July 13, 2026, 2:14 am | Read time: 4 minutes
Around 500,000 people in Germany are newly diagnosed with cancer each year. Time and again, we hear about universal miracle diets that are supposed to prevent cancer. “A misconception,” says renowned French oncologist Prof. David Khayat to FITBOOK. Everyone processes food differently. According to Khayat, about 40 percent of cancer cases are preventable through small, realistic, and sustainable steps.
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FITBOOK: There are many myths about cancer. Which ones are particularly persistent?
Prof. Dr. David Khayat: “There are many myths about cancer. One of them is the notion that cancer is a kind of punishment—either from God or for some supposedly wrong behavior. Another widespread misconception is the belief in a universal anti-cancer diet. That’s not true. We are all different. Each person has a different genome and therefore different enzymes. That’s why we process food differently. Some people can consume dairy products without any issues, while others are intolerant or sensitive to lactose. The same goes for spices and many other foods. Moreover, we never consume just a single nutrient. We always eat combinations of foods, such as carrots with meat. We still don’t know everything about the interaction of different nutrients. The best advice for people who want to reduce their cancer risk through diet is to eat a balanced diet, enjoy everything in moderation, prefer seasonal products, and ensure a wide variety in their diet. Following the seasons has accompanied humanity throughout its history and has significantly contributed to its survival.”
»About 40 Percent of All Cancer Cases Could Be Prevented by Changing Certain Lifestyle Factors
More and more people are monitoring their health with smartwatches and other wearables. Does this self-monitoring possibly distract from important cancer prevention measures?
“I think that’s indeed the case. Many people lose sight of the truly important measures for early cancer detection and prevention because they focus too much on their devices’ data. This often creates significant pressure and can cause anxiety. This additional stress can, in turn, be harmful to health. Yet, about 40 percent of all cancer cases could be prevented by changing certain lifestyle factors! However, recommendations often meet resistance when they consist solely of prohibitions or largely restrictive demands. That’s why we should focus more on small, realistic, and sustainable steps. It’s about limiting harmful habits and promoting positive ones—not about completely banning everything that has been part of life so far.”
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Which trends in health and longevity research do you currently consider particularly significant?
“I would name two developments in particular. The first is the biology of aging, including the role that dietary supplements can play. The second is the growing understanding of the importance of the microbiome. The various microbiomes in our bodies—such as in the mouth, lungs, or gut—are being intensively researched. Every day we understand better how important they are for our health.”
Which development in the field of longevity excites you personally the most?
What fascinates me most is research in the field of neuro-psycho-immunology. It explores the connections between our thoughts, our feelings, and the biological mechanisms that influence health, resilience, and ultimately survival.”
»Life Is a Precious Journey! Let’s Use This Gift Every Day
When you look back on your life and career, would you do anything differently?
“No. If I could live my life over again, I would choose the same path. I have enjoyed my life on most days. If there is one lesson I can draw from the thousands of patients I have lost in my 45 years as an oncologist, it is this: Enjoy your life. Life is a precious journey. If we are fortunate enough to be in relatively good health, we should use this gift every day. We should consciously experience the beautiful moments, share them with the people we love, and shape our lives with enthusiasm, commitment, and motivation. Then we can wake up in the morning and look forward to another day in this wonderful life.”