Types of Niacin
There are several different types of niacin. While the term "niacin" generally refers to nicotinic acid (which has been shown to improve cholesterol levels), it may also be used to describe other related compounds, such as nicotinamide and inositol nicotinate (which may have no activity to improve cholesterol). These various types of niacin are not interchangeable and may have different medicinal activities.
Niacin (brand names include Niacor®, Niaspan®, Slo-Niacin®, and several others) is a vitamin most often used to improve cholesterol levels. It is very effective for increasing HDL cholesterol ("good cholesterol") while modestly lowering LDL cholesterol ("bad cholesterol") and triglycerides. However, not all types of niacin are equal, and the various different niacin products may vary widely in their safety and effectiveness.
The term "niacin" can have several different meanings. In the strictest sense, niacin refers to just one compound -- nicotinic acid. However, it can also be used generally to describe other related compounds, including nicotinamide (niacinamide) and inositol nicotinate (inositol hexaniacinate). These niacin types are not interchangeable and may have different medicinal activities.
Nicotinic acid has been demonstrated to improve cholesterol levels; niacinamide has no (or at best, very little) activity to improve cholesterol. People often mistakenly think that taking niacinamide is a good, "no-flush" alternative to nicotinic acid, since nicotinic acid is transformed in the body into niacinamide anyway. However, the body transforms only a small amount of nicotinic acid (such as is normally obtained in the diet or through low-dose dietary supplementation) into niacinamide. At high doses (such as those used to treat cholesterol), much of the nicotinic acid is not changed into niacinamide. This explains why the two closely related compounds have drastically different effects on cholesterol. Niacinamide and nicotinic acid can be considered to be equivalent only for the purposes of nutritional supplementation (at low doses, not intended to treat cholesterol).
Inositol nicotinate is a compound that consists of six molecules of nicotinic acid attached to a molecule of inositol. The idea behind this compound is that the body slowly breaks it down into niacin (and inositol) slowly, helping to reduce flushing. Inositol nicotinate products are usually sold as "flush-free" or "no-flush" niacin. While it is true that these products theoretically create little or no flushing, it is not clear if they have the same properties as nicotinic acid for improving cholesterol. Critics claim that these products do not increase the level of niacin in the blood enough to have an effect on cholesterol.
For the remainder of this article, the term "niacin" will mean nicotinic acid (not the other forms), unless otherwise stated.