Nutrition and immune health |09 December 2022
There has been growing interest in the role that nutrition plays in our immune health. Despite all the hype however it is noteworthy that no food or nutrient can prevent an infection. Moreover, there is no supplement or special diet that can ‘boost’ your immune system. The term boost implies that you are enhancing your immune system above its normal level which is not physiologically possible. What you eat is however critical to how well your immune system functions.
A balanced and diverse diet with nutrient-dense foods is important for a functional immune system through the provision of essential nutrients that will help the body fight off an infection. It will also help prevent malnutrition and micronutrient deficiencies which can hinder the production and activity of your immune cells.
Aside from your dietary intake, there are many other factors that can affect your immune functions such as adequate sleep, exercise, your age, stress and existing medical conditions.
Our immune system
The immune system is a complex system of cells, chemicals and pathways interacting with each other to help protect the body from infections. The two main forms of immunity in the body is innate and adaptive immunity.
The innate system
Our innate system is our first-line defense against foreign bodies and consists of protective barriers such as the skin, mucus, stomach acid, certain enzymes and cells and is non-specific.
The adaptive system
The adaptive immune system on the other hand consists of specialised cells and various organs in the body such as the spleen, bone marrow and lymph nodes. It usually takes over when the innate system has been ineffective at destroying a pathogen (harmful substance).
When immune cells are activated, including certain types of white blood cells they produce antibodies to attack and destroy the pathogen. Following this initial exposure, the body then adapts by remembering the pathogen so it is able to mount an immune response much faster if exposed to it again in future.
The role of diet
Eating a well-balanced and varied diet is the best way to get all the nutrients your body needs for a functional immune system. This can easily be achieved by eating foods from all food groups as illustrated in the Seychelles food guide below.
Some key micronutrients that are crucial for good immune functions include vitamins A, B6, B12, C, D & E as well as folic acid and minerals like zinc, selenium and iron.
The table highlights some good food sources of these nutrients.
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Nutrient |
Food Sources |
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Vitamin A |
Liver and cheese are good sources of retinol (“pre-formed” vitamin A). Dark green leafy vegetables and orange-coloured fruits and vegetables, such as carrots, sweet potato, pumpkin, mango and papaya, are dietary sources of carotenoids (pro vitamin A), which can be converted into vitamin A by the body. |
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Vitamin B6 |
Poultry, fish, fortified breakfast cereals, egg yolk, soya beans, sesame seeds and some fruit and vegetables, such as banana, avocado and green capsicum. |
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Vitamin B12 |
Meat, fish, shellfish, milk, cheese, eggs and fortified breakfast cereals. |
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Vitamin C |
Guava, citrus fruits, papaya, green leafy vegetables, capsicum and tomatoes. |
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Vitamin D |
Oily fish, eggs, fortified breakfast cereals and fortified dairy products as well as sunlight exposure on our skin. |
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Vitamin E |
Seeds, nuts, vegetable oil and peanut butter. |
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Folic acid |
Green vegetables, pulses, oranges, nuts and seeds, cheese, bread and fortified breakfast cereals. |
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Zinc |
Offal, red meat, beans, pulses, nuts and seeds, fish and whole meal bread. |
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Selenium |
Nuts and seeds (such as Brazil nuts, cashews and sunflower seeds), eggs, offal, poultry, fish and shellfish. |
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Iron |
Meat, poultry, offal, fish and shellfish are great sources. Beans, lentils, nuts and seeds, green leafy vegetables, fortified soya and almond milk and tofu should be consumed together with a vitamin C source to increase its absorption. |
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Reduce highly processed foods
We have been saying this time and time again. There has been a lot of research in this area which confirms that a diet rich in calories, sugar, saturated fats and salt can have a negative impact on your immune health. This will include food options like fizzy drinks, energy drinks, juice, cordial, confectionary, crisps, cakes, processed meats and deep-fried foods.
Excessive intake of these foods can lead to inflammatory responses which affects your overall immune functions. Moreover, many people eating excessive amounts of highly processed foods have very limited intake of whole and nutritious foods hence they may be lacking in essential micronutrients mentioned above.
Supplements
You are encouraged as much as possible to get your vitamins and minerals from actual food rather than from supplements simply because food is more than just nutrients. They contain many other bioactive compounds with beneficial properties to the body. For the majority of people therefore a balanced and varied diet will provide all the essential nutrients required to support good immune functions.
There are certain ‘high-risk’ population groups like pregnant women, young children and older adults that have high nutritional needs or limited dietary intake and therefore a supplement may be necessary.
A supplement is designed with the intention of complementing or adding on to whatever you are already eating. It is not a diet replacement. Therefore, you should still aim to get the majority of your nutrients from actual food and your overall diet quality is still very important.
There is evidence that mega doses of certain nutrients offer no additional health benefits or can have adverse side effects. It is imperative therefore that you get supplements that provide less than 100% of the daily recommended allowance after consulting with your doctor first.
What you want ideally to maintain optimal functioning of the immune system therefore is good lifestyle habits as a whole, including good dietary choices.
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Please get in touch by emailing eat4ourhealth@gmail.com and let us know how you’re doing with these ideas, or better still, let us know how we can help you.
Yours in health
The E4OH Team