Vitamin C

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By Nikola · Precision Nutrition L1 · Updated 5 November 2026

Vitamin C (ascorbic acid) is a water-soluble vitamin that your body needs to make collagen, absorb iron from plant foods and protect cells from oxidative stress, and because the body can neither make nor store it, it has to come from food every day. EFSA sets a population reference intake of 110 mg a day for men and 95 mg for women. Fresh vegetables and fruit cover that easily: one medium red bell pepper gives about 150 mg, a kiwi about 65 mg. Heat, long storage and boiling water cut the amount, so raw and lightly cooked produce counts most.

What vitamin C does

Vitamin C is needed to build collagen, L-carnitine and some neurotransmitters, and it is one of the body’s main antioxidants (NIH). It also helps you absorb non-heme iron, the form found in beans, lentils, grains and leafy greens. The EU allows these health claims for foods that are at least a source of vitamin C (Regulation (EU) 432/2012):

• “Vitamin C contributes to normal collagen formation for the normal function of” blood vessels, bones, cartilage, gums, skin and teeth (six separate claims).
• “Vitamin C contributes to the normal function of the immune system”.
• “Vitamin C contributes to the protection of cells from oxidative stress”.
• “Vitamin C increases iron absorption”.
• “Vitamin C contributes to the reduction of tiredness and fatigue”.
• “Vitamin C contributes to normal energy-yielding metabolism”, “to normal functioning of the nervous system” and “to normal psychological function”.
• “Vitamin C contributes to the regeneration of the reduced form of vitamin E”.
• “Vitamin C contributes to maintain the normal function of the immune system during and after intense physical exercise” – only for foods that provide 200 mg a day, on top of the recommended daily intake.

How much you need a day

Group	EFSA population reference intake	For reference: NIH RDA (US)
Men, 18+	110 mg	90 mg
Women, 18+	95 mg	75 mg
Pregnancy	105 mg	85 mg
Breastfeeding	155 mg	120 mg
Children 1-3 years	20 mg	–
Upper limit (UL)	Not set: EFSA found no adequate data to derive one	2,000 mg

EFSA’s values balance daily vitamin C losses and keep fasting plasma levels around 50 µmol/L. In the US, people who smoke are advised to get 35 mg a day more than non-smokers (NIH). The NHS notes that less than 1,000 mg a day from supplements is unlikely to cause harm, and that more than that can cause stomach pain, diarrhoea and wind.

Best food sources

Food	Vitamin C, 100 g	Portion	Per portion
Rose hips, wild, raw	426 mg	10 g	43 mg
Parsley, fresh	133 mg	10 sprigs, 10 g	13 mg
Red bell pepper, raw	128 mg	1 medium, 119 g	152 mg
Kale, raw	93.4 mg	1 cup, 21 g	20 mg
Kiwifruit, green, raw	92.7 mg	1 fruit, 69 g	64 mg
Broccoli, raw	89.2 mg	1 cup chopped, 91 g	81 mg
Broccoli, boiled, drained	64.9 mg	1/2 cup chopped, 78 g	51 mg
Brussels sprouts, raw	85.0 mg	1 cup, 88 g	75 mg
Green bell pepper, raw	80.4 mg	1 medium, 119 g	96 mg
Strawberries, raw	58.8 mg	1 cup halves, 152 g	89 mg
Orange, raw	53.2 mg	1 fruit, 131 g	70 mg
Lemon, raw, without peel	53.0 mg	1 fruit, 58 g	31 mg

Source: USDA FoodData Central, SR Legacy, checked 5 November 2026: rose hips FDC 168998, parsley FDC 170416, red bell pepper FDC 170108, kale FDC 168421, kiwifruit FDC 168153, broccoli raw FDC 170379, broccoli boiled FDC 169967, Brussels sprouts FDC 170383, green bell pepper FDC 170427, strawberries FDC 167762, orange FDC 169097, lemon FDC 167746. Portions are USDA household measures, except rose hips (10 g is our example); values per portion are calculated and rounded.

A single raw red pepper covers a day’s reference intake on its own, and a cup of strawberries or one orange plus a kiwi gets you close. Greens add up too: broccoli, Brussels sprouts, kale and a handful of parsley on a salad. A squeeze of lemon over lentils or spinach is a practical way to use the iron effect.

Cooking losses. Vitamin C dissolves in water and breaks down with heat, so cooking and long storage reduce it (NIH). Per 100 g, boiled broccoli has 64.9 mg against 89.2 mg raw in USDA data. Steaming or microwaving may lessen the losses (NIH), and eating part of your vegetables raw helps more. In winter, sauerkraut still gives 14.7 mg per 100 g (canned, USDA FDC 169279).

Deficiency: signs and who is at risk

Severe deficiency causes scurvy. Signs can appear within about a month of eating little or no vitamin C (below about 10 mg a day): tiredness, inflamed gums, small red or purple spots on the skin, joint pain, poor wound healing and corkscrew hairs. Bleeding can lead to iron deficiency anaemia, and untreated scurvy is fatal (NIH).

Groups more likely to fall short (NIH):

• People who smoke or breathe second-hand smoke.
• People who eat a very limited variety of food.
• People with severe malabsorption, some cancers, or kidney disease treated with haemodialysis.

