Spinach’s Lutein Reserve

Builds Up In Immune Cells, Protects Arteries

Woman making smoothie

Woman making smoothie

This reserve is much better than the federal one: you can touch and feel it in a form of your body’s resilience to coronary artery disease, vision decline and many other aging health problems arising from increasing levels of inflammation in the body.

Spinach’s best comes in the form of a smoothie or juice, according to research published in Food Chemistry and from Linköping University, Sweden. High levels of lutein are found in dark green vegetables, and researchers at the university have compared different ways of preparing fresh spinach in order to maximize lutein levels in finished food. The findings are published in the journal Food Chemistry.

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“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,” Lena Jonasson, professor in the Department of Medical and Health Sciences and consultant in cardiology, told the scientific press.

Lutein Lowers Inflammation

Many people 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 heart attacks. The Linköping University team had previously studied the role of the antioxidant lutein’s ability to dampen inflammation in immune cells from patients with coronary artery disease.

They also showed lutein can be stored in immune cells, which means it is possible to build up a reserve of lutein within the 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.

To Cook Or Not To Cook

In order to simulate methods of preparation that are used in everyday life, the researchers subjected the spinach to frying, steaming, or boiling for up to 90 minutes and measured the lutein content at different times.

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Spinach cooked in a soup or stew is not heated to as high a temperature or for as long as spinach in a lasagne, for example. This is why the researchers compared 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.

Reheating lunch boxes in a microwave oven is a very common practice in modern life. The researchers found that reheating the food in a microwave to some extent compensated for the loss of lutein in cooked 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 yogurt. 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,” says postdoc Rosanna Chung, principal author of the article.

ReferenceRosanna W.S. Chung, Per Leanderson, Nelly Gustafsson, Lena Jonasson. Liberation of lutein from spinach: Effects of heating time, microwave-reheating and liquefaction. Food Chemistry, 2019; 277: 573 DOI: 10.1016/j.foodchem.2018.11.023
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