Active enzyme in carrots may unlock keys to heart health

URBANA, Ill. — Mom was right, carrots really are good for your eyes. What mom may not have known is this superfood is also important to heart health. Beta-carotene, a precursor of vitamin A, is famous for giving carrots their orange hue. Now, researchers from the University of Illinois find it also plays a role in lowering bad cholesterol in the blood. This protects against clogged arteries and heart disease, the number one killer globally.

Researchers conducted two studies, one on humans and another on mice, to get a better grasp of how beta-carotene impacts cardiovascular health. The results reveal the importance of beta-carotene on circulatory health and also identify an important step in the process. The study finds converting beta-carotene into vitamin A requires a specific enzyme called beta-carotene oxygenase 1 (BCO1). Because of a genetic variation however, up to 50 percent of the population has a less robust version of this enzyme that processes beta-carotene at a slower pace.

Carrot enzyme helps clean up the heart

In the first study, published in the Journal of Nutrition, scientists looked at blood and DNA samples from 767 healthy young adults between 18 and 25 years-old. The research team saw, as expected, a correlation between greater BCO1 activity and lower levels of bad cholesterol.

“People who had a genetic variant associated with making the enzyme BCO1 more active had lower cholesterol in their blood,” says lead study author Jaume Amengual, assistant professor of personalized nutrition in the Department of Food Science and Human Nutrition in a university release. “That was our first observation.”

Researchers then undertook a second study, published in the Journal of Lipid Research.

“In the human study, we saw that cholesterol was higher in people who do not produce much vitamin A. To know if that observation has an effect in the long run, we would have to wait 70 years to see if they develop cardiovascular problems,” Amengual explains.

To garner information at a faster pace, researchers used mice for the second study. Regardless of switching species, the results matched those uncovered in the first study.

“We saw that when we give beta-carotene to mice, they have lower cholesterol levels,” Amengual reports. “These mice develop smaller atherosclerosis lesions, or plaques, in their arteries. This means that mice fed beta-carotene are more protected against atherosclerosis than those fed a diet without this bioactive compound.”

Tracking the enzyme’s path through the body

Another goal of the second study was to explore the biochemical pathways of the process.

“We narrow it down to the liver as the organ in charge of producing and secreting lipoproteins to the bloodstream, including those lipoproteins known as bad cholesterol,” Amengual explains. “We observed that in mice with high levels of vitamin A, the secretion of lipids into the bloodstream slows down.”

Researchers say that knowledge of the relationship between BCO1 activity and cholesterol is important, but there’s a caveat. While the results might point to high beta-carotene levels in the blood equating to improved health, researchers question if the presence of those high levels are instead an indication of a sluggish BCO1 enzyme that leaves beta-carotene in its original, unconverted state. The team adds this could spell trouble for people who lack the more energetic version of BCO1. Fortunately there is a remedy for this.

Although we tend to think of vitamin A originating solely from plant sources in the form of beta-carotene (provitamin A), other great sources of vitamin A include meat and dairy products (preformed vitamin A).

Amengual warns that people with the less-active variant of the enzyme may not be able to convert plant-sourced beta-carotene to vitamin A quickly enough to avoid becoming vitamin A deficient. They can solve the problem by consuming this vital nutrient directly from animal sources or other fortified foods.

Whether you have the more active or less active version of the BCO1 enzyme, eating a variety of produce along with plenty of meats and dairy products should be the ticket to a healthier ticker.

Symptoms of a vitamin A deficiency include hair loss, skin problems, dry eyes, night blindness, and increased infections. Researchers recommend consulting your doctor if you have concerns about your health or any vitamin deficiencies.

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