Most adults need between 75 and 90 mg 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 they’re easily met through a normal diet that includes fruits and vegetables. But several factors, from smoking to pregnancy, shift that number higher.
Daily Needs by Age and Sex
Children need less vitamin C than adults, and requirements increase with age. Kids ages 1 to 3 need about 15 mg per day, while those ages 4 to 8 need 25 mg. Between ages 9 and 13, the recommendation rises to 45 mg. Teenage boys need 75 mg and teenage girls need 65 mg.
For adults 19 and older, the baseline is 90 mg for men and 75 mg for women. Pregnant women need 85 mg, and breastfeeding women need 120 mg, the highest recommendation of any group. These amounts represent what’s needed to maintain healthy tissue and adequate stores in the body, not just to prevent deficiency.
Why Smokers Need More
If you smoke, add 35 mg to whatever your baseline is. That means men who smoke should get at least 125 mg per day, and women who smoke should get at least 110 mg. Smoking increases oxidative stress throughout the body, which burns through vitamin C faster. Studies consistently show that smokers have lower levels of vitamin C in their blood and immune cells compared to nonsmokers, even when dietary intake is similar. People regularly exposed to secondhand smoke should also consider aiming higher, though no specific number has been set for them.
What Vitamin C Actually Does
Vitamin C plays a direct role in building collagen, the protein that gives structure to your skin, joints, blood vessels, and bones. It stabilizes collagen at the molecular level and increases collagen production, which is why severe deficiency causes the connective tissue breakdown seen in scurvy. Beyond structural support, vitamin C acts as an antioxidant, neutralizing harmful molecules that damage cells. It also helps your body absorb iron from plant-based foods, which matters if you eat little or no meat.
The Upper Limit: 2,000 mg
The tolerable upper intake level for adults is 2,000 mg per day. Going above that on a regular basis raises the risk of real side effects. The most common problems from taking too much vitamin C include stomach cramps, nausea, diarrhea, and heartburn. Some people experience headaches, fatigue, or insomnia.
The more serious concern is kidney stones. In some people, high-dose vitamin C supplements increase the formation of oxalate stones, particularly with long-term use above 2,000 mg daily. People with a genetic condition called G6PD deficiency face an additional risk: high doses can trigger a type of anemia where red blood cells break down too quickly. If you have a history of kidney stones or known G6PD deficiency, large supplemental doses are worth avoiding.
Your Body Absorbs Less as the Dose Goes Up
Vitamin C absorption isn’t linear. At doses around 200 mg or less, your body absorbs nearly all of it. As the dose climbs toward 500 mg and beyond, the percentage your gut actually takes in drops significantly, and your kidneys start flushing the excess through urine. This is why taking a single 1,000 mg supplement is less efficient than eating vitamin C-rich foods throughout the day. If you do supplement, splitting doses into smaller amounts taken at different times improves how much you retain.
Food Sources That Cover Your Needs
A single medium orange provides about 70 mg of vitamin C, which nearly covers the daily need for most adults. Red bell peppers are even richer, with roughly 95 mg in half a cup. Strawberries, broccoli, kiwi, and Brussels sprouts are all strong sources. A cup of raw broccoli delivers about 80 mg, and a single kiwi has around 65 mg.
Most people eating a varied diet with a few servings of fruits and vegetables per day will hit 75 to 90 mg without thinking about it. Vitamin C is water-soluble and sensitive to heat, so raw or lightly cooked produce delivers more than heavily boiled vegetables. Frozen fruits and vegetables retain most of their vitamin C because they’re processed quickly after harvest.
Supplements: What’s Worth Knowing
Standard ascorbic acid is the most studied and least expensive form of vitamin C. It absorbs well at reasonable doses and is the form used in the vast majority of clinical research. Buffered forms (mineral ascorbates) are less acidic and sometimes recommended for people who get stomach upset from plain ascorbic acid, though there’s limited scientific evidence confirming they’re genuinely easier on the gut. Both the vitamin C and the mineral in these formulas are well absorbed, so if you’re taking large doses of calcium ascorbate, for example, you’re also getting a meaningful amount of calcium.
Liposomal vitamin C, which wraps ascorbic acid in fat-based particles, is marketed as having superior absorption. Early reports suggest it may be better absorbed than standard forms, but large-scale studies comparing the two haven’t been done yet. For most people meeting the 75 to 90 mg target, the form of vitamin C matters far less than simply getting enough.
Signs You’re Not Getting Enough
True vitamin C deficiency, which leads to scurvy, is rare in developed countries but not nonexistent. It shows up in people with very restricted diets, chronic alcoholism, or conditions that impair absorption. The earliest symptoms are vague: fatigue, weakness, muscle and joint pain. These can go unnoticed or get attributed to other causes.
As deficiency progresses, more distinctive signs appear. Small red or purple spots develop on the skin from tiny hemorrhages beneath the surface. Hair follicles become raised and rough, particularly on the legs and buttocks. Gums swell, bleed easily, and teeth can loosen. Wounds heal slowly, and existing scars may reopen. In children, the legs become tender and painful, sometimes to the point where a child refuses to move them. These symptoms reverse relatively quickly once vitamin C intake is restored, often within days to weeks.