Study: Increased mortality risk from multivitamins?

It is hard to imagine supermarkets and pharmacies without multi-vitamin supplements. Many people reach for them in the hope of improving their health and perhaps even extending their longevity. However, a new study has cast doubt on the effectiveness of these little helpers.

What is the real story? This article draws on another very interesting analysis by Peter Attia.

The study: Multivitamins and mortality

A recently published study examined the data of more than 390,000 adults in the United States over a period of several decades. The researchers wanted to find out whether regular multivitamin intake was linked to a longer life expectancy. The result: people who took multivitamins daily had a 4% higher mortality risk than people who did not take multivitamins. Sounds alarming, right? Not so fast.

The study: biases and limitations

The study is prospective cohort study. Such studies examine changes in participants over time and can be divided into dynamic, open and closed studies, as well as prospective and retrospective approaches. While prospective cohort studies are considered the gold standard because they are more likely to reveal causal relationships, they are time-consuming and resource-intensive.

Prospective cohort studies are extremely complex and can often be misleading if the results are not examined in detail. When assessing the validity of such studies, particular attention should be paid to bias, as it can distort the true relationship between variables. Known biases include sick user bias and healthy user bias. Both can distort the validity of studies by creating misleading associations between a treatment or behavior and health outcomes.

In this study, the intake of multivitamins (MV) was associated with a slightly increased risk of mortality, but this could be due to the fact that people with a poorer general state of health start taking multivitamins, which gives the false impression that vitamins increase the risk (“sick user bias”).

At the same time, study participants who choose to take multivitamins may already be more health-conscious and exhibit other healthy behaviors that may affect their overall health independently of the multivitamins. This poses a challenge when it comes to separating the effects of multivitamins from the effects of a generally healthier lifestyle. This phenomenon, whereby healthier people are more likely to adopt healthy behaviors, is known as the healthy user bias.

Both biases can significantly relativize the study results, and it is hardly possible to control all influencing factors in a single study. The selection of study participants also plays a role: in this study, people with severe pre-existing conditions were excluded. This meant that only very healthy older people were examined, which could have further distorted the results.

What does this mean for you?

Just because this study found no positive effect of multivitamins on life expectancy does not mean that multivitamins are useless. They can still play an important role in health care, especially when there is a deficiency. For people who cannot always eat a balanced diet, multivitamins can be a useful supplement.

"Are multivitamins the be-all, end-all key to longevity? Certainly not. But whether or not they move the needle in this regard remains an open question – and this present study did little to add to the conversation." Dr. Peter Attia M.D.

Although this study raises doubts, the question of the benefits of multivitamins for longevity remains open. More research is needed to find out under what conditions and for which groups of people multivitamins can actually be helpful.

The details of a study are what count

Even if the current study could not prove that multivitamins prolong life, that does not mean that they are not useful. Rather, it shows how important it is to critically examine study results and pay attention to details. This is the only way to get a complete picture and decide whether multivitamins are useful for you.

Assessment matrix of the study

Would you like to find out more? Then we recommend the following:

• A recent study does little to supplement earlier knowledge on multivitamins and health | PETER ATTIA (August 10, 2024)
• Multivitamin Use and Mortality Risk in 3 Prospective US Cohorts | Nutrition, Obesity, Exercise | JAMA Network Open | JAMA Network