Carotenoids are a group of pigments found mainly in plants, some of which can be converted into retinol, also known as vitamin A. It has been suggested that carotenoids, which are obtained solely in the diet, play a role in metabolic processes within the liver and adipose tissue. Carotenoids have been implicated in obesity, but it remains unclear whether lower concentrations of carotenoids in adipose tissue, liver, and muscle are associated with glucose dysregulation. A new study published in The Journal of Nutrition suggests that higher concentrations of carotenoids in the blood and adipose tissue are associated with more favorable metabolic traits, including insulin sensitivity in the liver and adipose tissue.

Blood and adipose tissue carotenoids in adult men and women were analyzed in samples collected in 2 separate studies conducted between 2008 and 2013. Retinol, 7 different carotenoids, body composition, and insulin resistance were measured. Subcutaneous, visceral, liver, and pancreatic fat were also measured. A subcutaneous fat biopsy was performed, and carotenoids and retinol measures were taken.

“Most carotenoids detected in blood and in adipose tissue correlated inversely with total body fat content and central adiposity.”

Dr. Dorit Samocha-Bonet

This study reports, for the first time, associations between serum and adipose tissue carotenoids and adiposity as well as insulin resistance in humans. According to lead author Dorit Samocha-Bonet (Garvan Institute of Medical Research) and colleagues, “Most carotenoids detected in blood and in adipose tissue correlated inversely with total body fat content and central adiposity.”

Although many serum carotenoids were negatively correlated with insulin resistance in liver and adipose tissue, none of the carotenoids correlated with muscle insulin resistance. Although favorable relations between serum and adipose tissue carotenoids and metabolic health were found, tissue-specific roles of the various carotenoids should be further investigated.

Read the full article.

Reference Harari A, Coster ACF, Jenkins A, Xu A, Greenfield JR, Harats D, Shaish A, Samocha-Bonet D. Obesity and insulin resistance are inversely associated with serum and adipose tissue carotenoid concentrations in adults. The Journal of Nutrition, nxz184, https://doi.org/10.1093/jn/nxz184.

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Kathy Beerman, PhD

Dr. Kathy Beerman teaches in the School of Biological Sciences at Washington State University. The author of several published articles, she is interested in research that focuses on the efficacy of a novel approach to treating iron deficiency anemia in rural regions of Guatemala and Ecuador. Dr. Beerman teaches an undergraduate nutrition course for health majors, as well as a course that prepares students to participate in a 10-day medical mission to Guatemala. Since joining the faculty at Washington State University in 1990, she has been the recipient of several teaching awards (the Burlington Northern Faculty Meritorious Achievement in Teaching Award, the R.M. Wade Foundation Award for Excellence in Teaching, and the Sahlin Faculty Excellence Award for Instruction). More recently, she received the CAS Outstanding Achievement Award in International Activities (2017) and the President’s Award for Leadership (2018). Other scholarly activities include co-author of two introductory nutrition textbooks (Nutritional Sciences: From Fundamentals to Food and NUTR).