Vitamin C is a water-soluble vitamin that you can only get through your diet. It's good for your skin, bones and blood vessels. Vitamin C also supports your immune system, protecting you from infections — like the common cold.

What is vitamin C?

Vitamin C, also known as ascorbic acid, is a water-soluble vitamin — a type of nutrient. Your body can’t make vitamin C so you must get it from your diet. You also can’t store vitamin C so you must continually get enough from your diet.

What does vitamin C do?

Vitamin C has many important functions in your body. Firstly, vitamin C is needed to produce a structural protein called collagen. Collagen is a type of protein that makes up an essential part of connective tissue — found in your skin, blood vessels, ligaments, bones, cartilage, and so on. And because of this, vitamin C is important for proper wound healing.

Vitamin C is also a powerful antioxidant, which helps protect your cells against damage from oxidative stress. Oxidative stress has been linked to chronic diseases like cancer and heart disease, so a high intake of antioxidants might help protect against these. Vitamin C might also help regenerate other antioxidants in your body, like vitamin E.

Vitamin C has also been shown to build-up in immune cells called phagocytes, possibly enhancing their function. These are cells that ingest and destroy something that’s harmful, like bacteria and viruses.

Vitamin C also helps increase the absorption of calcium and non-heme iron (the type of iron in plant foods) in your body. 

How much vitamin C do you need?

The recommended amount of vitamin C is 40 mg a day for adults aged 19-64 years — equivalent to about an orange a day.

What foods contain vitamin C?

Good sources of vitamin C include:

  • kiwis — particularly gold kiwifruit
  • citrus fruits — like oranges, lemons, and satsumas
  • dark leafy greens — like spinach and cabbage
  • peppers
  • broccoli
  • tomatoes
  • potatoes

What can cause vitamin C deficiency?

Not having enough vitamin C as part of your diet is the main cause of low vitamin C levels — as your body can't make it. But a deficiency is quite uncommon. You might develop a mild deficiency if you follow a poor or very restricted diet.

What are the symptoms of vitamin C deficiency?

Symptoms of low levels of vitamin C include:

  • fatigue (low energy and motivation)
  • muscle and joint aches
  • bleeding gums

Vitamin C deficiency has also been linked to a weakened immune system, increasing your susceptibility to infections. 

Extreme cases of vitamin C deficiency is called scurvy. 

How to improve vitamin C levels

A balanced and varied diet should provide you with all the vitamin C you need. 

If you do take a vitamin C supplement, don't take too much as this could be harmful. Less than 1,000 mg of vitamin C supplements a day is unlikely to cause any harm. If you take more than this per day, it can cause stomach pain, diarrhoea, and flatulence. It’s always a good idea to speak to your pharmacist or GP before starting any supplement.


Hemilä, H. (2017). Vitamin C and infections. Nutrients, 9(4), 339.

National Institute of Health (2020). Office of dietary supplements. Vitamin C: Fact sheet for health professionals. Retrieved 17 March 2020 from

National Health Services (2017). Vitamins and minerals: Vitamin C. Retrieved 17 March 2020 from

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Aisling Moran BSc (Hons)

Written by Aisling Moran BSc (Hons)

14th Apr 2021 • 4 min read