The easiest way to get vitamin C is through fruits and vegetables, and most people can hit their daily target with just a few servings. Adults need 75 to 90 mg per day, a goal you can reach with a single cup of sliced kiwifruit (167 mg) or a cup of Brussels sprouts (75 mg). If your diet falls short, supplements work too, though your body absorbs them best at lower doses.
How Much You Actually Need
The NIH sets the recommended daily allowance at 90 mg for adult men and 75 mg for adult women. During pregnancy, the target rises to 85 mg, and during breastfeeding it jumps to 120 mg. Children need less: 15 mg for toddlers ages 1 to 3, 25 mg for kids 4 to 8, and 45 mg for those 9 to 13. Teenagers need 65 to 75 mg depending on sex.
Smokers are a notable exception. The official guidance adds 35 mg per day for smokers, but population-level data suggests the real gap is larger. One analysis found smokers needed roughly 80 mg more than nonsmokers, about double the typical requirement, to maintain adequate blood levels. That puts a smoker’s practical target around 165 mg per day.
Best Food Sources
Vitamin C is concentrated in fruits and vegetables, and the richest sources may not be the ones you’d guess. Black currants top the list at about 203 mg per cup. Green kiwifruit delivers 167 mg per cup of slices. After that, the numbers drop but remain impressive: lychees at 136 mg per cup, oranges with peel at 121 mg, and grapefruit at 72 to 85 mg per cup depending on the variety.
On the vegetable side, Brussels sprouts offer 75 mg per raw cup, cauliflower about 56 mg, and snap peas around 59 mg. Mangos contribute 60 mg per cup of pieces, and even plantains provide about 50 mg each. The practical takeaway: eating two or three servings of fruits and vegetables daily virtually guarantees you’ll exceed the minimum requirement.
Pairing Vitamin C With Iron-Rich Foods
If you eat a plant-based diet, vitamin C does something especially useful: it dramatically increases iron absorption from beans, grains, leafy greens, and other non-heme iron sources. The effect is dose-dependent. In one study, iron absorption from a meal containing 4 mg of non-heme iron increased from 0.8% to 7.1% as vitamin C was raised from 25 mg to 1,000 mg. The catch is that both nutrients need to be consumed at the same meal. Squeezing lemon over lentils or eating bell peppers alongside spinach makes a real difference in how much iron your body takes in.
How Cooking Affects Vitamin C
Vitamin C is water-soluble and sensitive to heat, so how you cook your food matters. Steaming is the gentlest method, retaining essentially 100% of vitamin C in most vegetables according to USDA retention data. Boiling with a small amount of water and draining also performs well, keeping about 95% of the vitamin intact, as long as you don’t use excess water. When you boil vegetables and use the cooking liquid (in a soup, for example), the vitamin C stays in the dish rather than going down the drain, so retention is close to 100%.
Raw is ideal when it’s practical. A raw red bell pepper, a handful of strawberries, or sliced kiwi on yogurt gives you the full vitamin C content with zero cooking loss. For cooked dishes, shorter cooking times and less water preserve more of the nutrient.
Supplements: What Your Body Can Absorb
Your intestines absorb vitamin C through dedicated transport proteins, and those transporters have a ceiling. At doses between 30 and 180 mg, your body absorbs up to 90% of what you swallow. Above 1,000 mg, absorption drops below 50%, and your kidneys excrete the excess. This means taking mega-doses of standard vitamin C is mostly wasteful.
The most common supplement form is plain ascorbic acid, which is inexpensive and reaches peak blood levels within 2 to 3 hours. If high doses of ascorbic acid upset your stomach, buffered forms (calcium ascorbate, sodium ascorbate, magnesium ascorbate) are gentler on the gut. One study found calcium ascorbate had 128% greater bioavailability than standard synthetic vitamin C over a 10-hour measurement period.
Liposomal vitamin C, which wraps the vitamin in tiny fat-based bubbles, does show meaningfully better absorption. A randomized crossover study of 27 adults found that a 500 mg liposomal dose produced 27% higher peak blood levels and 20% greater total absorption over 24 hours compared to standard vitamin C. Another study found even larger differences, with the liposomal form showing 1.77 times greater total exposure. However, liposomal vitamin C leaves your bloodstream at the same rate as the regular kind. No study has shown it stays elevated in the blood beyond 12 hours. It gets in more efficiently, but doesn’t stick around longer.
Splitting Doses Works Better Than One Large Dose
Because absorption efficiency drops at higher doses, you’ll get more vitamin C into your bloodstream by taking two 250 mg doses at different meals than one 500 mg dose at once. This applies to all supplement forms. If you’re trying to raise low vitamin C levels through supplementation, spreading your intake across the day makes better use of your intestinal transporters.
Signs You’re Not Getting Enough
Mild vitamin C deficiency doesn’t always announce itself clearly. Early signs include fatigue, irritability, and slow wound healing. Your gums may bleed more easily when brushing, and you might bruise from minor bumps. Dry, rough skin and splitting hair are also common with chronically low intake.
Severe deficiency, known as scurvy, takes about one to three months of near-zero intake to develop. Clinical deficiency is defined as a serum level below 11.4 µmol/L. At that point, symptoms escalate to joint pain, swollen gums, loose teeth, and small red or purple spots on the skin from bleeding under the surface. Scurvy is rare in developed countries but still occurs in people with extremely limited diets, particularly older adults living alone, people with alcohol use disorder, and those with very restricted eating patterns.
Who Needs More Than Average
Beyond smokers, several groups tend to have lower vitamin C levels or higher needs. People exposed to secondhand smoke face similar oxidative stress as active smokers and benefit from higher intake. Those with limited food variety, whether from poverty, food allergies, or restrictive diets, are at greater risk of falling short. Certain digestive conditions that reduce nutrient absorption can also lower vitamin C status.
Pregnancy and breastfeeding increase requirements modestly, to 85 mg and 120 mg respectively. If you’re in one of these higher-need groups and struggle to eat enough fruits and vegetables consistently, a modest supplement of 250 to 500 mg daily is more than sufficient to close the gap, given the absorption limits at higher doses.