The best way to consume a fruit or a veggie is to eat it as is (raw form), but you may also consume them in the juice form or add them to your smoothie. If the findings of a recent study, published in the journal Food Chemistry, are to be believed, consuming fruits and vegetables in their juice or smoothie form will reap you the maximum benefits - this is the best way to obtain the antioxidant lutein. The research was conducted by Linkoping University, Sweden.
Dark green vegetables like spinach are packed with lutein, an antioxidant that promotes our health, including eye health. The researchers at the university have compared different ways of preparing fresh spinach in order to maximise the levels of lutein in finished food. People with heart-related problems, especially with atherosclerosis (narrowing of the arteries), have low-grade, chronic inflammation that can be measured in the blood. This inflammation is linked to an increased risk of myocardial infarction. The researcher in their previous analysed the importance of the antioxidant lutein, which is a natural fat-soluble pigment commonly found in plants, especially dark green vegetables.
Previously, the researchers found that lutein can dampen inflammation in immune cells from patients with coronary artery disease. They also showed that lutein can be stored in immune cells, which means it is possible to build up a reserve of lutein within your body. This led the researchers to wonder whether it is possible to influence the level of lutein in the blood by increasing lutein dietary intake.
However, in the new study, the researchers analysed the various ways of obtaining lutein. They chose to study spinach, which contains comparatively high levels of lutein and is eaten by many people. Just as many other nutrients, lutein is degraded by heat. "What is unique about this study is that we have used preparation methods that are often used when cooking food at home, and we have compared several temperatures and heating times. We have also investigated methods of preparation in which the spinach is eaten cold, such as in salads and smoothies", said Lena Jonasson.
In order to simulate methods of preparation that are often used in everyday life, the researchers purchased baby spinach at a supermarket. They subjected the spinach to frying, steaming, or boiling for up to 90 minutes, and measured the lutein content at different heating times. It turned out that the heating time is important when spinach is boiled. The longer it is boiled, the less lutein the spinach retains. The cooking method is also important: when spinach is fried at high temperature a large fraction of the lutein is degraded after only two minutes.
Moreover, it was also found that reheating our food in microwave somewhat reduces the level of lutein in our food. More lutein is released from the spinach as the plant structure is broken down further by the microwave.
"Best 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 yoghurt. When the spinach is chopped into small pieces, more lutein is released from the leaves, and the fat increases the solubility of the lutein in the fluid", said Rosanna Chung, principal author of the article.
So, it is always advised to consume more raw fruits and veggies, or toss them in your salad, juice or smoothie to reap their maximum benefits.