To B or not to B (Vitamin B, that is)

Should we load up on supplements to protect against certain diseases? It seems we’re always on the look-out for ways to reduce our risk, but not all vitamins are living up to their potential when it comes to disease-preventing benefits.

The latest let-down is vitamin B. Chances are you’ve seen one type or another on a list of recommendations. After all, this group of eight vitamins — thiamin, riboflavin, niacin, pantothenic acid, biotin, B6 (pyridoxine), B9 (folate or folic acid) and B12 (cyanocablamin) — are essential for the body’s metabolic processes and for overall good health. Despite the fact that our bodies aren’t equipped to store these vitamins (with the exception of B12 which is stored in the liver), deficiency is rare amongst most people in Western countries. Most of what we need comes from a balanced diet.

But an extra helping of some of these vitamins is thought to have health benefits like reducing the risk or affects of certain illnesses — including cancer, heart disease and Alzheimer’s disease. However, new research suggests they might not be as useful we’d hoped.

So what’s the scoop?

Not so helpful in the fight against cancer

Previous research indicated that people who got more of the B-group vitamins had a lower risk of developing cancer — particularly colorectal cancer (which is one of the most common types of cancer in Canada). Unfortunately, a recent study out of Brigham and Women’s Hospital and Harvard Medical School contradicts these earlier results.

The study followed 5542 women, all health care professionals with an average age of 63, over a period of seven and a half years. One group took a daily supplement which included vitamins B6, B9 (folic acid) and B12 while the other half received placebos. The results showed that women in the supplement group had roughly the same incidence of cancer as women in the placebo group (187 women versus 192). The two groups had similar risks of developing or dying from any type of cancer. In other words, women who took the supplement didn’t have a lower incidence of colorectal cancer (as was thought in previous research).

“This study shows that supplementation with the combined B vitamins provided no beneficial effect and no harmful effect. So in terms of cancer risk, this may not be an effective approach,” said the study’s leader, Dr. Shumin Zhang, in an interview with Reuters.

But there may be some good news for Zoomer women. The study did find that women over age 65 who were taking the B vitamins were 25 per cent less likely to develop any type of cancer and 38 per cent less likely to develop breast cancer. However, researchers aren’t sure if this is a genuine finding or simply a fluke.

To complicate matters further one of the study’s investigators, Dr. JoAnn Manson of Brigham and Women’s Hospital, notes that other research suggests that foods high in folic acid may lower cancer risk. Clearly, more research is needed. (See the article from Reuters for more information).

What about Alzheimer’s disease?

Previous research showed that elevated levels of homocysteine are associated with brain cell damage, but those levels can be lowered with vitamin B. It would stand to reason that supplements could be used to slow the progression of Alzheimer’s — but it turns out that’s not the case.

Results of a US study released this past October showed that high doses of B6, B9 and B12 didn’t reduce cognitive decline. Until further research proves otherwise, researchers say there’s no justification for taking vitamin B supplements to prevent or slow the progression of Alzheimer’s. (See the recent article from Bloomberg for full details).

But there is some good news: Researchers out of the University of California recently published a study showing that high doses of nicotinamide (a form of B3) prevented memory loss in mice that had an animal version of Alzheimer’s. In fact, the mice who were given the supplement “performed as if they’d never developed the disease” according to study author Kim Green, quoted in the Washington Post.

There’s a human trial now in the works, and if successful the results could yield an inexpensive yet effective way to treat the disease. (Imagine an effective treatment that’s available for about $30 a year). An estimated one in eight Baby Boomers will develop the disease in their lifetime, so this breakthrough could have a significant impact.

For now, researchers aren’t recommending that people test the hypothesis themselves by taking larger-than-normal doses of B3. Even seemingly safe measures can be harmful.

Good for the heart… or not?

When it comes to matters of the heart, yet another study has shown that neither B12 nor folic acid is useful for preventing heart disease. This study from the University of Oxford examined whether or not the supplements could prevent “major vascular events” in people who have already survived heart attacks. Unfortunately, the supplements were found to have no affect on future prevention.

As an offshoot, the doctors did find that cancer death rates were the same in the control group and the treatment group — results which they say demonstrate that folic acid doesn’t increase the risk of certain types of cancer as previously feared. (See Modern Medicine for the full story).

The B-ottom line

If you’re thinking of changing your usual routine — either by introducing a supplement or eliminating one — you should talk to your doctor first. Deficiencies are rare in people who aren’t in high risk groups (such as people who drink excessive amounts of alcohol and the elderly), and should be diagnosed by a professional. Vitamin B supplements can mask other vitamin deficiencies, and excessive intake of some types can be harmful. For example, large doses of B6, which is thought to help premenstrual syndrome and carpel tunnel syndrome, can lead to nerve damage and overdose.

There are many benefits of vitamin B not covered in this article, but health experts agree that you should talk to a professional before you reach for that bottle on the drug store shelf.

In the meantime a balanced diet is your best defence, particularly one that includes:

– leafy green vegetables like kale, spinach, swiss chard and bok choy.

– legumes, lentils, seeds, peanuts

– whole grain products (particularly those enriched with folic acid).

– milk, cheese, cottage cheese and yoghurt (especially for riboflavin)

– eggs, fish, shellfish and meat (especially the liver and kidneys).

These vitamins are water soluble but quite delicate so be careful how you prepare your foods. Food processing and extended cooking will destroy or damage them, as will alcohol.

No doubt future research will find new benefits and treatments, but it may also debunk what we currently know (or think we know).

Mayo Clinic Drugs and Supplements
Vitamin B Fact Sheet

Photo © Anthony Hall