How can we support our immune system this winter?
Over the last year many of us have been so careful about protecting ourselves from COVID that we didn’t socialise or meet people last year, and as a result many of us didn’t get those usual colds and coughs that are common over the winter.
But, now that most of us are ‘out & about’, life is returning to some sort of normal, and coughs & colds are reappearing. So how can we support our immune system, lessen the impact of those colds and stop feeling under the weather.
I’m focusing in this blog on Vitamin C which, evidence suggests, support our immune system and offer some protection against the usual seasonal colds and flus and may even offer some protection against COVID-19. In my next blog, we’ll focus on Vitamin D!
What does Vitamin C actually do?
Most people have heard of Vitamin C. Who wasn’t urged as a child to eat fruit – preferably oranges – to keep up their vitamin C levels? There is lots of research about the effectiveness of vitamin C and its role in immunity, particularly in warding off colds and flu.
Vitamin C is involved in 15,000 metabolic processes, and no other vitamin has such a wide variety of effects. Now, don’t worry, I’m not going to list the 15,000 jobs of vitamin C, but I’d like to highlight a few that are crucial in your immune defence.
Vitamin C protects mucous membranes inside the mouth, the nose, the lungs, along the digestive tract, the urethra and the vagina. As all of these surfaces are in contact with the outside world and, therefore, potentially nasty microbes, you want them to be healthy, strong and hold tight.
Vitamin C supports the immune response by stimulating the production of special immune cells called B-cells, T-cells and phagocytes. More B- and T-cells means more antibodies to fight against trouble like viruses – and this is a good thing. Phagocytes are immune cells that gobble up intruders like viruses and bacteria, a bit like the iconic arcade game icon Pac Man. Vitamin C protects these phagocytes helps them work better, and promotes the “suicide” of damaged cells (called apoptosis).
A crucial function of vitamin C is that it helps dampen down inflammatory cytokines, substances the body produces when under attack. By interfering with the production of certain cytokines, vitamin C can reduce the risk of a “cytokine storm”, which is something you really don’t want happening.
Vitamin C and infections – what does the science say?
Three controlled trials found that vitamin C prevented pneumonia. Two controlled trials found pneumonia patients benefitted from vitamin C.
In 2020, the COVID-19 pandemic has, of course, prompted researchers to look into the effectiveness of vitamin C in the treatment of the disease. There was already some evidence that vitamin C prevented pneumonia. When COVID-19 – or even the flu or a cold – has a deadly outcome, this is due to pneumonia. So, even if vitamin C didn’t prevent the original infection, if it prevents pneumonia, that’s worth knowing.
Are we vitamin C deficient?
Worldwide recommendations for Vitamin C range from 40mg and 220mg of vitamin C per day – the equivalent of between 1 and 35 oranges per day. That’s a vast difference! And that’s just the daily requirement before you’re even sick and require therapeutic doses.
For us humans, vitamin C is an essential nutrient as we can’t make it ourselves. Thankfully, it is abundant in fresh fruit and veg. The riper and unprocessed those are, the higher their vitamin C content. Animal products contain vitamin C as well, mainly within offal. Vitamin C is water-soluble and highly sensitive to light, heat and oxidation. That means that storage and processing (including cooking) have a significant impact on the vitamin C content of fruit and veg and can reduce it by up to 90%. So, even if you regularly eat fruit and vegetables – and so many people sadly don’t – you may not get all the vitamin C you need from your diet.
So, chances are that many of us are deficient even to begin with, in which case there is very little chance that we can combat an infection with what we’ve got.
What can you do to increase your vitamin C levels?
- Reduce stress and practise relaxation techniques.
- Quit smoking
- Reduce or cut out alcohol
- Eat lots of fresh seasonal and ideally local fruit and vegetables every day. Aim for 7 to 10 servings. Great sources of vitamin C are citrus fruits, such as oranges, lemons, tangerines and grapefruit, but also plants from the cabbage family or brassica: kale, cauliflower, broccoli, Brussels sprouts, red, white and pointed cabbage. Other excellent sources are bell peppers and potatoes, rosehips, chillies, parsley, kiwi and papaya.
- If you decide to supplement with Vitamin C, the British Association for Nutrition and Lifestyle Medicine recommends 1000mg (1g) a day as part of a preventative strategy for COVID-19 and other cold viruses.
What if you already have an infection?
Nutritional therapist Patrick Holford recommends taking 1-2g at the first sign of a cold and then another gram of vitamin C every hour until your symptoms go away.
Supplementing high dose vitamin C at the onset of any viral infection (bearing the counter-indications in mind) is not going to do you any harm yet may do you good without any adverse effects save lose stools – which you can stop by reducing the dose. I’d say it’s worth a shot, don’t you?
Can you overdose on vitamin C?
The most common side effect of vitamin C toxicity are loose stools, but considering that most people have a high requirement due to stress, inflammation, smoking, alcohol, medication and more, toxicity is very, very rare. If loose stools should occur, you can take that as a good sign: You have decent vitamin C levels and can reduce your dose back down to bowel tolerance (the point at which your bowel movements become normal again). High dose vitamin C supplementation is, however, counter-indicated in people with iron storage problems (haemochromatosis), renal insufficiency, disorders of oxalic acid metabolism, retinal bleeding and favism, a hereditary disorder causing allergy-like reactions to broad (fava) beans.