Vitamin A (Retinol): Essential Nutrient for Health

Key Takeaways:

Natural Vitamin A, also known as Retinol, is crucial for vision, immune function, and skin health.
Retinol is essential for healthy vision, particularly in low-light conditions.
Deficiency in Vitamin A can lead to vision problems, weakened immunity, and skin issues.
Foods like liver, egg yolks, and dairy products are the richest sources of Retinol.
Beta-carotene, found in plant foods, must be converted to Retinol, but this process is inefficient.

What is Vitamin A (Retinol)?

Vitamin A, specifically Retinol, is a fat-soluble vitamin essential for several bodily functions. Retinol, the active form of Vitamin A, plays a key role in maintaining healthy vision, supporting immune function, and promoting healthy skin.

Unlike its plant-based precursor, beta-carotene, Retinol is ready to be used by the body without needing conversion.

Benefits of Vitamin A (Retinol)

Vision Health

Retinol is vital for vision, especially in low-light conditions. It forms a component of rhodopsin, a protein in your eyes that absorbs light.

Adequate levels of Vitamin A prevent night blindness and support overall eye health.

Healthy Blood

Retinol, is very important for hemoglobin production and overall blood health. Retinol plays a significant role in restoring hemoglobin levels and curing anemia, while iron alone cannot sustain healthy blood without it.

The body primarily relies on the reticuloendothelial system to recycle iron rather than dietary intake, making Retinol essential for efficient iron utilization and maintaining healthy red blood cell levels.

Immune Support

Vitamin A strengthens the immune system by maintaining the integrity of mucous barriers in your eyes, lungs, gut, and genitals, acting as a line of defense against infections.

It also supports the production and function of white blood cells, crucial in fighting off pathogens.

Skin Health

Retinol is known for its skin-enhancing properties. It supports cell production and growth, making it a common ingredient in skincare products.

Retinol helps reduce acne, smooth wrinkles, and improve skin texture by stimulating collagen production.

Sources of Vitamin A (Retinol)

Animal-Based Sources

Retinol is most abundantly found in animal-based foods. Liver, particularly from beef, lamb, or cod, is an exceptional source.

Other sources include egg yolks, whole milk, cheese, and butter. These foods provide Retinol in a form that your body can immediately utilize.

Plant-Based Sources

While plant-based foods do not contain Retinol, they do provide beta-carotene, a precursor that some people can convert to Vitamin A.

However, this conversion is often inefficient. Carrots, sweet potatoes, spinach, and kale are rich in beta-carotene but require large amounts to meet the body’s needs for Vitamin A.

Deficiency and Health Risks

Vitamin A (Retinol): Essential Nutrient for Health

A deficiency in Vitamin A can lead to serious health issues. The most common symptom is night blindness, where individuals struggle to see in low light.

Other symptoms include a higher susceptibility to infections, dry skin, and issues with fertility.

In severe cases, prolonged deficiency can lead to complete blindness and increase the risk of maternal mortality during pregnancy.

Recommended Daily Intake

The recommended daily intake of Vitamin A varies by age, sex, and life stage. For adult men, the RDA is around 900 micrograms (mcg), while for women, it is 700 mcg.

Pregnant and breastfeeding women require higher amounts to support fetal development and lactation.

Beta-carotene vs Retinol

While beta-carotene from plant sources is beneficial, it’s not as effective as Retinol from animal sources.

The body’s ability to convert beta-carotene to Retinol is limited, making animal sources a more reliable way to meet Vitamin A needs.

Some individuals cannot even convert beta-carotene to Retinol.

Those following a strict vegetarian or vegan diet may need to monitor their Vitamin A intake closely and consider supplements.

Conclusion

Vitamin A (Retinol) is indispensable for maintaining good vision, a strong immune system, and healthy skin. The best sources of this nutrient are animal-based foods, which provide Retinol in a form readily used by the body. Ensuring adequate intake of this vitamin is crucial to avoid deficiency and its associated health risks.

FAQs

Q: Can I get enough Vitamin A from a plant-based diet?
A: It’s challenging to get adequate Retinol from a plant-based diet because the conversion of beta-carotene to Retinol is inefficient. Monitoring intake and considering supplements may be necessary.

Q: What are the signs of Vitamin A deficiency?
A: Common signs include night blindness, dry skin, frequent infections, and in severe cases, complete blindness.

Q: Is too much Vitamin A harmful?
A: Yes, excessive intake of Vitamin A, especially from supplements, can lead to toxicity. Symptoms include dizziness, nausea, and even liver damage.

Q: How does Vitamin A benefit the skin?
A: Vitamin A supports skin health by promoting cell production, reducing acne, and smoothing wrinkles. It is often used in anti-aging skincare products.

