Niacin -- vitamin B-3 -- poses serious health risks if taken in large quantities. Persons with diabetes face particular risks because niacin can drastically elevate blood sugar levels. Although you can purchase niacin without a prescription, it could prove dangerous for anyone with diabetes to self-medicate with the vitamin. Talk to your doctor before taking niacin and strictly adhere to her guidelines about dose.
Niacin and Diabetes
If you have diabetes, you are twice as likely as someone without the disease to suffer a heart attack or stroke, according to the American Diabetes Association. Niacin can help to alleviate some conditions -- high cholesterol and hardening of the arteries, for instance -- that increase your susceptibility to cardiovascular disease. But, taking large doses of niacin -- more than 100 mg a day -- can cause hyperglycemia -- very high blood sugar -- in persons with type 2 diabetes.
Doses
Doctors may prescribe niacin in doses of 500 mg to 2,000 mg a day. If you take niacin, check your blood sugar levels frequently and report problems to your physician. If you take insulin, you may need to change the timing of your doses to accommodate blood sugar elevations caused by niacin. For persons with type 1 diabetes, niacinamide -- a different form of niacin -- may help to lengthen the time between diagnosis and your need to take insulin.
Risks
If you take niacin in doses of more than 100 mg per day, you may experience skin flushes -- reddening and burning of your face and chest. Remedies to prevent or alleviate skin flushes include taking aspirin 30 minutes before taking niacin, gradually increasing your dose and taking timed-release formulas of niacin. All forms of niacin may cause liver damage, but taking timed-release formulas increases your risk. Niacin in doses of more than 100 mg per day may also cause stomach ulcers. Persons in a National Institutes of Health study who took 2,000 mg a day of timed-release niacin suffered twice as many strokes as persons in the study who did not take niacin. The NIH ended the study 18 months early, in May 2011.
Considerations
You can purchase niacin in doses of up to 500 mg without a prescription. But don't take niacin without your doctor's consent. A number of foods in your diet -- chicken, eggs, tuna and beets, for example -- provide your body with niacin. The small amount of niacin in your diet -- about 14 mg to 16 mg a day -- will not elevate your blood sugar levels or cause other side effects. Dietary niacin helps you metabolize fats and proteins, convert carbohydrates to energy and maintain the health of your skin, hair and eyes.
