Individuals diagnosed with prediabetes have blood sugar levels that are higher than normal, but below the levels indicating type 2 diabetes mellitus (T2DM). Development of prediabetes can be influenced by age, race, lifestyle, and being overweight or obesity. These conditions can also cause or are coupled with increased insulin, glucose, free fatty acids, inflammation, and increased oxidative stress and endothelial damage. Studies investigating the efficacy of green cardamom (Elettaria cardamomum, Zingiberaceae) to reduce inflammation and oxidative stress have reported conflicting results. These authors conducted a double-blind, placebo-controlled trial to investigate the effects of green cardamom on inflammatory and oxidative biomarkers in females with hyperlipidemia and prediabetes who are overweight or obese.
The study was conducted among females who were newly diagnosed with prediabetes and who were attending two health care centers in Karaj, Iran, from February to April 2014. The women were aged between 30 and 70 years and had a body mass index (BMI) between 25 kg/m2 and 39.9 kg/m2. They had to meet one of the following criteria: fasting blood sugar of 100-125 mg/dL, glycosylated hemoglobin of 5.7-6.4%, or 2-hour blood glucose of 140-199 mg/dL. They also had to have at least one of the following risk factors: triglyceride levels of 150-300 mg/dL; total cholesterol >200 mg/dL; low-density lipoprotein cholesterol >100 mg/dL, or high-density lipoprotein cholesterol <50 mg/dL. The eligible subjects were randomly assigned to two groups to receive one capsule of either cardamom (n=40) or placebo powder (n=40) three times daily with meals for eight weeks. The capsules contained either 1 gram green cardamom powder or placebo (breadcrumb) powder. Similar to the green cardamom capsules in shape, size, and appearance, the placebo capsules were placed near the green cardamom so that they would smell like it.
At baseline and at the end of the study, a 24-hour food recall questionnaire was completed, anthropometric characteristics were measured, and physical activity was assessed by using a short form of the International Physical Activity Questionnaire. After fasting for 12 hours, the subjects had blood drawn at baseline and at the end of the study. Inflammatory markers measured were tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), and high-sensitivity C-reactive protein (hs-CRP). Also measured were the oxidative stress biomarkers protein carbonyl (PC), malondialdehyde (MDA), and antioxidant superoxide dismutase. The serum of one subject in the green cardamom group was not available for assessment. All subjects consumed 90% to 100% of the prescribed capsules.
Baseline anthropometric characteristics were similar in both groups, and no significant difference was observed in weight, BMI, or physical activity between the groups at the end of the study. However, at the completion of the study, saturated fatty acid (SFA) intake was higher (P=0.005) and polyunsaturated fatty acid (PUFA) intake was lower (P=0.02) in the cardamom group compared with the placebo group.
The green cardamom group showed higher levels of TNF-α (P<0.001) and lower levels of hs-CRP (P=0.04), hs-CRP: IL-6ratio (P=0.01), PC (P<0.001), and MDA (P=0.003) compared with the placebo group. After adjusting for SFA and PUFA intake changes and baseline values, the authors report that significant between-group differences remained for inflammatory markers hs-CRP (P=0.02), hs-CRP: IL-6 ratio (P=0.008), and for the oxidative stress marker MDA (P=0.009), with lower levels seen in the green cardamom group.
The authors note that a “complete restoration of inflammatory and oxidative stress parameters was not achieved,” suggesting that because overweight and obese people have more oxidative stress than normal-weight people with prediabetes, a higher dose and longer duration of the green cardamom supplement may be needed. The small sample size, short duration of the study, use of a single 24-hour food recall questionnaire (which could result in measurement error), and the inclusion of women only (which precludes generalization of the results to men with prediabetes) are limitations of this study.
Compared with placebo, cardamom reduced inflammatory indices and MDA levels in women with prediabetes. Cardamom consumption may help reduce inflammation-associated diseases, such as cardiovascular diseases, in people with prediabetes.
The authors report no conflicts of interest.
Kazemi S, Yaghooblou F, Siassi F, et al. Cardamom supplementation improves inflammatory and oxidative stress biomarkers in hyperlipidemic, overweight, and obese pre-diabetic women: a randomized double-blind clinical trial. J Sci Food Agric. December 2017;97(15):5296-5301. doi: 10.1002/jsfa.8414.