Multivitamins are used by one in three Americans to maintain (or improve) health and prevent chronic diseases. However, this consumption is not in line with the recommendations of US health authorities because there is no conclusive evidence of their potential benefits.  

Loftfield et al. conducted a study that is notable for the large number of people studied (some 390,000 people) and the long follow-up time (more than 20 years). The researchers' hypothesis was that the use of a multivitamin complex could reduce the risk of mortality. The result, however, shows that people who take daily multivitamins have a higher risk of all-cause mortality compared to those who do not take multivitamins. This is an increase in risk of only 4% and is not maintained in the second follow-up period of the analysis, which may not be significant at the individual level, but is of great public health importance. At the population level, the risks that have the greatest impact are low risks but affect a large percentage of the population. 

The study of multivitamins is complex because they are used by people who are very concerned about their health and by elderly people with chronic diseases. This new study has taken into account most of the factors that could confound the results found. It may not have been possible to adjust for all of these factors and it would be interesting to know what effect the use of multivitamins has over a lifetime.  

Nevertheless, the results are sufficiently robust to recommend that the population should not consume multivitamins unless there is a specific nutritional deficiency and under the supervision of a health professional. There is ample scientific evidence that the best way to extend life is to follow a healthy lifestyle, including physical activity, a healthy diet, avoiding stress and getting adequate rest. This takes more effort than taking a pill, but in the end it will thank both your body and your wallet. 

Multivitamins are a combination of vitamins and/or minerals that in Europe are regulated as a "food supplement" under the European Union's Food Supplements Directive. It is therefore the European Food Safety Agency (EFSA) that assesses the scientific evidence on the safety of a multivitamin and it is the responsibility of producers, suppliers and distributors to ensure that multivitamins reaching the consumer are safe. However, it is important to note that, as they are not considered pharmaceuticals and are not regulated by the European Medicines Agency, multivitamins can be marketed without clinical trials or scientific documentation demonstrating their efficacy.  

While interest in multivitamin use in Europe is perhaps lower than in the United States, the popularity of the use of dietary supplements has increased in recent years as people have become more concerned about their health and wellbeing. According to survey data from Food Supplements Europe's survey of 13,200 adults in 14 European countries in 2022, 29% of the European population had consumed a multivitamin in the last year and Spain is no exception to these trends, with the food supplement sector expected to have a turnover of 2 billion euros by 2023.    

But is the consumption of multivitamin foods really beneficial to health and prevent mortality? To date, the results from the various scientific studies have been inconsistent. In fact, the US Preventive Task Force (USPSTF) concluded in 2022 after reviewing clinical trials on multivitamin consumption and mortality that there was insufficient evidence to determine the benefits or harms of multivitamin consumption due, in part, to the limited follow-up and lack of external validity of the studies, i.e. the difficulty of extrapolating the results of these trials to the general population.    

Therefore, a group of American scientists have assessed using three prospective cohort studies with a total sample of 390,124 participants whether the use of multivitamin supplements was associated with lower mortality. During the follow-up of up to 27 years of participants, the researchers identified 164,762 deaths. The study used a very robust scientific methodology, taking into account repeated measures of multivitamin use, as well as other information from the participants, including their lifestyles, which could confound the results. The study findings show, with more than 20 years of follow-up, that daily multivitamin use was not associated with lower mortality. In contrast to expectations, the risk of mortality was 4% higher among daily multivitamin users compared to non-users in the initial years of follow-up (adjusted Hazard ratio: 1.04, Confidence Interval 9%: 1.02-1.07). However, despite the follow-up and the exclusion of people with cancer and other chronic diseases at the start of the study, the existence of a possible reverse causality due to the so-called sick user effect cannot be completely ruled out. Nevertheless, the results are clear that there is a lack of efficacy in preventing mortality associated with daily multivitamin intake.    

These results indicate that the benefits of vitamins and minerals present in foods that form a healthy dietary pattern such as the Mediterranean pattern, rich in fruits, vegetables, legumes, nuts, olive oil and fish, have a large amount of bioactive substances that promote health and the absorption of these nutrients. However, if vitamins and minerals are ingested as isolated supplements, the potential interactions and synergies between the different foods present in healthy eating patterns disappear. Multivitamin intake can never replace a healthy diet. While it is true that there are situations in which supplementation is indicated, such as vitamin B12 intake in people who follow a vegetarian or vegan diet, vitamin D supplementation in people with insufficient serum vitamin D levels, the use of multivitamins after bariatric surgery or the intake of folic acid during the first trimester of pregnancy to prevent spina bifida in newborns, always [should be done] under the advice of a health professional.    

In short, if we want to be healthier, it is wiser to spend the money for vitamin supplements on a quality shopping basket with fresh, local, seasonal products that help us to follow a healthy Mediterranean diet and support the necessary sustainability of the rural world.