Does niacin, taken for high cholesterol, pose a danger to the liver? At all levels, or just higher doses? What, if any, tests should be performed to ensure safety?

Some people are sensitive to niacin (vitamin B-3). When that occurs, nausea, then vomiting, and finally increases in liver enzymes will occur if the person persists in taking it. The dose that causes it depends on your sensitivity, but it usually takes more than 250 milligrams three times a day. If you get nausea from the nutrient, it should be lowered or discontinued. That's why I don't use time-release forms.

The good news is that even if your liver enzymes went very high, they would return to normal when you stopped taking niacin without any permanent damage (not true of many drugs). That sensitivity is not the same as the niacin "flush," which is a side effect but not a toxic one. The tingle and redness is a normal vasodilating effect from niacin, but its alter ego, niacinamide, does not have the same side effect. Unfortunately, niacinamide, though it may help with some forms of arthritis, doesn't lower cholesterol. However, inositol hexanicotinate, which is more expensive, avoids the flush and does work to lower serum cholesterol levels. Adding a moderately high-fiber diet makes it even more effective.

For therapeutic doses you should have your doc monitor you. Liver enzymes are an easy blood test to perform and are part of the general panel that most doctors order in every physical exam anyway. It's not a bad idea to have a baseline level taken to know just where your starting point is.

Good health,
A.N. Spreen, M.D.