Evidence to Support the Supplements for Immune Health

Evidence to Support the Supplements for Immune Health

Reduce stress

Have you noticed that in stressful periods of your life, you seem to come down with every bug or virus going? This is because stress has a direct effect on immunity. When you experience a stressful event, your body responds by releasing hormones like cortisol and adrenaline, which affect your production of T-cell lymphocytes (1), a type of immune cell responsible for fighting infections. If a stressful event is short term, then your immune system will recover. But when stress becomes chronic, you can become susceptible to viruses and bacterial infections. There is much you can do to consciously manage stress, like introducing more time to relax, taking regular moderate exercise, and getting more sleep.


Research shows that moderate exercise strengthens the immune system and can potentially reduce the severity of an upper respiratory tract infection. However, overdoing it adds to stress levels, raising cortisol, and weakening your immune system (2). The good news is that you don't need to go to a public gym to exercise; moderate exercise means raising your heartbeat for around 150 minutes per week, and you can do this by taking a brisk walk or a jog. If you're pounding the pavements night after night, you might want to reduce your exercise load until the threat of coronavirus has passed.

Quit Smoking

It will come as no surprise to learn that smoking appears to increase your risk of developing an upper respiratory tract infection (3). Coronavirus is a disease that attacks the lungs, and if they are already damaged by smoking, then it increases the risk of complications. Stopping smoking is the single most helpful step you can take for your health. It will help you deal with the effects of coronavirus, but will also improve your risk of numerous chronic conditions like cancer and heart disease, which can shorten life expectancy. Incidentally, if you enjoy a glass of wine in the evening, this might offer some protection, but only for non-smokers (3).

Get sufficient sleep

There appears to be a link between insufficient sleep and upper respiratory tract infections. A study of over 22,000 Americans showed that participants who slept for 5 hours or fewer per night, or who reported low-quality sleep, had an increased likelihood of reporting a head cold or chest infection in the previous 30 days than people who slept for 6 or 9 hours (4). For some people, getting some extra shut-eye is easy, but for others, where sleep doesn't come easily, it can be a problem. Establishing a bed-time routine, banning smart-phones and computers from the bedroom and keeping your bedroom dark and cool are just some of the things you can do to improve your sleep.

Improve diet

Most people turn to supplements when they want to boost their immunity, but there is good evidence that simply increasing the amount of fruit and vegetables in your diet will have a positive effect on your immune function and inflammation markers. Research shows that eating fruit and vegetables increases the production of T-cells and is associated with lower levels of C-Reactive Protein, a marker for inflammation (5). In severe cases of coronavirus, the inflammatory response is exaggerated, attacking not just the virus, but also healthy tissue. Keeping inflammation levels low through following a healthy diet may offer some protection against the worst effects of the virus.

Take vitamins and minerals

There is no shortage of supplements that promise a boost to immunity, but are there nutrients that can affect upper respiratory tract infections specifically? We take a look at the evidence:

Vitamin D

A review of existing research in 2012 which looked at 5 clinical trials found that taking vitamin D supplements may help to prevent respiratory infections (6). Aim to keep your vitamin D in the normal range (between 50 and 175 nmol/L) – vitamin D levels can easily fall, especially in the winter months.

Vitamin C

The evidence around vitamin C and the prevention of respiratory tract infections is mixed. However, once you are infected, vitamin C appears to shorten the duration of the infection, although this effect appears to apply only to women and children (7, 8). It is difficult to measure vitamin C in a blood test as levels of vitamin C change rapidly according to what you've just eaten. However, vitamin C is safe to take as any excess passes out of your body in your urine. It would seem sensible to supplement with vitamin C, especially if you become infected.


Selenium is a trace mineral that is a powerful antioxidant and also supports the immune system. Modern agricultural methods mean that levels of selenium in the soil are becoming depleted, which directly affects the amount of selenium in the food we eat. Selenium deficiency appears to place you at a higher risk of viral infections, including SARS, and also means that the virus mutates more quickly.


Zinc may not stop you from getting coronavirus, but it may help you recover more quickly. A meta-analysis conducted in 2012 of over 2000 participants showed that the people taking oral zinc supplements recovered faster from the common cold than people in the placebo group (10). You can test your zinc levels if this is of interest we can organise a test for you at Orchard Barn, please get in touch.


The bacteria in your gut is a relatively new area of research, and we are learning more every day about the beneficial effects of fibre and probiotics for a healthy microbiome. Surprisingly, your gut bacteria play an essential role in regulating your immune system. A study in 2015 of almost 4,000 adults and children found evidence of protection against upper respiratory tract infections for those taking a probiotic compared with those taking a placebo (10). An excellent way to increase the good bacteria in your gut is to increase your fibre intake. Alternatively, you can take a probiotic in the form of cultured foods like sauerkraut or live yoghurt. If this doesn't appeal, there are plenty of commercially available probiotics available.

Information from medichecks.

Further information on the research is available of the College of Medicine.

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