Sustainable diet: more than just eating less meat

It wouldn’t have made much difference if Renée Cardinaals (31) had started studying equine sciences. She rode horses, never felt as comfortable as with animals in nature, and was at the riding school almost every day. “But for that study I had to go to Vienna, and I was a bit afraid to go to a big city.” And so she chose animal sciences in Wageningen.

“Gradually I started to find it more and more strange to sit on an animal and determine what it should do.” She already did running, and she continued to push her limits. Now people are more likely to know Renée Cardinals as a trail runner – she was on the cover of Runner’s World – than from her research into eating patterns that are healthy for people and the planet. Yet she excels in both: she is the Dutch champion in trail running, running on unpaved paths, and was the best Dutch woman at the World Cup ‘short trail’ (45 km) last year. And she recently received her PhD with honors.

It seems simple: healthy and sustainable usually go hand in hand. Less meat, more plant-based and consuming less food all helps. “If the whole of the Netherlands follows the Wheel of Five, you will make great strides in terms of sustainability. But many people find it difficult to understand what ‘just healthy eating’ means. Is a little meat good or not? Or you hear: no red meat, but milk. And does it have to be raw milk?”

In broad terms it is correct, but not always the healthy choice is also the most sustainable, and vice versa. Cardinals investigated to what extent an eating pattern that remains within the limits of the planet is also optimal for people’s health. This is how she ended up in a web of complex models with different assumptions and indicators. It was clear: a diet that reduces the environmental impact of… production takes food as a starting point, is difficult to compare with a diet in which healthy consumption are central.

The concept of a sustainable, healthy diet seems clear. But it matters what the starting point is: do you calculate what the most sustainable agricultural system would be and follow from that what we eat, or do you optimize the human diet separately from the production system?

Researchers who look at the production side calculate with biomass flows and CO₂emissions or land use per kilo of beef or wheat produced. “But with animal production that is optimal in terms of environmental impact, you will encounter health issues.” Not in Western countries, but beyond, deficiencies of calcium and vitamins B2, B3 and B12 are lurking if little meat, dairy and eggs are produced and eaten.

Cardinals also looked at bioavailability – the extent to which the body absorbs nutrients – and that makes everything even more complex. “We can also get almost all the nutrients from animal products from plants. And plants also provide good things that animals do not provide – such as fiber and antioxidants. But for some nutrients you have to eat large amounts of plant-based foods to get enough. That is not realistic for everyone. And how much land do you need to produce those amounts?”

Meat and milk dilemmas

She concludes that the environmental impact of a healthy diet is greater than previously thought, because much larger quantities of grains and vegetables must be grown to meet actual nutrient needs.

At the same time, Cardinals puts the focus on nutrients into perspective. Red meat, for example, is a good source of vitamins, iron and zinc. But too much meat increases the risk of certain types of cancer, type 2 diabetes and cardiovascular disease. Healthy food is more than the sum of nutrients. And you quickly encounter dilemmas. “From a health perspective, you would say: don’t eat red meat. At the same time, it is recommended to drink milk, if only because of calcium for healthy bones. But keeping cows for milk and then not eating the meat does not actually fit in with sustainable, circular agriculture.”

How much milk fits into a healthy and sustainable diet depends largely on methodological choices: if you only look at the emissions of milk compared to legumes, you will end up lower than if health is leading, or if you take circular agriculture as a starting point. It becomes even more complex if you take a systems approach and try to put everything into one holistic model.

“Animals can therefore have a place in the food system,” says Cardinaals. “But different than now.” For example, by feeding cows and goats only with residual flows from arable farming or the food industry, or letting them graze in places where nothing else grows, such as in the mountains or peat meadow areas. In such a system, you no longer use land where you can grow vegetables, fruit and potatoes for animal feed. “In this way you free up more agricultural land for human food, and thus increase food security.”

A separate study devoted Cardinals to fish. “Half of the catch is now not used to feed people,” she says. “It is thrown overboard as bycatch, ends up in animal feed, or is seen as waste.” People can eat twice as much healthy omega-3 fatty acids, Cardinals calculates, as all that fish can be eaten by people.

Many PhD students hesitate to give their opinion, or to say something that falls outside the lines of their own research. Cardinals also dares to rise above it all and reflect on its contribution to science. “My supervisor, Hannah van Zanten, also said: a good final chapter is not a summary of your research. I am encouraged to think beyond that.”

Hyperfocus on protein

For example, she is critical of the protein transition, the shift from animal to vegetable protein. “Because of the hyperfocus on protein, it seems as if that is the problem. As if there is a threat of protein shortages in the Netherlands. The protein transition is intended to get people to eat more legumes and nuts, but I am afraid that the emphasis on protein will hinder progress.”

For example, look at meat and dairy substitutes. “They can help consumers reduce their environmental impact, but from a health perspective, veggie burgers are not where we should be going.” Producing this type of highly processed food requires energy and packaging materials. In low-income countries, it is also questionable whether people have access to these substitutes, she says. “A cow in the backyard is more accessible than a plant-based burger. And a cow in the meadow also has cultural value,” she says. “An animal is more than a packet of protein.”

She gets it – from one protein to another, people still understand that. “A radically different diet is much further away from us,” says Cardinaals, “and that demands a lot from consumers. But now we are putting a band-aid on a problem that we do not really want to face. Just as electric cars are a band-aid for the problem that we simply drive too much.”

She mainly owes her PhD cum laude to her broad perspective. “I also wanted to understand the connection with topics in which I am not an expert, and I spoke to many people who gave me new ideas.” And yet she managed to write her dissertation in four years.

One of her statements was that ultrarunning in the mountains helps you get promoted faster. “You learn that setbacks are temporary, you can always work through them. That made the bumps in my research smaller and irrelevant compared to the physical challenges you encounter as a trail runner. I don’t freeze when things get difficult. Just put one foot in front of the other and you’ll get to the finish line.”

She wants to continue her research as a freelance consultant in the near future. That gives her the space to do what she has dreamed of for a long time. “I would like to live in the mountains for a while and see how far I can go with my sport. There is now a campaign to get trail running at the Olympic Games in Brisbane. Even if I turn out to be too old in 2032, I can still train for it and promote the sport.”

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