What Is Niacin Deficiency?

Niki Foster
Niki Foster

Niacin deficiency is characterized by lethargy, loss of appetite, weight loss, and a sore or inflamed mouth in the early stages. If it progresses, the deficiency can cause an illness known as pellagra. The major symptoms of pellagra are sometimes called the "four D's": diarrhea, dementia, dermatitis, and death. It is important to have a healthy diet with adequate amounts of niacin to avoid developing a deficiency.

Beans are a good source of niacin.
Beans are a good source of niacin.

Niacin, also known as Vitamin B3 or Vitamin P, is an essential nutrient. In other words, the body requires niacin for its normal metabolic function, but does not produce any on its own. Niacin, like the other essential nutrients, can only be obtained through one's diet.

Mushrooms are high in niacin.
Mushrooms are high in niacin.

If one has a healthy, balanced diet, niacin deficiency is not a concern. It is, however, widespread in developing countries including Mexico, Indonesia, parts of China, and some African countries. In developed nations, alcoholics, and the very poor, are most susceptible to niacin deficiency. A diet poor in tryptophan or leucine, two amino acids, can also cause a deficiency.

Insomnia is one possible symptom of pellagra.
Insomnia is one possible symptom of pellagra.

The main symptoms of niacin deficiency are diarrhea, dementia, and dermatitis. Diarrhea can lead to dehydration and prevent sufferers from absorbing other nutrients. Dementia may take the form of irritability, poor memory, or fatigue, or it may cause hallucinations and aggression. Dermatitis is a skin condition characterized by dry, dark, scaly patches, especially on areas of the skin exposed to sunlight. Other possible symptoms of pellagra include insomnia, sensitivity to sunlight, hair loss, swelling or edema, and ataxia or lack of control over muscle movement.

If untreated, pellagra will result in death within five years. Niacin deficiency is treated with oral niacin or nicotinamide, a related chemical. In addition, a person suffering from this deficiency should try to add more niacin to the diet. Foods high in niacin include dairy products, meats or other high-protein foods, whole grain cereals, beans nuts, mushrooms, and a variety of vegetables.

It is important to have adequate niacin in the diet, but most people with relatively balanced diets do not need to supplement niacin. In fact, too much can be toxic. Anything over 35 mg. a day can be dangerous for adults. The recommended daily allowance of niacin is 16 mg. for men, 14 mg. for women, 2-12 mg. for children, and 18 mg. for pregnant women.

Niacin may be found in meats.
Niacin may be found in meats.
Niki Foster
Niki Foster

In addition to her role as a wiseGEEK editor, Niki enjoys educating herself about interesting and unusual topics in order to get ideas for her own articles. She is a graduate of UCLA, where she majored in Linguistics and Anthropology.

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Discussion Comments


@anon255693: Sorry to hear about your dad's experience and I'm glad he's OK. However, there has never been 1 recorded death from Niacin. It cannot kill a human. It is water soluble, so it flushes from the body very easily. The first time I took it, I took 500mg and even though I'm 37 I thought I was going to die. My breathing slowed, skin turned red, I had severe itching, etc. but then I found out that was actually the "normal" reaction for such a high dose for a first timer. Niacin causes all of the blood vessels in the skin to dilate. Some people will use it as a way of helping flush their body usually as part of a larger protocol.

Now, just because no one has died, it doesn't mean a person should go out and start taking 2-3 grams without supervision. Still though, no one has ever died due to niacin alone.

As for the general dosage, usually the level needed to lower LDL and raise HDL is in the 1-3 gram range (broken up) daily. I still take it in the range of 500 mg and sometimes 1000mg. It does make me burn and itch but it did relieve my chronic eye twitching after a single dose, which was well worth it.

When I go back to the doctor, we'll see how my cholesterol is doing. While most people generally can get enough niacin in their diet, those with intestinal problems (IBS, Crohns, etc.) may not be able to absorb enough to meet the daily recommended amount on a regular basis thus leading to a deficiency. Also, Niacin (flushing kind) has been proven to lower LDL and raise HDL and is just as, if not more effective, than many prescription drugs with the only real side effect being the flushing/itching feeling. After a while I'm told most people adjust and are able to move up to a higher dose within a few weeks of beginning Niacin "therapy" shall we say.

I've read of people regularly taking over 3 grams daily with no adverse effects and no liver problems whatsoever. Again, I'm not telling anyone to go out and down a bottle for the fun of it. Use your head, talk to your doctor, take if for a reason if needed and yes monitor your own response. If you start it, begin small, with 50mg and work your way up to the point of beginning to flush, stay there until you no longer flush and then increase your dosage. That's the right way of doing it.

I was able to tolerate 500mg from the start, even though I wasn't aware at how red I was going to turn (looked like a lobster) I was still in no danger. Oh and niacin is needed to help produce testosterone, so men may find an extra benefit from it too.


@anon102581: Your doc might want you to take it for many reasons. The most common one is to lower your cholesterol or blood pressure. I think the lady or whoever called you might have given you the wrong message on the dosage. Don't take that much if you never touched the stuff.

You can find vitamin B3 in many areas. Monster energy drinks have them and so does one a day vitamins. If I were you, I wouldn't take it unless you get to talk to your doctor directly. Also, when you're taking it, ease on to it. If you take too much and have a allergic reaction, you would need to go to the hospital quickly.


@anon68774: Not true. It can kill. My dad for the first time took one-eighth of a tablespoon in powder form. He put it in water and stirred it. The next thing I know, in a few seconds his skin turns all red. He then tells me he doesn't feel good. I knew he had some kind of reaction. Then it progressed to the point where he got tired. He sat down and then seemed to stop breathing, and it's something I won't forget. He then woke up and I could see only the whites of his eyes, like his eyes were looking upwards, and as this was happening he started to fall towards the table.

I had my mom call 911 and I actually had to hold my dad and slowly lay him down. I then ended up talking with the 911 dispatcher while my mom got a pail and he started to vomit.

When he got to the ER, they checked his liver and his blood. I asked the doctor questions about it and he said yes, if you take too much you can die in two ways: either by poisoning your liver, or by having an allergic reaction where your oxygen to your brain can get cut off. You can die or be brain damaged.


I took 500 mg of Niacin as prescribed by my doctor and had an allergic reaction. I turned scarlet from head to toe, and itched all over. I took a benedryl but the reaction lasted at least two hours.


I got a phone call from my doc --not even him-- saying "the doctor wants you to start taking 2,000-3,000mg of niacin every day." When I asked why the simple reply was, "I don't know. He just said call you and have you start right away." No follow-up was ordered. Any ideas? I tried getting him to tell me why and what kind of B-3 and I can't be given a different doc. Any info would help. Thanks crick


What is the source for this article? I'm taking 1000 mg of niacin twice a day. There is no known toxicity level for humans as no one has ever died from Niacin poisoning. It takes 2 pounds of the stuff to kill a dog.

People should take enough niacin to get a warm, itchy feeling and continue with that amount. Niacin greatly reduces cholesterol which is why I wonder if this post doesn't have its origin in some drug company's database.

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