Are you about to make a “green smoothie” and you don’t know which liquid to choose? If you’re hesitating between cow’s milk or a plant-based soy drink, here’s a tip for make your green juices (even) healthiereven if they are already filled with spinach, kale or other leafy vegetables.
According to a study by researchers from Linköping University in Sweden published in the journal Nutrients, certain liquids would indeed further increase the levels of lutein naturally present in these vegetables. But what is it ? Lutein is an antioxidant that notably reduces cell inflammation, a major risk factor for diseases such as cardiovascular disease or certain cancers. It also helps keep your eyes healthy. The body cannot produce it on its own, hence the need for supplementation.
This is how you mix the healthiest #smoothies with spinach, according to new #research at Linkoping University.
The unexpected discovery – do not use soy milk. pic.twitter.com/mTtu1zDHDh— Linköpings university (@liu_universitet) May 2, 2023
And depending on the type of liquid chosen for your smoothie, the lutein level may be reduced. Researchers looked at the effects of 14 plant-based dairy products and drinks on the amount of lutein after mixing them with spinach. They then added digestive enzymes to the mix, to simulate human digestion.
Result ? Lutein levels were highest in smoothies made with coconut milk (42% increase in lutein) and were closely followed by those made with cow’s milk (36% increase). In total, only 4 of the 14 products increased the release of lutein from spinach compared to water.
Conversely, preparations based on vegetable drinks with oats and almonds were little better than water, and resulted in only a weak release of lutein. Yogurt also did not give good results: fermentation could prevent the release of lutein.
Avoid soy drinks
“We could see that only 4 of the 14 products examined increased the release of lutein from spinach compared to water. High-fat cow’s milk and coconut milk enhance lutein release. However, yogurt, which is considered comparable to cow’s milk and is often used in cafes and the like, did not perform particularly well.“, says Rosanna Chung.
Even more revealing: in soy drinks – very popular – lutein levels have dropped. “In other words, soy milk had a negative effect on lutein release in our study.“, explains Jan Neelissen, a doctoral student and one of the researchers behind the study. It would therefore be better to use water than plant-based vegetable drinks, which have “a negative effect on the release of lutein“.
Finally, the researchers recommend consume your smoothie as soon as possiblelutein breaking down relatively quickly.
Sources:
- The Effects of Dairy and Plant-Based Liquid Components on Lutein Liberation in Spinach Smoothies, Nutrients, February 2023
- The best liquids to maximize antioxidant content in spinach smoothiesLinköping University, May 1, 2023