Niacin, also known as vitamin B3, is a nutrient commonly used to manage high cholesterol. It is available in both prescription and over-the-counter forms and is considered safe when used appropriately. However, excessive doses of niacin can lead to rare but serious side effects, including a condition that affects vision.
In a study by researchers at the New York Eye and Ear Infirmary of Mount Sinai, a high dose of over-the-counter niacin was found to cause damage to a specific type of cell in the retina, leading to significant vision problems. Fortunately, this condition, called niacin-induced cystoid maculopathy, can be reversed if the vitamin is discontinued in time.
The case involved a 61-year-old man who arrived at the hospital with progressively worsening blurry vision in both eyes. He had been experiencing the problem for about a month.
At the time of his initial examination, his vision was severely impaired, with best-corrected visual acuity of 20/150 in the right eye and 20/100 in the left—almost meeting the criteria for legal blindness.
The patient’s medical history included high blood pressure and high cholesterol. He eventually disclosed that he had been self-prescribing niacin at doses far exceeding the recommended amount—between three and six grams daily—for several months.
He had started taking the supplement after a doctor informed him of his high cholesterol, believing it would lower his risk of heart disease. Unaware of the risks, he purchased the supplement over the counter and used it without medical supervision.
Doctors typically prescribe niacin in controlled doses of one to three grams per day, with a maximum of six grams for certain cases. However, such high doses should be monitored by healthcare professionals due to the risk of side effects, including toxicity to the retina.
Using advanced imaging technologies, the researchers diagnosed niacin-induced maculopathy. This rare condition occurs when high doses of niacin cause fluid buildup in the macula, the central part of the retina responsible for detailed and focused vision. The fluid buildup leads to swelling, impairing vision.
After diagnosing the problem, doctors advised the patient to stop taking niacin immediately. Within a week, his vision began to improve significantly. By the two-month follow-up, his retinal function had returned to normal, and his vision was fully restored to 20/20.
This case highlights the risks associated with using over-the-counter supplements without proper guidance. Although niacin is widely available and marketed as safe, excessive doses can cause serious harm, particularly to the eyes. People who rely on their vision for work or daily activities should be cautious, as the consequences of overdosing on niacin could be lasting.
The researchers emphasized the importance of consulting healthcare professionals before taking high doses of any supplement, even those available without a prescription. Over-the-counter availability does not guarantee safety when the product is misused or taken in excessive amounts.
This study serves as a reminder that nutritional supplements, while beneficial in the right doses, can pose risks if used improperly. Seeking medical advice before starting a supplement regimen is essential for avoiding unintended side effects. The findings were published by Dr. Richard Rosen and his team in the Journal of VitreoRetinal Diseases.
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