The spices and aromatic herbs of the Mediterranean diet with significant benefits in improving glycemic health in type 2 diabetes are limited to gingercinnamon, and black cumin, turmeric, and saffron, with ginger, black cumin, and cinnamon having the strongest effects on fasting glucose, according to a systematic review and meta-analysis of research.

The meta-analysis also evaluated clove, thyme, turmeric, and various other spices and herbs common in the diet but showed no other correlations with glycemic benefits


The studies’ inclusion criteria included adult patients with type 2 diabetes, with data on fasting glucose and/or HbA1c and/or insulin, and involving any supplementation with black cumin, clove, parsley, saffron, thyme, ginger, black pepper, rosemary, curcumin, cinnamon, basil, and/or oregano.  Analysis was primarily focused on the  five ingredients of cinnamon, curcumin, ginger, black cumin, saffron, and rosemary.


Improvements in fasting glucose of subjects with type 2 diabetes were observed with all five ingredients of cinnamon, turmeric, ginger, black cumin, and saffron.

However, the most significant decreases in fasting glucose, between 17 mg/dL and 27 mg/dL, occurred after supplementation with black cumin, followed by cinnamon and ginger.

Notably, only ginger and black cumin were associated with a significant improvement in A1c.

Only cinnamon and ginger were associated with a significant decrease in insulin values.

Of the 11 studies including cinnamon in the meta-analysis, 6 reported significant differences in fasting glucose, while 4 had differences in A1c after the supplementation.

However, ginger was the only component associated with a significant decrease in each of the 3 outcomes examined of fasting glucose, A1c, and insulin.


“The Mediterranean Diet is the dietary pattern par excellence for managing and preventing metabolic diseases, such as type 2 diabetes,”.

“When focusing on HbA1c, only ginger and black cumin demonstrated therapeutic effects,”. “However, our meta-analysis highlights ginger as an herb with substantial translational potential for diabetes treatment, impacting all three glycemic parameters.”

“Regarding clove, parsley, thyme, black pepper, rosemary, basil, and oregano, more studies are needed to analyze the effect of these herbs on the glycemic profile in type 2 diabetes subjects,” the authors concluded.


The study was published on March 7, 2024, in Nutrients. The first author was Maria Carmen Garza, PhD, of the Department of Human Anatomy and Histology, School Medicine, University of Zaragoza, Zaragoza, Spain.