Vitamin C and Zinc in Human Health

Learn why vitamin C and Zinc are important for your body

Vitamins and minerals are micronutrients required by the body for basic body functions and to perform everyday tasks. These are obtained by eating a balanced diet. A balanced diet includes vitamin A, B, C, D, E, and K, and some micronutrients such as zinc, sodium, potassium, calcium, chloride, and phosphorus which may be beneficial in various infectious diseases.1 Vitamin C and zinc play important roles in providing adequate nutrition, immune defence and health maintenance.2

Let’s learn more about vitamin C and Zinc.

Vitamin C Vitamin C or ascorbic acid is a water soluble vitamin with antioxidant properties. It helps to protect cells from the damage caused by free radicals. While most plants and animals produce vitamin C for their requirement, humans are not equipped to produce vitamin C. Hence, it has to be supplemented mainly through fruits, vegetables and tablets. It is present in fruits like orange, lemons, grapefruit, watermelon, papaya, strawberries, mango, pineapple, raspberries and cherries. Vitamin C is also found in green leafy vegetables, tomatoes, broccoli, green and red peppers, cauliflower and cabbage.3

Functions of vitamin C in the human body

  • Vitamin C is required for the formation of collagen. Collagen is a type of protein found in many different types of tissue of skin, blood vessels, bones and cartilage, tendons, blood vessels, heart valves, intervertebral discs, cornea and eye lens. Its deficiency impairs collagen synthesis. Collagen provides structure to the connective tissue throughout your body. Without vitamin C, collagen cannot be replaced and the different types of tissue break down.3
  • It has antioxidant properties. Antioxidants prevent reactive free radicals from damaging cells in our body. Free radicals can cause inflammation, early aging, cancer, and even heart disease.1,3
  • It is also required for iron regulation within the body.3 Low levels of Vitamin C in the body may lead to anemia, increasing fatigue and lethargy.
  • It helps in proper functioning of the immune system and reduces susceptibility to infection.4
  • Vitamin C is essential for the production and metabolising of dopamine, carnitine and other neurotransmitters which are required for energy production.3
  • Promotes wound healing.3

Deficiency of Vitamin C
A deficiency in vitamin C leads to scurvy. It is a condition characterised by general weakness, spongy swollen and bleeding gums, and skin haemorrhages. Vitamin C is completely destroyed by boiling and cooking.3

Groups at Risk of Vitamin C inadequacy4:

  • Alcoholics.
  • Smokers.
  • Individuals with eating disorders and who follow restrictive diets due to food allergies.
  • Elderly population with poor dietary habits.
  • Crohn’s disease – A chronic inflammatory bowel disease that affects the lining of the digestive tract.
  • Ulcerative colitis – A condition that results in inflammation and ulcers of the colon and rectum where the body’s ability to absorb nutrients is impaired.
  • Low income group people where the diet may be lacking in fresh fruits and vegetables.
  • Type 1 diabetics who have high requirement of vitamin C.

Health benefits Vitamin C is known to have beneficial effect for the prevention or relief of common cold. It reduces the severity and duration of symptoms of cold during the period of infection. Supplementation improves immune response during cold infection.3

It may also decrease the incidence of colds in people under extreme physical stress. Athletes should consider a vitamin C supplementation to prevent upper respiratory tract infection symptoms during limited periods of enhanced heavy stress (such as, sports competitions).5

  • It accelerates healing process by stimulating collagen synthesis therefore recommended for wound repair and burns.3
  • Vitamin C might lower the risk of stomach cancer due to its antioxidant activity. It protects stomach lining from oxidative damage.3
  • Age-related macular degeneration (AMD) and cataracts are two of the leading causes of vision loss in older people. Research suggests that vitamin C combined with other nutrients might help slow AMD progression.6
  • Vitamin C acts as an immunity booster and has a positive impact on the recovery of Covid-19 infection.7

Zinc is one of the most important trace mineral in the body that is needed to stay healthy. Moreover, it is the second most abundant trace mineral in the body after iron. It is needed for the body’s defense (immune) system to work properly. It has an essential role in cell division, cell growth, wound healing, and the breakdown of carbohydrates.13

