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Boosting immunity: Which is the Best Vitamin?

by Maria Kirmanidou, Dietitian & Sport Nutritionist

16 May 2024 • 0 min read

The immune system is our body's defence centre, the function of which is crucial for the effective treatment of pathogenic microorganisms. Just as the army of a nation army protects it from invaders, the immune system is prepared to protect us from potential "invaders" such as bacteria, viruses, fungi. "Officers" of the crew that play a key role in coordinating healthy defence are the spleen, tonsils, lymph nodes, bone marrow as well as our gut microbiome, which has very recently demonstrated its vital role in the effective functioning of the immune system. Finally, antibodies as well as immune cells are considered be the "soldiers" that get the job done and chase the "invaders", trying to ensure the integrity of our health.

Nutritionally rich vitamin C sources

Oranges and the whole citrus family - lemons, tangerines, grapefruit, sanguine - are one of the most famous and rich sources of vitamin C. However, kiwi, colorful peppers and all berries (blueberries, raspberries, strawberries) are even richer sources, while tomatoes, mango, pineapple, broccoli and dark leafy vegetables contain considerable amounts.

The recommended daily intake of vitamin C is 75-90 mg per day for the general population.  Two small kiwis or a large orange are enough to meet the recommended dose. However, let's not forget that we are all different and have different needs. That's why our vitamin C needs increase if we...

  • are a smoker.
  • get sick often.
  • have malabsorption (usually when a clinical gastrointestinal condition such as Crohn's disease and ulcerative colitis co-exists).
  • are pregnant or breastfeeding.

Functions of vitamin C

Although boosting immune system is the main concern that you have in mind, its multifaceted functionality is a fact. Let's take a look together at just how valuable it is!

  • It offers powerful antioxidant activity. If not the strongest antioxidant - one of the strongest antioxidants in our body is vitamin C. But what does it mean that an ingredient exhibits antioxidant activity/is an antioxidant? It means that it protects against the damage caused by free radicals in the body.

The presence of free radicals in the body is a normal process. Free radicals are particles produced by the breakdown of food, exposure to air pollution, smoking, and exercise. However, the accumulation of large amounts of free radicals in the body threatens our long-term health, as free radicals circulating in the bloodstream are able to attack active tissues such as proteins and DNA, threatening the integrity of cell membranes. That's why adequate intake of antioxidants, such as vitamin C, helps to neutralise free radicals in time, thus protecting cellular life.

  • Fighting disease. Due to its strong antioxidant and anti-inflammatory properties, vitamin C appears to have a protective effect on the occurrence of various diseases, such as cardiovascular disease and cancer, as well as reducing the likelihood of neurodegenerative diseases, such as Alzheimer's disease.
  • Collagen production and tissue healing. Vitamin C, as well as zinc, is essential for the synthesis of collagen, one of the most important proteins on skin. Collagen - along with elastin - is responsible for firmness and maintaining healthy skin. For this reason, vitamin C is found in many beauty products. In addition, collagen is not only present in the skin, but also in almost all tissues, such as muscles, bones and tendons. Thus, vitamin C is vital in injury recovery to fully restore vital tissues to their original state.
  • It is essential for the synthesis of cholesterol, catecholamines, carnitine, amino acids and peptides.
  • Iron absorption. Vitamin C also has an active role in iron metabolism. Iron is found in many foods - heme and non-heme - but is "hard" to absorb. Vitamin C is the most effective iron absorption enhancer, especially in plant sources where absorption rates are less than 10%!
  • Nervous system. Vitamin C appears to play a very important role in brain function, improving communication between nerve cells involved in learning, memory, locomotion & concentration.

Vitamin C deficiency

Symptoms of vitamin C deficiency are varied and can occur in a wide range of functions.

  • Intense feelings of fatigue
  • Bruises
  • Dry - damaged skin
  • Muscle and joint pains
  • Bleeding gums
  • Nasal Bleeding
  • Weak immune system

As we can see, vitamin C is actively involved in almost all systems of the human body and its deficiency can bring about adverse effects on our health.  To avoid deficiency, be sure to consume at least one fruit rich in vitamin C and focus on different colors each day. Holland & Barrett provides a variety of vitamin C-rich dried fruits, dried berry blends that you can add to your yogurt, and a variety of vitamin C supplements to provide for everyone and every individual need.

Scientific references

Bendich, A., & Langseth, L. (1995). The health effects of vitamin C supplementation: a review. Journal of the American College of Nutrition, 14(2), 124-136.

Grosso, G., Bei, R., Mistretta, A., Marventano, S., Calabrese, G., Masuelli, L., ... & Gazzolo, D. (2013). Effects of vitamin C on health: a review of evidence. Front Biosci (Landmark Ed), 18(3), 1017-1029.

Lane, D. J., & Richardson, D. R. (2014). The active role of vitamin C in mammalian iron metabolism: much more than just enhanced iron absorption!. Free radical biology and medicine, 75, 69-83.

Padayatty, S. J., Katz, A., Wang, Y., Eck, P., Kwon, O., Lee, J. H., ... & Levine, M. (2003). Vitamin C as an antioxidant: evaluation of its role in disease prevention. Journal of the American college of Nutrition, 22(1), 18-35.