Eat for stronger immunity

Obtaining an adequate amount of the nutrients mentioned above and establishing a healthy lifestyle such as adequate exercise and sleep are very important in order to build a strong immune.

Our immune system protects our body from invading pathogens (such as bacteria, viruses and parasites) that can infect our body.  It also manages and restores functions of damaged cells.  The immune system is made up of cell tissues, blood, blood cells and organs such as the skin and lymphoid tissue.  If our immune system is weak, the body will be easily affected by pathogenic invasion which causes infection.  On the other hand, a strong immune system can enhance our immunity and defend against pathogens.

A good and balanced nutrition will not only build a strong immunity to defend off invasion of pathogenic sources, minimize infection or illness.

The function of the body’s immune system usually works optimally at adolescence and starts to decline at around the age of 50.  However, if one does not look after their nutrition intake and stress level, the defense capability will start to decline earlier at around the age of 20 to 30.  Factors such as UV exposure, stress, environmental pollution, smoking and free radicals can cause varying degrees of cell damage to the body.  Free radical causes oxidation of tissues which accelerate the rate of degradation of cells and organs, as well as increase the risk of developing cancer.


Protein is made up of different amino acids linked together.  It is needed to repair cells and help production of blood cells, antibodies and hormones.  Our body needs enough protein in order to achieve the above mentioned functions.  Adults should consume 4-5 tael fresh meat, beans or its products and 1-2 serve of dairy or its products in order to obtain the recommended amount of protein intake.  In addition, meat is rich in iron, while vegetarians can choose black beans, kidney beans, sesame etc as their iron sources.  Adequate intake of iron can prevent iron deficient anemia which affects the body’s immune function.

Antioxidant vitamins

Vitamins A, C and E have antioxidant properties that can protect cells from free radical damages.  Vitamin A helps to maintain healthy mucosal tissues such as intestinal and respiratory mucous membrane that can help prevent invasion of pathogens.  Food sources include: pumpkin, carrots and tomatoes etc. Vitamin C help with the activity of immune cells, but also the production infections.  Food sources include: kiwi orange and potatoes etc.  Vitamin E neutralizes free radical damages, reduces cell oxidation and promotes wound healing.  Food sources include:  vegetable oil and nuts etc.


Zinc is an essential nutrient for our immune system, is needed to maintain cells growth and functions.  Deficient in zinc can affect the development of the immune system, hence it is necessary to obtain adequate zinc intake.  Food sources include: oysters, beef and kidney beans etc.


Selenium is a potent antioxidant.  Studies have shown that selenium can be bound to protein to form seleno-proteins, which can regulate free radicals and provide antioxidant properties to almost all cells and tissues to minimize cells damages.  Food sources include: dairy products etc.

Additionally, our digestive tract also plays a very important role in our immune function.  The human gut contains the largest lymphoid tissue.  There is a great chance that we ingest in microorganism and their antigens every day.  Moreover, the large intestine is our temporary stool storage and a suitable place for microorganisms to grow.  Hence, keeping the intestinal tract healthy will maintain a better immune system.  Probiotic and prebiotic fiber are very good for your intestine.  Probiotics can increase the acidity of the intestinal tract and hence suppress the growth of bacteria.  Lactobacillus Bifidobacterium can be found in lactic acid containing foods.  Foods such as onions, cabbages and potatoes etc. contain prebiotic fibre which can help the growth of probiotics or good bacteria in the gut.

330 Tips provided by:  Ms Grace Lam  (Senior Dietitian - Centre for Nutritional Studies, School of Public Health and Primary Care, Faculty of Medicine, CUHK)

Date: 2014-10-01