Vitamin C
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My experience of supplementing with Vitamin C
I often supplement with Vitamin C, particularly now that I no longer drink gallons of freshly squeezed fruit juice and bags of potatoes. I use it in higher doses when I think I’m developing colds or covid, which used to be often!
What is vitamin C?
Arguably the most popular and well-known vitamin, this nutrient has to be derived from what you eat because the body doesn’t make or store it.
Citrus fruits are most commonly associated with vitamin C. I remember getting free orange juice at school to boost kids’ levels of the water-soluble vitamin. In reality, oranges don’t reign supreme in the vitamin C stakes – guava, kiwi fruit, and blackcurrants contain higher amounts.
The same is true of broccoli and red peppers; other vegetables, such as potatoes and Brussels sprouts, have decent amounts. That said, it all depends on the cooking method – vitamin C is easily destroyed by heat (as well as light and freezing). Consider steaming instead of boiling or microwaving (1).
Vitamin C is important for a healthy immune system and is a powerful antioxidant which means it protects or delays the harm done to cells by free radicals (unstable molecules).
Another crucial role is building healthy blood vessels. The vitamin assists in producing collagen, a vital component in connective tissue which in turn maintains a sturdy blood vessel wall.
Vitamin C is also good for healthy gums, strong teeth, skin elasticity, wound healing, iron uptake, and for boosting energy levels (it transports fatty acids needed in energy metabolism).
Impact of vitamin C deficiency
A poor diet, smoking and drinking excessively deplete vitamin C in body tissue.
A lack of the vitamin in the diet for several months leads to scurvy, a condition causing bleeding gums, swollen arms and legs, persistent bruising and fatigue. This deficiency is uncommon in developed countries where fresh fruit and vegetables are widely available.
Scurvy cases in the UK may be increasing (usually as a result of malnutrition) with 171 hospital admissions in 2020 to 2021 and 82 in 2010 to 2011 (2) but are still low. This is when you consider there are over 16 million hospital admissions in total annually for every illness.
Benefits of vitamin C
Most of us reach for this vitamin supplement when feeling rundown and full of cold (or at the first sniffle). According to various studies, vitamin C may effectively reduce a cold’s duration but not frequency.
This is based on evidence from a systematic review (3) of existing trials involving more than 11,000 people who took 200mg to 2,000mg a day. The results showed that supplements did not reduce the incidence of colds. But vitamin C did halve the risk of the common cold among people who took part in short periods of extreme exercise, such as marathon runners, according to a small number of studies analysed in the systematic review.
Lower vitamin C levels are present in people with Alzheimer’s disease even when they have enough in their diet. On this basis, research is ongoing into the benefits of the antioxidant effects of vitamin C in people with Alzheimer’s. Studies have suggested that brain lesions associated with the disease are caused by excess free radicals ‘attacking’ brain cells. However, research in mice (4)(5) has shown that vitamin C reduces the oxidative stress which triggers this cell damage.
The antioxidant properties of vitamin C have also been investigated in cancer research. Data suggests (6) that high daily doses in mice reduce growth rates of ovarian and pancreatic tumours and those affecting the brain/spinal cord. However, human studies would be needed to determine if this could work as a treatment.
There is evidence that vitamin C’s role in reducing oxidative stress may improve sperm quality (7).
How much vitamin C should you take?
Supplementation isn’t usually necessary because a balanced diet will provide sufficient amounts.
If you decide to take supplements, how much you need is debatable.
The NHS and World Health Organisation (WHO) recommend a daily intake of 40mg and 45mg, respectively. However, a review published last year (8) concluded these amounts are too low, and a separate study suggested obese people should take more (9). Indeed, the recommended daily minimum in the US is 75 mg for women and 90 mg for men; and the European Food Safety Authority recommends 95 mg for women and 110 mg for men.
The safe maximum daily limit also varies. US regulators set a 2,000mg safe limit and some athletes take up to this dose to support their immune systems. However, the NHS guidance is that a daily dose above 1,000mg can cause gastric issues, including diarrhoea.
Anyone with diabetes should remember that fresh orange juice is high in (natural) sugar, so it's best to avoid it and buy sugar-free supplements.
What type of vitamin C should you take?
Ascorbic acid is the form of vitamin C found naturally in food, but this is highly acidic and anyone with a sensitive gut can find it hard to tolerate.
An alternative is salts of ascorbic acid – or ascorbates – which are considered gentler on the stomach, although there is no conclusive evidence. Ascorbates are often marketed as ‘gentle’ or ‘buffered’ vitamin C. This means that the ascorbic acid's pH (acidity value) has been changed by adding mineral salts such as calcium-L-ascorbate (often branded as Ester-C), sodium-L-ascorbate or magnesium ascorbate.
Some vitamin C supplements may also contain bioflavonoids, compounds found in citrus peel and rose hips which are thought to boost the vitamin’s health benefits.
What the science says:
1 Yuan G, Bo Sun, Yuan J and Wang Q. Effects of different cooking methods on health-promoting compounds of broccoli. Journal of Zhejiang University-SCIENCE B; Aug 2009; 10(8); pages 580–588; doi: 10.1631/jzus.B0920051
2 NHS Digital https://digital.nhs.uk/supplementary-information/2022/scurvy-rickets-and-malnutrition-admissions-by-age-2007-08-to-2021-22
3 Hemilä H and Chalker E. Vitamin C for preventing and treating the common cold. Cochrane Database of Systematic Reviews Jan 2013; https://pubmed.ncbi.nlm.nih.gov/23440782/
4 Christen Y. Oxidative stress and Alzheimer disease. The American Journal of Clinical Nutrition February 2000; vol 71 (2), February 2000; 621S–629S; https://doi.org/10.1093/ajcn/71.2.621s
5 Heo J-H, Lee K-M. The Possible Role of Antioxidant Vitamin C in Alzheimer’s Disease Treatment and Prevention. American Journal of Alzheimer’s Disease & Other Dementias 2013;28(2):120-125; doi:10.1177/1533317512473193
6 Chen Q, Espey MG, Sun AY and Levine M. Pharmacologic doses of ascorbate act as a prooxidant and decrease growth of aggressive tumor xenografts in mice. PNAS August 2008; 105 (32) 11105-11109; https://doi.org/10.1073/pnas.0804226105
7 Ahmadi S, Bashiri R, Ghadiri-Anari A, Nadjarzadeh A. Antioxidant supplements and semen parameters: An evidence-based review. Int J Reprod Biomed 2016 Dec; 14(12):729-736. PMID: 28066832; PMCID: PMC5203687.
8 Hujoel P and Hujoel M. Vitamin C and scar strength: analysis of a historical trial and implications for collagen-related pathologies. The American Journal of Clinical Nutrition January 2022; vol 115, (1); pages 8–17; https://doi.org/10.1093/ajcn/nqab262
9 Carr AC, Block G and Jens Lykkesfeldt. Estimation of Vitamin C Intake Requirements Based on Body Weight: Implications for Obesity. Nutrients March 2022; vol 14 (7); DOI: 10.3390/nu14071460