Zinc also enhances the action of insulin and also needed for the senses of smell and taste. The body needs zinc for growth during pregnancy, infancy, and childhood.13

As per World Health Organization (WHO), nearly two billion people in the developing world may be zinc deficient.14

Zinc is distributed in a wide range of food, including meat (fish, red meat, and meat products), grains, cereals, dairy products, and dietary supplements.15 It is also present in lamb, nuts, whole grains, legumes, and yeast.13

Functions of Zinc in the human body Zinc is necessary for carrying out many primary functions in the body such as:

  • Enhances nervous system function, brain activity, memory and concentration.16
  • Aids wound repair.13
  • Preserving a normal sense of taste and smell.13
  • Promoting optimal cell growth and division.13
  • Improves immunity.14
  • It helps in preventing chronic diseases in old age, like heart disease, diabetes and age-related macular degeneration, by promoting healthy ageing process.14

Zinc deficiency
The symptoms of Zinc deficiency in various severities include:13,15

  • Compromised immune function.
  • Frequent infections.
  • Diarrhea.
  • Poor appetite.
  • Problems with the sense of taste and smell.
  • Skin sores and slow wound healing.
  • Loss of memory.
  • Cognitive disorders.
  • Sperm damage in males.
  • Trouble seeing in the dark.

In addition, the groups at risk of zinc inadequacy are:16

  • People with gastrointestinal diseases and other chronic illnesses such as diabetes, liver disease, sickle cell disease, kidney disease, HIV infections.
  • Vegetarians: The zinc available from vegetarian diets is lower than from non-vegetarian diets. Meat is high in bioavailable zinc and may enhance zinc absorption. In addition, vegetarians typically eat high levels of legumes and whole grains, which contain phytates that bind zinc and prevent its absorption.
  • Pregnant and lactating women – Zinc requirements increase up to two-fold during these times.
  • Alcoholics.

Health Benefits

  • Zinc supplementation in children would reduce the incidence of acute lower respiratory tract infection, diarrhea and pneumonia, and boost growth.14
  • Zinc, if taken regularly, may reduce the risk of developing the common cold and can reduce symptoms.13
  • It improves depression as well as concentration in adults.15
  • It improves sperm quality and pregnancy rate.15
  • It can be effective in decreasing the risk of incidence of ocular diseases correlated to aging and the progression of age-related macular degeneration.14
  • Zinc supplementation can be used an adjuvant therapy in COVID-19 treatment due to its antiviral properties as well as its positive role in immunity boosting.7
  • Supplementation with zinc reduces the risk of atherosclerosis or hardening of arteries.14
  • Helps in wound healing.13

Vitamin C and Zinc are two essential micronutrients that play vital roles in nutrition, immune defence and maintenance of health. Humans cannot synthesize them and has to be obtained from diet. Deficiency of vitamin C or Zinc leads to impaired immune response with altered resistance to infections, impaired growth, and weakened collagenous structures with delayed healing. Several trials document that adequate intake of vitamin C and Zinc ameliorates symptoms and shortens the duration of respiratory tract infections including common cold. Moreover, vitamin C and Zinc reduce the incidence and improve the outcomes of pneumonia, diarrhea infections, especially in children in developing countries.


