Micronutrient Basics: Vitamin C

Vitamin C, or you may see it written as ascorbic acid, is an important micronutrient for humans. It is a water soluble vitamin that can be found in many foods. Many animals can make their own vitamin C but humans are unable to do so and must acquire it from their diets(1)

The functions of vitamin C include:

  • helps to produce collagen (an important protein which aids in wound healing) 
  • has antioxidant properties
  • increase absorption of iron from plant sources(2)
  • supports your immune system

Some studies have shown that high intakes of vitamin C could lower your risk of developing chronic diseases, such as cancer and heart disease(1). However, the reduced risk of developing a chronic illness may be down to eating an all round healthy diet and not purely because of vitamin C.

How much Vitamin C do I need per day?(3)

Children aged 1-18 years : 30-40 mg/day

Adults 19+ years : 40mg/day

Can I take too much vitamin C?(4)

Yes, taking more than 1000 mg a day can have a negative impact and lead to side effects such as:

  • diarrhoea
  • abdominal cramping
  • nausea

Should I take vitamin C supplements?

I like to take a food first approach, and 40mg can easily come from your diet. Make sure to include a fruit or vegetable with every meal. Take a look at the list below of foods that contain high amounts of vitamin C.

A lot of vitamin C supplements contain high doses of the stuff and at 400mg our bodies opt to pee it out(4).

If you are in the at risk group of vitamin C deficiency taking a careful look at your diet and seeing where you could add more fruits and veggies is a good way to increase your vitamin C. If you are concerned consult with your doctor before starting supplementation.

But for the general population, a vitamin C supplement is not necessary.

Will Vitamin C boost my immune system?

No one food or vitamin can boost your immune system.

One study found that in those who participated in extreme activity, taking a 200mg dose of vitamin C reduced there risk of getting sick. But for the general population this would have no effect. Some studies suggest taking 200mg of vitamin C could shorten the length of time you suffered from the cold(5). However, these were small studies and they concluded it was not necessary to take vitamin C supplements.

Vitamin C Deficiency

Not getting enough vitamin c in your diet can lead to scurvy. This is usually caused after not eating enough vitamin C for at least 3 months(6). This disease can be seen alongside other nutritional deficiencies and symptoms can overlap. However, it is  easily fixed by increasing the vitamin C in your diet.

Symptoms of scurvy include – loss of appetite, swollen joints, mood changes, fatigue/ muscle pain, spontaneous bleeding

At risk groups for vitamin C deficiency include(7):

  • smokers – it has been recommended that if you smoke you may require 35mg of vitamin C more than non-smokers
  • very restricted diet/ people with eating disorder – can lead to malnutrition
  • those with chronic illnesses and malabsorption

If you feel that you are nutritionally deficient or are worried about your diet and health, consult with your GP.

Sources of Vitamin C

Traditionally, when we talk about vitamin C our minds go straight to oranges, but this isn’t the only source of vitamin C and actually doesn’t have the highest dose of vitamin C when compared to other fruit and vegetables.  It is important to include a variety of sources to make sure you are getting the amount of vitamin C you need daily but also so ensure you received adequate intakes of other micronutrients.

  • Peppers
  • Strawberries
  • Kale
  • Broccoli
  • Potato
  • Orange and orange juice
  • Kiwi
  • Blackberries
  • Lemons and Lime
  • Guava
  • Tomato and tomato juice

Variety is key. Add colour to your diet and try new fruits and vegetables to make sure you are hitting your needs for vitamin C.


  1. Jacob, R.A. and Sotoudeh, G., 2002. Vitamin C function and status in chronic disease. Nutrition in clinical care, 5(2), pp.66-74.
  2. Committee on International Nutrition–Vitamin C in Food Aid Commodities and Institute of Medicine, 1998. Vitamin C fortification of food aid commodities. National Academies Press.
  3. Gov UK: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/618167/government_dietary_recommendations.pdf
  4. Institute of Medicine. Food and Nutrition Board. Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoidsexternal link disclaimer. Washington, DC: National Academy Press, 2000.
  5. Douglas, R.M., Hemila, H., Chalker, E. and Treacy, B., 2007. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev, 3, p.CD000980.
  6. NHS: https://www.nhs.uk/conditions/scurvy/
  7. National Institute of Health Fact Sheet: https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/

*Disclaimer: I am not a doctor/medical professional – if you feel ill, have concerns about your health or IBS please contact your healthcare provider or in an emergency – the emergency services.

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