Vitamin B3 is another one of the water-soluble B vitamins. It was first discovered in 1873 by Hugo Weidel during his studies of nicotine. Vitamin B3 is essential in multiple steps in metabolism and is needed for good adrenal gland and nervous system function. It is mostly obtained in the diet from animal sources such as chicken, beef, and fish. Liver and kidney and heart have the highest amounts. The best plant sources include shiitake mushrooms, nuts, whole grains, beans, avocados and dates. The body can also synthesize Vitamin B3 using the amino acid tryptophan. Interestingly vitamin B3 deficiency became epidemic when corn started being adopted by Europeans as a food source after the discovery of the Americas (corn is native to central america and therefore was unknown in Europe until the 1500s). The Mayans and other native americans that ate corn did not have vitamin B3 deficiency. This was because they cooked the corn using a process called nixtamalization where they cook it in a limewater (calcium oxide lime, not the fruit) making it very alkaline. This made the corn more easy to grind and improved the flavor. However, it also released the Vitamin B3 which is otherwise bound and not bioavailable in corn and allowed it to be absorbed by the body, hence preventing vitamin B3 deficency in Mayans and other native americans. However, the Europeans who adopted corn did not understand the benefit of nixtamalization and therefore did not use this process, and an epidemic of vitamin B3 deficiency ensued.
The recommended daily allowance is approximately 14 to 16 mg/day. The upper tolerable limits is about 35 mg/day but the only side effect to this is skin flushing. Not until doses as high as 2000 mg or more are significant side effects seen, and even then are rare. Some liver toxicity, skin irritation or eczema, heart arrhythmias, increased blood glucose, eye problems, birth defects if given to pregnant women, and indigestion have all been reported. Supplements of Vitamin B3 come in two forms. Niacin is what is used most commonly by physicians to decrease cholesterol. It is used at very high doses (sometimes as much as 3000 mg) and can cause significant side effects at those doses and almost always causes flushing. Nicotinamide is what is used in most dietary supplements found in stores without a prescription. Niacin is converted into nicotinamide by the body so it has the same nutritional value. However that conversion plays a key role in lowering the cholesterol and causing flushing so nicotinamide does neither of these. Nicotinamide has much lower risk for toxicity as well.
Mild niacin deficiency can slow the metabolism causing fatigue and intolerance to cold. Severe deficiency causes what is referred to as pellagra. Pellagra causes a constellation of symptoms including diarrhea, skin irritation and darkening, inflammation of the mouth, dementia and other mental disturbances, and eventually death if not treated.
Niacin has been used since the 1950s as a cholesterol drug. Many studies have been done on the topic the best of which is likely the multicenter placebo controlled trial by Canner et al. With 3 grams of niacin a day subjects saw a 27% reduction in heart attack and 26% reduction in stroke and the cholesterol panel improved significantly as compared to placebo. 9 year follow-up of subjects showed an 11% reduction in mortality as compared to placebo. Overall the benefits seem clear but its role in combination with other cholesterol lowering drugs, more specifically with statins such as Lipitor,Zocor, and Crestor, is still being worked out. Also, the very high doses needed for cholesterol lowering does cause significant flushing which decreases compliance. However, it has not been looked at yet to see if lower doses that may not have as dramatic effect on cholesterol levels may still show stroke and heart attack prevention by other mechanisms. I feel this is an open question that should be addressed.
Test tube studies are showing evidence that vitamin B3 deficiency may increase the risk for cancer. Vitamin B3 deficiency seems to be associated with instability of genes which is a first step to forming cancer. A 1999 study by Jacobson et al from the University of Kentucky showed that one part of this may be vitamin B3’s role in supporting the tumor suppressor gene p53. They also showed a clear correlation of low vitamin B3 in tissues of people who had increased skin tumors such as squamous cell carcinoma. Kirkland from the University of Guelph in Canada also further explained how Vitamin B3 may decrease the risk for cancer (see link below). A study done by Dr. Yong with OSHA (the national institute of occupational safety and health) in 2011 of 81 pilots who were exposed routinely to ionizing radiation due to their work found that those with the higher intake of Vitamin B3 had a significantly lower rate of DNA damage. However this was merely observation and not a randomized controlled trial so the effect cannot be definitively linked to Vitamin B3. Similar studies looking at Vitamin B3 intake in those with esophageal and throat cancer found a 40% reduction in risk in those eating 5 to 6 mg more per day.
Early data did show promise for Vitamin B3 to possibly treat and/or prevent type 1 diabetes. However this was followed up with good randomized trials including by Lampeter et al. and Greenbaum et al and unfortunately they found no benefit. The data when taken together show that it is possible that Vitamin B3 actually does help prevent destruction pancreatic insulin secreting cells that leads to diabetes type 1. However Greenbaum’s study showed that this effect may be offset by an increase in insulin resistance caused by high dose Vitamin B3. Basically you may be trading type 1 diabetes for type 2. This is still an open question.
The association of mental issues with pellagra has led some to look into niacin and mental conditions such as schizophrenia. Interestingly it was found that Schizophrenics do show less tendency to flushing when treated with niacin. Messamore from the Portland VA in a 2012 study showed that severity of schizophrenia correlated well with less tendency to flushing with niacin. Dr Puri in 2001 showed that this reaction has a 90% sensitivity and 75% specificity to schizophrenia and it has actually been proposed to use it as a diagnostic tool for schizophrenia. A randomized controlled trial of Vitamin B3 supplementation by Dr. Ramsay et al in 1970 was done with newly admitted schizophrenic patients and found no benefit, however I found no mention of the number of patients. Conversely, Hoffer et al in 1957 did a trial of 30 schizophrenics and found a 80% recovery in the vitamin B3 group vs 30% recovery with placebo. In a follow-up study by Dr. Hoffer he found 79.5% vs 41.9% recovery in the niacin group vs placebo group respectively. Morris et al in a 2004 study also showed that higher dietary intake of Vitamin B3 decreased the risk for Alzheimer’s disease dramatically. And studies as far back as 1953 and one in the 1970s showed some benefit of nicotinamide on depression but have never been followed up with any good randomized controlled trials.
A study by Dr. Melton all the way back in 1943 also showed a dramatic improvement in asthma is subjects treated with niacin. However, to the best of my knowledge this study was never followed up with a randomized controlled trial. In fact the only other trial I can find exploring the matter was a 1974 study by Dr. Bekier that showed a decreased allergic response in guinea pigs treated with nicotinamide.
Also a 2006 study out of the University of Pittsburg laid out the benefits of nicotinamide for inflammatory skin conditions such as acne and rosacea.
Overall vitamin B3 shows a lot of promise. I feel one main issue may be our overemphasis on niacin while neglecting the less toxic nicotinamide. I feel we need to investigate to see if we can get the same heart attack and stroke prevention (our real goal) from nicotinamide as we do with niacin. And nicotinamide’s role in the treatment of Alzheimer’s, schizophrenia, depression, bipolar disorder and other common psychiatric disorders needs to be determined. Lastly, vitamin B3’s role in treating acne and rosacea is definitely needs to be investigated further.