Eat your spinach in the form of a smoothie or juice – this is the best way to obtain antioxidant lutein, according to research from Linköping University, Sweden. High levels of lutein are found in dark green vegetables, and university researchers have compared different ways of preparing fresh spinach to maximize the levels of lutein in finished products. The results are published in the journal food Chemistry.
Many people with atherosclerosis (narrowing of the arteries) have low levels of chronic inflammation that can be measured in the blood. This inflammation is associated with an increased risk of myocardial infarction. A research group at Linköping University has previously investigated the role of antioxidant lutein. This is a natural fat-soluble pigment found in plants, especially in dark green vegetables. The researchers found in their last study that lutein can inhibit inflammation in immune cells from patients with coronary artery disease. 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. This led the researchers to wonder if it is possible to influence the level of lutein in the blood by increasing the lutein intake.
In the new study, researchers have investigated which method of manufacture is the best way to achieve lutein. They chose to study spinach, which contains relatively high levels of lutein and is eaten by many people. Lyme is just as many other nutrients degraded by heat.
"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 investigated methods for making spinach foods such as salads. and smoothies, "says Lena Jonasson, professor in the Department of Medicine and Health Sciences and consultant in cardiology.
To simulate methods of preparation that are often used in everyday life, the researchers bought baby spinach at a supermarket. For example, they subjected the spinach to roasting, steaming or boiling for up to 90 minutes and measuring the lutein content at different times.
Spinach cooked in a soup or stew is not heated to such a high temperature or as spinach in a lasagne, for example. Therefore, the researchers compared different heating times. It turned out that the heating time is important when spinach is boiled. The longer it boils, the less lutein the spin retains. The cooking method is also important: When spinach is cooked at high temperature, much of the lutein breaks down after only two minutes.
Reheating food boxes in a microwave oven is a very common practice in modern life. The researchers found that reheating the food in a microwave oven to some extent compensated for the loss of lutein in cooked foods. More lutein is released from spinach, as the plant structure is further degraded by the microwave oven. "The best thing is not to heat the 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 leaves and the fat increases the solubility of Lutein in the liquid, "says postdoc Rosanna Chung, lead author of the article.
Do you like this article? Click here to subscribe to free newsletters from Lab Manager