What is Vitamin B3 & What Does it Do?

Vitamin B3 is also known as niacin.  It is a water-soluble vitamin that plays many important roles, as we will see.  Niacin is metabolized into NAD for its role in the generation of energy and in reducing oxidative stress. (1)  If you are interested in a deep dive into these processes, you can review energy generation in last week’s article on B2, where we saw how it is metabolized into FAD, and you can review oxidative stress in the Vitamin E article. 

The quick and easy explanation is, NAD:

1. Moves electrons around using them to make ATP - the form of energy our bodies use

2. Prevents free radicals from causing cell damage and inflammation

Disease Prevention: 

First, let’s take a look at clinical niacin deficiency - pellagra.  This is a condition that causes symptoms in the skin, digestive tract, and nervous system.  

Given the publishing of this article right before Halloween, and the permanent connection between pellagra and vampires in my mind, I thought we could take a moment to look at the European myth of vampires and its relationship to two very real illnesses: pellagra and rabies.

There is some debate as to whether cases of pellagra or rabies were the origins of vampire myths in Europe, as both were well known in the area and there were increases of cases in both when corn was introduced from the Americas. (2)  Let’s compare and contrast the two shall we... 

Similarities between rabies and pellagra: 

• Both create symptoms that result in victims avoiding sunlight - a photosensitive rash in pellagra and photophobia in rabies.  

• The urge to bite and transmission from animal bites (especially bats and wolves/dogs which feature strongly in vampire myths) is seen in rabies but not pellagra.  While pellagra doesn’t induce biting, it does cause a rash around and inside the mouth that can bleed, giving the illusion of the victim having bit someone.

• Rabies and pellagra also cause delirium and psychotic behavior. 

• Both conditions, if allowed to run their course, end in death.

Differences between rabies and pellagra: 

• Rabies is caused by a virus and is transmitted through saliva and infected nervous system tissue.

• Pellagra is caused by a deficiency of niacin and is linked to a diet high in corn that has not been treated with lime (calcium oxide - not the fruit) to make it bioavailable. 

• Rabies is far more deadly and once the clinical symptoms develop, it is nearly always deadly.  There is an incubation period where treatment with immunoglobulins and the rabies vaccine can prevent the disease from progressing.  If you have been bitten by a wild animal, seeking care as soon as possible is needed - this care is also covered by patient assistance programs in the U.S., so care is available even if you do not have the resources to pay for it. (3)

• Pellagra can be reversed with administration of pharmacological doses of niacin either oral or IV. 

Other than preventing pellagra, niacin has been found to have a role in the prevention of other diseases: (1)

• Skin cancers - squamous and basal cell

• Breast cancers

• Lung cancers - not tobacco related

• Chemically induced leukemia during chemotherapy

• Oral, pharyngeal, and esophageal cancers

Despite promising results in lowering cholesterol levels, we have not seen a corresponding decrease in heart attack or stroke with niacin therapy.  

Also, while there was hope regarding a possible role in preventing the development of Type 1 diabetes, this did not end up preventing disease progression in patients with increased risk. 

Treatment of Disease: 

Niacin has a role in the treatment of several diseases: (1)

• Pellagra

• Niacin responsive genetic disorders such as errors in tryptophan metabolism

• High cholesterol levels

• Possibly helpful in schizophrenia

Toxicity: 

Before you run out and stock up on niacin or hook yourself up to an “anti-aging” NAD IV, do be aware that there are some pretty serious side effects of taking too much niacin. (1)

• Niacin flush - this is relatively common and often occurs with doses beyond 30mg, some forms of niacin can be taken in slightly higher doses, but most seem to eventually cause this flush.  It’s similar to the heat and redness of blushing. 

• Kidney damage 

• Liver damage

• Headaches

• Low blood pressure

• Increased uric acid production 

• Vision changes

• Insulin resistance

Where to Find Vitamin B3: 

Other than a multivitamin, B-complex, or other supplement, niacin is easily found in a varied whole-food diet.  Foods particularly rich in niacin include: (1)

• Yeast

• Meat

• Fortified cereal

• Poultry

• Red fish (tuna/salmon)

• Coffee

• Lentils

• Peanuts

• Seeds

• Green leafy vegetables

Applications:

Summary:  

So far, our takeaways can be summarized as: 

• Niacin, in the form of NAD,  is important for the production of energy and reducing oxidative stress.

• Pellagra should be avoided!  Also, avoid rabies!

• Adequate levels of dietary niacin can be protective against many different kinds of cancer and some of the side effects of chemotherapy.

• Niacin therapy can lower cholesterol levels, but it doesn’t seem to prevent heart attack and stroke - there must be something else going on besides cholesterol levels…

• Niacin therapy may be helpful in cases of schizophrenia.

• Niacin therapy gets toxic quickly - do not try this at home!

• There are quite a few food sources of niacin.

Daily Intake: 

Next, let’s look at the recommendations for niacin intake.  The RDA for niacin is a minimum of 14-16 mg daily for adults with an increase to 18 mg during pregnancy and 17 during breastfeeding.  This is the minimum recommended intake.  The tolerable upper limit for niacin in adults is 35 mg. This is the most you should consume to avoid any of the potential toxic effects. (1) 

The Linus Pauling recommendation is around 20 mg daily through diet and a multivitamin/multimineral. (1)

Now, if you are under the supervision of a medical professional using niacin as a treatment for a known condition, these levels do not necessarily apply to you.  You should follow your provider’s instructions for intake and monitoring.  These recommendations are for the general disease prevention in the absence of a known condition. 

Medication Interactions:

Lastly, let’s look at a few medication interactions, so you can discuss your niacin needs with your healthcare team if any apply to you: (1)

• Niacin supplementation in the form of nicotinic acid can increase the muscle pain and inflammation associated with cholesterol lowering medications such as statin drugs and bile acid sequestrants. 

• Liver damage may be more likely when combining niacin and acetaminophen, amiodarone, and carbamazepine. 

• If you are on medications to decrease uric acid levels, taking niacin may block their effectiveness. 

• Some medications can decrease niacin absorption or metabolism and they include: 

  • Estrogen

  • Estrogen containing birth control pills

  • Long term chemotherapy

There we have it, a review of vitamin B3 - niacin.  I hope you learned something new; I certainly received a good review and several reminders while researching and writing this article!  I hope these articles are as helpful for you as they are for me; it’s been quite a while since my nutrition classes and new information comes out every year!

Next week, we will turn our attention to vitamin B5: Pantothenic acid.

To our health!

References: 

1. Higdon, J, “Niacin” Linus Pauling Institute, 2000, accessed October 5, 2021  https://lpi.oregonstate.edu/mic/vitamins/niacin

2. Théodoridès J. (1998). Origin of the myth of vampirism. Journal of the Royal Society of Medicine, 91(2), 114. https://doi.org/10.1177/014107689809100231

3. CDC, “Rabies”, accessed October 6, 2021 https://www.cdc.gov/rabies/index.html