When you think of vitamin C, you probably picture bright oranges and citrus fruits. But there's a lot more to this essential vitamin than that – from supporting your immune system to its role in your skin, vitamin C is one of those nutrients your body needs every single day. Here's what it does, where to find it, and when a supplement can help.
What are the benefits of vitamin C?
Vitamin C is an essential vitamin, meaning your body can't produce it on its own. In fact, humans are among the few mammals unable to make their own vitamin C, thanks to a quirk in our genetic code – which is exactly why we need to get it from food or a supplement every day.
Also called ascorbic acid, vitamin C is one of the most important antioxidants in the diet: it contributes to the protection of cells from oxidative stress. It also contributes to the normal function of the immune system, which is the role it's best known for. And it has a genuinely wide reach across the body, contributing to normal energy-yielding metabolism, the normal function of the nervous system, normal psychological function, and the reduction of tiredness and fatigue.
One of its most important jobs is in collagen. Vitamin C contributes to normal collagen formation, which in turn supports the normal function of your skin, blood vessels, bones, cartilage, gums and teeth. This collagen role is why vitamin C is such a familiar name in skincare too – though topical vitamin C is a separate subject from taking it as a supplement. As a nice bonus, vitamin C also increases iron absorption, so it helps your body make the most of the iron in plant-based foods.
Which foods are high in vitamin C?
The best way to get enough vitamin C is through a balanced diet with plenty of fruit and vegetables. You'll find it in citrus fruits like oranges, lemons and grapefruits, and also in bell peppers, strawberries, broccoli, kale, Brussels sprouts and tomatoes.
While oranges are the most famous source, other foods often contain even more. One cup of chopped red pepper, for example, provides nearly three times the vitamin C of an orange (which contains around 70mg). The NHS recommends that adults aged 19–64 get 40mg of vitamin C a day – an amount most people can reach comfortably through diet alone.
Are vitamin C supplements safe to take every day?
Vitamin C is water-soluble, which means your body can't store it – you need a steady supply every day, and any excess is simply passed out in your urine. For most people, a varied diet provides plenty. But there are times when a supplement is sensible: if your diet doesn't regularly include vitamin-C-rich foods, for instance, or during periods of recovery when you may find it harder to eat as well as usual.
Smokers also have a higher requirement, as smoking depletes the body's vitamin C. And because vitamin C contributes to normal collagen formation and helps protect cells from oxidative stress, some people choose to take it as part of their daily routine for those reasons.
Vitamin C supplements are generally well suited to daily use, and come in various forms such as capsules, pastilles and effervescent tablets, so you can choose what works best for you. A daily supplemental intake of 1,000mg or less is considered safe for adults; very high doses can cause stomach upset, so there's no benefit in overdoing it.
What about vitamin C and colds?
You've almost certainly heard that vitamin C wards off colds – it's one of the most enduring beliefs in nutrition. The honest picture is more nuanced than the reputation suggests, and it's not something we can make claims about here. What we can say with confidence is the authorised, well-established point: vitamin C contributes to the normal function of the immune system, both during and after intense physical exercise. If you'd like to understand how the different immune-supporting nutrients fit together, our Discover blog looks at the topic directly (below).
Explore further
These pieces from our Discover blog pick up where this article leaves off:
- Which vitamins support immunity? A clear guide – how vitamin C and other nutrients contribute to normal immune function.
- Do collagen supplements for skin really work? – a level-headed look at collagen, which vitamin C helps your body form.
Explore our range of vitamin C supplements to support normal immune function, collagen formation and the protection of cells from oxidative stress.