Health risks of unnecessary vitamin and multivitamin supplementation

Medical experts warn against the indiscriminate use of vitamin supplements, noting that taking vitamins without a diagnosed deficiency can lead to health complications rather than benefits.

Regarding Vitamin B12, excessive intake—specifically doses exceeding 1 mg per day—may trigger skin conditions like acne or rosacea, increase the risk of heart attack, and cause liver damage. In some diabetic patients, it may worsen renal disease. Even at lower doses, side effects can include nausea, diarrhea, headaches, and vomiting. The World Health Organization recommends a daily intake of 2.4 mcg for adults, ideally through animal-based foods.

A 2024 study published in Jama Network Open, involving over 390,000 adults tracked for 20 years, found that daily multivitamin use was not associated with lower mortality. In fact, the study suggested a 4% higher risk of death compared to non-users. Risks are particularly high with fat-soluble vitamins (A, D, E, and K), which can accumulate in the body and cause toxicity. For example, excessive Vitamin D can lead to high blood calcium and kidney stones, while excessive Vitamin E may increase hemorrhage risks.