New European research has found that eating spinach that is not cooked in the form of a smoothie or juice is the best way to obtain antioxidant lutein, especially when adding healthy fats to auxiliary absorption.
Performed by researchers at Linköping University, Sweden, the new study examined different ways of preparing spinach to maximize the amount of lutein available after cooking.
Lutein is a natural fat-soluble pigment found in plants. Dark green vegetables contain particularly high levels. But like many other nutrients, the levels of lutein are reduced by cooking.
The researchers chose to study spinach, as it contains relatively high levels of lutein, and is one of the more popular dark green vegetables. To replicate how it is cooked in the home, the team bought spinach at a supermarket and fried, steamed or cooked it for up to 90 minutes, measuring the lutein content at different times.
The results, published in the journal Food Chemistry, showed that heating times and cooking methods are both important for keeping lutein.
The longer the spinach boils, the less lutein it retains, and when spinach is cooked at high temperature, a large amount of lutein loses after only two minutes.
"What is unique about this study is that we have used preparation methods that are often used for home cooking, and we have compared several temperatures and heating times. We have also examined methods of preparation where spinach is eaten cold, such as in salads and smoothies, "says study author Lena Jonasson.
The team also looked at the effect of heating spinach in a microwave oven as part of a food package, a common practice. They found that microwave heating apparently partially compensated for the previous cooking method, with more lutein released from spinach and made available to the body, as the plant structure is further degraded by the microwave.
The researchers, however, concluded that eating spinach is best for untreated.
"The best thing is not to heat spinach at all. And even better is to make a smoothie and add fat from dairy products such as cream, milk or yogurt. When spinach is cut into small pieces, more lutein is released from the leaves and the fat increases the solubility of The lutein in the liquid, "says Rosanna Chung, lead author author.
In a previous study, the team found that lutein can reduce inflammation in immune cells from patients with coronary artery disease. Low-grade chronic inflammation is associated with an increased risk of heart attack.
They also showed that lutein can be stored in immune cells, which means that it is possible to build a reserve of lutein in your body.