Multivitamins: deadly or desirable?

A recent study published in the Archives of Internal Medicine led to headlines in news outlets like “Vitamins linked with higher death risk”. The original article was a little less alarmist in its heading, juts being titled “Dietary Supplements and Mortality Rate in Older Women” but it still did draw some disconcerting conclusions about vitamin use. So are multivitamins lethal or not? Let’s dig a little deeper.

The study that has caused the recent fuss was based on analysis of data gathered on more than 38 000 women in the Iowa Women’s multivitamin study. The study authors concluded that “In older women, several commonly used dietary vitamin and mineral supplements may be associated with increased total mortality risk; this association is strongest with supplemental iron.”

The information was gathered between 1986 and 2008 and supplement usage was self-reported by the women involved. This could lead to many errors especially as the average age of the women was nearing 80 at the last checkpoint. The authors of the study themselves stressed that the information relied on the women recalling their vitamin usage. That usage was only checked after lengthy intervals allowing many variations in usage during the intervening periods that may not have been reported.

Aside from the uncertainty surrounding the data gathered there are other factors to consider here. Supplements can interact with medications but no data on these interactions was included in the study. Neither was the initial health of the women recorded so there is no standard baseline of health and cause of death and age at death is not identified. Blood levels of each of the vitamins involved were not checked meaning that there is no evidence on how much of these vitamins were being absorbed into the body.

So we could say that the study design was tenuous but even if you accept the design a new analysis of the same data has come to different conclusions. This new analysis, it must be said, was released by the Nutritional Magnesium Association of the US, so it does not come without bias. However, the researchers conducting the new analysis were Carolyn Dean, MD., ND and Robert G Smith, a Research Associate Professor at the University of Pennsylvania’s Department of Neuroscience and so are not without credentials. This new analysis reported that:
• vitamin B complex use was linked with a seven per cent decrease in death rate
• vitamin D supplementation was linked with an eight per cent reduction in deaths
• vitamin C use was linked with four per cent percent reduction in deaths
• magnesium was linked with a three per cent reduced percent reduction in deaths
• selenium and zinc supplementation also reduced deaths.

Additionally, the new analysis did not deny the risks associated with iron and copper supplements that were revealed by the initial study’s researchers. However, Professor Smith commented in a press release, “Iron and copper supplements, which are known to be potentially inflammatory and toxic when taken by older people, because they tend to accumulate in the body, should not be generalized to imply that all vitamin and nutrient supplements are harmful.”

So the alarmist reporting of this study can be dismissed. People can take vitamins with safety. In fact as was reported by the Journal of Orthomolecular Medicine an analysis of the American Association of Poison Control Centres’ data shows that in 27 years of reporting there have been eleven deaths possibly attributed to vitamins and that all of these eleven cases were more likely not due to vitamins meaning that as the study’s authors stated, “Vitamin therapy is tens of thousands of times safer than drug therapy.”

It is important to remind ourselves of course, that not only are vitamins safe they are efficacious. For instance, a study published in the American Journal of Clinical Nutrition, observed that women with no history of heart disease who used either multivitamins alone or multivitamins in combination with other supplements had a lower risk of heart disease. One study (Vaccine Feb 2005) reported that multivitamin supplementation improves antibody response. Another study (J Am Ger Soc Jan 2004) found that taking a multivitamin improved the immune response of elderly people.

There are so many studies supporting the use of supplemental vitamins and minerals that to begin quoting them seems pointless. It also makes sense that supplements are useful for modern humans. Of course, the ideal scenario is to get all the nutrition that you need from your food. With fruit picked pre-ripening and with crops grown in depleted soils it is hard to find nutritionally rich food unless you are consistently choosing organic. Even then, if you are stressed and exposed to pollutants then your nutritional requirements are increased.

It is not surprising that most people today have nutritional deficits, despite a dazzling array of food being available in countries like Australia. That is exactly why most people will benefit from vitamin and mineral supplements and in most instances they can be taken with complete safety.