The researchers have studied various dairy and plant-based products available from food shops.
Newswise — Researchers at Linköping University in Sweden have found that various market products have different effects on the liberation of the antioxidant lutein from spinach in smoothies. Out of the 14 common dairy and plant-based products studied, only four increased the liberation of lutein. Additionally, some drinks had a negative effect on the lutein content in spinach smoothies when compared to water.
Spinach and kale are considered healthy because they contain a substance called lutein. Lutein has been shown in experiments to help reduce inflammation, which is a major risk factor for heart disease.
According to Rosanna Chung, a researcher at Linköping University, lutein is a substance found in spinach that has health benefits. They studied lutein in a similar way to studying a drug and looked at how well it was released from spinach in this study.
Our bodies cannot make lutein, so the researchers wanted to know how to get more lutein from food. They discovered that cooking spinach can decrease the amount of lutein, but blending spinach into a smoothie can increase the amount of lutein that can be absorbed by the body.
The researchers wanted to find out how to get more lutein from foods since our bodies cannot produce it. They previously found that blending spinach into a smoothie makes more lutein available for absorption. However, they also found that the type of liquid used can affect the amount of lutein in the smoothie. Lutein dissolves in fat, not in water. The researchers suspected that food components such as fat, carbohydrates, proteins and fibers can affect how much lutein is available for absorption. They also believed that products like yogurt might have different effects because of fermentation. However, there is not enough scientific research on commonly available products in the market.
The researchers tested different types of liquids, including dairy and plant-based products, to see how they affect the amount of lutein released in smoothies.
To conduct the study, the researchers blended spinach with different dairy and plant-based products. They then added digestive enzymes to simulate digestion in the gastrointestinal tract, before comparing the amount of lutein available for absorption in smoothies made with different products to that in smoothies made with only water.
In the study, the researchers tested 14 different products, both dairy and plant-based, to see how they affect the amount of lutein that can be absorbed by the body from spinach smoothies. They found that only four of these products increased the liberation of lutein from spinach compared to water. Cow's milk with high fat content and coconut milk were among the products that improved lutein liberation, while yogurt did not show particularly good results.
The reason for yoghurt's poor performance in liberating lutein might be due to the fermentation process. Additionally, the study found that plant-based drinks made from nuts, legumes, or oats showed significantly different results compared to other drinks.
The researchers found that soymilk was less effective than water when it came to releasing lutein in spinach smoothies. In fact, it had a negative effect on lutein liberation. Jan Neelissen, a doctoral student and one of the researchers, explained that plant-based liquids are becoming increasingly popular in smoothies, but they had significantly different results.
According to the study, most of the plant-based products examined did not affect the liberation of lutein compared to water, except for soymilk which had a negative effect. Additionally, it's recommended to consume smoothies immediately as lutein breaks down quickly.
The study mentioned in the article only focused on how much lutein is available for the body to absorb, but it did not determine how much lutein is actually absorbed. To measure the amount of lutein that the body absorbs from smoothies made with different products, the researchers will conduct a human study.
The study was supported by project grants from the Dr P Håkanssons Stiftelse, the Swedish Heart-Lung Foundation and the Swedish Research Council, and was carried out in collaboration with researchers at the Occupational and Environmental Medicine Unit of the University Hospital in Linköping.
Article: The Effects of Dairy and Plant-Based Liquid Components on Lutein Liberation in Spinach Smoothies, Jan Neelissen, Per Leanderson, Lena Jonasson och Rosanna W. S. Chung, (2023), Nutrients, published online on 2 February 2023, Vol. 15, 779, doi: 10.3390/nu15030779
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