Research

Alberts B et al. Molecular Biology of the Cell. 4th edition. New York: Garland Science; 2002.

Balmer JE, Blomhoff R. Gene expression regulation by retinoic acid. J Lipid Res. 2002 Nov;43(11):1773-808. doi: 10.1194/jlr.r100015-jlr200. PMID: 12401878.

Biesalski HK, Frank J, Beck SC, Heinrich F, Illek B, Reifen R, Gollnick H, Seeliger MW, Wissinger B, Zrenner E. Biochemical but not clinical vitamin A deficiency results from mutations in the gene for retinol binding protein. The American Journal of Clinical Nutrition. 1999;69(5):931-936.

Burrows, M.T., 1931. Clinical and Experimental Observations Relative to the Etiology of Cancer. Radiology, [online] 17(4), pp.775–788.
https://doi.org/10.1148/17.4.775.

BURROWS MT, JORSTAD LH. CAUSE OF GROWTH OF SARCOIDS OR OIL TUMORS. JAMA. 1927;88(19):1460–1462. doi:10.1001/jama.1927.02680450004002

BURROWS, M.T., 1926. CANCER, VITAMIN IMBALANCE, AND ROENTGEN-RAY ACTIVITY. JAMA: The Journal of the American Medical Association, [online] 87(2), p.86. https://doi.org/10.1001/jama.1926.02680020014004.

Cantorna MT, Waddell A. The vitamin D receptor turns off chronically activated T cells. Annals of the New York Academy of Sciences. 2014;1317(1):70–75.

Caire-Juvera G, Ritenbaugh C, Wactawski-Wende J, Snetselaar LG, Chen Z. Vitamin A and retinol intakes and the risk of fractures among participants of the Women’s Health Initiative Observational Study. The American Journal of Clinical Nutrition. 2009;89(1):323-330.

Chai W, Cooney RV, Franke AA. Plasma levels of retinol, carotenoids, and tocopherols in cancer survivors and their association with circulating 25-hydroxyvitamin D. Journal of Clinical Medicine. 2021;10(3):516.

Chaves GV, Peres WAF, Gonçalves JC, Ramalho A. Vitamin A and retinol-binding protein deficiency among chronic liver disease patients. Nutrition. 2015;31(5):664-668.

Chiplonkar SA, Agte VV, Mengale SS, Tarwadi KV. Are lifestyle factors good predictors of retinol and vitamin C deficiency in apparently healthy adults?. European Journal of Clinical Nutrition. 2002;56(2):96-104.

Cureus. Etiology, Epidemiology, Pathophysiology, Signs and Symptoms, Evaluation, and Treatment of Vitamin A (Retinol) Deficiency. 2023;15(11).

Dawson-Hughes B, Staten MA, Knowler WC, Nelson J, Vickery EM, LeBlanc ES, Neff LM, Park J, Pittas AG. Intratrial exposure to vitamin D and new-onset diabetes among adults with prediabetes: A secondary analysis from the vitamin D and type 2 diabetes (D2d) study. Diabetes Care. 2015;38(8):1420–1428.

Doldo E, Costanza G, Agostinelli S, Tarquini C, Ferlosio A, Arcuri G, Passeri D, Scioli MG, Orlandi A. Vitamin A, cancer treatment and prevention: the new role of cellular retinol binding proteins. BioMed Research International. 2015;2015(1):624627.

De Pee S, Dary O. Biochemical indicators of vitamin A deficiency: serum retinol and serum retinol binding protein. The Journal of Nutrition. 2002;132(9):2895S-2901S.

Dushnicky LG, Khurana S, Ng WP, Wang YT. Vitamin D signaling alters nuclear receptor induced hepatic drug metabolism and liver injury in mice. Scientific Reports. 2021;11(1):1–13.

Fakhrzadeh H, Larijani B, Sanjari M, Baradar-Jalili R, Amini MR, Bandarian F, Adibi H, Hoseini M. Effect of vitamin D supplementation on glucose control and insulin resistance in patients with diabetes mellitus type 2. International Journal of Vitamin and Nutrition Research. 2011;81(4):205–211.

Folli C, Viglione S, Busconi M, Berni R. Biochemical basis for retinol deficiency induced by the I41N and G75D mutations in human plasma retinol-binding protein. Biochemical and Biophysical Research Communications. 2005;336(4):1017-1022.

Ganji V, Kim ES. Serum vitamin A status is associated with circulating levels of 25-hydroxyvitamin D. Nutrients. 2014;6(3):1167–1179.

Hedrén E, Diaz V, Svanberg U. Estimation of carotenoid accessibility from carrots determined by an in vitro digestion method. Eur J Clin Nutr. 2002 May;56(5):425-30. doi: 10.1038/sj.ejcn.1601329. PMID: 12001013.

