Nutrition for Stronger Immunity

Written by Huda Fareed – Reviewed by Zoha Matin

“Improve your immunity…”

These words are hammered more than usual nowadays, especially since the advent of corona. Besides, winter is often perceived as the “flu season” and so, it is not uncommon to be concerned about one’s immunity during such times. But have you ever wondered what immunity really is? Why do we need to focus on it so much? While this article mainly focuses on the role of certain nutrients in improving our immunity, let’s take a minute to understand what the “immune system” is. To put it simply, our skin, organs, tissues, mucous membranes and white blood cells are all a part of the immune system that protects us from pathogens. Virus, bacteria, fungi and parasites are all examples of pathogens. (10)

Pathogens that enter our bodies can make us sick. The white blood cells either engulf the pathogens or produce antibodies to destroy them. The mucous membranes are the inner linings of various structures of the body. They are moist and help trap germs and infectious particles. (10)

Thus, immunity is the body’s ability to fight against any pathogens (virus, bacteria, etc.) that could cause us harm. There are two types of immunity; innate and adaptive immunity. (3,7) Innate immunity is already present in our body and includes the physical barriers (our skin, cell membranes) that keep pathogens from entering our bodies (9). Meanwhile, adaptive immunity, also known as acquired immunity, is attained by exposure to a pathogen (disease causing agent). (7) For example, if you get a COVID-19 vaccine, or if you get infected by coronavirus, later you have adaptive immunity for some time.

There are many different factors that affect our immunity and one of them is nutrition. Certain micronutrients play a very important role in our immune system.

For a healthy and strong immune system, a healthy gut is very important. Diet plays a major role in keeping the gut healthy because it impacts the microbes present in the intestines. Along with this, inflammatory processes and action of antibodies are also affected by your diet. (3)

Let’s talk about the nutrients that are essential for a healthy and strong immune system.

Vitamin C

Vitamin C, also known as Ascorbic acid, is one of the water-soluble vitamins. We cannot store it in our bodies for long, so we need to take Vitamin C daily. Vitamin C is an antioxidant that prevents the formation of free radicals in our body that could cause harm. (8)

Vitamin C affects innate as well as adaptive immunity. (2,5) It maintains the physical barriers such as our membranes, skin layers and respiratory tract.  It also helps antibodies to perform their function. (5)

Fruits and vegetables are the main source of vitamin C. Red bell peppers and Citrus fruits such as oranges have the highest amount of it. Kiwis, strawberries, green peppers and broccoli also contain vitamin C. (1)

Vitamin A

The vitamin A, when present in plants, is in the form of Beta-Carotene, and in animals it is in the form of Retinol.  Vitamin A controls the number and function of white blood cells that fight against viruses, bacteria and any other pathogens. (2,5)

Retinol is found in fish in high amounts. It is also found in milk and eggs. Beta-carotene is present in yellow-orange vegetables, tomatoes and dark green leafy vegetables.

Vitamin E

Vitamin E is known as Tocopherol. It maintains the integrity of our protective physical membranes and enhances the function of white blood cells (2,5).

Vegetable oils contain high amounts of vitamin E. Nuts, seeds, mangoes, and avocadoes are good sources as well.  

Vitamin D

Vitamin D is known as calciferol. It promotes the movement and the ingesting ability of white blood cells (2).

One main source of vitamin D is sunlight.  However, if you are not exposed to much sunlight, then vitamin D enriched foods such as cereals or milk should be consumed. Oily fish such as salmon, mackerel and herring are also good sources of vitamin D.

Vitamin B9/ Folate

Folate enhances the activity of the antibodies. (2,5)

It is present in high amounts in dark green leafy vegetables such as spinach, asparagus, broccoli, and Brussel sprouts. Peanuts, beans and eggs are good sources of folate as well.

Zinc

Zinc maintains the integrity of all the membranes. Zinc helps in the growth of antibodies and improves their disease-fighting activity. (4) Poultry and meat are good sources of zinc. Whole grains, milk, chickpeas and beans contain high amounts as well.

Selenium

Selenium plays an important role in adaptive immunity by improving the function of antibodies. (4) Tuna and sardines contain high amounts of selenium. Meat, poultry, brown rice and lentils are also good sources.

Glutamine

Glutamine plays an important role in our immune system response as it is essential for the maintenance of our gut health. The microorganisms in the gut help in keeping the immune cells healthy. (4,6)  

Glutamine is a non-essential amino acid that can be found in high protein foods such as eggs, dairy and fish. Non-animal sources of glutamine are nuts, red kidney beans and dark green leafy vegetables, such as spinach and kale.

In a nutshell

Overall, a diet rich in fruits and vegetables along with appropriate amounts of fish, poultry and meat tend to improve our immunity. It is important to note that the consumption of a variety of food categories and nutrients is essential; reliance on one specific food item alone does not guarantee good immunity.

Apart from a balanced diet, vitamin and mineral supplements are proven to be beneficial if a person is deficient and has a weak immune system. However, it’s best to consult a dietitian for proper guidance before starting any supplements. To make sure you are having the right nutrients in your diet that would benefit your immunity, feel free to contact Zoha Matin for a 1:1 consultation session.

References

  1. National Institutes of Health. Office of Dietary Supplements – Vitamin C. Nih.gov. Published March 26, 2021. https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/
  2. Gombart AF, Pierre A, Maggini S. A Review of Micronutrients and the Immune System–Working in Harmony to Reduce the Risk of Infection. Nutrients. 2020;12(1). doi:10.3390/nu12010236
  3. Boston 677 HA, Ma 02115 +1495‑1000. Nutrition and Immunity. The Nutrition Source. Published May 1, 2020. https://www.hsph.harvard.edu/nutritionsource/nutrition-and-immunity/
  4. Childs C, Calder P, Miles E. Diet and Immune Function. Nutrients. 2019;11(8):1933. doi:10.3390/nu11081933
  5. Maggini S, Pierre A, Calder P. Immune Function and Micronutrient Requirements Change over the Life Course. Nutrients. 2018;10(10):1531. doi:10.3390/nu10101531
  6. Cruzat V, Macedo Rogero M, Noel Keane K, Curi R, Newsholme P. Glutamine: Metabolism and Immune Function, Supplementation and Clinical Translation. Nutrients.2018;10(11):1564.doi:10.3390/nu10111564
  7. Healio. The Innate vs. Adaptive Immune Response. Healio.com. Published 2018. https://www.healio.com/hematology-oncology/learn-immuno-oncology/the-immune-system/the-innate-vs-adaptive-immune-response
  8. Carr AC, Maggini S. Vitamin C and Immune Function. Nutrients. 2017;9(11):1211. doi:10.3390/nu9111211
  9. Aristizábal B, González Á. Innate Immune System. El Rosario University Press; 2013. https://www.ncbi.nlm.nih.gov/books/NBK459455/
  10. MedlinePlus. Immune System and Disorders. Medlineplus.gov. Published 2018. https://medlineplus.gov/immunesystemanddisorders.html