Essential Vitamin C

We all know we need it but, how much vitamin C do we need?

We all know that vitamin C is necessary in our diet but what does it do and how much do you need? Do you need more in winter and can you have too much? What are the best sources and what about kids who are fussy eaters, or elderly family members, do they get enough?

The role of Vitamin C in our body

Vitamin C plays an important role in our body as an antioxidant. You may have heard this term but not really know what it means. During the course of a day our body generates a vast quantity of free radicals which can damage our cells. Vitamin C has a role in mopping up these free radicals and protecting our cells from damage.


Vitamin C also helps in many other reactions in the body. It is important in making collagen that helps with the healing of the body’s various tissues when wounded. Vitamin C also helps with many other bodily functions including using energy, creating neurotransmitters, and regulating our metabolic rate.


When under extreme physical stress the body uses more vitamin C, think infections, burns or extreme hot or cold temperatures. All these require the immune system to step up which produces more free radicals that in turn uses more vitamin C.


Another important fact about vitamin C is that it helps us to absorb iron. Iron deficiency is the most common nutrient deficiency globally and approximately 12% of NZ women (aged 31-50) are iron deficient ¹.  Hence why it’s so important to eat vitamin C rich vegetables or fruit with your protein.

How much Vitamin C do we need?

Our bodies don’t make vitamin C so we need to ensure we get sufficient quantities from our diet. The recommended daily intake for the average adult is 45 milligrams (mgs) per day. If you are pregnant you’ll want to have 55-60 mgs per day, and breastfeeding increases your need to around 80-85 mgs per day. Children need smaller amounts, 1-8 year olds need 35 mgs per day and 9-18 year olds need 40 mgs per day.


If you are a smoker you will need an 35 mgs per day additional to the amounts stated above. Smoking causes a lot of oxidative stress (free radicals) so more vitamin C is needed to counteract this damage.


So do we need more in winter and will it prevent the dreaded ‘cold’? The research into this is conflicting. Some shows no relationship and some shows a small benefit (fewer sick days, fewer colds and a shorter duration of severe symptoms).


In 2013, a review of the available research for vitamin C as a prevention and treatment of the common cold ² found there was no consistent effect of vitamin C on duration or severity of colds. 

How much is too much?

There is currently no specified upper limit for vitamin C however, 1000 mgs is considered a large dose. There is little benefit of having more than 200 mgs a day as that’s the maximum absorption capability the body can handle with any excess being excreted.

So, if you’re having fresh fruit or veggies every day, there’s no need for expensive (or cheap) supplements.

The best sources of Vitamin C

Vitamin C can be purchased in tablet form of various strengths from pharmacies and supermarkets. However, with a normal diet high in fresh fruit and vegetables you will get all the vitamin C you need.


It is useful to know which fruit and veggies are high in the vitamin – especially when feeding fussy eaters.


  • A single orange or kiwifruit contains your daily vitamin C requirement. Strawberries and blueberries are another great source. 


  • 1/2 cup of raw broccoli or red capsicum provides more vitamin C than your daily requirement. Even when cooked, these vegetables still give you your daily vitamin C requirement. Other vegetables with a good source of vitamin C are brussels sprouts and tomatoes.


  • Cauliflower and spring onions provide more vitamin C when cooked than when raw. Just be sure to steam or microwave these vegetables as boiling them allows the nutrients to leach into the water and then they’re lost.

If you are interested in knowing more about the importance of vitamins in our diet, then please get in touch. As a qualified nutritionist*, I’m happy to answer any questions you may have.

  1. University of Otago and Ministry of Health. 2011. A Focus on Nutrition: Key findings of the 2008/09 New Zealand Adult Nutrition Survey. ISBN 978-0-478-37348-6
  2. Hemilä, H. Chalker, E. 2013, Vitamin C for preventing and treating the common cold.. DOI: 10.1002/14651858.CD000980.pub4.

*  Bachelor of Science (Biochemistry and Biological Science) University of Canterbury

   Graduate Diploma (Human Nutrition) Ara Institute of Canterbury

   Member of the Nutrition Society of New Zealand, working to become a registered nutritionist