Excess and Deficiency of Vitamins: Impacts on Health
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Vitamins are essential nutrients for the proper functioning of the human body, contributing to energy production, regulation of the immune system, maintenance of bone health, protection against oxidative stress, among others.
Although vitamins are needed in small amounts, both deficiency and excess can have significant health consequences.
Vitamin deficiency continues to be a global problem, and these deficiencies are associated with health complications, on the other hand, the excess of vitamins, often driven by the popularization of supplementation without clinical monitoring, also poses significant risks. Understanding these two extremes is essential to ensure a nutritional balance.
Vitamin Deficiency: Avitaminose
Vitamin deficiency affects different populations at various ages, also having several consequences, as described below.
Vitamin A: Deficiencies are associated with visual changes, immunosuppression, and higher risk of infant morbidity and mortality in developing countries (1).
Food sources: liver, carrots, sweet potatoes, pumpkin, spinach.
Vitamin B: B12 deficiency is linked to megaloblastic anemia and neurological changes; a lack of B6 can cause neuropathies and seizures in severe cases (2,3).
B12 food sources: meat, fish, seafood, eggs, milk and dairy products.
B6 food sources: chicken, bananas, potatoes, chickpeas, nuts.
Vitamin C: Prolonged absence causes scurvy, characterized by gingival bleeding, weakness, and delayed healing (4).
Food sources: orange, kiwi, strawberry, red pepper, broccoli.
Vitamin D: Low levels are linked to rickets in children, osteomalacia in adults, and a higher risk of osteoporosis (5,6).
Food sources: salmon, sardines, egg yolks, liver; in addition to skin synthesis by sun exposure.
Vitamin K: Deficiency can compromise blood clotting, increasing the risk of hemorrhages, especially in newborns (7).
Food sources: kale, spinach, broccoli, parsley, vegetable oils.
Excess Vitamins: Hypervitaminosis
Contrary to common belief, excess vitamins, especially fat-soluble vitamins (A, D, E, and K), can be harmful.
Vitamin A: In excess, it can lead to hepatotoxicity, bone changes and is teratogenic in pregnant women (8).
Vitamin D: Intoxication causes hypercalcemia, which can progress to renal failure and tissue calcifications (9,10).
Vitamin E: Megadoses increase the risk of bleeding and may interfere with the action of anticoagulants (11).
Vitamin K: Although rare, excessive supplementation can affect clotting and interact with drugs such as warfarin (12).
B vitamins: B6 can cause irreversible sensory neuropathy; niacin (B3) can induce hepatotoxicity (13,14).
Recommendations
According to the European Food Safety Authority (EFSA), there are intake reference values and maximum tolerable levels defined for different populations. The greatest risk arises when intake exceeds these limits chronically or when there are specific clinical conditions that increase vulnerability (15).
Supplementation should always be evaluated individually, considering age, physiological state (pregnancy, lactation), usual diet and clinical factors. In populations at risk of proven deficiency, supplementation is essential (as in the case of vitamin D in infants or the elderly). However, indiscriminate supplementation can bring more risks than benefits (5,16).
Conclusion
Maintaining balance is essential when we talk about vitamins, since both deficiency and excess can bring important health risks. The safest way to ensure this balance is through a varied and balanced diet, supported by supplementation only when recommended by health professionals and always based on scientific evidence. In addition, moderate sun exposure contributes to adequate vitamin D levels.
As a rule, a balanced diet already covers most nutritional needs, with supplementation being a support tool in specific situations and not a substitute for healthy eating.
At Oh! My Snacks We are always attentive to the most current scientific research, always trying to ensure that our snacks can be part of a balanced diet. In this way, I leave you here some examples of snacks that you can include in your daily life and that give you several of the nutrients you need throughout the day:
- Dried Fruit with Apple and Mango Juice
- Nuts Australian Mix
- Fruit Balls Strawberry
- Fruit Bar Super Food Lemon Matcha
Bibliography:
1-World Health Organization. Global prevalence of vitamin A deficiency in populations at risk 1995–2005. WHO; 2009.
2-O'Leary F, Samman S. Vitamin B12 in health and disease. Nutrients. 2010; 2(3):299–316.
3-EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA). Scientific opinion on the tolerable upper intake levels for vitamin B6. EFSA J. 2023; 21(8):7970.
4-Maggini S, Wenzlaff S, Hornig D. Essential role of vitamin C and zinc in child immunity and health. J Int Med Res. 2010; 38(2):386–414.
5-Jolliffe DA, Greenberg L, Hooper RL, Griffiths CJ, Camargo CA, Kerley CP, et al. Vitamin D supplementation to prevent acute respiratory infections: systematic review and meta-analysis of aggregate data. Lancet Respir Med. 2021; 9(3):276–292.
6-Coussens AK, Martineau AR. Vitamin D deficiency and its role in tuberculosis. Thorax. 2014; 69(7):590–591.
7-Shearer MJ, Fu X, Booth SL. Vitamin K nutrition, metabolism, and requirements: current concepts and future research. Adv Nutr. 2012; 3(2):182–195.
8-Penniston KL, Tanumihardjo SA. The acute and chronic toxic effects of vitamin A. Am J Clin Nutr. 2006; 83(2):191–201.
9-Vieth R. Vitamin D toxicity, policy, and science. J Bone Miner Res. 2007; 22(S2):V64–V68.
10-Shahriar A, Rezaie S, Razzaghi MR. Vitamin D intoxication: clinical findings, diagnosis and treatment. Curr Clin Pharmacol. 2022; 17(2):139–145.
11-Miller ER, Pastor-Barriuso R, Dalal D, Riemersma RA, Appel LJ, Guallar E. Meta-analysis: high-dosage vitamin E supplementation may increase all-cause mortality. Ann Intern Med. 2005; 142(1):37–46.
12-Suttie JW. Vitamin K in health and disease. CRC Press; 2009.
13-Parry GJ, Bredesen DE. Sensory neuropathy with low-dose pyridoxine. Neurology. 1985; 35(10):1466–1468.
14-McKenney JM. Niacin for dyslipidemia: considerations in product selection. Am J Health Syst Pharm. 2003; 60(10):995–1005.
15-EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA). Dietary reference values for vitamins for all populations. EFSA J. 2024; 22(3):9052.
16-Zhou C, Xu Y, Wu J, Xu G, Fan M, Huang J. Comparative efficacies of vitamin D supplementation regimens in infants: a systematic review and network meta-analysis. Br J Nutr. 2021; 125(5):531–541.
Author
Sofia Silva 5784N