Khan NC, West CE, de Pee S, Bosch D, Phuong HD, Hulshof PJ, Khoi HH, Verhoef H, Hautvast JG. The contribution of plant foods to the vitamin A supply of lactating women in Vietnam: a randomized controlled trial. Am J Clin Nutr. 2007 Apr;85(4):1112-20. doi: 10.1093/ajcn/85.4.1112. PMID: 17413113.

Leung, W.C., Hessel, S., Méplan, C., Flint, J., Oberhauser, V., Tourniaire, F., Hesketh, J.E., von Lintig, J. and Lietz, G. (2009), Two common single nucleotide polymorphisms in the gene encoding β-carotene 15,15′-monoxygenase alter β-carotene metabolism in female volunteers. The FASEB Journal, 23: 1041-1053. https://doi.org/10.1096/fj.08-121962

Michaëlsson K, Lithell H, Vessby B, Melhus H. Serum retinol levels and the risk of fracture. New England Journal of Medicine. 2003;348(4):287-294.

Newman NJ, Capone A, Leeper HF, O'Day DG, Mandell B, Lambert SR, Thoft RA. Clinical and subclinical ophthalmic findings with retinol deficiency. Ophthalmology. 1994;101(6):1077-1083.

Olsen T, Blomhoff R. Retinol, retinoic acid, and retinol-binding protein 4 are differentially associated with cardiovascular disease, type 2 diabetes, and obesity: an overview of human studies. Advances in Nutrition. 2020;11(3):644-666.

Palmer AC, West KP, Dalmiya N, Schultink W. The use and interpretation of serum retinol distributions in evaluating the public health impact of vitamin A programmes. Public Health Nutrition. 2012;15(7):1201-1215.

Patil S, Zamwar UM, Mudey A. Etiology, Epidemiology, Pathophysiology, Signs and Symptoms, Evaluation, and Treatment of Vitamin A (Retinol) Deficiency. Cureus. 2023;15(11).

Reboul E, Richelle M, Perrot E, Desmoulins-Malezet C, Pirisi V, Borel P. Bioaccessibility of carotenoids and vitamin E from their main dietary sources. J Agric Food Chem. 2006 Nov 15;54(23):8749-55. doi: 10.1021/jf061818s. PMID: 17090117.

Reay WR, Kiltschewskij DJ, Di Biase MA, Gerring ZF, Kundu K, Surendran P, Greco LA, Clarke ED, Collins CE, Mondul AM, Albanes D. Genetic influences on circulating retinol and its relationship to human health. Nature Communications. 2024;15(1):1490.

Sauberlich HE, Hodges RE, Wallace DL, Kolder H, Canham JE, Hood J, Raica Jr N, Lowry LK. Vitamin A metabolism and requirements in the human studied with the use of labeled retinol. Vitamins & Hormones. 1975;32:251-275.

Saraiva BC, Soares MC, Santos LCD, Pereira SC, Horta PM. Iron deficiency and anemia are associated with low retinol levels in children aged 1 to 5 years. Jornal de Pediatria. 2014;90(6):593-599.
https://doi.org/10.1016/j.jped.2014.03.003

Seeliger MW, Biesalski HK, Wissinger B, Gollnick H, Gielen S, Frank J, Beck S, Zrenner E. Phenotype in retinol deficiency due to a hereditary defect in retinol binding protein synthesis. Investigative Ophthalmology & Visual Science. 1999;40(1):3-11.

Steinhoff JS, Lass A, Schupp M. Retinoid homeostasis and beyond: how retinol binding protein 4 contributes to health and disease. Nutrients. 2022;14(6):1236.

Stephensen CB. Vitamin A, infection, and immune function. Annu Rev Nutr. 2001;21:167-92. doi: 10.1146/annurev.nutr.21.1.167. PMID: 11375434.

Talsma, E. F., Verhoef, H., Brouwer, I. D., Hulshof, P. J., & Melse-Boonstra, A. (2015). Proxy markers of serum retinol concentration, used alone and in combination, to assess population vitamin A status in Kenyan children: A cross-sectional study. BMC Medicine, 13.
https://doi.org/10.1186/s12916-014-0256-5

Tang G. Bioconversion of dietary provitamin A carotenoids to vitamin A in humans. American Journal of Clinical Nutrition. 2010;91(5):1468S-1473S.

Thurnham DI, McCabe GP, Northrop-Clewes CA, Nestel P. Effects of subclinical infection on plasma retinol concentrations and assessment of prevalence of vitamin A deficiency: meta-analysis. The Lancet. 2003;362(9401):2052-2058.

World Health Organization. Serum retinol concentrations for determining the prevalence of vitamin A deficiency in populations. 2011. No. WHO/NMH/NHD/MNM/11.3.

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