Slow Down There, Popeye, You’re Doing Your Spinach Smoothie All Wrong

Here’s a fun thing to hold over the head of the health nut you loathe most: They’re most likely doing their spinach smoothies all wrong. 

As Popeye knows best, spinach is rich in antioxidants like lutein, which has anti-inflammatory properties but isn’t naturally produced in the body. However, when the scientists behind a recent study on this not-so-beloved vegetable looked at what happens when spinach is blended with various liquids, they discovered that its lutein content can be enhanced or obliterated depending on what else it’s being mixed with. 

These researchers tested “lutein liberation,” or how to optimize the production of this antioxidant from spinach, by blending spinach in 14 different dairy and plant-based liquids, including cow’s milk, plant-based milks and yogurt with varying fat content. They found that compared to water, only coconut milk and medium- to high-fat cow’s milk increased lutein in smoothies, whereas yogurt wasn’t as helpful in harnessing the antioxidant, potentially due to the fermentation process it goes through. 

And soy milk? Don’t even get them started on soy milk. “We saw that soy milk was actually less effective than water when it comes to liberating lutein in spinach smoothies,” study co-author Jan Neelissen explained. “In other words, soy milk had a negative effect on lutein liberation in our study.”

For their part, oat milk and almond milk had little impact on lutein liberation compared to water. But given that coconut milk boosted lutein by up to 42 percent, it’s probably best that a spinach smoothie not contain much else.

Of course, you could also just chug the stuff straight like Popeye. His forearms are definitely tough to argue with.