Adequate intake of fruits and vegetables for optimal health and immunity
May Yeung, Dietitian, Health Promotion Branch, Department of Health
During this COVID-19 pandemic, many people are seeking ways to boost our immunity in order to fight against and preventing infections. Actually a well-balanced diet consisting of plenty of fruits and vegetables is something simple and achievable during our routine to maintain a good immune system. Let’s take a quick look at which nutrients are essential to our immune system, and where can we find from our diet.
Vitamin C is probably the first nutrient in our mind when talking about immunity, as our immune system requires vitamin C to function properly. Vitamin C helps stimulating formation of antibodies, which aids in fighting against infection. We can obtain vitamin C from fresh fruits and vegetables, such as citrus fruits (e.g. oranges and grapefruits), tomatoes, kiwifruits, strawberries, green peppers and broccoli. Another key function of vitamin C is to enhance non-heme (plant source) iron absorption, which is important for our immunity as well.
Tips to include vitamin C from our diet:
- Eat fruits as snack
- Include fruits and vegetables as ingredients in our dishes, such as stir-fry green pepper and beef, skinny orange chicken dish. Since vitamin C is heat-sensitive, therefore, we should add fruits and vegetables during the last stage of cooking to minimize its lost from cooking.
Beta-Carotene (a provitamin A), is another nutrient we can obtain from fruits and vegetables. Our body will convert beta-carotene to the active form of vitamin A. Vitamin A plays a key role in the development and differentiation of white blood cells, such as lymphocytes, which are essential for immune response. Since vitamin A is fat-soluble, excess intake will be stored in liver, which can be harmful to our body. Therefore, it is not recommended to take vitamin A supplement. We should obtain vitamin A from food sources, such as green leafy vegetables, orange and yellow vegetables, such as tomatoes, sweet potato, carrots and pumpkin. The animal source of vitamin A include oily fish, such as salmon and herring.
In summary, there is no “magic pill” to boost our health. Our body relies on different nutrients to function properly. We should maintain a well-balanced diet by following the food-guide pyramid recommendations, together with healthy lifestyle, such as regular exercise, these all will contribute to good health as well.