15% off €35

Use code:GET15

Food sources of vitamin C and supplements

How to take vitamin C, dosage, what it does & more

17 Apr 2023 • 4 min read


Vitamin C: functions, foods, deficiency, & supplements

Find out all about vitamin C, including what it does, how much you need, where to find it, and who might need to supplement their diet.

Skip to: 

What is vitamin C?

Vitamin C is an essential vitamin, necessary for the healthy functioning of the body. Also known as ascorbic acid, vitamin C is a water-soluble vitamin; our bodies don’t store it, so we must get enough from our diets. ¹

The benefits of vitamin C and its roles include:

  • An antioxidant – it helps protects cells against damage from free radicals ² 
  • Maintaining a healthy nervous system ¹ 
  • Collagen co-creator - contributing to the production of collagen for tendons and ligaments, skin, cornea, bones, blood vessels, and cartilage ³ 
  • Iron enabler - helping the body to absorb non-heme iron from plant sources ⁴ 
  • Defender – vitamin C supports our immune system ⁵ •
  • As it can help us to produce collagen, vitamin C can help to preserve skin elasticity, which is key for healthy-looking skin ⁶

Vitamin C is found in lots of fruits and vegetables, especially citrus fruits and juices, dark green leafy veg, peppers, and berries. ⁷ Vitamin C deficiency is rare, but can lead to scurvy. ⁸


  • Vitamin C supports multiple body functions, from supporting bones, joints and skin, to helping absorb non-heme iron from plant foods

Facts about vitamin C

Lots of animals can produce their own vitamin C,but humans, other primates, and guinea pigs can’t!

Vitamin C was officially discovered by Albert Szent-Györgyi, a Hungarian biochemist, in the 1930s. ⁹

What does vitamin C do in the body?

We’ve already briefly discussed what vitamin C is and what it does, but let’s go into more detail.

The functions of vitamin C in the body include: 10 1

Healthy skin

Two of the main compounds that helps us to do this are collagen and antioxidants – and vitamin C helps to make both!

Our bodies need vitamin C to make collagen, which provides both strength and structure for skin. That’s why it’s often referred to as our skin’s scaffolding.

However, several factors contribute to declining collagen production, like: ¹¹

  • Getting older 
  • Smoking
  • UV light exposure

Making sure you’re getting enough vitamin C through your diet can help to slow down this decline in collagen production.

Vitamin C also contains antioxidants that help to protect the skin. ⁶

Handpicked content: 10 best vitamins for healthy skin

Maintaining normal blood vessels

One of the organs most affected by vitamin C are our blood vessels, which also help to distribute it throughout our bodies.

Vitamin C has been seen to help support the cells that line the walls of blood vessels as well as form their basement membrane (helps to send and receive signals).

Our blood vessels also help to distribute vitamin C and other nutrients throughout our body - they make quite the harmonious pair! ¹²

Bone support

The connection between bone health and vitamin C was first discovered when maritime explorers with scurvy complained about severe bone pain. Vitamin C helps our bodies to develop and maintain healthy bones by aiding collagen production. ⁴


Healthy joints and cartilage

Some other parts of the body that rely on healthy collagen levels are our joints and cartilage. Vitamin C aids collagen production, which helps to keep joints and cartilage healthy and supported. ¹³

Supporting immune function

Vitamin C helps keep our immune system functioning normally in general, especially during and after intense exercise.

One of the ways it does this is by strengthening the skin to keep pathogens out and reduce oxidative stress. When pollutants make contact with the skin, they can contribute to producing free radicals (unstable atoms that can cause cell damage). The stronger the skin barrier, the better it can prevent this cell damage from occuring. ¹⁴

Being deficient in vitamin C can result in impaired immunity and higher susceptibility to infections. ¹⁵

Normal nervous system function

Our nervous system is a complex network of cells and neurons from the brain and spinal cord to various body parts.

Vitamin C can be found inside the neurons in our central nervous system. In fact, these neurons contain some of the richest concentrations in human body tissues. ¹⁶

Improved absorption of iron from plant sources

Vegetarians and vegans listen up: you need vitamin C to absorb iron from plant foods.

Iron is the most abundant metal in the human body; women need around 15mg per day and men around 9mg. Luckily, it’s usually possible to obtain it through a balanced diet. ¹⁷

There are two main types of iron: ¹⁸

  • Heme iron: the most common type of iron found in red meat, poultry, and fish
  • Non-heme iron: found in plant foods

Heme iron is generally well-absorbed, whereas non-heme iron is slightly more difficult, especially if you are lacking in vitamin C.

Vitamin C helps our bodies absorb iron from plant sources like citrus fruits and green leafy vegetables. ¹⁸


  • Vitamin C benefits include maintaining healthy skin, bones, blood vessels, joints, immune function, and iron absorption.

How much vitamin C do you need a day?

