Niacin is a B vitamin your body uses to turn food into energy and repair DNA

Niacin, also called vitamin B3, is one of eight B vitamins that help your cells convert the food you eat into usable energy. Your body also uses niacin to maintain healthy skin, nerves, and digestion. Unlike some vitamins, your body cannot store niacin, so you need a steady supply from food or supplements.

You may have heard niacin called by other names: nicotinic acid, nicotinamide, or NAD (nicotinamide adenine dinucleotide). These are all forms of the same vitamin, though they work slightly differently in your body and have different effects on cholesterol.

Most people in developed countries get enough niacin from their diet without thinking about it. But understanding what niacin does, where to find it, and when someone might need more can help you make informed choices about your own nutrition.

Key Takeaways

  • Niacin helps your body produce energy from carbohydrates, fats, and proteins, and it plays a role in DNA repair and cell communication.
  • Common food sources include chicken, tuna, turkey, peanuts, mushrooms, and fortified grains and cereals.
  • The recommended daily amount is 14 mg for adult women and 16 mg for adult men, though individual needs vary by age and life stage.
  • High-dose niacin supplements can cause flushing (temporary redness and warmth in the skin) and may affect liver function or blood sugar, so medical supervision is important if you take them.
  • Severe niacin deficiency is rare in developed countries but can cause a condition called pellagra, which affects skin, digestion, mood, and nerves.

How niacin works inside your cells

Niacin's main job is to help your cells make energy. Specifically, it becomes part of two coenzymes—NAD and NADP—that act like tiny workers inside your cells. These coenzymes help break down carbohydrates, fats, and proteins so your body can use them for fuel.

Beyond energy production, niacin supports DNA repair, which means it helps your cells fix damage and maintain themselves properly. It also plays a role in cell signaling, the process by which cells communicate with each other. Some research suggests niacin may help reduce inflammation, though this area is still being studied.

Your body can actually make a small amount of niacin from an amino acid called tryptophan, which you get from protein-rich foods. However, this conversion is not efficient enough to meet all your niacin needs, which is why dietary sources matter.

Where to find niacin in food

Niacin appears naturally in many common foods, and many grain products are fortified with it. Animal proteins tend to be rich sources: chicken breast, turkey, tuna, and other fish contain substantial amounts. Beef and pork also provide niacin, though in smaller quantities than poultry.

Plant-based sources include peanuts, peanut butter, mushrooms, green peas, and sunflower seeds. Whole grains and fortified cereals, breads, and pasta are reliable sources as well. If you eat a varied diet that includes protein and whole grains, you are likely meeting your niacin needs without effort.

Cooking can affect niacin content—some is lost in water when you boil foods—but most cooking methods preserve enough that it is not a practical concern for most people.

How much niacin you need

The recommended dietary allowance (RDA) for niacin is 14 mg per day for adult women and 16 mg per day for adult men. Pregnant women need 18 mg, and breastfeeding women need 17 mg. Children and teenagers have lower requirements that increase with age.

These amounts are based on what prevents deficiency and supports normal body function. Individual needs can vary based on age, sex, pregnancy status, and overall health. If you have a medical condition or take medications that affect niacin absorption or metabolism, your doctor may recommend a different amount.

Most multivitamins contain niacin, usually in amounts well below the upper safe limit. If you are considering a niacin supplement beyond what is in a standard multivitamin, talk with your doctor first, especially if you have liver disease, diabetes, or gout.

What happens when you do not get enough niacin

Severe niacin deficiency causes a condition called pellagra, which is rare in developed countries today. Pellagra affects four main systems: skin (causing a distinctive rash), digestion (causing diarrhea and nausea), mood (causing depression and anxiety), and nerves (causing confusion and numbness). The condition is sometimes remembered by the phrase "four Ds": dermatitis, diarrhea, dementia, and death—though modern treatment prevents the last outcome.

Pellagra was common in the early 20th century in populations that relied heavily on corn without niacin fortification. It is now seen mainly in people with severe malnutrition, untreated alcoholism, or certain medical conditions that prevent nutrient absorption. In developed countries, grain fortification has made pellagra almost nonexistent.

Mild niacin deficiency does not produce obvious symptoms, which is why it often goes unnoticed. If you have concerns about your niacin intake—for example, if you follow a very restricted diet—a conversation with a doctor or registered dietitian can help you assess whether you need to adjust your food choices or consider a supplement.

High-dose niacin and its effects

High-dose niacin supplements, typically 1,000 mg or more per day, are sometimes used to support cholesterol levels. At these doses, niacin can cause flushing—a temporary sensation of warmth, redness, and tingling in the skin, usually lasting 15 to 30 minutes. This is harmless but uncomfortable, and some people find it intolerable.

Extended-release forms of niacin cause less flushing than when ready-release forms. Taking niacin with food or taking a low-dose aspirin beforehand can reduce flushing in some people. However, high-dose niacin also carries real risks: it can affect liver function, raise blood sugar levels, and trigger or worsen gout.

If you are considering high-dose niacin for any reason—whether for cholesterol, energy, or any other purpose—medical supervision is essential. Your doctor can monitor your liver function and other markers, adjust your dose, and help you weigh the benefits against the risks for your specific situation.

Niacin and overall wellness

Getting adequate niacin through a balanced diet supports your body's basic energy production and cell maintenance. You do not need to seek out niacin specifically or take supplements unless you have a reason to do so—a varied diet that includes protein and whole grains naturally provides what you need.

If you are interested in niacin for a specific health concern, or if you follow a diet that might be low in niacin (such as a very restricted eating pattern), a registered dietitian or doctor can help you understand your actual needs and whether food changes or a supplement makes sense for you.

Frequently Asked Questions

Can niacin give you energy or help with fatigue?

Niacin helps your body convert food into energy, so it is necessary for normal energy production. However, if you already get enough niacin from food, taking extra will not boost your energy. Fatigue usually points to other causes—sleep, stress, iron levels, or an underlying condition—so it is worth exploring those with a doctor rather than assuming niacin is the answer.

Is niacin safe to take every day?

Niacin from food and standard multivitamins is safe to take every day because the amounts are well below any risk threshold. High-dose niacin supplements (over 1,000 mg daily) should only be taken under medical supervision, as they can affect your liver and blood sugar. The upper safe limit for adults is 35 mg per day from supplements and fortified foods combined.

What is the difference between nicotinic acid and nicotinamide?

Both are forms of niacin, but they work slightly differently. Nicotinic acid (also called niacin) can affect cholesterol levels and causes flushing at high doses. Nicotinamide does not affect cholesterol and causes less flushing, but it is not used for cholesterol management. Your body converts both into the active forms it needs.

Can you get too much niacin from food?

No. Niacin from food sources alone cannot reach toxic levels because you would need to eat unrealistic amounts. Excess niacin from food is straightforward excreted in urine. Only high-dose supplements pose a risk of toxicity.

Do vegans and vegetarians get enough niacin?

Yes, if they eat a varied diet. Plant sources like peanuts, mushrooms, whole grains, and fortified cereals provide adequate niacin. Vegans and vegetarians who eat a range of foods typically meet their niacin needs without supplements, though individual diets vary.