7 questions about B vitamin supplements

If you follow professional or collegiate sports, you’ve probably heard at least a few athletes say they needed a B12 injection to boost their energy levels.

You may have also heard claims that B vitamins can reduce anxiety, nausea, insomnia, depression, or other conditions that cancer patients commonly experience as side effects of treatment.

But how many different kinds of B vitamins are there, and how do our bodies use them? Are B vitamin supplements safe for cancer patients to take during treatment?

We went to clinical dietitian Juhina Farooki for answers to these questions and more.

What are B vitamins, and how do our bodies use them?

B vitamins are naturally occurring micronutrients that help our bodies convert carbohydrates, fats and protein into glucose, a simple sugar that the body uses for fuel. They’re sometimes called “anti-stress vitamins,” because they boost the body’s immune system during times of strain. 

B vitamins play a key role in the nervous system, too, as they’re needed for good brain function. They also help keep the liver, skin, hair, and eyes healthy.

Do our bodies produce B vitamins themselves or must we get them from our diet?

B vitamins occur naturally in a variety of plant- and animal-based foods, but they can also be taken as a nutritional supplement. Some B vitamins are added to “fortified” foods, too, such as enriched flour, pastas, breads, and breakfast cereals. 

Are there different types of B vitamins?

Yes. Most are known by their “B name” as well as another title.

• B1 (thiamine)
• B2 (riboflavin)
• B3 (niacin)
• B5 (pantothenic acid)
• B6 (pyridoxine)
• B7 (biotin)
• B9 (folate)
• B12 (cobalamin)

What’s the difference between vitamin B and a vitamin B complex?

Any of the eight different B vitamins can be taken individually, or you can take all or most of them in a variety of combinations. Any given combination of B vitamins in a pill or liquid form is known as a B vitamin complex.

How would you know if you have a vitamin B deficiency?

Most people who are healthy, well-nourished and eating well-balanced meals don’t need a vitamin B supplement. But we might do a blood test if someone is showing any of the following symptoms:

• chronic constipation
• confusion
• fatigue
• loss of appetite
• numbness
• weakness
• weight loss

Can you overdose on vitamin B?

It’s possible, but not very likely. 

Vitamins come in two different categories: fat-soluble and water-soluble. 

• Fat-soluble vitamins are stored in our bodies, so getting too much of them can be dangerous.
• Water-soluble vitamins are circulated in the bloodstream, so any excess is removed by our kidneys and secreted in our urine.

Only the vitamins A, D, E and K are fat-soluble. All the rest are water-soluble. So, while there are upper limits that people should stay below for B vitamins, it’s pretty unusual for anyone to reach them. 

Is it safe for cancer patients undergoing treatment to take a vitamin B supplement?

That depends on each person’s particular situation.

Ideally, we’d like for patients to obtain all the B vitamins they need from the foods they eat. But if someone has a history of bariatric surgery, for instance, then thiamin and B12 injections might be beneficial. 

This is because B12 is absorbed in the latter part of the small intestine, but the process requires hydrochloric acid from the stomach. Thiamine is absorbed in the small intestine, but often with gastric surgeries, part of the small intestine is bypassed, leading to a potential deficiency. 

If someone is not eating enough due to appetite changes, nausea or vomiting, then they might need a supplement.

But some types of B vitamins can be unsafe for certain patients to take, either because they reduce the effectiveness of particular cancer treatments or because they can interact adversely with certain medications. That’s why it’s super important to check with your doctor before taking any kind of nutritional supplement.

Request an appointment at MD Anderson online or by calling 1-877-632-6789.