How effective are multivitamins

Food supplements: Does a person even need vitamin pills?

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Quickly add a multivitamin preparation to the shopping cart and then go to the checkout: Dietary supplements have become a lifestyle product that has long been available in drugstores and supermarkets. A tablet should often contain all the vitamins or minerals the body needs. The most important things in vegetables and fruit are pressed together to form an uncomplicated guarantee of health. At least some manufacturers of vitamin preparations and other dietary supplements promise this. And according to statistics, a lot of Germans seem to believe them: 165 million packs of dietary supplements are sold every year, around 30 percent of adults in Germany regularly take supplements that contain vitamins or minerals. Magnesium sells best in this country, followed by calcium and iron. But what do the pills do? Or do they even harm?

First of all, it is correct that the human body needs minerals such as magnesium or calcium and vitamins on a regular basis. In addition to cramps and muscle twitching, a tangible deficiency can also lead to fatigue, gastrointestinal complaints and cardiac rhythm disorders. Only: "In Germany there is usually no shortage," says Christian Sina, Director of the Institute for Nutritional Medicine at the University Medical Center Schleswig-Holstein in L├╝beck. Even if you don't eat fruit or vegetables every day, you usually get enough vitamins, trace elements and minerals from your diet.

Only a particularly low-micronutrient and one-sided diet - frozen pizza and toast with Nutella, for example - over a longer period of time can lead to deficiency symptoms that have a negative impact on health. But even if it does get that far, the pills are of no use: "Such deficiencies can hardly be prevented by dietary supplements, because they can never replace fruit or vegetables," says Sina. The reason: It's not about individual vitamins or minerals. "In many types of vegetables there are more than 400 ingredients that are important for the body. Vitamins only make up a small part of that," says Sina. Secondary plant substances, fiber, minerals and trace elements are also important for the body - and many of them cannot be "packaged" in food supplements.

No use in large studies

So is it all pointless with the colorful pills? Not quite. After all, food supplements contain at least a fraction of the substances that are important for the body. But the next difficulty: do they even reach the body in order to develop their effect there? Because whether and to what extent the substances are absorbed in the gastrointestinal tract depends on many things. About the preparation, for example, but also about how old you are, what you eat and drink before and after taking the tablet. For example, high-fat foods can hinder the absorption of calcium and magnesium in the gastrointestinal tract, while in turn they promote the absorption of fat-soluble vitamins.

Even so, over the past few years, researchers have conducted hundreds of studies to determine whether dietary supplements and vitamin pills have a positive effect on health (e.g. PLoS One: Anders & Schroeter, 2017 or: JAMA: Rizos et al., 2012) A task that is anything but easy, partly because clear cause-and-effect relationships can hardly be determined due to the many influences on illness and health. And because the diet is very difficult to control anyway. Taken together, the result is sobering: The majority of studies show that the intake of food supplements cannot be equated with the intake of corresponding substances in a natural way, e.g. in fruit or vegetables. No additional benefit was found in larger studies. The consequence: "We now know that the substances from dietary supplements should not be equated with naturally occurring substances," says Christian Sina.