Bitter and Strong-Tasting Vegetables Associated with Greater Cardiometabolic Benefits than Mild and Sweet-Tasting Vegetables

Written by Angeline A. De Leon, Staff Writer. Study findings suggest bitter and strong-tasting vegetables, such as cabbage, cauliflower and Brussels sprouts, show a favorable impact on insulin sensitivity, lipid profile, and blood pressure. 

The importance of following a nutrient-rich diet high in fruits and vegetables has long been recognized, with studies particularly underscoring the prophylactic role of vegetable intake in the prevention of chronic diseases like type 2 diabetes ¹. Dietary consumption of root vegetables like yams, beets, carrots, and radishes is associated with lower risk of cancer and heart disease ^2,3, an effect attributed to the potent antioxidant activity of phytochemicals found in vegetables ⁴. Glycosinolates are a group of phytochemicals found in Brassica vegetables (cabbage, cauliflower, Brussel sprouts) and are associated with a bitter flavor ^5,6. Previous work has shown that the bitter taste in certain root vegetables like carrots shares a direct correlation with phytochemical content ⁷. Along with evidence suggesting that the quality of vegetable intake, and not total vegetable intake alone, is predictive of the health-promoting effects connected with vegetable consumption ⁸, a relevant question is whether strong, bitter-tasting vegetables (BST) are associated with greater health benefits (potentially due to higher phytochemical content), compared to mild, sweet-tasting (MST) vegetables. To explore this possibility, a recent study ⁹ in Nutrients compared the cardiometabolic effects of consuming BST vs. MST vegetables in subjects with type 2 diabetes.

A total of 92 patients with type 2 diabetes (mean age = 62.6 years) were enrolled in a randomized, controlled, parallel-group study, in which they were randomly assigned to follow one of three diets for 12 weeks: a diet consisting of 500 g BST vegetables daily (BST), one consisting of 500 g MST vegetables daily (MST), or a normal diet consisting of 120 g MST vegetables daily (control). At baseline and at 12-week follow-up, participants underwent an oral glucose tolerance test (OGTT) and provided fasting blood samples to determine plasma glucose and insulin concentrations, HbA1c (glycated hemoglobin), and lipid profile. Subjects also completed a dual-energy X-ray absorptiometry (DEXA) scan to assess body composition and were measured for blood pressure levels.

Test results indicated that compared to controls, both treatment conditions appeared to significantly improve HbA1c levels (p < 0.01 and p < 0.05 for BST and MST, respectively), body mass index (BMI) (p < 0.01 for both), weight (p < 0.01, p < 0.001), and fasting insulin levels (p < 0.05, p < 0.01). However, in comparison to MST, the BST group also demonstrated a significant decrease in the incremental Area Under the Curve (iAUC) glucose 240 minutes (OGTT) (p < 0.05) and significantly lower fasting glucose levels (p < 0.05). Moreover, in BST alone, the calculated Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) and total cholesterol were seen to significantly decline (p < 0.0001, p < 0.05). Finally, relative to controls, only BST subjects showed a significant decrease in total body fat mass (p < 0.01) and diastolic blood pressure (p < 0.05).

Overall findings suggest that while consumption of both types of vegetables is linked to meaningful health benefits, BST vegetables show a unique, favorable impact on insulin sensitivity, lipid profile, and blood pressure. In line with hypotheses, results indicate greater cardiometabolic benefits in connection with BST vs. MST vegetables. However, a comparative analysis of phytochemical content in the two vegetable groups is needed to confirm whether observed differences in health effects are related to the presence of certain bioactive compounds. A primary limitation of the present study is its relatively small sample size, and it would be valuable for prospective studies to repeat this dietary intervention over a longer time period. Based on the current trial, however, findings appear to confirm the importance of quality, as well as quantity, in vegetable consumption for overall health, and the adoption of a diet like the Nordic Diet, which is high in BST vegetable intake, is recommended for diabetic patients.

Source: Thorup AC, Kristensen HL, Kidmose U, et al. Strong and bitter vegetables from traditional cultivars and cropping methods improve the health status of type 2 diabetics: a randomized control trial. Nutrients. 2021; 13: 1813. DOI: 10.3390/nu13061813.

Click here to read the full text study.

Posted August 9, 2021.

Angeline A. De Leon, MA, graduated from the University of Illinois at Urbana-Champaign in 2010, completing a bachelor’s degree in psychology, with a concentration in neuroscience. She received her master’s degree from The Ohio State University in 2013, where she studied clinical neuroscience within an integrative health program. Her specialized area of research involves the complementary use of neuroimaging and neuropsychology-based methodologies to examine how lifestyle factors, such as physical activity and meditation, can influence brain plasticity and enhance overall connectivity.

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