Kees de Graaf passes on the baton. "There’s still a lot to do when it comes to enjoyable, healthy food"

June 28, 2022

Kees de Graaf, professor of Sensory Science and Eating Behaviour, has said farewell to Wageningen University & Research after decades. During his career, he became an expert on eating behaviour and, bluntly but modestly, denounced several key points regarding nutrition and health. “Health is not just about having the right blood pressure or wanting to live longer.”

When you say goodbye to a professor of nutrition, you might expect a heavy story about obesity and processed food. This is not the case with Kees de Graaf. When it comes to talking about eating healthily and sweet things, he comes to life. “Eating badly makes you grumpy; eating well makes you happy,” he says with a smile in the Helix building on the WUR campus, shortly after giving his farewell address. “They grasped this a little better in France than in the Netherlands. Health is not just a physical thing, such as correct blood pressure, but also a psychological thing. People who enjoy eating are happier. ‘You are what you eat.’ This also plays a role in health.” The chair where he was a professor, Sensory Science and Eating Behaviour, is located at that intersection. It is about health, but also about psychology, biology, taste, and wellbeing.

Health is not just physical, but also a psychological thing
Kees de Graaf, professor of Sensory Science and Eating Behaviour

Children's vegetable preference

One of the first studies in which De Graaf participated, twenty years ago, was research into children's vegetable preference. Can children like vegetables and develop a preference for spinach or lettuce, for example? “We've done a lot of studies on this with babies, toddlers, and children. This wasn’t easy, but a lot of fun to do. It has not been possible to get children to develop a preference for vegetables. Vegetables can be experienced as tasteless. That's why it's good to do something with them and mix other things with them, mashing them or making a soup or a curry. It would be nice to develop soups for kids because I think we should not ignore the convenience of ready-made options for parents.”

Another fun discovery from that time: kids who like sour also seem to be more adventurous. “Beside choosing sour tastes, they more often chose an unknown candy over a vanilla candy. They seek the suspense.”

Photo: Guy Ackermans
Photo: Guy Ackermans

A better quality of life for the elderly

As well as researching eating behaviour in children, De Graaf has also been extensively involved with the elderly. “Elderly people often find it difficult to eat. In initial studies, we tried to make food for the elderly tastier by enhancing the taste. However, that was too simplistic. Just adding something doesn’t help. Taste and smell issues are tricky. An olfactory and taste centre was therefore set up at Gelderse Vallei Hospital. Now there is a place where people with these issues are taken seriously, which is very positive. There is smell training and medication if needed. New studies are emerging from this center.”

A study in nursing homes was one of the best I've done
Kees de Graaf, professor of Sensory Science and Eating Behaviour

A study that immediately yielded positive results took place in nursing homes. “One of the best studies I've done,” says de Graaf. He and his group investigated whether the elderly ate better when they ate together and in a pleasant environment, instead of in their room. That helped. “When they ate at the table rather than off a tray and used real cutlery, plates, and glasses, the elderly ate more and were happier. In short: better quality of life.” Many nursing homes have taken the results into account.

Sweetness is not the culprit

Paying attention to food and eating well is important. At the same time, De Graaf thinks that some things are under a magnifying glass. “Pure, unprocessed, no additives, and fresh are terms lots of people use to describe eating well. And let’s not forget no sugar and reduced sugar. However, I think these things are relatively insignificant compared to the important, major risks that can affect your health. The main reason for being overweight is eating high-energy food too quickly.”

Photo: Guy Ackermans
Photo: Guy Ackermans

The issue here is the so-called energy intake rate. “‘Apples and spinach do not make you put on weight, because they do not contain much energy per gram and you eat them slowly. The foods that have the most effect on your weight are the products that you just wolf down such as sugary drinks and, for example, sausage rolls, which are easy to eat and contain lots of calories. Plus, because they are in your mouth for such a brief amount of time, no signals of satiety are passed on to your brain.”

The taste mainly influences what food you choose afterwards, not your weight
Kees de Graaf, professor of Sensory Science and Eating Behaviour

This is because it isn’t only fibre that provides satiety, but also taste. “You can't eat too many sweet things in one go. The sweet taste transmits signals of satiety. It is therefore a misconception that you will eat more because something is sweet. At some point, you won’t want any more sweet things. You don't want more sweet after sweet. Sweeteners are therefore not necessarily a bad thing. It's time to stop placing the blame on sweetness.”

Thirty years ago De Graaf was already studying sweet things. “After eating sweet carbohydrates, the test group ate less sweet things. After something savoury, they ate less savoury. The taste mainly influences what you choose afterwards, not your weight.” A study is currently underway at WUR into the effects of giving a test group foods that are very sweet and food that is not very sweet. De Graaf confidently predicts the outcome: “The participants won’t put on weight because of the highly sweet aspect.”

Affordable food through mass production

Besides the fact that De Graaf is not against sweet things, he is also not against processed food, which was the last point in his farewell speech. “I see processing as a neutral term. It is very often necessary. Think of tomatoes grown in a greenhouse, grown until they are flavourful and contain less water: is that unprocessed? A sandwich from the supermarket that has a lot of added fibre has also been processed. That's why I think waging a crusade against processed food is crazy. He says that we need processing to produce food for everyone. “Mass production ensures affordable food. You should not underestimate how important cheap food is to many people. That's why I'm not really with the romantic idea of unprocessed food. This idea doesn’t fit the daily reality for many people.”

Processing is also often necessary for products to have a long shelf life. Food colourants are also necessary to make products more attractive. De Graaf sees nothing wrong with this. “What else do you want? Food with a shorter shelf life that is less appealing and more expensive? What's wrong with easy and cheap?” However, he does accept that there is also deception in the industry. “Guacamole with only a few percent avocado, for example. I don't like that. The TV programme Keuringsdienst van Waarde (inspection of goods) often exposes such things. But as I said, for lot of people it is important that products are affordable.”

Healthy, tasty, and affordable

However, couldn't purer food be made more affordable? “The offer has to be healthy. I side for that. A sausage roll for 1 euro is not okay. There must be alternatives. The government could do more about this. However, I do think it should be enjoyable. When it comes to consumers making food choices, taste is number one. That will stay that way. There is still a lot to be learnt when it comes to creating healthier products with limited energy intake, that also makes people happy. Dr Forde, my successor, has an inspiring vision for the field.”

What does De Graaf intend to do with himself in the future? “I will gradually slow down. I plan to do a lot of sports, read a lot, and travel. However, for the moment I am supervising a number of PhD students and I am still working on two major projects.” One of these projects concerns food processing and not surprisingly the other is about sweetness.