It is busy on Monday morning in the Turkish restaurant Beymen on the Zuidplein in Rotterdam. The women – and one man – have filled their plates at the buffet and are seated at full tables. Famke Mölenberg sits down with a puff pastry roll with spinach and feta, egg salad, bread, cake, some fruit, a juice and a cup of tea. Without sugar.
Mölenberg received his PhD on environmental interventions to improve public health on 25 June, ways to make the city healthier for Rotterdammers. All in all, we are in her laboratory: her research questions are out there. How can you design the environment in such a way that it invites healthier behaviour, how do you encourage exercise and healthier food? The Zuidplein shows what cities struggle with. The Taco Mundo, Waw Burgers and Vietnamese MeMe are just a taste of the indoor shopping center across the street where the churros, fries, stroopwafels, shakes and döners are flying around you. The first sports and playing field is at least a kilometer away.
The differences between neighborhoods are great on all fronts, says Mölenberg: “If you get on the metro here and get off in the new Nesselande district, you can increase your life expectancy by eight years. The difference in healthy life years between neighborhoods can be up to fifteen years. In one neighborhood one in ten residents is obese, in a neighborhood with a lot of poverty and financial stress perhaps one in four.”
In a fast food paradise, a neighborhood full of unhealthy food, one snack bar probably makes no difference
You can say: that is because of the behavior of individuals. People who smoke, exercise little and eat too much are at higher risk of developing cardiovascular disease or type 2 diabetes. “The assumption is often that you choose what you eat. But it’s not that simple. Marketing is not so successful for nothing. In the supermarket and on the street you are constantly reminded of food and people are extremely sensitive to offers. You have to make an effort not to choose something. And in neighborhoods with the largest supply, resilience to fast food may be the lowest.”
Play areas and snack bars
While doctors and dietitians look at individuals, Mölenberg, as a health scientist, starts from the environment. “If half the population is overweight, you can hardly call it an individual problem. Human behavior is related to their environment. How livable is a neighborhood, are there enough play areas, is there a snack bar around the corner from the school?”
Everyone can see that the city is overrun with donut shops and hamburger chains. But the fact that the advance is so strongly and skewedly divided was not noticed by politicians in Rotterdam until Mölenberg mapped it out. “I saw it as a small part of my research, but for the municipality it was quite a shock: between 2004 and 2020 the number of fast food locations has increased by about half, while the population has only grown a few percent. The number of greengrocers and other fresh food shops fell almost 40 percent. And here again, the differences are most impressive: in neighborhoods with a lower socio-economic status, fast food grows faster, in affluent neighborhoods it hardly increases.”
Mölenberg investigated whether these changes can be related to the weight of residents in those neighbourhoods. “We only saw a small effect in children of less-educated mothers, but we did not find a clear increase in overweight.” So it’s not that bad, you might think. But the reality is more cynical. “In a fast food paradise, a neighborhood full of unhealthy food, one snack bar probably won’t make a difference.”
To get moving
The city is fairly powerless against the snack invasion. However, the municipality is trying to get Rotterdammers moving. Mölenberg investigated the effect of a number of environmental interventions, such as the arrival of a Cruyff Court or Krajicek Playground: will children play outside more often if such a playground is located within 600 meters of their home? “We have linked those playing fields, which have been built over time in neighborhoods where children play less sport, to the data from the Generation R study, a population survey with which Erasmus MC follows the development of more than ten thousand Rotterdam children.”
Again, no unambiguous conclusions, but a number of interesting findings. Children from less wealthy families, in particular, were more likely to play outside when a playing field was nearby: the intervention therefore benefited the children who needed them most. But it is striking: children who played outside more often also started to play games and watch TV more. “Maybe playing outside was rewarded with gaming. Or was the physical effort compensated. There are all kinds of factors that are difficult to get a picture of.”
The growth of overweight and fast food has been going in parallel for thirty years
The criticism of natural experiments is obvious. They do not meet the gold standard of randomized controlled trials, where intervention and control groups were randomly selected and all factors that could influence the outcome were excluded. Hard evidence that cycling paths, top sporting events or playing fields make people healthier is rarely produced by this type of research, unlike when the effect of a drug is tested.
Going through the doors
In addition, the response to surveys is generally declining, and with it representativeness. “You have to keep a close eye on whether certain groups do not get the upper hand. And we will have to look more and more actively for the groups that drop out: going door-to-door, translating questionnaires, so that enough young people and lower income groups continue to participate.”
Mölenberg writes in her dissertation that investigating sudden changes over which you as a researcher have no influence is nevertheless useful and useful. “The confounding factors are a given in natural experiments. The researcher must identify them as well as possible and ensure that the intervention group and the control group are comparable. But if you find something in a natural experiment, you know it works in real life. For individuals, the impact may be small, but for the population, intervention in the environment can yield significant gains.”
During her research, Mölenberg worked one day a week at the Research Department of the Municipality of Rotterdam. “That kept me sharp. I was able to pick up questions faster and bring together knowledge and data from the municipality and the university. And the best part is: the moment you have results, they immediately come to people who can do something with them. They do not disappear in a big publication mill.” Which Mölenberg doesn’t say you can’t do anything without proof. “The growth of overweight and fast food has gone hand in hand for thirty years. If you wait for the best evidence before every intervention, you can never handle it.”