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The cardiometabolic health benefits of Mediterranean-style diets are well documented, with these nutritional approaches associated with reduced risk of cardiovascular disease¹ and improved glucose control.² Mediterranean-style diets emphasize the intake of nutrients, fiber, and antioxidant-rich foods like colorful fruits and vegetables, hearty whole grains, and healthy fats from sources such as olive oil, nuts, and seeds. In addition, a variety of herbs and spices are used in Mediterranean-style meals, providing not only bursts of flavor but also concentrated amounts of vitamins, minerals, phytonutrients, and anti-inflammatory compounds.³

A new meta-analysis⁴ now takes a closer look at several herbs and spices frequently used in Mediterranean-style cooking to investigate their impact on blood glucose levels and the overall glycemic profiles of patients with type 2 diabetes.

Improving Glycemic Profiles With Herbs & Spices

The 2024 Garza et al meta-analysis included 45 controlled clinical trials (n=3,050 participants with T2DM aged 18 to 80 years) in the quantitative analysis and specifically analyzed the glycemic control benefits of five aromatic herbs and spices commonly used in the Mediterranean diet: cinnamon, curcumin/turmeric, ginger, black cumin, and saffron.⁴ According to the authors, this is the first systematic review and meta-analysis to evaluate the effect of Mediterranean diet–related herbs and spices on the glycemic profile of individuals with T2DM.⁴

Most of the clinical interventions included in the Garza et al meta-analysis lasted between two and three months and administered the herb and spice supplements daily at a range of doses.⁴

• Black cumin: Eight of the included studies examined the effect of black cumin supplementation in capsule and oil forms. For capsules, the doses ranged from 500 to 3,000 mg, with 500 mg as the most common. For oils, daily doses were either 2.5 mL or 5 mL. Of note, black cumin seed contains several phytochemicals, including thymoquinone, and has been studied for its antioxidant, anti-inflammatory, glycemic control, and neuroprotective effects.⁵
• Cinnamon: 10 of the included studies examined the effect of cinnamon supplementation at doses that varied from 360 to 3,000 mg, with 1,000 mg the most common.
• Curcumin/turmeric: Seven of the included studies examined the effect of curcumin/turmeric supplementation at doses that ranged between 80 and 2,000 mg, with 2,000 mg the most common.
• Ginger: Nine of the included studies examined the effect of ginger supplementation at doses that greatly varied between 600 to 3,000 mg, with 2,000 mg the most common.
• Saffron: 10 of the included studies examined the effect of saffron supplementation at a dose range between 15 to 3,000 mg, with between 30 and 100 mg the most common range.
• One study with four intervention groups examined the effect of cinnamon (3,000 mg), cardamom (3,000 mg), saffron (1,000 mg), and ginger (3,000 mg) supplementation.

The overall results showed the following:⁴

• Cinnamon, turmeric, ginger, black cumin, and saffron significantly improved fasting glucose levels in patients with T2DM.
  • The greatest decreases in fasting glucose levels were noted between 17 and 27 mg/dL for black cumin, followed by cinnamon and ginger.
• Significant improvements to HbA1c among patients with T2DM were reported for ginger (reduction of 0.56%) and black cumin (reduction of 0.41%).
• Among patients with T2DM, cinnamon and ginger were the treatments that showed a significant decrease in insulin values, with reductions of 0.76 UI/µL and 1.69 UI/µL, respectively.

The authors noted that the most effective dosage for each herb or spice could not be determined due to the dosage heterogeneity between studies and highlighted that potential confounders (e.g., changes in body weight and BMI; physical activity and lifestyle changes) were not necessarily considered in all included studies. Even with these limitations, the authors concluded that some herbs and spices frequently used in Mediterranean diets have potential therapeutic benefits for the management of T2DM.⁴

A Focus on Cinnamon Spice

Research studies continue to study the potential cardiometabolic benefits associated with some of the herbs and spices that were analyzed in the Garza et al meta-analysis.^6-8 Of note, recent meta-analyses have focused specifically on the positive cardiovascular and metabolic impact of cinnamon consumption without increased adverse effects.⁹ The studies’ results suggest that this spice may help not only with glycemic control in T2DM management¹⁰ but also with reducing blood pressure¹¹ and improving lipid profiles, including triglyceride and both low- and high-density lipoprotein cholesterol levels.¹²

A 2024 double-blind randomized controlled crossover trial has also investigated the benefits of cinnamon in a prediabetic population.¹³ The treatment in this small trial (n=18 adults with obesity and prediabetes; mean age of 51 years) was 4 gms (~1 tsp) of cinnamon or placebo per day for four weeks. The cinnamon supplementation resulted in lower glucose peaks and significantly lower 24-hour glucose concentrations compared to placebo in the prediabetic treatment group.¹³

