Stephan van Vliet – The first randomised clinical trial comparing agro-ecological grown and supermarket food

A conversation with Stephan van Vliet, assistant professor of nutrition studies at the Center for Human Nutrition Studies at Utah State University, about nutrient density food, human health and the world’s first randomized clinical trial of 14 weeks comparing a whole diet of supermarket food vs food grown using agro-ecological and regenerative practices.


This episode is part of the Nutrient Density in Food series!
This series is supported by the A Team Foundation, who support food and land projects that are ecologically, economically and socially conscious. They contribute to the wider movement that envisions a future where real food is produced by enlightened agriculture and access to it is equal. The A Team are looking to make more investments and grants in the space of bionutrients. You can find out more on

Stephan van Vliet is one of the leaders in the scientific world when it comes to measuring nutrient density and connecting that to soil health and importantly human health.


You can definitely taste the difference between food bought at farmers’ markets to food from grocery stores. And part of that is because the latest is probably grown in ways that do not maximize carotenoids or do not maximize flavonols in the polyphenols in the strawberries, for instance, which we know are higher when they are grown in more agro- ecological ways. People lost touch with what real food is supposed to taste like. You can taste many of these phytochemicals. These are flavour compounds and you can taste that.

“If you go to the farmers market, and you buy a carrot, just a raw carrot, sinking your teeth in that it’s just chock full of flavour, and you can really… it just tastes amazing, and the same with a fresh strawberry or something like that. And then you go to the grocery store, and you eat a carrot or a strawberry, it’s like water with a slight hint of carrot flavour or water with a slight hint of strawberry flavour.” – Stephan van Vliet

“Maybe they were able to see the difference even because the carrots that we get from the agroecological farmers, they’re not the prettiest ones […] they will never be shown in the sales. When we talked to the participants, all these participants are saying, ‘Wow, I feel so much better. I can’t believe I didn’t do this earlier in my life.’ – Stephan van Vliet

“Let your palate also guide you a little bit because if you look at a carrot, you can’t measure the nutrient density. But if you go to a farm or a farmers market, or even in a grocery store, you can definitely taste the difference in some of these.” – Stephan van Vliet


One of the problems is that, at the moment, we are paying farmers for yield and not for nutrient-density food. There’s not enough incentive for the farmer to maximize nutrient density. We live in a capitalistic society. So there has to be some sort of financial incentive.

“One tiny example is that if you have a blueberry that is five times more rich in polyphenols than blueberry B… let’s say you grow blueberries in agroecological ways, five times more phytochemicals than blueberry grown in conventional ways. When the farmer goes to sell that, you’re going to get paid for yields, not for nutrient density. Even though that other blueberry might be twice as expensive and contain five times more phytochemicals, that’s not what you’re being paid for, you could eat five times less and get the same amount of phytochemicals.” – Stephan van Vliet

“I think we need to come up with biomarkers or methods that we can easily test that, and we’re definitely working on that as well. And then, of course, it’s going to take an overhaul on sort of the institutional and government level where we start to value that more and start to pay more for that. The initial step is to make sure that we don’t greenwash of course, and that the nutrient density piece becomes or remains evidence-based.” – Stephan van Vliet


The study, one of the first to make the connection between human health and food, involves seven weeks of consuming fruits from agroecological farming systems versus the conventional non-organic farming system. When we look at healthy soils, healthy plants, healthy animals and even healthy foods, the connection is a lot easier to make. But, once you get to the human piece, it becomes incredibly challenging because we’re so diverse in our diets and in our lifestyles, compared to other animals.

“We source all of our foods from regenerative farms for the agro-ecological diet and for the conventional produce is just bought in the store of non-organic produce […] that’s what someone would normally get at the moment in most grocery stores.” – Stephan van Vliet

“The way that we control it is that we provide people with all of their food. So, every piece of food that they eat for 14 weeks, 7 weeks on each diet, so, it might be a conventional onion versus an agroecological grown onion, the participants cannot tell the difference […] So we provide them with all their foods and people make them at home according to their liking. But on both sides, we asked people to prepare these foods in a similar way […] The participant is blinded to it. So, they don’t know what they’re getting at the end, so we let them guess, what they ate. And we have a bunch of questionnaires asking what you think about the taste, flavour. How do you feel? And things like that…” – Stephan van Vliet


Koen and Stephan also talked about:

  • Lab-grown meat
  • The scalability of fully-grass-fed farms
  • Phytochemical richness and phytochemicals in grass-fed beef.




Feedback, comments, suggestions? Reach me via Twitter @KoenvanSeijen, in the comments below or through Get in Touch on this website.

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The above references an opinion and is for information and educational purposes only. It is not intended to be investment advice. Seek a duly licensed professional for investment advice.

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