Although carrots are a good source of beta-carotene, the precursor of vitamin A, an individual must possess the active enzyme to produce the vitamin and get the full health benefits of the superfood, according to a study published in the Journal of Nutrition.

Beta-carotene is the bioactive compound that gives carrots their orange color, with studies in humans and mice showing the conversion of beta-carotene to vitamin A as reducing bad cholesterol in the blood. Therefore, beta-carotene can help protect against atherosclerosis development, which leads to the accumulation of fats and cholesterol in the arteries, according to the study authors.

Two studies were conducted to further understand the effects of beta-carotene on cardiovascular health. The first study analyzed blood and DNA samples from 767 healthy young adults from 18 to 25 years of age. The researchers discovered a correlation between beta-carotene oxygenase 1 (BCO1) activity and bad cholesterol.

A second study was conducted to follow up on these findings using mice.

“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,” said Jaume Amengual, assistant professor of personalized nutrition in the Department of Food Science and Human Nutrition at University of Illinois, in a press release. “In real life, that is not doable. That's why we use animals for certain studies, so we can speed up the process.”

Amengual added that the main findings of the mice study reproduce what we found in humans.

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

The second study investigated the biochemical pathways of these processes, determining where in the body the effect occurs, according to the study authors.

“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 said in a press release. “We observed that in mice with high levels of vitamin A, the secretion of lipids into the bloodstream slows down.”

Understanding how the BCO1 enzyme relates to cholesterol has important implications since high beta-carotene levels in the blood are associated with health benefits. However, it could be a sign of a less active BCO1 enzyme that is not converting the beta-carotene we eat into vitamin A.

Amengual noted that up to 50% of the population have the less-active variant of the enzyme, meaning that their body is slower at producing vitamin A from a plant source, with many needing to get the nutrient directly from an animal source such as milk or cheese.

Carrots are healthy, but active enzyme unlocks full benefits. University of Illinois Urbana-Champaign. Published December 11, 2020. Accessed December 14, 2020.