Conclusion

Personalized lifestyle-based interventions are at the core of functional medicine treatments for optimized cardiometabolic health. A Mediterranean-style diet is one nutritional approach that supports cardiovascular and metabolic function, from its primary ingredients to the inconspicuous sprinkles of flavor and aroma. The Garza et al study suggests the glycemic benefit of Mediterranean-based herbs and spices for patients with T2DM. Further, studies such as this meta-analysis highlight the importance of incorporating a wide variety of herbs and spices into any personalized nutritional treatment to ensure bountiful amounts of healthy phytochemicals and nutrients.

References

1. Taylor RM, Haslam RL, Herbert J, et al. Diet quality and cardiovascular outcomes: a systematic review and meta-analysis of cohort studies. Nutr Diet. 2024;81(1):35-50. doi:1111/1747-0080.12860
2. Jing T, Zhang S, Bai M, et al. Effect of dietary approaches on glycemic control in patients with type 2 diabetes: a systematic review with network meta-analysis of randomized trials. Nutrients. 2023;15(14):3156. doi:3390/nu15143156
3. Mandal D, Sarkar T, Chakraborty R. Critical review on nutritional, bioactive, and medicinal potential of spices and herbs and their application in food fortification and nanotechnology. Appl Biochem Biotechnol. 2023;195(2):1319-1513. doi:1007/s12010-022-04132-y
4. Garza MC, Pérez-Calahorra S, Rodrigo-Carbó C, et al. Effect of aromatic herbs and spices present in the Mediterranean diet on the glycemic profile in type 2 diabetes subjects: a systematic review and meta-analysis. Nutrients. 2024;16(6):756. doi:3390/nu16060756
5. Yimer EM, Tuem KB, Karim A, Ur-Rehman N, Anwar F. Nigella sativa (black cumin): a promising natural remedy for wide range of illnesses. Evid Based Complement Alternat Med. 2019;2019:1528635. doi:10.1155/2019/1528635
6. Altobelli E, Angeletti PM, Marziliano C, Mastrodomenico M, Giuliani AR, Petrocelli R. Potential therapeutic effects of curcumin on glycemic and lipid profile in uncomplicated type 2 diabetes-a meta-analysis of randomized controlled trial. Nutrients. 2021;13(2):404. doi:3390/nu13020404
7. Ebrahimzadeh A, Ebrahimzadeh A, Mirghazanfari SM, Hazrati E, Hadi S, Milajerdi A. The effect of ginger supplementation on metabolic profiles in patients with type 2 diabetes mellitus: a systematic review and meta-analysis of randomized controlled trials. Complement Ther Med. 2022;65:102802. doi:1016/j.ctim.2022.102802
8. Amatto PPG, Chaves L, Braga GG, Carmona F, Pereira AMS. Effect of Crocus sativus (saffron) and crocin in the treatment of patients with type-2 diabetes mellitus: a systematic review and meta-analysis. J Ethnopharmacol. 2024;319(Pt 2):117255. doi:10.1016/j.jep.2023.117255
9. Gu DT, Tung TH, Jiesisibieke ZL, Chien CW, Liu WY. Safety of cinnamon: an umbrella review of meta-analyses and systematic reviews of randomized clinical trials. Front Pharmacol. 2022;12:790901. doi:3389/fphar.2021.790901
10.  Moridpour AH, Kavyani Z, Khosravi S, et al. The effect of cinnamon supplementation on glycemic control in patients with type 2 diabetes mellitus: an updated systematic review and dose-response meta-analysis of randomized controlled trials. Phytother Res. 2024;38(1):117-130. doi:1002/ptr.8026
11.  Jamali N, Jalali M, Saffari-Chaleshtori J, Samare-Najaf M, Samareh A. Effect of cinnamon supplementation on blood pressure and anthropometric parameters in patients with type 2 diabetes: a systematic review and meta-analysis of clinical trials. Diabetes Metab Syndr. 2020;14(2):119-125. doi:1016/j.dsx.2020.01.009
12.  Yu T, Lu K, Cao X, et al. The effect of cinnamon on glycolipid metabolism: a dose-response meta-analysis of randomized controlled trials. Nutrients. 2023;15(13):2983. doi:3390/nu15132983
13.  Zelicha H, Yang J, Henning SM, et al. Effect of cinnamon spice on continuously monitored glycemic response in adults with prediabetes: a 4-week randomized controlled crossover trial. Am J Clin Nutr. 2024;119(3):649-657. doi:1016/j.ajcnut.2024.01.008