By Roberta H. Anding, MS, Baylor College of Medicine and Texas Children’s Hospital
Edited by Kate Findley and proofread by Angela Shoemaker, Wondrium Daily
Did you know that niacin can lower cholesterol? Or vitamin B6 can alleviate PMS? However, you should use caution with both these supplements. Professor Anding explains.
Functions of Niacin
Niacin, or vitamin B3, is actually named for two compounds: nicotinic acid and nicotinamide. In the 1940s, there was confusion between nicotinic acid and nicotine, so the name was changed to niacin.
Niacin is a powerhouse B vitamin. It helps to catalyze reactions in over 200 enzymes under normal conditions and during times of intense activity such as running or jogging.
Tryptophan, an essential amino acid, is a precursor for niacin and provides about half of the niacin needed. Riboflavin, vitamin B6, and iron are all needed to convert tryptophan to niacin, so a deficiency of these nutrients can worsen a niacin deficiency. In fact, a web of interaction exists between all the B vitamins.
Niacin Deficiency and Clinical Use
Pellagra, the deficiency disease of niacin, means “rough skin” in Italian. It describes a dermatitis that is coarse and blackened where the skin is exposed to sun.
Sometimes you can see a black ring around the collar. The signs of this deficiency include dermatitis (skin), diarrhea, dementia, and death. Chronic alcoholism and malnourishment due to significant poverty can contribute to a niacin deficiency.
Doses of niacin higher than the upper limit of 35 milligrams per day can be used to lower cholesterol, and according to Professor Anding it’s very effective. Before statin resins and some of the other drugs on the market, niacin was often a mainstay of cholesterol lowering. The 8-Week Cholesterol Cure, which was popular in the 1990s and is still used today, touted high-dose niacin.
Toxicity
Side effects of high-dose niacin, though rare, are noticeable when they do occur. They include flushing, redness, and itching.
“I worked with a professor at the University of Texas, and he oftentimes would bring in his students to take a look at what’s called a ‘niacin flush,’ with redness and itchy skin,” Professor Anding said.
Enteric-coated niacin, which has an outside covering and is time-released, can reduce some of the flushing and itching. Another potential side effect associated with high-dose niacin is elevated liver enzymes, though. Thus, its use should be monitored by a physician.
“Niacin is also a vasodilator, and that’s one of the reasons why you get that red flushing to your skin,” Professor Anding said. “So please be careful if you’re taking high-blood pressure medication that also functions as a vasodilator.”
Additionally, high-dose niacin may elevate blood sugar, so if you have pre-diabetes, metabolic syndrome, or slightly elevated blood sugar, niacin as a drug may not be the compound for you.
What is Vitamin B6?
Vitamin B6 exists in multiple forms, known collectively as a compound called “pyridoxine.” What does vitamin B6 do? Like niacin, it’s needed for the functioning of over 100 enzymes.
Vitamin B6 helps in protein synthesis, particularly that of non-essential amino acids. Non-essential amino acids are needed by the body, but you can make them, so vitamin B6 is critical for the synthesis of non-essential amino acids. It can convert protein to glucose if energy needs are not being met.
In terms of stability, B6 can be destroyed by heat. When preparing foods that are sources of Vitamin B6, it’s often best to cook them with minimum heat.
Although it is rare, a B6 deficiency causes a type of anemia called “microcytic hypochromic anemia.” “Microcytic” means small cell and “hypochromic” means pale in color. This is where it gets confused with iron deficiency.
In fact, iron deficiency also causes a microcytic hypochromic anemia. This can damage the nervous system and elevate homocysteine levels, which are a marker for heart disease.
Toxicity and Medicinal Use
Medicinal use first became prevalent when vitamin B6 was linked with the treatment of premenstrual syndrome, also known as PMS. Doses as low as 50 milligrams per day might be helpful. As with most supplements, more is not better.
A study in the mid-1980s identified a syndrome in women taking high-dose B6—greater than 500 milligrams per day over a period of time—who developed neuromuscular ataxia, which means they couldn’t put one foot in front of the other. They had an uncoordinated gait. This was the first time in modern history that a water-soluble vitamin exhibited toxicity.
The upper limit of this vitamin—the maximum you should consume per day—is 100 milligrams per day, yet supplements are available on the market that contain more than this amount without any warning of toxicity. Thus, when it comes to supplements, you must always keep in mind that just because it’s water-soluble doesn’t mean it goes through your body without an interaction.
Professor Roberta H. Anding is a registered dietitian and Director of Sports Nutrition and a clinical dietitian at Baylor College of Medicine and Texas Children’s Hospital. She also teaches and lectures in the Baylor College of Medicine’s Department of Pediatrics, Section of Adolescent Medicine and Sports Medicine, and in the Department of Kinesiology at Rice University.
