What Is Niacin? - Benefits, Foods & Side Effects

Instructor: Carol King Kennard

Carol has a master's degree in Nutrition/Dietetics and taught nutrition-related courses at the university level for 10 years.

Is there a superhero in every family? There is at least one caped crusader in the B-vitamin family. Niacin can be amazingly produced from the common amino acid tryptophan. This lesson explores niacin's benefits, food sources, and deficiency/toxicity symptoms.


Sometimes we aren't able to see the whole picture. That was certainly the case when niacin was first discovered in the early 1900s. The introduction of corn as a staple food and subsequent replacement of other more traditional grain foods resulted in a devastating, dreaded disease called pellagra. No one knew the cause of this disease, and it was assumed to be highly contagious. That is, until one day scientists discovered the super hero that would save the day: a B-vitamin called niacin.


Like many other members of the B-vitamin family, niacin is well-known for its role in energy metabolism (breaking down substances in the body to yield energy). Actually, niacin plays a part in the energy metabolism of all cells in the body. Another benefit of water-soluble vitamin is its versatility. Niacin can be eaten in its preformed state (in other words, the food contains the actual nutrient, niacin) or it can be made by the body from the ordinary, essential amino acid known as tryptophan. This makes niacin a very versatile nutrient. It goes without saying that a huge bonus of having niacin in the body is to prevent the serious illness, pellagra (which we will discuss later in this lesson). There are other potential experimental benefits that will be discussed later in the lesson as well.

Niacin Recommendations and Food Sources

Just like a superhero being seen all around town doing good deeds, niacin is found throughout many different food groups, providing its unique services to the human body.

Niacin Food Sources

• seafood (such as tuna, mackerel, wild salmon, swordfish, and halibut)

• poultry (like chicken and turkey)

• pork

• liver

• peanuts

• beef

• mushrooms

• green peas

• sunflower seeds

• avocado

• potatoes

• tomatoes

Food Sources of Niacin

Since our bodies can mysteriously convert tryptophan (an essential amino acid) to niacin, high-protein foods are indirectly a great source of niacin too. Even though this conversion doesn't take place in a phone booth like the change from Clark Kent into Superman, it's still pretty amazing. For this reason, niacin recommendations are written in Niacin Equivalents (NE) instead of milligrams of niacin. It is commonly thought that the tryptophan we get from protein-heavy foods can meet about half the niacin needs in most people. For most folks, the average diet easily provides enough preformed niacin, so a nutritious diet including a variety of healthy foods should easily meet your niacin needs.

Tryptophan Sources(which can be converted to niacin)

• milk

• eggs

• meat

• poultry

• fish

• whole-grains

• fortified & enriched grain products

• nuts

• all protein-containing foods

Recommended Dietary Allowance for Niacin

16 mg NE (niacin equivalents) per day for men

14 mg NE per day for women

Tolerable Upper Intake Level for Niacin (consuming above this amount could lead to toxic levels from supplements)

Adults: 35 mg/day

Deficiency and Toxicity Symptoms of Niacin

Niacin is a nutrient that should be kept in balance--not too little and not too much. As mentioned earlier, the deficiency disease from insufficient niacin is called pellagra, and it is characterized by what's known as the '4 Ds' (diarrhea, dermatitis, dementia, and death). Those with pellagra suffer with a flaky skin rash on skin exposed to sunlight, mental depression, apathy, fatigue, loss of memory, headache, diarrhea, abdominal pain, vomiting, and abnormal tongue (swollen, smooth, bright red or black).

Dermatitis of Pellagra

To unlock this lesson you must be a Study.com Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use Study.com

Become a Study.com member and start learning now.
Become a Member  Back
What teachers are saying about Study.com
Try it risk-free for 30 days

Earning College Credit

Did you know… We have over 200 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? Study.com has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it risk-free for 30 days!
Create an account