle to eat enough produce, or those recovering from surgery or illness where vitamin C demands are temporarily higher.
If you do supplement, a dose of 100 to 200 mg per day is enough to fully saturate your body’s vitamin C stores without hitting diminishing absorption returns. There’s no strong evidence that going higher provides additional benefits for the average person, and the risks start to outweigh any marginal gains once you move past 1,000 mg per day.