According to the NHS, adults aged between 19 and 64 need 40mg of vitamin C every day. ¹ That’s the same as about a quarter of an orange. ¹⁹

Vitamin C is water-soluble, so it can’t be stored in the body. This means you need to replace it in your diet every day. ¹ ¹⁸

Vitamin C deficiency

Vitamin C deficiency in the UK is rare, as people usually get enough from their diet. However, it’s still possible to develop vitamin C deficiency – and this could lead to scurvy . ¹ And, because vitamin C aids iron absorption, people with low levels of vitamin C can also develop iron-deficiency anaemia. ²⁰

People at risk of scurvy include those whose diets lack fruits and veg, as well as alcohol abuse or smoking: they reduce how much vitamin C is absorbed by the body, increasing your need for the nutrient.

However, it is worth noting that vitamin C deficiency is very rare in the UK. ⁸

How much vitamin C is too much?

Is too much vitamin C bad for you? It could be.High doses of vitamin C may lead to diarrhoea and stomach cramps. ¹

However, the DHSC advises that doses below 1000mg a day is not likely to cause any harm. ¹

Best vitamin C supplements

There are a few different types of vitamin C supplements you can take if you choose to take one, like:

  • Vitamin C tablets/capsules

And if you don’t like tablets or struggle to take them:

  • Vitamin C drink sachets
  • Vitamin C effervescent tablets
  • Vitamin C powder
  • Vitamin C oral sprays

Children may prefer to take vitamin C gummies.

If you’re taking a tablet or capsule, you’ll need to take your vitamin C supplements with water. Powders can be dissolved in water and mixed to make an easy drink – just sip away.

You can take vitamin C supplements at any time of day, but it’s best to pick a time that you’ll remember regularly.

Wondering which is best for you? Read our article on 10 of the best vitamin C supplements.

Should I take vitamin C supplements?

You should be able to get all the vitamin C you need from a balanced diet. But there are some people who should pay particular attention to their vitamin C intake, like:

Smokers and passive smokers

Studies have shown time and time again that smokers tend to have lower vitamin C levels than non-smokers. ²¹

That also includes “passive smokers”, people who spend a lot of time with smokers and inhale their smoke, even if they don’t smoke themselves.

Those with limited diets

If you don’t eat many fruits, vegetables, or other sources of vitamin C, you may want to consider taking a vitamin C supplement.

Do I need more vitamin C if I’m vegan or vegetarian?

Fruits and vegetables are the best sources of vitamin C. Many vegan and vegetarian diets probably contain a lot of fruit and vegetables. But, if you’re not a fan and you’re plant-based, it’s even more essential to maintain healthy levels of vitamin C.

This is because vitamin C is essential for helping our bodies absorb iron from plant foods. ⁴

Vegetarians and vegans may find it harder to meet the recommended iron intake through their diet. They’re more at risk of becoming iron deficient, and it’s increasingly likely if they don’t get enough vitamin C to help absorb their iron.

If you don’t eat meat, you should take extra care to include plenty of iron and vitamin C in your diet.

To increase iron absorption, you must eat iron-rich foods and vitamin C-rich foods at the same time. This is because vitamin C is water-soluble, meaning your body doesn’t store it for later: any excess is quickly excreted.

If you decide to take a supplement, beware – most of them are a vegan source of vitamin C, but not all! Some gummies will use gelatine (sourced from animals). Look out for the vegan leaf symbol on the front of our supplements to make sure you’re getting plant-based vitamin C. 

Should children take vitamin C supplements?

The NHS says children under the age of five may not get enough vitamins A and C. So, the government recommends all children aged between six months and five years old take a daily multivitamin containing vitamin C. ²²

Do women need to take a vitamin C supplement during pregnancy?

There is no specific need, as you should be able to get all the vitamin C you need from a healthy, balanced diet. ²³

The final say

  • Vitamin C is essential for many bodily functions
  • Our bodies can’t make it, so you need to make sure you get enough every day through your diet or supplementation
  • You can find vitamin C in a wide variety of plant foods, including citrus fruits and green leafy vegetables

Last updated: 9 February 2023





Author: Donia HilalNutritionist

Joined Holland & Barrett: Jan 2018

Bsc in Nutrition, Registered Associate Nutritionist and Certification in Pre and Post Natal Nutrition

Donia started her career as a freelance nutritionist, later she joined Nestle as their Market Nutritionist to help support their healthier product range, before joining the team at Holland & Barrett in January 2018.

Donia has over 6 years experience as a Nutritionist and also works with clients on a one to one basis to support their goals which include weight loss, prenatal and postnatal nutrition and children’s health.

Read more
  • Visa
  • MasterCard
  • AmericanExpress
  • PayPal
  • Facebook
  • Twitter
Copyright © Holland & Barrett Limited, 2023. All rights reserved. hollandandbarrett.ie is a trading name of Holland & Barrett Limited. Registered office: 45 Henry Street, Dublin, Dublin 1, D01 E9X8. Registered in Ireland: Company no. 79819. Registered VAT no. 4682002U.