How Much Vitamin C Per Day? Needs, Upper Limit and Colds
Adult men need 90 mg of vitamin C a day and women 75 mg. Smokers need 35 mg more. The upper limit is 2,000 mg a day; above that, diarrhea and stomach upset become common. Most people get enough from fruit and vegetables. Taking vitamin C regularly may slightly shorten colds but doesn't prevent them for most people.
Vitamin C is one of the most widely taken supplements, often in doses far above what the body uses. So how much vitamin C per day do you actually need, and when is more pointless or problematic?
Daily needs
| Group | RDA per day |
|---|---|
| Men 19+ | 90 mg |
| Women 19+ | 75 mg |
| Pregnancy (19+) | 85 mg |
| Breastfeeding (19+) | 120 mg |
| Smokers | Add 35 mg |
| Upper limit, adults | 2,000 mg |
Your body can't store much vitamin C. At intakes above a few hundred milligrams a day, absorption falls and extra is passed in the urine.
Food sources
| Food | Serving | Vitamin C |
|---|---|---|
| Red bell pepper, raw | ½ cup | about 95 mg |
| Orange juice | ¾ cup | about 93 mg |
| Orange | 1 medium | about 70 mg |
| Kiwi | 1 medium | about 64 mg |
| Broccoli, cooked | ½ cup | about 51 mg |
| Strawberries | ½ cup | about 49 mg |
A couple of servings of fruit and vegetables covers the RDA. Cooking and long storage reduce vitamin C, so raw or lightly cooked produce is best.
Vitamin C and colds
A large Cochrane review of placebo-controlled trials found:
- Regular vitamin C (at least 200 mg a day) shortened colds slightly: by about 8% in adults and 14% in children.
- It did not reduce how often most people caught colds.
- In people under extreme physical stress, such as marathon runners and soldiers in subarctic conditions, it roughly halved the risk of colds.
- Starting vitamin C after symptoms began showed no consistent benefit.
Who might need more
- Smokers and people exposed to secondhand smoke
- People with limited diets, such as some older adults or people with alcohol use disorder
- People with malabsorption or on kidney dialysis
Severe deficiency causes scurvy: fatigue, gum bleeding, easy bruising and poor wound healing. It's rare in high-income countries but still occurs.
Side effects of high doses
- Diarrhea, nausea and stomach cramps above about 2,000 mg a day
- Possible higher risk of kidney stones in men taking high doses long term
- People with hemochromatosis (iron overload) should avoid high doses, as vitamin C increases iron absorption
For other immune-related nutrients, see our guides to zinc and vitamin D3.
The bottom line
Most adults need just 75–90 mg of vitamin C a day, easily reached with fruit and vegetables. If you supplement, 100–500 mg covers any gap, and staying under 2,000 mg avoids digestive side effects. Regular use may shave a little off cold duration, but it won't stop you catching one.
Frequently asked questions
Is 1,000 mg of vitamin C a day too much?
It's within the 2,000 mg upper limit and safe for most adults, though more than you need. Some people get loose stools at this dose. People prone to kidney stones should ask their doctor before taking high doses.
Does vitamin C help with colds?
Taken regularly, it slightly shortened colds in studies. Starting it after a cold begins showed no consistent benefit. Regular use reduced colds only in people under heavy physical stress, such as marathon runners.
What foods are highest in vitamin C?
Red peppers, oranges, kiwi, broccoli, strawberries and Brussels sprouts. Half a cup of raw red pepper alone has about 95 mg.
Sources
This page is for education and is not a substitute for advice from your doctor. Read our medical disclaimer.