What happens if you take too many vitamins
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The Impact of Excessive Vitamin Intake on Health
Adverse Effects of Vitamin Overdose
Taking too many vitamins, particularly through supplements, can lead to significant health issues. While it is rare to overdose on vitamins from food, vitamin poisoning from supplements is a documented concern. High doses of vitamins can cause side effects such as nausea, diarrhea, and vomiting, with severity increasing with dosage1. Recovery from these side effects typically involves reducing the vitamin intake1.
Long-Term Health Consequences of High-Dose Vitamin Supplements
The long-term health effects of consuming high doses of vitamins are not fully understood. However, some vitamins, especially fat-soluble ones like vitamins A, D, and E, and even some water-soluble vitamins like folic acid, can cause adverse events when taken in large amounts. High-dose supplements of these vitamins are not always effective in disease prevention and can be harmful2.
Vitamin Interactions and Toxicity
Vitamins interact with each other and with other nutrients, which can complicate their effects on the body. For instance, vitamin C is involved in the metabolism of folic acid, and vitamin E aids in the absorption and storage of vitamin A. When taken in excess, vitamins can act more like drugs, leading to clinical toxicities and abnormal utilization of other vitamins3.
Specific Vitamin Toxicities
Vitamin A
Excessive intake of preformed vitamin A can lead to both acute and chronic toxic effects. Acute hypervitaminosis A can occur with a single large dose, while chronic toxicity can develop from prolonged high intake. Symptoms of vitamin A toxicity include headaches, dizziness, and even more severe outcomes like liver damage and increased intracranial pressure4 6.
Vitamin B12
Although rare, high doses of vitamin B12 can also cause toxicity. A case study reported that a young woman treated with multiple high doses of cyanocobalamin for pernicious anemia developed symptoms such as acne, palpitations, anxiety, and insomnia. These symptoms resolved after discontinuing the supplement7.
Conclusion
While vitamins are essential for health, excessive intake through supplements can lead to significant adverse effects. It is crucial to adhere to recommended dietary allowances and consult healthcare providers before starting high-dose vitamin supplements. Understanding the potential risks associated with vitamin overdose can help prevent harmful health outcomes.
Sources and full results
Most relevant research papers on this topic
A review on adverse effects of overdose vitamins on human health
Overdosing on vitamins can cause side-effects like nausea, diarrhea, and vomiting, with recovery often achieved by reducing the dosage.
Literature ReviewVitamins, Are They Safe?
High-dose supplements of vitamins A, E, D, C, and folic acid may not always be effective for disease prevention and may even be harmful to the health.
Systematic ReviewVitamin supplementation and megadoses.
Vitamin supplementation can enhance a healthy diet, but excessive use may cause health risks.
The acute and chronic toxic effects of vitamin A.
Excessive vitamin A supplementation can cause adverse effects, particularly subtoxicity, and diet diversification and biofortification are safer and more sustainable approaches to combat vitamin A deficiency.
Literature ReviewVitamins for chronic disease prevention in adults: scientific review.
Inadequate intake of several vitamins is linked to chronic diseases, such as coronary heart disease, cancer, and osteoporosis, and may be linked to excess vitamin intake through supplementation.
Systematic Review
Highly CitedSafety of vitamin A.
Vitamin A toxicity is rare and associated with overconsumption of supplements, but deficiency can cause xerophthalmia and permanent blindness, and increased mortality rates in children.
Highly CitedToxicity induced by multiple high doses of vitamin B12 during pernicious anemia treatment: a case report
Multiple high doses of vitamin B12 during pernicious anemia treatment can cause unexpected and unusual side effects, such as acne, palpitations, anxiety, and insomnia.
Case ReportEffect of vitamin A on maternal, fetal, and neonatal outcomes: An overview of deficiency, excessive intake, and intake recommendations.
Maintaining a balanced vitamin A status during pregnancy is crucial for promoting better outcomes for fetuses and newborns, with effective monitoring and intervention strategies needed to address deficiency and excess.
Literature ReviewEffect of two different sublingual dosages of vitamin B12 on cobalamin nutritional status in vegans and vegetarians with a marginal deficiency: A randomized controlled trial.
Sublingual dosages of 350 g/week (350 g/day) of vitamin B12 are more effective than 2000 g/week (one large oral dose) in improving vitamin B12 nutritional status in vegans and vegetarians with a marginal deficiency.
RCT
Very Rigorous JournalExcessive Vitamin A Supplementation Increased the Incidence of Acute Respiratory Tract Infections: A Systematic Review and Meta-Analysis
Excessive vitamin A supplementation may increase the incidence of acute respiratory tract infections in children with normal nutritional status.
Meta-AnalysisVery Rigorous Journal