Reduced plasma carotenoids in individuals suffering from metabolic diseases with disturbances in lipid metabolism: a systematic review and meta-analysis of observational studies

Abstract

This review summarises the association between serum carotenoids, serum retinoids and dietary intake outcomes with obesity/overweight and individuals with metabolic diseases with disturbances in lipid metabolism. Observational studies reporting dietary intakes and serum concentrations of carotenoids and retinol were collected from Medline and Web of Science. Mean differences were calculated between “cases” (classified as obese, overweight or having a metabolic disease with disturbances in lipid metabolism; i.e. non-alcoholic fatty liver disease, type 2 diabetes, dyslipidaemia or metabolic syndrome) and “comparator group” (classified as normal weight healthy individuals) and summarised in meta-analyses. Significant summary measures were observed for most serum provitamin A and non-provitamin A carotenoids. Studies reporting total serum carotenoids had shown the greatest decrease (–0.28 µmol/l [–0.33, −0.23], p<.001, I²=62.5%, n = 7). There were no significant summary measures for dietary outcomes, suggesting a physiological role of low serum carotenoids in the development of obesity and associated diseases.

Keywords:

• Non-communicable disease
• metabolic diseases
• carotenoids

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

The content of the review was conceived by WI and GL with input from AO and KF. Systematic review methods were designed by WI and kindly validated by GS. Statistical methods were designed and conducted by WI. Search terms and the search strategy were devised by WI and IM. Data was extracted into a custom-made Excel database by WI. The manuscript was written by WI, with inputs from GL and AO. All authors approved of the final manuscript.