Specifically, vitamin B3 plays an important role in digestion, mental health, heart health, the nervous system, maintaining healthy skin, making a variety of hormones, and acting as a precursor to the coenzyme nicotinamide adenine dinucleotide (NAD+).
But vitamin B3 is also a little more complex than your average vitamin. It's naturally found in several different forms—including nicotinic acid, nicotinamide, and nicotinamide riboside—each of which has a slightly different effect on the body.
Let's take a deeper dive into everything you should know about niacin.
Different forms of vitamin B3 (niacin)
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 food and oxygen into energy. It also plays an important role in protecting cells all over the body from age-related damage and decline in function.
Sources & function of each form of niacin
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 manage 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.
[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.]
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 skin3 conditions, arthritis4, and early-onset type 1 diabetes. Increasingly, it's also being added to skin care 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 efficient5 at supporting neuronal NAD+ synthesis 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, trauma, and even chronic use of medication.*"
Why do you need niacin?
Niacin is an essential nutrient, meaning you have to get it from the diet (or supplements in the amounts needed to see the health benefits. And since it's water soluble, your body doesn't store it, and you need regular, daily intake of it.
- Nervous system function
- Skin health
How to tell if you have vitamin B3 deficiency
Vitamin B3 deficiency is extremely rare in developed countries. There are two forms of deficiency: primary and secondary.
- Primary deficiency is caused by poor nutritional intake, when someone doesn’t consume enough vitamin B3 or tryptophan in their diet.
- Secondary deficiency occurs with another health condition—like alcoholism, chronic diarrhea, Crohn's disease—that interferes with your ability to absorb vitamins.
*Alcoholism is the main cause of vitamin B3 deficiency in the United States. Blood and urine tests can diagnose a deficiency.
Common symptoms of mild vitamin B3 deficiency, which can usually be addressed with diet changes and/or a multivitamin, often include indigestion, fatigue, canker sores and/or a bright red tongue, poor circulation, and depression.
Severe vitamin B3 deficiency is known as pellagra7. This disease affects the skin, digestive system, and nervous system and can be deadly if it's not treated. Symptoms, which can be treated with a prescription nicotinic acid or nicotinamide supplement from your doctor, often include delusions or mental confusion, scaly and cracked skin, a swollen mouth, diarrhea, vomiting, headaches, fatigue, and depression.
Niacin's health benefits
The various forms of vitamin B3 or niacin in the form of food, supplements, and even topical creams have been associated with everything from supporting heart and mood to clearer skin. Here are some of their most well-researched perks, along with some promising preliminary findings that warrant further study:
Supports heart health and lowers cholesterol
High doses of vitamin B3 in the form of nicotinic acid are an established treatment for lowering "bad" LDL cholesterol, raising "good" HDL cholesterol, and lowering triglycerides, a type of fat found in your blood that can lead to atherosclerosis—a condition characterized by narrowing of the arteries due to fatty plaque buildup. Specifically, studies8 show that nicotinic acid favorably affects all lipids (e.g. raising HDL cholesterol and lowering LDL cholesterol and triglycerides), making it a natural alternative for treating patients with mixed hyperlipidemia. Additionally, nicotinic acid plays a role in altering the composition of LDL cholesterol particles from small and dense to large and more buoyant8. Larger LDL particles are far less damaging, suggesting that nicotinic acid could play a role in reducing risk of atherosclerosis.
But even though some research is promising, cardiologists like Joel Kahn, M.D., warn that this vitamin is not always a foolproof fix. "Generally we only need about 20 to 35 mg a day of niacin, but doses of up to 3,000 mg a day or more are used to control cholesterol," Dr. Kahn told mbg—and these high doses can be associated with issues like ulcers, muscle damage, and gout.
So, before taking high doses of vitamin B3 to help control cholesterol, always talk with your doctor to make sure it's the right approach. Tweaking your diet and exercising could be all you need!
Protect against skin damage
In one animal study10, use of a topical cream containing nicotinamide decreased the risk of UV-induced skin cancers in mice. And in humans, a recent analysis11 of two prospective cohort studies following men and women for up to 26 years found that higher dietary intake of vitamin B3 (from food and oral supplements) may offer protection against certain types of skin cancer. This is good news since it suggests that you can consume enough vitamin B3 from food to reap this benefit. Sunscreens containing nicotinamide (where it's usually listed as niacinamide) are already on the market and may offer further protection.
Helps manage persistent acne
Expanding on its skin-healing properties, both topical and oral nicotinamide may help treat acne as well—likely due to its anti-inflammatory properties. In a recent review13, researchers found that six out of eight studies using topical nicotinamide led to a significant reduction in acne or at least performed as well as more mainstream acne creams. And, two of the studies using an oral form of this vitamin led to a significant reduction in acne. Some researchers believe this form of vitamin B3 may be an effective way to treat severe acne without antibiotics. (Just remember, getting your diet and stress in check is super important for clear skin!)
More studies are needed to confirm appropriate dosing of nicotinamide for acne. If you're interested in taking it orally to manage skin conditions, talk to a dermatologist first to make sure it's the best possible option—not everyone's fully on board yet. Some over-the-counter facial cleansers and creams containing nicotinamide containing lower doses than what has been used in studies may be a safe option to experiment with, just watch out for potential side effects such as skin irritation.
Soothes achy joints
Vitamin B3 has been shown to have anti-inflammatory effects14 in the body, which may translate to reduced joint pain and arthritis symptoms. In one small study15, patients with osteoarthritis who took a nicotinamide supplement were able to reduce the number of anti-inflammatory pain meds they used by 13 percent compared to the placebo group. They also experienced greater joint flexibility.
