By Roberta H. Anding, MS, Baylor College of Medicine and Texas Children’s Hospital

Edited by Kate Findley and proofread by Angela Shoemaker, The Great Courses Daily

You’ve probably heard of vitamin B₁₂, but this is only one member of the B family. Professor Anding explores the B vitamins, why they’re important, and why caution is needed to avoid either excess or deficiency.

What Are B Vitamins?

What are B vitamins? Let’s start by with a bit of history. The scientist who first discovered vitamin B soon learned that there was not just one B vitamin. Instead it’s a group of eight substances, necessitating the numbering system that we see today. 

Sometimes you hear the number and sometimes you hear the name. This group of eight compounds includes thiamin (vitamin B₁), riboflavin (vitamin B₂), niacin (vitamin B₃), pantothenic acid (vitamin B₅), pyridoxine (vitamin B₆), biotin (vitamin B₇), folic acid or folate (vitamin B₉), and cyanocobalamin (vitamin B₁₂).

The B vitamins are a group of water-soluble vitamins, which means the excess is excreted in your urine. They act as cofactors or coenzymes in the release of energy from food, and this is an important concept. They don’t provide energy, but they facilitate the release. 

An analogy is that metabolism is the engine in your body, and B vitamins are the lubrication to keep the engine moving optimally. They don’t substitute the engine; they just help the engine run.

 B Vitamin Deficiency

A common misconception is that vitamins have calories—they do not. Also, Professor Anding recommends that you always tell your primary care provider about any vitamin, mineral, or herb that you might be taking, as they may interact with your diet or your medication. 

B vitamins as a family of compounds are intertwined. Food sources are shared and oftentimes similar, and if you have a deficiency of one, you more than likely have a deficiency of another B vitamin. 

Alcohol is the ultimate destroyer. Alcohol destroys or alters the use of most B vitamins, and alcoholics can exhibit signs and symptoms of deficiency of many B vitamins. 

B vitamin deficiencies are manifested in the mouth, possibly in the form of mouth ulcers or a swollen tongue. Keep in mind that if they’re manifested in the mouth, that means that they’re going to be manifested down the entire GI tract, but we only see them in the mouth.

Other symptoms of deficiency include weight loss, confusion, constipation, fatigue, and loss of appetite. If you think you might be deficient, you should tell your doctor, as they may be able to provide a blood test to check your levels.

Avoiding Excess

When it comes to B vitamins, though, it’s also important not to go too far in the other direction—particularly when you’re taking supplements and not getting your vitamins primarily from food sources. Professor Anding has witnessed this firsthand. 

“We had a young gymnast who came to see us with four fractured vertebrae in her back, and we were looking at the reasons why,” Professor Anding said. “Was she overtraining? We looked at all the other things that you could look at.”

The young woman started to describe her fatigue. She said, “I’m tired all the time, and I just don’t have any energy. My coach told me to take a lot of vitamin B₆ because vitamin B₆ is really important to get energy out of my food.” 

As it turned out, she had vitamin B₆ poisoning. When she went to grab the uneven bars, she couldn’t grip and hang on, fell back, and broke her back. This ended her career, and it was caused by vitamin B₆ poisoning.

When it comes to supplementation, keep in mind that B vitamins, even if they’re water-soluble, don’t go through the body without having any kind of effect. Thus, it’s always important to stay within the daily recommended requirement and check with your provider, especially if you are taking other supplements or medications.

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.

This article was edited by Kate Findley, Writer for The Great Courses Daily, and proofread by Angela Shoemaker, Proofreader and Copy Editor for The Great Courses Daily.