Should Grandma take a multivitamin?
I read medical and chiropractic journals and research articles every day. I do it to stay on top of the latest research and I pass the relevant pearls of wisdom onto my chiropractic patients. Today I read an article that will definitely be passed on but with the ‘junk-science’ qualification.
A study published in Arch Intern Med. 2011;171:1625-1634, attempts to draw a conclusion that taking vitamin supplements has a negative effect on life expectancy in older women. So does that mean that the vitamins Grandma is taking will shorten her life? Unlikely.
The framework of the study is so weak, it should not have been published. There are a number of problems with the study. The first problem I see is that the participants self-reported their supplement use and the reporting was only collected 3 times in 22 years. How reliable can the data be when it is that sketchy?
The statistical analysis was pretty weak. Their use of the numbers showed that the use of multivitamin supplements increased the risk of death by 2.4%. The risk of certain specific supplements was also considered. Copper supplementation has an increased risk of death by 18%. The authors of the study failed to consider this very important question: “Why were the supplements being taken?”
If someone is supplementing copper, they are doing it for a reason. The most likely cause is grey hair, or iron metabolism. In a word, anemia. So Grandma has a disease which is causing anemia, she reads about copper in some self-help magazine. She decides to give it a try to help her manage her disease. Maybe the copper helps, maybe it doesn’t. Grandma dies a few years earlier than she would have. But she dies due to the loss of life expectancy from the anemia, not the copper supplement. The authors of the study would have us believe that the copper supplement did her in. They only reported that Grandma died, not the cause of death. Grandma could have died from an infected blister she got while running a marathon and it would still be counted as death while taking vitamins.
That is the major problem with the study. The authors needed to ask why they participants were taking supplements and eliminate participants if they had a disease process that was being treated with supplements.
Another major flaw in the study is just the dynamics of the individuals who take supplements. The study does admit that the participants who used vitamins were more physically active than those who didn’t supplement. That is a risk factor for early demise! People who are more physically active simply have greater risk exposure. As an example, Grandma and Grandpa enjoy outdoor activities. They drive to the golf course 2x/week. They drive to the bocci-ball court 1x/week and they drive to the pool 2x/week. All that time in the car is risk exposure. Increased car-time means increased risk of accident and hospitalization.
In addition to the car time, there is a certain amount of inherent risk with physical activity. If Grandma is playing golf twice a week and injures her shoulder, she might need a doctor visit to get some anti-inflammatory drug. Taking those drugs have a dramatic risk for death.
Maybe Grandma’s knees are bothering her during her golf game and she decides to go in for a knee replacement surgery and she dies on the operating table, or from a post-operative infection, or some other known risk factor.
The point is, the conclusion that taking a multivitamin is associated with an increased risk of death is just absurd. Connecting the two events in this study is junk-science.
Featured image courtesy of FreeDigitalPhotos.net and Serge Bertasius