Vitamin B3 (niacin, nicotinic acid)

Like all B vitamins, vitamin B3 (niacin) plays a role in converting carbohydrates into glucose, metabolizing fats and proteins, and keeping the nervous system working properly. Niacin is an essential vitamin required for processing fat in the body, lowering cholesterol levels, and regulating blood sugar levels.

Niacin also helps the body make sex- and stress-related hormones and improves circulation and cholesterol levels.

It is used in treating vitamin B3 deficiency (pellagra), and for treament of high cholesterol levels.

Vitamin B3 deficiency

Symptoms of mild niacin deficiency include:

  • indigestion
  • fatigue
  • canker sores
  • vomiting
  • depression

Severe deficiency, called pellagra, can cause symptoms related to the skin, digestive system, and nervous system. They include:

  • thick, scaly pigmented rash on skin exposed to sunlight
  • swollen mouth and bright red tongue
  • vomiting and diarrhea
  • headache
  • apathy
  • fatigue
  • depression
  • disorientation
  • memory loss

Food source

Vitamin B3 is often found in combination with other B vitamins, including thiamine (B1), riboflavin (B2), pantothenic acid (B5), pyridoxine (B6), cyanocobalamin (B12), and folic acid (B9). Here is the list of foods rich in niacin:

  • Fish (tuna, mackerel, salmon, swordfish)
  • chicken and turkey
  • pork
  • coffee
  • liver (beef, pork, chicken)
  • peanuts
  • mushrooms
  • green peas
  • sunflower seed
  • avocado


Everyone needs a certain amount of niacin — from food or supplements — for the body to function normally. This amount is called the dietary reference intake (DRI). For niacin, the DRIs vary with age and other factors.

  • Children: between 2-16 milligrams daily, depending on age
  • Men: 16 milligrams daily
  • Women: 14 milligrams daily
  • Women (pregnant): 18 milligrams daily
  • Women (breastfeeding): 17 milligrams daily
  • Maximum daily intake for adults of all ages: 35 milligrams daily

However, the ideal dosage of niacin depends on how you’re using it.

For instance, much higher doses — 2 to 3 grams or more — are used to treat high triglycerides.

For age-related macular disease (eye disease), 500 milligrams of immediate-release niacin has been taken by mouth.

For erectile dysfunction, 500-1,500 milligrams of niacin has been taken by mouth for 12 weeks.

For high cholesterol, 300-1,2000 milligrams of niacin has been taken by mouth daily for 6-44 weeks as wax-matrix.

For pellagra, or niacin deficiency, 50-1,000 milligrams of niacin has been taken by mouth daily.

Can it be harmful?

Niacin does have risks.

People with any health condition including liver or kidney disease, diabetes,high blood pressure, or cardiovascular problems need to talk to a doctor before using niacin supplements. Do not treat high cholesterol on your own with over-the-counter niacin supplements.

Niacin can cause flushing (harmless but uncomfortable redness and warmth in the face and neck) especially when you first begin taking it. Your health care provider will probably suggest increasing the dose slowly to reduce this problem. Niacin can cause upset stomach and diarrhea. However, all of these side effects tend to fade over time.

Niacin may increase blood sugar levels. Caution is advised in people with diabetes who are not monitored by a qualified healthcare provider and in those taking drugs, herbs, or supplements that affect blood sugar.

Niacin may increase the risk of bleeding. Caution is advised in people with bleeding disorders or taking drugs that may increase the risk of bleeding. Dosing adjustments may be necessary.

Use cautiously in people with kidney disorders and gout.



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