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How Nutrition & Lifestyle Can Boost Immunity Against Viral Infections

Fortunately immunity to viruses is generalizable, and strong immunity will help to protect us against all viruses. A healthy lifestyle with sound nutrition will not only protect us against cold and flu, but also yield multiple other health benefits, such as delaying ageing and enhancing the quality of life.

A healthy diet is a cornerstone of good health. With modern farming practices food has become less nutritious, therefore, eating well is even more important. A diet rich in healthy meat, fish, vegetables and fruit will usually deliver sufficient micronutrients. Junk food, refined cereals, sugar and sweet drinks (including fruit juice) contain high levels of sugar and add little nutritional benefit. GovHK has their recommendation and guidelines to the importance of a balanced diet1.

In this article I am going to focus on four micronutrients and a supplement that are helpful for good immunity. These are Zinc, Selenium, Vitamin D , Vitamin C and Probiotics.

Zinc is a trace element, the daily requirement being about 15mg. Zinc is used by 300 different proteins in the human body and it is essential for normal immunity. Zinc deficiency is common and affects as many as 2 billion people worldwide2. Many studies have shown that Zinc deficiency causes poor immunity. Other symptoms of Zinc deficiency include hair loss (often after child birth) brittle nails and poor taste. Children may have white spots in their nails. Supplementation with Zinc is safe although after many months Copper levels may fall.

Selenium is also a trace element, the daily requirement is 50mcg. Selenium is used in antioxidant proteins and is needed for normal immunity to viruses. We have tested large numbers of patients’ Selenium and found deficiency to be common in our population. This is probably because the soil in China is low in Selenium and therefore food produced in China is also low in Selenium. Supplementation with Selenium in modest doses is safe with no long-term negative consequences3.

Vitamin D is the sunshine Vitamin. It is produced by the effect of sunlight on our skin. Naturally Vitamin D levels fall in the winter which is also the flu virus season and the season for Coronavirus outbreaks. Many studies have shown that Vitamin D is important for normal immunity and that supplementation can decrease the likelihood of virus infections, including flu4Deficiency is very common in our population and supplementation improves immunity along with multiple other health benefits5. Supplementation without testing is safe at lower levels such as 1,000iu daily for children and 2,000iu daily for adults. If in doubt please consult your GP and consider testing for it.

Vitamin C is helpful to prevent and treat viral infections. Supplementation has been shown to shorten the duration of the common cold6. All people have a limit to the amount of Vitamin C that can be taken by mouth without causing stomach upsets. However for adults 6gm spread over a day during a virus illness is usually tolerated. Unlike Vitamin D the duration of the effect of Vitamin C is short lived so supplements must be taken regularly.

In modern life our diet, antibiotics and hygiene have altered our microbiome, bacteria that live with us in and on our bodies. The change of gut microbiome has been shown to have many negative health impacts on our immunity including allergies, digestive issues and autoimmune diseases. Fortunately medical research has shown that taking simple probiotic supplements can help strengthen our immune system7In one study a simple combined daily probiotic supplement in children decreased antibiotic usage by 84% and episodes of feverish illnesses by 72%8.

Psychological stress is a key cause of poor immunity. When we are stressed we trigger our flight and fight reaction, which was developed while we were evolving to deal with an immediate physical threat. In modern life most of our stressors are actually psychological such as work, relationships or threats and anxiety caused by health concerns and rather than being immediate the stress can persist for a long period of time.  As a consequence of the fight and flight all systems for long-term health are downgraded to allow resources for the immediate threat.  Therefore levels of Sex Hormones and Growth Hormones will fall and the stress hormones adrenaline and cortisol will rise. Pulse and blood pressure will rise. Appetite and digestion will be downgraded. The immune system will switch its focus from surveillance for viruses and cancer to the immediate threat of bacterial infection from injury9.

Prolonged exposure to adrenaline causes high blood pressure, anxiety and poor sleep. The gut effects cause ulcers and irritable bowel syndrome. The immune effects make us more vulnerable to viral infections. Other psychological effects include an inability to see the big picture and poor short term memory. Fortunately one sure way to burn adrenaline is exercise, particularly exercise that you enjoy and exercise in nature. In other articles on the OT&P website we describe how to avoid and treat stress.

Viruses such as Influenza or Coronavirus have a range of severity from asymptomatic cases to severe cases requiring intensive care. The health of the infected person is key to preventing severe disease. In the short term a healthy lifestyle and nutrition will boost immunity. In the long term it will prevent diseases such as heart disease and diabetes that not only increase susceptibility to viruses but also decrease lifespan and the quality of life.

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1. (, G. H. K. (2019, October 14). GovHK: Healthy Eating. Retrieved February 26, 2020, from

2. Prasad, A. S. (2003, February 22). Zinc deficiency. Retrieved February 26, 2020, from

3. Steinbrenner, Saleh, Wunderlich, Frank, Helmut, & Sies. (2015, January 7). Dietary Selenium in Adjuvant Therapy of Viral and Bacterial Infections. Retrieved February 26, 2020, from

4. Urashima, M., Segawa, T., Okazaki, M., Kurihara, M., Wada, Y., & Ida, H. (2010, May). Randomized trial of vitamin D supplementation to prevent seasonal influenza A in schoolchildren. Retrieved February 26, 2020, from

5. Cannell, J. J., Vieth, R., Umhau, J. C., Holick, M. F., Grant, W. B., Madronich, S., … Giovannucci, E. (2006, December). Epidemic influenza and vitamin D. Retrieved February 26, 2020, from

6. Hemilä, H. (2017, March 29). Vitamin C and Infections. Retrieved February 26, 2020, from

7. Leyer, G. J., Li, S., Mubasher, M. E., Reifer, C., & Ouwehand, A. C. (2009, August). Probiotic effects on cold and influenza-like symptom incidence and duration in children. Retrieved February 26, 2020, from

8. Sarah, Irene, Gould, Kelsie, Vann, Hailey, … Dan. (2018, November 14). Does probiotic consumption reduce antibiotic utilization for common acute infections? A systematic review and meta-analysis. Retrieved February 26, 2020, from

9. PMC, E. (2017, July 21). Retrieved February 26, 2020, from

Topics: COVID-19, Health & Wellness

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OT&P Healthcare

OT&P Healthcare is a Premium Private Healthcare Practice in Hong Kong. Our priority is to help individuals to enhance and optimise their health by providing easy access to a wide range of excellent practitioners and information, supported by management systems and technology that ensure quality of service and value. Our Mission is to provide pre-eminent private healthcare in Hong Kong. We aim to be the best in class fully integrated healthcare service, providing a circle of care for all our patients' needs.