This article is for educational purposes only and does not replace the advice of a qualified healthcare or nutrition professional.
Vitamin C is a well recognised nutrient. For most people a couple of fizzy vitamin C tablets or a large glass of orange juice is used with the onset of a cold. But vitamin C is more than a seasonal remedy. It is involved in several essential processes in the body.
What is Vitamin C?
Vitamin C, known scientifically as ascorbic acid, is a water soluble vitamin. Water soluble means that your body does not store it in the same way it stores fat soluble vitamins like vitamin D or vitamin A. Any excess is excreted through urine, which has two important implications.
First, you need to consume it consistently through your diet because your body has limited reserves. Second, toxicity from dietary sources is extremely unlikely, though very high dose supplementation over time warrants some consideration.
Unlike most animals, humans cannot synthesise vitamin C internally which makes dietary intake essential. Without a consistent and adequate supply, the body cannot perform a significant number of its most critical functions.
What Does Vitamin C Actually Do?
The role of vitamin C in the body is broad and understanding its functions helps to contextualise why getting enough of it consistently is so important.
- Firstly, collagen synthesis. Collagen is the most abundant protein in the human body and it forms the structural backbone of your skin, tendons, ligaments, cartilage, blood vessels and bones. Vitamin C is an essential cofactor in the enzymatic reactions that produce and stabilise collagen. Without adequate vitamin C, collagen synthesis is impaired. This is why severe deficiency, known as scurvy, presents with symptoms including poor wound healing, bleeding gums, fragile skin and joint pain. These are all expressions of collagen breakdown.
You do not need to reach clinical scurvy to feel the effects of suboptimal collagen production though. Poor skin integrity, slow wound healing and joint discomfort can all be subtle indicators that vitamin C intake could be better.
- Immune function is the role most people are familiar with, and the evidence here is legitimate. Vitamin C supports the production and function of white blood cells, particularly neutrophils and lymphocytes, which are central to your immune defence. It also accumulates in immune cells at concentrations far higher than those found in the blood, which reflects how important it is to immune activity.
During periods of illness or infection, the body depletes its vitamin C stores rapidly, which is why increased intake during these periods is well supported.
- Antioxidant protection is another critical role. Vitamin C is one of the body's most important water soluble antioxidants. It neutralises free radicals, the unstable molecules generated through normal metabolic processes, environmental exposure, stress and poor diet, that cause oxidative damage to cells and tissues.
Chronic oxidative stress is a driver of inflammation, accelerated aging and the development of chronic disease. Consistent vitamin C intake is part of your body's defence against this.
- Iron absorption is a function of vitamin C that is particularly relevant for anyone eating a predominantly plant based diet. There are two forms of dietary iron. Haem iron, found in animal products, is absorbed relatively efficiently. Non-haem iron, found in plant sources such as legumes, leafy greens and fortified foods, is absorbed far less readily.
Vitamin C consumed alongside non-haem iron sources significantly enhances its absorption by converting it into a form the body can take up more easily. If you are plant based or iron deficient, this interaction is important practical knowledge.
Vitamin C also plays a role in the synthesis of certain neurotransmitters including norepinephrine, supports adrenal function during periods of stress, contributes to the regeneration of other antioxidants including vitamin E, and is involved in the metabolism of cholesterol into bile acids. The more you look at vitamin C, the more central it becomes to everyday physiological function.
How Much Do You Need?
The recommended daily intake for vitamin C in the UK sits at 40 milligrams per day for adults, which is the amount required to prevent deficiency, though many experts advocate 75-90mg for optimal health.
However, requirements increase during illness, periods of high stress, pregnancy, smoking and intense physical training. Smokers in particular have significantly higher vitamin C requirements because smoking dramatically accelerates its depletion in the body.
Food Sources
A food-first approach is where to start. Vitamin C is abundant in a wide variety of whole foods, and getting it through diet means you are also benefiting from the full spectrum of nutrients those foods provide.
Bell peppers, particularly red and yellow, are among the richest dietary sources and contain significantly more vitamin C than oranges (though, still a great source). Kiwi fruit, strawberries, citrus fruits, broccoli, Brussels sprouts, papaya, blackcurrants, watercress and tomatoes are all excellent sources.
The key is variety and consistency. Because vitamin C is water soluble and sensitive to heat, raw or lightly cooked vegetables retain more of their vitamin C content than heavily cooked ones. Steaming is preferable to boiling if you want to preserve it.
Should You Supplement?
For many people, a well constructed diet will provide adequate vitamin C. However, if your diet is limited in fresh fruits and vegetables, if you are under significant ongoing stress, recovering from illness or injury, or if you smoke, supplementation is a sensible and straightforward way to ensure your needs are being met.
Standard supplemental doses of 500 to 1,000 milligrams daily are generally considered safe and well tolerated for most adults. Very high doses above 1,000 milligrams per day can cause digestive discomfort in some individuals, so if you are sensitive, a lower dose taken consistently will serve you better than a very high dose taken sporadically. Liposomal forms of vitamin C have become increasingly popular due to their enhanced absorption, and the evidence supporting their bioavailability is reasonable, though a quality standard supplement remains effective for most people.
The Bottom Line
Vitamin C is not just for cold and flu season. It is a daily essential that underpins collagen production, immune defence, antioxidant protection, iron absorption and much more. Most people can meet their needs through a diet rich in colourful fruits and vegetables, but consistency is key given that the body cannot store it. If your diet is not consistently providing it, supplementing is a simple and well supported step to take.
Give your body what it needs every day, not just when you feel run down. That is the shift that makes the real difference.
Sources:
https://www.mdpi.com/1420-3049/30/3/748
https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/
https://www.ncbi.nlm.nih.gov/books/NBK499877/
