Nigella sativa supplementation improves cardiometabolic indicators in population with prediabetes and type 2 diabetes mellitus: A systematic review and meta-analysis of randomized controlled trials.

Saeede Saadati, Kaveh Naseri, Omid Asbaghi, Khadijeh Abhari, Pangzhen Zhang, Hua-Bin Li, Ren-You Gan

Journal: Frontiers in nutrition 2022;9():977756

PMID: 36034891

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Plain Language Summary

Chronic, non-infectious diseases contribute to nearly three-quarters of deaths worldwide. Type 2 diabetes mellitus (T2DM) together with cardiovascular disease, are the two most common conditions in this category. Insulin resistance, obesity, elevated blood fats, and high blood pressure are typical hallmarks of T2DM and its development and are also significant risk factors for diabetes-related cardiovascular events. The prolonged nature of T2DM and the complications that can go alongside make the condition one of the most costly diseases for healthcare systems hence finding cost-effective therapeutic strategies should be of high importance. Many functional plants and their bioactive components have shown to exert anti-diabetic effects, including Nigella sativa, commonly known as black cumin. Previous studies also reported promising benefits of Nigella on cardiometabolic health. How these effects manifest in individuals with T2DM and those who are prediabetic was analysed in this systematic review and meta-analysis. The review included 11 randomised controlled trials with a total of 666 subjects. The review focused on cardiometabolic measures such as body measurements, blood sugar control, insulin resistance and secretion, blood fats, and markers of inflammation and oxidative stress. Nigella supplementation appeared to have favourable effects on blood sugar control overall but with no changes in the outcomes of oral glucose tolerance tests. Furthermore, Nigella appeared to positively influence on various blood fats, and markers of inflammation and oxidative stress. There were no changes to fasting insulin, insulin resistance, triglyceride, high-density lipoprotein (HDL)-Cholesterol and body mass index (BMI) when compared to the control group. Yet, in a sub-analysis Nigella supplementation enhanced serum levels of 'good' HDL-Cholesterol in a particular group. An improvement in insulin resistance and a decrease in BMI were seen in supplementation trials lasting over 8-weeks with doses of over 1 g/day of Nigella. The authors concluded that Nigella has the potential to improve cardiometabolic parameters by favourably influencing blood sugar metabolism and blood fats, inflammation, and oxidative stress in individuals with prediabetes and T2DM. Hence Nigella supplementation has promsing potential as an adjunct therapeutic in the management of prediabetes and T2DM.

Abstract

OBJECTIVE

Nigella sativa (N. sativa) from the family Ranunculaceae has medicinal properties. Previous studies have reported promising findings showing that N. sativa may benefit cardiometabolic health; however, current evidence on its cardiometabolic effects on those with prediabetes and type 2 diabetes mellitus (T2DM) is still unclear. Hence, we conducted a systematic review and meta-analysis to assess the efficacy of N. sativa on cardiometabolic parameters in population with prediabetes and T2DM.

METHODS

PubMed/Medline, ISI Web of Science, Scopus, and Cochrane library were systematically searched up to June 20, 2022. Meta-analyses using random-effects models were used.

RESULTS

Eleven randomized controlled trials (RCTs) were included in the meta-analysis. N. sativa intervention resulted in significant changes in fasting plasma glucose (FPG), hemoglobin A1c (HbA1c), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), c-reactive protein (CRP), and malondialdehyde (MDA), without overall changes in glucose levels after oral glucose tolerance test (OGTT), fasting insulin, homeostatic model assessment of insulin resistance (HOMA-IR), triglyceride, high-density lipoprotein cholesterol (HDL-C), and body mass index (BMI) when compared with the control group. In subgroup analyses, N. sativa supplementation enhanced serum levels of HDL-C in subjects with baseline HDL-C lower than 40 mg/dL. Furthermore, HOMA-IR and BMI values decreased in the N. sativa-supplemented group compared with the control group, when the length of follow-up was more than 8 weeks and the dose was more than 1 g/day for N. sativa supplementation, respectively.

CONCLUSION

Our findings indicate that N. sativa supplementation may effectively improve cardiometabolic profiles in individuals with prediabetes and T2DM.

Address: Department of Medicine, School of Clinical Sciences, Monash University, Melbourne, VIC, Australia.; Gastroenterology and Liver Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran.; Cancer Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.; Department of Food Science and Technology, National Nutrition and Food Technology Research Institute, Faculty of Nutrition Sciences and Food Technology, Shahid Beheshti University of Medical Sciences, Tehran, Iran.; School of Agriculture and Food, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, VIC, Australia.; Guangdong Provincial Key Laboratory of Food, Nutrition and Health, Department of Nutrition, School of Public Health, Sun Yat-sen University, Guangzhou, China.; Research Center for Plants and Human Health, Institute of Urban Agriculture, National Agricultural Science and Technology Center, Chinese Academy of Agricultural Sciences, Chengdu, China.

DOI: 10.3389/fnut.2022.977756