Niacin is actually a blanket term for three different compounds that have similar activity in the body: nicotinic acid, nicotinamide (aka niacinamide), and nicotinamide riboside (NR). You’ll find that “vitamin B3” and “niacin” are often used interchangeably to refer to these compounds.
Of these, nicotinic acid and nicotinamide are the main forms of vitamin B3 or niacin—they’re both widely available from the same food sources and sold as dietary supplements. NR, on the other hand, is quite scarce in food and only recently started being sold as a supplement.
All three forms of vitamin B3 are converted to an important coenzyme called NAD+ in the body. NAD+ is found in all living cells, and it plays a vital role in energy metabolism and maintaining proper cell functioning—particularly the functioning of our mitochondria, the power plants in our cells that turn our food and oxygen into energy. It also plays in important role in protecting cells all over the body from age-related damage and decline in function.
While all three forms of vitamin B3 share common traits, each has a slightly different effect on the body and serves a different role when taken as a supplement:
Nicotinic acid: This form of vitamin B3 is readily available from food. As a supplement, it’s frequently used to to treat high cholesterol and heart disease; and it often just goes by the name niacin. It also promotes circulation, and supplemental doses can cause what’s called “niacin flush,” skin that becomes red and itchy. Our bodies can convert nicotinic acid into nicotinamide.
Nicotinamide (aka niacinamide): This form of vitamin B3 is also readily available from food. It’s the form that typically appears in multivitamins and fortified foods, like cereal, since it does not cause flushing. As a supplement, it doesn’t treat cardiovascular conditions, but it does hold promise for treating skin conditions, arthritis, and type 1 diabetes. Increasingly, it’s also being added to skincare products (where it’s often listed as niacinamide) for its anti-inflammatory and photoprotective perks.
Nicotinamide riboside (NR): Found predominantly in NR supplements (and in trace amounts in milk), NR is the most recently discovered form of vitamin B3. It’s not commonly used, but it holds great promise in boosting cognitive function and slowing the aging process. Compared to the other two forms of vitamin B3, it is the most efficient at increasing levels of NAD+ in the body and brain, which is really appealing:
“Appropriate levels of NAD+ are critical to support the body’s response to stress,” Ilene Ruhoy, M.D., Ph.D., integrative neurologist, told mbg. “That’s because NAD+ is used by enzymes to modulate cellular activity in response to extrinsic and intrinsic assaults, including those triggered by environmental toxins, pro-inflammatory foods, microbes such as viruses and bacterium, trauma, disease, and even chronic use of medication.”[Pro tip: Many articles that reference “niacin” without specifying which form usually mean nicotinic acid—even though niacin is technically a blanket term. It’s confusing, so we’ll call everything by its true name in this article.]