  1. Morris AL, Mohiuddin SS. Biochemistry, Nutrients. [Updated 2021 May 12]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from:
  2. Maggini S, Beveridge S, Suter M. A combination of high-dose vitamin C plus zinc for the common cold. J Int Med Res. 2012;40(1):28-42.
  3. Naidu, K.A. Vitamin C in human health and disease is still a mystery? An overview. Nutr J 2, 7 (2003).
  4. Maxfield L, Crane JS. Vitamin C Deficiency. [Updated 2021 Jul 18]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022
    Jan-. Available from:
  5. Cerullo G, Negro M, Parimbelli M, Pecoraro M, Perna S, Liguori G, Rondanelli M, Cena H, D’Antona G. The Long History of Vitamin C: From Prevention of the Common Cold to Potential Aid in the Treatment of COVID-19. Front Immunol. 2020 Oct 28;11:574029.
  6. Wong, I.Y.H., Koo, S.C.Y. & Chan, C.W.N. Prevention of age-related macular degeneration. Int Ophthalmol 31, 73–82 (2011).
  7. Kumar P, Kumar M, Bedi O, Gupta M, Kumar S, Jaiswal G, Rahi V, Yedke NG, Bijalwan A, Sharma S, Jamwal S. Role of vitamins and minerals as immunity boosters in COVID-19. Inflammopharmacology. 2021 Aug;29(4):1001-1016.
  8. Johnston CS, Barkyoumb GM, Schumacher SS. Vitamin C supplementation slightly improves physical activity levels and reduces cold incidence
    in men with marginal vitamin C status: a randomized controlled trial. Nutrients. 2014 Jul 9;6(7):2572-83.
  9. Gao D, Xu M, Wang G, Lv J, Ma X, Guo Y, Zhang D, Yang H, Jiang W, Deng F, Xia G, Lu Z, Lv L, Gong S. The efficiency and safety of high-dose vitamin C in patients with COVID-19: a retrospective cohort study. Aging (Albany NY). 2021 Feb 26;13(5):7020-7034.
  10. Pisalsitsakul N, Pinnoi C, Sutanthavibul N, Kamolratanakul P. Taking 200 mg Vitamin C Three Times per Day Improved Extraction Socket Wound Healing Parameters: A Randomized Clinical Trial. Int J Dent. 2022 Mar 10;2022:6437200.
  11. Gunton JE, Girgis CM, Lau T, Vicaretti M, Begg L, Flood V. Vitamin C improves healing of foot ulcers: a randomised, double-blind, placebo-controlled trial. Br J Nutr. 2021 Nov 28;126(10):1451-1458.
  12. Elste V, Troesch B, Eggersdorfer M, Weber P. Emerging Evidence on Neutrophil Motility Supporting Its Usefulness to Define Vitamin C Intake Requirements. Nutrients. 2017 May 16;9(5):503.
  13. Rabinovich D, Smadi Y. Zinc. [Updated 2021 May 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from:
  14. Prasad AS. Zinc is an Antioxidant and Anti-Inflammatory Agent: Its Role in Human Health. Front Nutr. 2014;1:14. Published 2014 Sep 1. doi:10.3389/fnut.2014.00014
  15. Li J, Cao D, Huang Y, Chen B, Chen Z, Wang R, Dong Q, Wei Q, Liu L. Zinc Intakes and Health Outcomes: An Umbrella Review. Front Nutr. 2022
    Feb 8;9:798078.
  16. Maxfield L, Shukla S, Crane JS. Zinc Deficiency. [Updated 2021 Nov 28]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan- Available from:
  17. Rerksuppaphol S, Rerksuppaphol L. A randomized controlled trial of zinc supplementation in the treatment of acute respiratory tract infection
    in Thai children. Pediatr Rep. 2019 May 23;11(2):7954.
  18. Barffour MA, Hinnouho GM, Wessells KR, Kounnavong S, Ratsavong K, Sitthideth D, Bounheuang B, Sengnam K, Chanhthavong B, Arnold CD, Brown KH, Larson CP, Hess SY. Effects of therapeutic zinc supplementation for diarrhea and two preventive zinc supplementation regimens
    on the incidence and duration of diarrhea and acute respiratory tract infections in rural Laotian children: A randomized controlled trial. J Glob
    Health. 2020 Jun;10(1):010424.
  19. Perera M, El Khoury J, Chinni V, Bolton D, Qu L, Johnson P, Trubiano J, McDonald CF, Jones D, Bellomo R, Patel O, Ischia J. Randomised controlled trial for high-dose intravenous zinc as adjunctive therapy in SARS-CoV-2 (COVID-19) positive critically ill patients: trial protocol. BMJ Open. 2020 Dec 2;10(12):e040580
  20. Bao B, Prasad AS, Beck FW, Fitzgerald JT, Snell D, Bao GW, Singh T, Cardozo LJ. Zinc decreases C-reactive protein, lipid peroxidation, and inflammatory cytokines in elderly subjects: a potential implication of zinc as an atheroprotective