Niacin, or vitamin B3, is necessary for the proper function of over 50 different enzymes. It is utilized by the body to unlock the energy in the calories you eat. In addition, niacin helps nerves and the digestive system function and is used to form sex hormones and other vital chemicals. While high doses of niacin have been used to treat certain conditions, a dose of 250 milligrams may present serious risks.
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Sources and Daily Recommendations
Niacin is present in many dietary sources, including eggs, fish, lean meats, nuts, legumes, dairy and enriched breads and breakfast cereals. MedlinePlus notes that the RDA -- Recommended Daily Allowance -- for niacin is 16 milligrams per day for males 14 and older and 14 milligrams per day for females ages 14 and older. A dosage of 250 milligrams, therefore, represents more than 15 times the RDA for this nutrient. Because niacin is a water-soluble vitamin, it is not stored in the body. Although the body can excrete any unused niacin through urine, high doses can still be dangerous.
As the dosage of niacin increases, the side effects can become more serious. Doses around 50 milligrams can present a non-serious side effect, known as a "niacin flush." This side effect is characterized by a feeling of warmth and itching or tingling in different areas of the body, including the arms, face and neck. According to MedlinePlus, this phenomenon can become less common if you begin taking niacin on a regular basis. To help prevent niacin flushing, you should avoid drinking hot beverages or alcohol at the same time you take niacin.
High Dose Side Effects
Niacin is often used in high doses, typically around 500 milligrams or higher, for treating high cholesterol. While high-dose niacin products are available in prescription form, they can also be purchased in over-the-counter form. According to NYU Langone Medical Center, doses between 1 and 4 grams -- 250 times the RDA -- have been used as therapy for specific diseases. However, MedlinePlus notes that high doses of niacin can cause liver damage, peptic ulcers, skin rashes and increased blood sugar. Therefore, high-dose niacin should only be used under the supervision of a medical professional.
More Side Effects and Alternatives
While the side effects of 250 milligrams of niacin may vary from person to person, it is unnecessary to consume doses this high unless instructed by a medical professional. In addition to more obvious side effects, the University of Maryland Medical Center notes that consuming any one of the B vitamins for a prolonged period can result in imbalances in other B vitamins. Therefore, your best bet may be to take a B-complex vitamin that includes safe levels of each of the B vitamins. Those that should avoid supplemental niacin completely include individuals with kidney disease, liver disease or stomach ulcers. People with diabetes and gallbladder disorder should be closely monitored by their physician when taking niacin.