'Nutrition should help people get the best out of themselves'

For Witkamp, health has always meant more than simply the absence of disease. During his farewell symposium, he spoke about nutrition, medicines, GLP-1 agonists and the future of nutritional science. Yet all those topics revolved around the same central theme. “How can we use nutrition to help people get the best out of themselves?” he says. “Health is the ability to adapt to changing circumstances. Nutrition cannot simply cure someone who is seriously ill, but it can help them become healthier overall and thus better able to cope with their situation.”

This broad perspective on health and nutrition led him from pharmacology into nutritional science. After studying biology and pharmacy in Utrecht, he spent many years at TNO, where he gradually moved closer to nutrition research. “At one point they were looking for someone who understood both worlds. That’s how I was drawn into nutrition.” The combination proved fruitful. While pharmacology mainly focuses on treating disease, nutrition aims to strengthen health, he argues. “Lifestyle is incredibly important, but it is not a medicine. We need to keep that distinction clear.”

At Wageningen, Witkamp and his colleagues built a research group that developed into an internationally recognised force in nutritional biology. Yet, he prefers to talk about the people around him rather than his own achievements. “What am I most proud of? The group. People who share ideas, support one another and explore new directions together.” Their collaboration produced a wide range of scientific breakthroughs.

One of the issues Witkamp was particularly passionate about is something that receives relatively little attention: the impact of medication on patients’ nutritional status. “Doctors often know a great deal about how food affects medicines. Grapefruit, for example, can influence the action of certain drugs. Much less attention goes to the reverse question: what do medicines do to a patient’s nutritional status?” Antacids can reduce vitamin B12 absorption, eventually leading to a deficiency. Because the symptoms resemble normal ageing, doctors do not always make the connection. “That’s when you realise how important nutritional knowledge remains.”

Witkamp also spent much of his career exploring connections across disciplines. His research group helped show how nutrients influence the endocannabinoid system, a regulatory system first discovered through research into cannabis, but now known to play a key role in appetite, metabolism and inflammation. He also studied muscle wasting in cancer patients and developed nutritional strategies to help people maintain their physical condition and quality of life for as long as possible. “Sometimes you cannot cure a disease,” he says. “But you can add health to illness.”

In his farewell lecture, Witkamp also addressed another topic with major societal implications: GLP-1 agonists. The weight-loss drugs, better known by brand names such as Wegovy and Ozempic. He believes these medicines will fundamentally reshape the world of nutrition in the years ahead. “It seems as if pharmacology has defeated evolution,” he says.

At the same time, he sees the rise of these drugs as a reflection of broader societal trends. Their impact will extend far beyond healthcare, influencing what people eat, how food companies develop products, and even how supermarkets and restaurants shape their offerings. “This is not just about obesity,” he says. “It is about the way we approach health, lifestyle and disease.” That is why he argues that pharmacological solutions such as GLP-1 drugs should never be separated from nutrition, physical activity, sleep and other lifestyle factors.

Witkamp also expresses concern about potential long-term effects if large numbers of people use these medicines for extended periods. Muscle loss, nutrient deficiencies and weight regain after stopping treatment all deserve close attention. “But nobody knows exactly what the long-term effects will be,” he says.

After twenty years, Witkamp is leaving his chair, but not the university. He will remain involved in PhD supervision, the BIO-COMPaSS project on healthy ageing, the Institute for Medicinal Cannabis Netherlands (IMC), and the lifestyle intervention organisation Voeding Leeft. The curiosity that first drew him from pharmacology into nutrition remains as strong as ever. And so the same question that inspired him at the start of his career continues to drive him today: how can we help people get the best out of themselves? For Witkamp, the answer still does not lie in a single supplement, food product or scientific discipline. “Health emerges from the interaction between them.”