Enhances brain function
Vitamin B3 supports proper brain functioning, and a severe deficiency has been associated with dementia16, leading some researchers to believe that getting enough in your diet is crucial to the prevention of Alzheimer's disease. Deficiency has also been associated with symptoms of psychosis17, and supplemental nicotinic acid and nicotinamide has been used to treat schizophrenia18.
The form of vitamin B3 known as NR is of particular interest when it comes to brain health and Alzheimer's prevention, but research on this topic is still in it's infancy. In a recent study9, researchers found that the NR-treated mice had less DNA damage, higher neuroplasticity, increased production of new neurons, and lower levels of neuronal damage. In the hippocampus area of the brain (where damage and loss of volume is found in dementia), NR seemed to clear existing DNA damage or prevent it from spreading further. The mice also performed better on memory tests.
But studies on NR's long-term effects on human health are still few and far between. Much more research is needed to determine if it would have a similar effect.
Could promote good digestion and gut health
Vitamin B3 is critical for many digestive functions—the breakdown of carbs, fats, and alcohol—and keeping your GI tract happy. Low levels of vitamin B3 in the diet can cause an upset digestive system, and a severe deficiency can result in a disease called pellagra19, which causes diarrhea, vomiting, and other serious symptoms.
Preliminary research links vitamin B3 to digestive ailments such as irritable bowel syndrome, but further research is warranted. In the meantime, know that human studies looking at treatment with high supplemental doses o20f nicotinic acid has been associated with ulcers in the digestive tract. So for now, focus on eating quality food sources of vitamin B3, and don't self-treat with supplements unless you consult with a doctor.
What's the daily dose of vitamin B3 we need for optimal health?
We can typically get all the vitamin B3 we need through diet alone. Many of the same foods contain both nicotinic acid and nicotinamide. Our bodies can also convert the amino acid tryptophan to vitamin B3—60 mg tryptophan is equal to 1 mg niacin. Here are the recommended daily amounts (RDA)21 for adults:
- Men (19 years and older): 16 mg/day
- Women (19 years and older): 14 mg/day
- Pregnant women: 18 mg/day
- Breastfeeding women: 17 mg/day
13 major food sources of vitamin B3
It's possible to get more than enough vitamin B3 from either plants or animals. But keep in mind, all B vitamins are water-soluble, which means you need to consume them every day since our bodies don't store them. Here are some of the best vitamin B3 foods.
Nutritional yeast* (¼ cup): 46 mg
Turkey (3 oz): 10 mg
Chicken (3 oz): 9 mg
Tuna (3 oz, canned): 8½ mg
Salmon (3 oz): 8½ mg
Bran flakes (¾ cup): 5 mg
Beef (3 oz): 4½ mg
Peanuts (1 oz): 4 mg
Mushrooms (1 sliced cup): 2½ mg
Lentils (1 cooked cup): 2 mg
Coffee (1 brewed cup): 2 mg
Whole-wheat bread (1 slice): 1½ mg
Beets (1 sliced cup): 1 mg
*Add a drizzle of olive oil and a sprinkle of nutritional yeast to your next batch of popcorn for a cheesy flavor that's totally vegan!
Should you take a vitamin B3 supplement?
Most generally healthy people don't need to take a vitamin B3 supplement, since deficiency is rare and food sources are plentiful. Occasionally, though, doctors will prescribe a high dose of nicotinic acid or nicotinamide to treat a specific health condition, e.g., nicotinic acid for high cholesterol, especially if you can't tolerate statins. In these cases, following your doctor's dosing instructions carefully is crucial.
If you're interested in using a vitamin B3 supplement to manage a minor health condition on your own, it's still wise to consult a health care provider about the appropriate dose and form. Many nicotinic acid and nicotinamide supplements contain doses that are far higher than the RDA (typically around 500 mg per dose), which could be dangerous or cause side effects if taken unnecessarily or incorrectly.
If you want to supplement, integrative doctor Andrew Weil, M.D. recommends 50 milligrams of vitamin B3 in the form of nicotinamide (sometimes listed as niacinamide) as part of a B-complex vitamin.
Side effects of niacin supplements (as nicotinic acid and nicotinamide)
Minor side effects if these two common forms include,
- Stomach discomfort
They may also make seasonal allergies worse, as they trigger the release of histamine. With doses above 50 mg, nicotinic acid may also cause "niacin flush," or red flushed skin along with a burning or tingling sensation in the face or chest. Slow-release alternatives to nicotinic acid (under the name inositol hexaniacinate) may reduce flushing.
With very high doses of vitamin B3, like those used to treat specific health conditions, these supplements may cause liver damage, stomach ulcers, and nausea and vomiting, among other side effects. That's why doctors recommend periodic blood tests to check liver function with doses above 100 mg per day. High doses may also increase blood sugar, so people with diabetes should be cautious.
Vitamin B3 supplements could also interfere with a variety of medications, including common antibiotics and blood thinners, so always be sure to talk with your doctor about interactions before taking either of these forms of vitamin B3.
What about nicotinamide riboside (NR) supplements?
Unlike the more common forms of vitamin B3, nicotinic acid and nicotinamide, you can only get NR in meaningful quantities from supplements.* While more research is needed, preliminary research shows that these supplements support normal levels of the coenzyme NAD+, which promotes cellular metabolism and energy production.*
It's an exciting nutrient that could turn out to be a game-changer in healthy aging.* (For more info, read our complete guide to NR.)
Vitamin B3 (aka niacin) sure goes by a lot of names. It's found in a variety of foods (including nutritiona yeast, turkey, salmon, bran flakes, and peanuts) and in supplements as either nicotinic acid or nicotinamide. Most people don't need to seek out a standalone vitamin B3 supplement (as deficiency is rare), but it can be beneficial for folks when it's a part of a well-rounded B-complex.
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