Most adults need between 75 and 90 mg of vitamin C per day, an amount easily reached through diet alone. Women need 75 mg, men need 90 mg, and smokers need an extra 35 mg on top of those numbers. If you’re pregnant, the recommendation rises to 85 mg; if you’re breastfeeding, it’s 120 mg. These are the amounts needed to maintain healthy tissue, support your immune system, and help your body absorb iron.
Daily Recommendations by Age and Sex
Children need far less vitamin C than adults. Kids aged 1 to 3 need just 15 mg per day, which climbs to 25 mg between ages 4 and 8, then 45 mg from 9 to 13. Teenage boys need 75 mg and teenage girls need 65 mg. Once you hit adulthood, those numbers settle at 90 mg for men and 75 mg for women.
Smokers are a special case. Smoking depletes vitamin C faster because it generates more oxidative stress in the body. The NIH recommends smokers add 35 mg per day to their baseline, bringing the target to 125 mg for men and 110 mg for women who smoke. People regularly exposed to secondhand smoke should also aim higher, though no specific number has been set for them.
How Much Is Too Much
The tolerable upper limit for adults is 2,000 mg per day. Going above that regularly increases the risk of digestive problems like diarrhea, nausea, and stomach cramps. Your body has a built-in ceiling for vitamin C absorption: at doses around 200 mg, you absorb nearly all of it, but absorption efficiency drops sharply as the dose climbs. By the time you’re taking 1,000 mg or more in a single sitting, your body excretes most of the excess through urine.
The more serious concern with high doses is kidney stones. Research from Harvard Health found that high-dose vitamin C supplements appear to double a man’s risk of developing calcium oxalate kidney stones. Anyone with a history of kidney stones should be particularly cautious about supplementing beyond the recommended daily amount. Women appear to face less kidney stone risk from vitamin C, but the digestive side effects apply equally.
Can Vitamin C Help With Colds
This is probably the most common reason people reach for extra vitamin C, and the evidence is more modest than most people expect. Taking vitamin C regularly (anywhere from 250 mg to 2 grams per day) does not prevent colds in the general population. It does slightly shorten them: about 8% shorter in adults and 14% shorter in children, which translates to roughly half a day less of symptoms for a typical cold.
There’s an important caveat, though. Taking vitamin C after cold symptoms have already started shows no benefit. The modest protective effect only appears with consistent, daily supplementation before you get sick. The one group that does see a real reduction in cold frequency is people under heavy physical stress, like marathon runners, skiers, and soldiers training in extreme conditions. For these groups, regular vitamin C supplementation roughly halves the risk of catching a cold.
Food Sources vs. Supplements
Most people eating a reasonably varied diet already get enough vitamin C without a supplement. A single medium orange provides about 70 mg. A cup of strawberries delivers around 90 mg. Yellow bell peppers are among the richest sources available, packing 184 mg per 100 grams (roughly one medium pepper). Even green bell peppers contain 80 mg per 100 grams. Broccoli, kiwi, tomatoes, and potatoes all contribute meaningful amounts.
Getting your vitamin C from food has a practical advantage: you absorb it more efficiently in smaller, frequent doses spread across meals than in one large supplement dose. If you do supplement, splitting a larger dose into two or three smaller ones throughout the day will improve absorption compared to taking it all at once.
Types of Supplements
Standard ascorbic acid is the most common and least expensive form of vitamin C. It’s well absorbed at typical supplement doses (100 to 200 mg) and is the form used in most clinical research. Some people find it irritates their stomach, especially at higher doses. Buffered forms, sometimes labeled as sodium ascorbate or calcium ascorbate, are gentler on the digestive system because they’re less acidic.
Liposomal vitamin C has gained popularity with claims of superior absorption. These supplements wrap vitamin C in tiny fat-based capsules designed to survive stomach acid. Early evidence from Oregon State University’s Linus Pauling Institute suggests liposomal forms may be better absorbed than standard ascorbic acid, but large-scale studies confirming this haven’t been completed yet. For most people taking normal daily amounts, the difference between supplement forms is unlikely to matter much.
Signs You’re Not Getting Enough
True vitamin C deficiency is uncommon in developed countries, but it still happens, particularly among people who eat very few fruits and vegetables, heavy smokers, people with severe alcohol use disorders, and those with digestive conditions that limit nutrient absorption. Blood levels below 0.6 mg/dL are considered marginal, and levels below 0.2 mg/dL indicate outright deficiency.
Early signs include fatigue, irritability, and slow wound healing. As deficiency worsens, you may notice swollen or bleeding gums, easy bruising, dry or splitting hair, and joint pain. Full-blown scurvy, the severe form of vitamin C deficiency, is rare but develops after several weeks of intake below about 10 mg per day. Symptoms reverse quickly once intake returns to normal levels, often within days to weeks.