How to improve your immune system

How do you improve your immune system?

In 2020 this has been a common question, many individuals want to be as healthy as possible to help them if they should catch Covid-19.

In general your body has a pretty good defence system, but occasionally it can fail, but it is important to note that your immune system is just that a system and not a single entity, the whole system needs balance and harmony.

Researchers are exploring the effects of diet, exercise, age, psychological stress, and other factors on the immune response, both in animals and in humans, and while we wait for the exact science, in the the meantime, general healthy-living strategies are a good way to start giving your immune system the upper hand.

The first and best defence is a health lifestyle, this has many components.

  • Don’t smoke
  • Eat 5-6 portions of vegetables and 2-3 portions of fruit per day
  • Exercise regularly – depending on age both aerobic and strength training may be required
  • If you drink alcohol, drink in moderation
  • Get adequate sleep
  • Take steps to avoid infections, wash hands regularly, social distance where possible
  • Try to minimize stress

There are still relatively few studies of the effects of nutrition on the immune system of humans, however there is some evidence of micro nutrient deficiencies of of zinc, selenium, iron, copper, folic acid, and vitamins A, B6, C,D and E — alter immune responses .

If you do have a deficiency in one of these taking an off the shelf -multi vitamin will probably not be sufficient since the levels will not be high enough to correct a deficiency, but you should also not just take a megadose in one of them.

Copper and Zinc need to be balanced, if you take large doses of zinc, it will reduce the amount of copper in your bodies. Too much vitamin C will have a negative effect on an individuals bowels. Vitamin A is fat soluble and is stored within the body, too much can be dangerous, the studies have shown that high dose vitamin A supplements in smokers over 5-8 years increases the risk of lung cancer. ( Studies have found no risk with high dose Vitamin A obtained from foods). Too much iron can reduce your zinc levels. This is why a trained nutritional professional will look at the bigger picture to ensure your diet is balanced.

Which foods should I eat to get these Vitamins and Minerals?

Vitamin C

Vitamin C – research has shown that there is some reduction in respiratory infections in individuals, that are physically stressed most research has been done on military personal and marathon runners, both groups put their bodies under extreme physical stress and have been reported to have a higher incidence of respiratory infections.

Fruits are high in Vitamin C, aim for 200mg per day. Your body can take more than this if it has low levels of blood saturation, however if your body has reached maximum saturated any excess is excreted. One medium Orange is about 70 mg, one grapefruit about 90mg and a red bell pepper is around 150mg. Leafy green vegetables such as spinach and kale, bell peppers, brussels sprouts, strawberries and papaya are also excellent sources


Iron is an essential nutrient but too much is dangerous. Individuals suffering from iron overload not only experience cellular damage from adverse redox chemistry of free iron, but also are at enhanced risk of infection.

Men over 18 need around 8mg or Iron per day and women aged 19-50 , 18mg then 8mg once over 50 (or passed the menopause), however from food the absorption rate differs if its haem Iron (Animal source) or non-haem iron (plant based).

The bioavailability of iron is approximately 14% to 18% from mixed diets that include substantial amounts of meat, seafood, and vitamin C (ascorbic acid, which enhances the bioavailability of nonheme iron) and 5% to 12% from vegetarian diets. In addition to ascorbic acid, meat, poultry, and seafood can enhance nonheme iron absorption, whereas phytate (present in grains and beans) and certain polyphenols in some non-animal foods (such as cereals and legumes) have the opposite effect. Unlike other inhibitors of iron absorption, calcium might reduce the bioavailability of both nonheme and heme iron. However, the effects of enhancers and inhibitors of iron absorption are attenuated by a typical mixed western diet, so they have little effect on most people’s iron status.

Good sources are:-

  • Breakfast Cereals fortified with 100% RDA of Iron – 18mg
  • One cup white beans – 8mg
  • 3oz dark chocolate 45%+ coco solids – 7mg
  • 3oz Beef liver – 5mg
  • 1/2 cup lentils, boiled and drained – 3mg
  • 1/2 cup firm Tofu – 3mg
  • 1/2 cup Kidney beans – 2mg
  • 3oz Sardines – 2mg
  • 1/2 cup chickpeas – 2mg
  • 3oz beef – 2mg
  • 1 medium baked potato, flesh and skin – 2mg
  • Wholewheat slice of bread – 1mg
  • Rice – Brown – 1 cup – 1mg


Red meat and oysters are rich dietary sources of zinc . Foods prepared from unrefined cereals, legumes, or plant parts rich in phytates decrease zinc bio availability, by binding zinc very effectively, therefore it is recommended to soak your cereal and legumes before eating/ cooking.

Zinc deficiency, often seen in vegetarians or vegans, due to the consumption of high levels of zinc-chelating agents in food originating from cereals, legumes, or plant parts.

Vitamin D

Most vitamins can be absorbed via the diet but vitamin D may be the exception to that rule. You can increase your intake through foods such as fatty fish (salmon, mackerel, tuna and sardines) and fortified foods such as milk, orange juice and cereals. Many people have a hard time absorbing vitamin D from food, and especially in the Northern Hemisphere where we see less sun.

Vitamin D can modulate the innate and adaptive immune responses. Deficiency in vitamin D is associated with increased autoimmunity as well as an increased susceptibility to infection.

Vitamin D is also required for the absorption of calcium.


Recent evidence suggests that copper exacts an important role in the maintenance of immunocompetence. Copper deficiency results in decreased humoral and cell-mediated, as well as nonspecific immune function. Its a trace element only 900mcg are needed each day, but it is an essential mineral and one that the body can not produce on its own.

Foods that are good sources of copper include:-

  • Liver – 67g – gives you 10.3mg of copper
  • Oysters 3.5 oz – gives you 7.6mg of copper

Other good sources are include nuts, seeds, shitake mushrooms, lobster, leafy greens and dark chocolate.


Dietary selenium (Se) is an essential micronutrient that affects various aspects of human health, including optimal immune responses.

The amount of selenium in different foods depends on the amount of selenium in the soil where the food was grown. Rain, evaporation, pesticides, and pH levels can all affect selenium levels in soil. 

Regardless of where you live, certain factors can make it harder for your body to absorb selenium. For example, you may have difficulty absorbing selenium if you:

  • are receiving dialysis
  • are living with HIV
  • have a gastrointestinal condition, such as Crohn’s disease

An adult needs about 55mg of Selenium per day. Too much can be toxic so its advisable to have a varied diet and only have items high in selenium once or twice a week.

Foods high in Selenium include Brazil nuts – just 3 day will provide you with your requirements 220mg , a 3oz serving of ham will provide 60% of daily requirements. Fish is a very good source. Yellowfin tuna contains about 92 mcg of selenium per 3 ounces (oz), making it an excellent source of selenium. This is followed by sardines, oysters, clams, halibut, shrimp, salmon, and crab, which contain amounts between 40 and 65 mcg.

For Informational Purposes Only.

Any product recommendation is not intended to diagnose, treat, cure, or prevent any disease.

Copyright: Susan Monk 2015-2021