You can buy enough multivitamin and mineral pills to last a year for about twenty dollars.
If taking those multivitamins could possibly reduce your risk of breast cancer, or if you have cancer, reduce the fatality rate by 30% – what’s not to like?
The answer isn’t as positive as you might think.
A new study based on the 1993-1998 clinical trials of the Women’s Health Initiative and the Women’s Health Initiative Observational Study found that women who took vitamins and minerals (the MVM package) and who developed breast cancer had a 30% lower rate of death than those women who took no multivitamins and minerals.
Not only is this an obviously significant result, but it was based on a very large study conducted with 7,728 women ages 50-79 (post-menopausal) diagnosed with invasive breast cancer. The women registered at 40 clinics around the United States and took a regular daily supplement of about 30 vitamins and minerals in pill form. The study followed their medical record on average for seven years. There was no official control group, but the larger study enrolled 161,608 women.
In an effort to make the results statistically significant, the researchers adjusted their figures for a variety of factors including race, ethnicity, weight, depression, alcohol use, physical activity, age at the time of cancer diagnosis and if they had diabetes. None of these factors significantly changed the results, leaving a 95% confidence in their accuracy.
Sounds good, but no one is charging off to request that medical standards change to recommend multivitamins and minerals for breast cancer patients. Why?
There are some fundamental aspects of scientific research involved: For one thing, this is so far a one-of-a-kind study, the first one to look at the effect of MVM for women already diagnosed with breast cancer. At least one comparably reliable study needs to confirm the results.
For another thing, and more fundamentally important, the connection between various forms of cancer and taking vitamins has a long (three or more decades) and decidedly mixed history. It’s a difficult thing to study because with very few exceptions, scientists don’t know exactly how vitamins and minerals affect cancer. That is, at the biochemical level, they have only worked out some partial and mostly unproven explanations for how particular vitamins (or minerals) might have some beneficial effect on cancer.
Without confirmation of how vitamins and minerals work against cancer, what most studies provide is a correlation between taking them and good – or not good – results. And yes, there have been studies with a negative correlation between vitamins and cancer. A study reported in 2010 of more than 35,000 Swedish women seemed to show that women taking MVM were 19% more likely to develop breast cancer.
This study also adjusted for a variety of factors, which did not change the results. What this study went on to work out was that some vitamins/minerals such as folic acid, iron and zinc have other studies linking them to breast cancer – but again, these are correlations, not proven causes.
In the past few years, there has also been considerable controversy specifically over the value of vitamin D and the treatment of breast cancer. Some early studies show a correlation, but detailed studies such as one at Columbia University in New York (2013) failed to find a “causal relationship,” meaning that they could not pinpoint a particular effect of vitamin D at either the genetic or biochemical level. In short, this report concluded, “…there is still insufficient data from clinical trials to make recommendations for vitamin D supplementation for breast cancer prevention or treatment.”
Much the same can be said for the general correlation of MVM supplements. As the lead researcher of the new study, Sylvia Wassertheil-Smoller of the Albert Einstein College of Medicine at Yeshiva University (New York), pointed out, “We don’t know the full affect [of vitamins and minerals]. We only had 321 [women, out of 7,700] that started taking the vitamins after diagnosis. So, we don’t have the data basis to change the treatment [recommendations].”
In the ancient and honored tradition of science, this means more studies are needed.