Supplements: when they make sense

Most supplements contain ascorbic acid, which is as available to the body as the vitamin C in food. Sodium ascorbate and calcium ascorbate are other forms. In one study Ester-C and ascorbic acid gave the same blood levels, and the NIH concludes that plain ascorbic acid is the preferred form. You absorb about 70-90% at 30-180 mg a day but under 50% above 1 g, so much of a very large dose is never absorbed.

Colds. A Cochrane review (Hemilä and Chalker, 2013) pooled placebo-controlled trials that used at least 0.2 g a day. In 29 trial comparisons with 11,306 people, regular vitamin C did not reduce how often people caught colds. It shortened colds by 8% in adults and 14% in children. In people under heavy short-term physical stress, such as marathon runners, skiers and soldiers, it halved the risk of catching a cold (5 trials, 598 people). Starting vitamin C after symptoms begin showed no consistent effect. The authors concluded that routine supplementation is not justified for the general population.

Food first: two or three portions of the foods above give more than the reference intake without a tablet. A supplement may make sense if your diet is very limited, you smoke and eat little produce, or a doctor finds low levels.

Who should be careful

• Kidney stones. In a Swedish study of 23,355 men followed for 11 years, those who took ascorbic acid supplements (typically 1,000 mg tablets) had about twice the risk of kidney stones compared with non-users (relative risk 1.92). The NIH notes the clearest evidence is in people who already have high oxalate in their urine. If you have had kidney stones, ask your doctor before taking high doses.
• Haemochromatosis. Because vitamin C increases iron absorption, long-term high doses could worsen iron overload in people with hereditary haemochromatosis (NIH).
• Cancer treatment. People having chemotherapy or radiotherapy should talk to their oncologist before taking vitamin C supplements (NIH).
• Stomach. More than 1,000 mg a day can cause stomach pain and diarrhoea (NHS).

FAQ

How much vitamin C do I need a day?

EFSA sets 110 mg a day for men and 95 mg for women, 105 mg in pregnancy and 155 mg while breastfeeding. One medium red pepper or a cup of strawberries plus an orange covers that.

Does vitamin C help with colds?

For most people, taking it every day does not prevent colds, but it shortened them by about 8% in adults and 14% in children in a Cochrane review. Taking it only once symptoms start showed no consistent benefit. People under heavy physical stress, like marathon runners, caught about half as many colds.

Which foods have the most vitamin C?

Per 100 g in USDA data, wild rose hips have 426 mg, parsley 133 mg and red bell pepper 128 mg, followed by kale, kiwi, broccoli and Brussels sprouts at 85-93 mg. Eat some of them raw, because cooking reduces the amount.

Related entries and articles

• Bell peppers, kiwi and strawberries
• Broccoli, Brussels sprouts and kale
• Iron – why vitamin C helps you absorb it
• Vitamin E and zinc
• Stuffed peppers with bulgur and feta
• Kale, apple and walnut salad
• Pomegranate, walnut and parsley salad

Sources

1. EFSA NDA Panel (2013). Scientific Opinion on Dietary Reference Values for vitamin C. EFSA Journal 11(11):3418. efsa.europa.eu
2. EFSA: Summary of Dietary Reference Values, version 4 (September 2017). efsa.europa.eu
3. EFSA: Overview on Tolerable Upper Intake Levels as derived by the Scientific Committee on Food (SCF), version 11 (August 2025). efsa.europa.eu
4. Commission Regulation (EU) No 432/2012 – permitted health claims. eur-lex.europa.eu
5. NIH Office of Dietary Supplements: Vitamin C, Fact Sheet for Health Professionals. ods.od.nih.gov
6. NIH Office of Dietary Supplements: Vitamin C, Fact Sheet for Consumers. ods.od.nih.gov
7. Hemilä H, Chalker E (2013). Vitamin C for preventing and treating the common cold. Cochrane Database of Systematic Reviews, CD000980 (Europe PMC record). ebi.ac.uk
8. Thomas LD et al. (2013). Ascorbic acid supplements and kidney stone incidence among men: a prospective study. JAMA Internal Medicine 173(5):386-388. jamanetwork.com
9. NHS: Vitamin C. nhs.uk
10. MedlinePlus: Vitamin C. medlineplus.gov
11. USDA FoodData Central, SR Legacy: Rose Hips, wild (FDC 168998); Parsley, fresh (FDC 170416); Peppers, sweet, red, raw (FDC 170108); Peppers, sweet, green, raw (FDC 170427). fdc.nal.usda.gov
12. USDA FoodData Central, SR Legacy: Kale, raw (FDC 168421); Broccoli, raw (FDC 170379); Broccoli, cooked, boiled, drained (FDC 169967); Brussels sprouts, raw (FDC 170383). fdc.nal.usda.gov
13. USDA FoodData Central, SR Legacy: Kiwifruit, green, raw (FDC 168153); Strawberries, raw (FDC 167762); Oranges, raw (FDC 169097); Lemons, raw, without peel (FDC 167746); Sauerkraut, canned (FDC 169279). fdc.nal.usda.gov

This page is for information only and is not medical or dietary advice.