John Scharffenberg, physician and nutritionist: "Red meat has heme iron, and that increases the risk of cancer."

He's 102 years old , has an academic career linked to Harvard , and a firm conviction: what we eat determines how we live. Dr. John Scharffenberg , a leading expert in the study of longevity, has dedicated his career to investigating the impact of diet on health. In an interview with Viva Longevity!, he once again issued a direct warning: "Red meat has heme iron, and that increases the risk of colon cancer, diabetes, and heart attacks." His longevity, according to him, is not a coincidence, but a direct consequence of his eating habits.

Heme iron is a type of iron found only in animal products, such as organ meats and red meat. Unlike plant-based iron, it is absorbed more quickly and is not subject to regulatory mechanisms in the body. According to Scharffenberg, this excess can have a pro-oxidant effect, damaging cells and tissues. Even fish, in his opinion, should be consumed in moderation for the same reason: “Even fish has iron… and that also increases the risk of colon cancer, diabetes, and heart attacks.”

Science already supports his statements

Scharffenberg’s warning isn’t an isolated opinion. In 2015 , the World Health Organization classified processed meat as a Group 1 carcinogen and red meat as a probable carcinogen (Group 2A) . The conclusion was based on a report published in The Lancet Oncology , which reviewed more than 800 studies. According to that study, consuming 50 grams of processed meat a day can increase the risk of colorectal cancer by 18% . It also noted that compounds such as heme iron, nitrites, and high-temperature cooking damage DNA.

Although he doesn't consider himself vegan, Scharffenberg follows a primarily plant-based diet. He avoids ultra-processed foods, eats only twice a day, and has eliminated dinner. He claims his good health is not due to genetics, but to his lifestyle. "Some doctors prescribe meat if it's lean... but they shouldn't," he says. He argues that a diet without animal products , or with minimal consumption, is key to preventing chronic diseases . His personal case is living proof of how far the body can go if it's cared for from within.