Vitamin C-rich foods vs supplements to help your immune system?

Many people are taking large doses of vitamin C supplements daily at the moment in the hope it will help their immune system work better to protect them from Coronavirus.

If only life was that simple! Yes vitamin C can be helpful to supporting the immune system, but the body can’t absorb a big dose in one go.

In this article I will explain the issues with vitamin C supplementation, how to avoid problems if they are your only option, and how to trickle vitamin C foods through all your meals throughout your day for best absorption. I’ll show you how eating vitamin C-rich foods which also contain powerful plant chemical polyphenols as well as vitamin C, could be more beneficial for health than a pill option, if you have access to them.

Foods with vitamin C
The best place to get your vitamin C is from food. Here are some easily-accessible foods with high quantities of this vitamin in them:

• Cup of red bell pepper sliced 190mg

• Cup of kiwi 164mg

• Cup of strawberries 89mg

• Cup of orange in sections 83mg

• 1 cup of raw red cabbage 50mg

• 1 white potato baked including skin- 38mg

(Source Nutrition Data)

Our bodies can only absorb limited amounts of vitamin C supplementation at a time. The body takes what it needs, then junks the rest – you pee it out.

That is why peppering your diet with vitamin C rich foods through your meals throughout the day is a better strategy than taking a big supplement dose in one go. If the body isn’t saturated already with vitamin C, it will be in a position to absorb what is being offered to it.

The down side of dosing with vitamin C supplements
High dose vitamin C is a laxative – above 500mg a day is likely to cause diarrhoea and wind.
The government dietary recommendation of vitamin C is just 40mg. This figure needs to be taken with a pinch of salt as it is the minimum amount needed to avoid getting scurvy. (Remember the stories of scurvy among sailors without fresh fruit at sea in school history books?)

If you were to take say 2,000 mg of vitamin C in one go – which some people are doing to supposedly help their immune system at the moment - you are likely to absorb a fraction of that and then pee the rest out. You are also likely to give yourself diarrhoea which will deplete your energy. So though you think you are having high dose vitamin C each day, you aren’t.

How to keep your vitamin C levels topped up effectively
Here is an example of how you could get 500mg of vitamin D, usefully for the body. Let’s go back to the food above and work out a realistic strategy, with a realistic amount of vitamin C for one day.

Added to your breakfast:
Cup of stawberries 89mg vitamin C

Added to whatever else you are having for lunch:
Half a red pepper sliced (80mg of vitamin C) and eaten with hummus
An orange – 83mg

As part of your supper:
Cup of coleslaw 50g
A baked potato 38mg
Kiwi for dessert 164mg

Total throughout the day = 504mg of vitamin C

If supplementation is essential (eg you can't get hold of fresh fruit and vegetables due to shortages, or have a child who won’t accept fruit and vegetables, or are an adult who can’t chew real food) then the best way to get effect is to choose an effervescent vitamin C tablet or powder, dissolve it in a litre of water, and sip the liquid over the course of the whole day. This means the body will absorb the vitamin C bit by bit rather than if you were to swig it all down in one go, and find that a large chunk is peed out.

The extra bonuses to your immune system from foods v pills
In addition to vitamin C, vegetable and fruit foods contain powerful plant chemicals called polyphenols in their colours which also support your immune system. Flavanoids in particular. These feed beneficial bacteria in your gut which help your inner army that is your immune system, protect you appropriately. Frozen fruits also contain good levels of vitamin C and are a good option if fresh options are scarce.

Conclusion
Foods containing vitamin C offer the body amounts of vitamin C it can more easily absorb than big doses in supplements which are largely peed out. They also come with less gastrointestinal side effects, and contain polyphenols which also enhance the immune system. Many are also delicious and enjoyable.

More information
Padayatty and Levine (2001). New insights into the physiology and pharmacology of vitamin C. CMAJ 164(3):353-355