Vitamin A and D Roles in Health: Deficiency, Toxicity, and Immune Function of Micronutrients

The Role of Micronutrients in the Human Body

Micronutrients are a group of substances that includes vitamins and minerals. These nutrients are significant to a healthy lifestyle as they are substrates or catalysts in critical biochemical reactions (Gombart et al., 2020). However, the amount of consumption should be regulated to avoid excess, which is also dangerous. In particular, vitamins A and D can be discussed as illustrative of how low or high intake can affect the human body.

Essential Functions of Vitamin A

Vitamin A has several vital roles in an organism that explain toxicity and deficiency symptoms. It is utilized during organism development to catalyze cell growth and differentiation (Carazo et al., 2021). It is also essential for eyesight, allowing light sensitivity in the retina. Therefore, its deficiency is associated with impaired vision and unusual skin conditions due to the constant growth and multiplication of skin cells. On the contrary, the toxicity is commonly illustrated by nausea, headaches, weakness, blurred vision, and skin irritation, but more symptoms can occur according to the patient’s health conditions.

Impact on Health of Vitamin D

Vitamin D is also essential for a healthy organism as it takes part in calcium and phosphate metabolism (Dominguez et al., 2021). Its deficiency should be suggested in case of malabsorption syndromes as they can lead to rickets, osteomalacia, and immunosuppression. On the other hand, excess intake may lead to gastrointestinal symptoms such as anorexia, constipation, and vomiting. It can also cause bone pain, polyuria, renal failure, and urolithiasis.

The Protective Role of Micronutrients

Micronutrients are important for an effective immune system response to infections. For instance, vitamin A is necessary for immune cell growth and differentiation, and vitamin D regulates the gut barrier that does not let the infection enter the bloodstream (Gombart et al., 2020). Other possible functions include an inflammatory response (vitamins D, C, E, Zn, and Fe), cell-mediated and humoral immunity (vitamins B6, B12, folate, Mg, Se), and innate immune response (vitamins C, E, Cu, Mg). Therefore, these elements are vital for all parts of the immune system and should be consumed daily in sufficient doses.

References

Carazo, A., Macáková, K., Matoušová, K., Krčmová, L. K., Protti, M., & Mladěnka, P. (2021). Vitamin A update: Forms, sources, kinetics, detection, function, deficiency, therapeutic use and toxicity. Nutrients, 13(5), 1703. Web.

Dominguez, L. J., Farruggia, M., Veronese, N., & Barbagallo, M. (2021). Vitamin D sources, metabolism, and deficiency: Available compounds and guidelines for its treatment. Metabolites, 11(4), 255. Web.

Gombart, A. F., Pierre, A., & Maggini, S. (2020). A review of micronutrients and the immune system-working in Harmony to reduce the risk of infection. Nutrients, 12(1), 236. Web.

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StudyCorgi. (2025, November 7). Vitamin A and D Roles in Health: Deficiency, Toxicity, and Immune Function of Micronutrients. https://studycorgi.com/vitamin-a-and-d-roles-in-health-deficiency-toxicity-and-immune-function-of-micronutrients/

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StudyCorgi. (2025) 'Vitamin A and D Roles in Health: Deficiency, Toxicity, and Immune Function of Micronutrients'. 7 November.

1. StudyCorgi. "Vitamin A and D Roles in Health: Deficiency, Toxicity, and Immune Function of Micronutrients." November 7, 2025. https://studycorgi.com/vitamin-a-and-d-roles-in-health-deficiency-toxicity-and-immune-function-of-micronutrients/.


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StudyCorgi. "Vitamin A and D Roles in Health: Deficiency, Toxicity, and Immune Function of Micronutrients." November 7, 2025. https://studycorgi.com/vitamin-a-and-d-roles-in-health-deficiency-toxicity-and-immune-function-of-micronutrients/.

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StudyCorgi. 2025. "Vitamin A and D Roles in Health: Deficiency, Toxicity, and Immune Function of Micronutrients." November 7, 2025. https://studycorgi.com/vitamin-a-and-d-roles-in-health-deficiency-toxicity-and-immune-function-of-micronutrients/.

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