June 3, 2026, 11:34 am | Read time: 4 minutes
More and more people are taking dietary supplements. However, not every product delivers on its promises, and mistakes are often made in their use. At the Life Summit 2026 in Berlin, Germany’s largest longevity fair, FITBOOK Editor-in-Chief Nuno Alves spoke with four experts about which supplements are actually worth considering and what to pay attention to when taking them.
1. Mistake: Following Every Trend
For a few months, all advice and tips online revolved around vitamin D, then suddenly everyone seemed to be talking only about vitamin B12. And what about the perennial favorite protein and the fitness hype around creatine? It’s easy to get swept up in the latest “supplement trends.” Dr. Luisa Werner, an expert in gut health, considers this a mistake. “Many people follow trends instead of their actual needs. They take highly specialized products without having the basics in place. The basics are usually much more important,” she said in a conversation with Nuno Alves of FITBOOK on a panel at the Life Summit 2026. From her perspective, one should first take care of gut health, as only a healthy gut can properly utilize dietary supplements. “For the gut, general nutrition plays the most important role—not a single supplement.”
2. Mistake: Not Paying Attention to Quality
“Another issue is quality,” says Sophie Chabloz, co-founder and chief science officer of the Swiss dietary supplement manufacturer AVEA. “If a multivitamin product is extremely cheap, you should be skeptical. Often, inferior raw materials are used.” When choosing supplements, she advised paying attention to quality assurance. What information do manufacturers provide about ingredients, production, or testing? “Even small differences in purity and processing can significantly affect bioactivity,” emphasized Ari Bizimis, founder of the supplement company Artgerecht.
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3. Mistake: Not Knowing Your Individual Nutrient Levels
The correct dosage is also a challenge for consumers. “Many people combine multiple products and thus take individual nutrients in significantly high doses,” explains Dr. Luisa Werner. “An example is vitamin B6. Excessive amounts over long periods can be problematic.” She advocates for determining your levels before taking dietary supplements. Ronny Szelinsky, a women’s health creator and founder of the company Gethappy, also finds this sensible. “In case of a deficiency, supplementation is always advisable. For the right selection and dosage, such as with magnesium and iron, looking at the exact individual levels is crucial.”
These Supplements Are Taken by the Experts
As experts in medicine and the supplement industry, the four panel participants are much more familiar with the often confusing market for dietary supplements than most people. It is all the more remarkable that they also rely primarily on proven classics in their personal supplementation.
Dr. Luisa Werner revealed that she does not take the same products continuously but regularly adjusts her supplementation based on blood values. Among the dietary supplements she uses most frequently are vitamin D3 and K2, omega-3, magnesium, vitamin B12, and folic acid. She also adds proteins and iron as needed.
Magnesium, omega-3, and B vitamins are also part of Sophie Chabloz’s selection, along with creatine. Absolutely indispensable for her? “Clearly, vitamin D3 in combination with K2. It is practically impossible to get enough vitamin D through diet alone. Even in summer, many people do not reach optimal levels,” explained the trained nutritionist.
Ronny Szelinsky’s supplementation looks very similar. He is particularly convinced that creatine is beneficial—even for women. “We have studied creatine intensively. The positive effects go far beyond muscle building and also affect cognitive performance and especially women’s health.” He also occasionally takes probiotics selectively. However, the foundation remains: “The basis is always diet and lifestyle.”
Ari Bizimis agreed. He is not in favor of taking dietary supplements without knowing one’s own blood values. Only those who know their levels can make informed decisions about which products are actually useful. “I keep it classic: vitamin D, magnesium, and omega-3,” said Bizimis. Otherwise, he takes lactoferrin, with which he is also professionally involved. “Lactoferrin is a fascinating molecule. It naturally occurs in breast milk, supports the immune system, regulates iron balance, and has anti-inflammatory effects.”