Carotenoid Supplementation Shows Potential for Improving Blood Sugar Control in Type 2 Diabetes, Study Reveals

The researchers noted, "However, the certainty of the evidence was quite low, primarily due to small sample sizes and indirect findings. As a result, no specific recommendations can be made at this time, and well-designed randomized controlled trials are necessary." 

The findings were published online in the European Journal of Clinical Nutrition. 

Carotenoids are naturally occurring pigments in fruits and vegetables associated with various health benefits. Considering this, Nafiseh Shokri-Mashhadi, German Center for Diabetes Research (DZD), Partner Düsseldorf, Muenchen-Neuherberg, Düsseldorf, Germany, and colleagues conducted a systematic review and meta-analysis to evaluate the impact of carotenoid supplementation on glycemic indices and the reliability of the evidence.

For this purpose, a systematic literature search was performed across PubMed, SCOPUS, ISI–Web of Science, and the Cochrane Library, covering studies from inception until June 17, 2024. Randomized controlled trials (RCTs) that examined the effects of carotenoid supplementation on circulating glycemic parameters were included. Records were excluded if they involved co-interventions with other nutrients, did not report mean differences (MDs) and standard deviations (SDs) for outcomes, or used whole foods instead of carotenoid supplements.

Summary mean differences (MDs) between the intervention and control groups were calculated using a random-effects model. The risk of bias in the included studies was evaluated using the Risk of Bias 2.0 (RoB 2.0) tool.

Based on the review, the researchers reported the following findings:

• A total of 36 publications, encompassing 45 estimated effect sizes, were included in the meta-analyses.
• The results indicated a significant improvement in fasting blood glucose (FBG) levels, with a mean difference (MD) of −4.54 mg/dl, and hemoglobin A1C (HbA1C), which showed an MD of −0.25% in the intervention group compared to the control group.
• Among individuals with T2D, supplementation with astaxanthin and fucoxanthin resulted in a reduction in FBG by 4.36 mg/dl.
• The intervention with crocin was particularly noteworthy, leading to a decrease in FBG levels by 13.5 mg/dl (n = 5) and a reduction in HbA1C by 0.55% (n = 5) among T2D patients.
• The researchers emphasized that the certainty of the evidence was very low.

"While carotenoid supplementation may offer some benefits for glycemic control, particularly in individuals with type 2 diabetes, the current evidence lacks the robustness to guide clinical practice. Healthcare providers and patients should approach carotenoid supplementation cautiously until more conclusive research is available," the researchers concluded.

Reference:

Baechle, C., Schiemann, T., Schaefer, E., Barbaresko, J., & Schlesinger, S. (2024). Effects of carotenoid supplementation on glycemic control: A systematic review and meta-analysis of randomized clinical trials. European Journal of Clinical Nutrition, 1-13. https://doi.org/10.1038/s41430-024-01511-y