Vitamin B3 - Niacin
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Niacin does a little bit of everything. Like all the B vitamins, it is a key player when it comes to energy metabolism. It also guards against oxidative stress, helps recycle other important nutrients (like vitamin K and folate), helps keep blood lipids in balance, and can help lengthen telomeres (telomeres are little caps on the end of DNA that help protect them; telomere length is linked to longevity). Niacin is important for the health of the brain, the skin, and the gut. This is a vitamin you want to have. This is a vitamin you NEED to have.
Why is niacin so important? It is the precursor for two of the most important energy-producing molecules in the body: nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). NAD and NADP are coenzymes critical for oxidation reactions involved in energy production (as well as signaling pathways that affect gene expression, cell growth and death, and DNA repair). It is THE most fundamental B vitamin in energy metabolism.
What happens if you don’t have enough niacin? The classic condition of niacin deficiency is called pellagra, which is known for the 3 D’s: diarrhea, dermatitis, and dementia. The “diarrhea” component might include other GI symptoms, like nausea or anorexia (not wanting to eat). The dermatitis often shows up as a rash on parts of the skin exposed to the sun. It usually appears on both sides of the body, and while it starts as redness, it can become itchy and painful, and sometimes gets weepy--kind of like a sunburn. It looks a lot like a sunburn because it kind of is a sunburn. It only shows up on on sun-exposed parts of the body, and develops because the body doesn’t have enough energy supplies to repair DNA that gets damaged by the sun (in fact, all of the 3 D’s happen because your body doesn’t have enough energy supplies to repair cells that turn over quickly). The dementia component typically starts as depression, but can become much more severe and involve confusion, delirium, aggression, and hallucinations. And if left untreated, pellagra can lead to a 4th D: death. Niacin deficiency can be more subtle than pellagra, though, and might just have vague symptoms like fatigue, or trouble exercising, or reflux. It can also increase cancer risk because the body’s ability to repair DNA is impaired.
Niacin deficiency seems to be uncommon, with a large study in the US finding that only 1% of the population got less niacin than the estimated average requirement, or EAR (which is the amount estimated to meet the needs of 50% of people). That being said, suboptimal niacin deficiency is probably more common, especially in groups that are at higher risk (like people with a poor diet, people with guts that aren’t working optimally, those with cirrhosis, etc). For example, in a study based in China, the prevalence of niacin deficiency in 2018 was about 18% in females and almost 30% in males. Some medications (including drugs to treat cancer, autoimmunity, and Parkinson’s) can also increase the risk of niacin deficiency.
How much niacin do you need? It depends on your age and gender. For adults, the recommended daily allowance (RDA) for niacin is 16 mg of niacin equivalents (NE); for women, it’s 14 (it goes up during pregnancy and lactation and is less for younger folks). An NE is either 1 mg of niacin OR 60 mg of tryptophan (which the body can convert to niacin—but only if there’s enough iron, riboflavin, and B6 to do so). This amount isn’t hard to get with a good, varied diet. Many meats and fish have 5-10 mg per serving (a single 3 oz serving of beef liver gets you almost all the way to the RDA, with 14.9 mg); nuts, grains, and legumes have 2-5 mg. However, the niacin in these plant-based foods is often bound up in a way that makes it difficult for the body to access (in whole grains, this might be up to 90% of the niacin). Sprouting or fermenting these products can liberate these nutrients (which is why I’m such a fan of both—and why essentially every traditional culture was too). Another very good source of niacin is nutritional yeast – 1 tablespoon gives you more than a day’s supply.
How do you know if you’re getting enough niacin? You can track your intake, or you can tests your status with a micronutrient test (like the Nutreval). If you’re not getting enough, dietary change is the best approach. Niacin can be supplemented, and there are a variety of forms to choose from, including nicotinic acid, inositol hexanicotinate (a slow-release version), extended-release versions (such as Niaspan), niacinamide, nicotinamide, nicotinamide riboside (NR), and nicotinamide mononucleotide (NMN). NR and NMN have gained popularity as anti-aging compounds and do have some intriguing potential—they are in a category of their own and merit a deeper dive (they may support mitochondrial growth, and may have brain protective effects in conditions like Alzheimer’s disease). It is possible, though, to have too much of a good thing, and side effects can become relevant when you’re trying to use higher doses of niacin for specific purposes. For example, niacin is sometimes used for high lipid—especially for cases of high lipoprotein(a), which is a particularly sticky and difficult to manage type of blood lipid. Niacin doses for lipid management may be 500 mg twice daily or higher. The most well-known side effect of niacin is flushing, which is often accompanied by redness, heat, and itching, and can occur at doses as low as 50 mg per day (taking aspirin before the niacin can help). Nausea, reflux, and diarrhea can occur at doses of 1000 mg per day. Severe liver damage can occur at doses of 3000 mg per day. Other notable side effects of high doses include elevated uric acid (which can cause gout), blood glucose elevations, insulin resistance, headache, low blood pressure, and arrythmias. It’s all well and good if niacin helps you lower your lipids, but it’s not great if it causes diabetes or some other serious condition in the process.
In summary, niacin is a keystone B vitamin that does a little bit of everything. It’s fundamental in energy metabolism, protects against oxidative stress, balances blood lipids, and may play a role in longevity. It supports the brain, skin, and gut. Most people likely get enough from diet (with good sources being meat, fish, nutritional yeast, and sprouted or fermented seeds and legumes), though some groups are at risk for deficiency. High doses can be used to treat high lipid levels, though side effects are common at high doses. The best way to know how you are doing with niacin is to check your levels.
What’s your niacin status?
References
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3. Office of Dietary Supplements - Niacin. https://ods.od.nih.gov/factsheets/Niacin-HealthProfessional/
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