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Professor of Nutrition Martijn Katan to retire

During his farewell address "In praise of nutrients" on Friday 28 January, Katan will advocate a return to a chemistry-based approach to nutrition research.

Anyone who sings the praises of the Mediterranean diet's health benefits is missing a very important point: whether a given diet is healthy or not depends on the nutrients it contains. Simply saying a diet is 'Mediterranean' is far too vague. If we do not know which nutrients are present in food and their exact function, then we'll just keep hearing new and different dietary recommendations. Martijn Katan will speak on this topic during his farewell address In praise of nutrients on Friday 28 January. He will advocate a return to a chemistry-based approach to nutrition research.

Confusion about weight-loss diets
The confusion about healthy eating is mainly due to the ongoing quest for the ideal weight-loss diet. Previously, dieters were advised to eat a low-fat diet that was high in carbohydrates. These days the advice people receive is precisely the opposite. According to Katan, physical corpulence is in no way related to the choice between carbohydrates or fats. "People eat too much these days because food is good and cheap and easy to get. This is the root cause of excessive caloric intake. The composition of the food is not really a factor at all. There are calories in a healthy diet, too, and eating too much healthy food can also make you fat." 
 
"Eat lots of vegetables" is too vague
The composition of food does have an influence on conditions other than obesity. The role of nutrition researchers, according to Katan, is to discover which substances in foodstuffs have an effect on diseases. This requires chemistry, because chemistry makes it possible to split food into proteins, lipids and vitamins so that experiments can be carried out. Once we discover whether a particular substance is healthy or unhealthy, then a recommendation can be made that will not be amended quite so readily. Vitamin C, for instance, keeps us from contracting scurvy, and folic acid prevents spina bifida in babies. Simply saying "eat lots of vegetables" is too vague, however. Vegetables help prevent high blood pressure, but we do not know which substance in vegetables is responsible for this beneficial effect. This has practical consequences. If the minerals in the vegetables are responsible for lowering blood pressure, then organic vegetables would definitely be better, since they often have a higher mineral content. The effect on blood pressure might also be ascribed to nitrates, and vegetables that are cultivated with lots of artificial fertilizer are rich in nitrates. What is healthier, organic foods or those cultivated using chemical fertilizers?

Seven challenges for nutritional science
Katan advocates a return to the chemistry-based approach to nutrition research, because this will lead to durable recommendations that people can count on. During his farewell address, he will present seven challenges for nutritional science on this very topic. One of Katan's challenges is for researchers to determine whether vegetables reduce blood pressure because of the nitrates they contain from being cultivated using artificial fertilizers.