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Randomized Controlled Trial
. 2024 Oct 26;16(21):3641.
doi: 10.3390/nu16213641.

Beneficial Effects of a Freeze-Dried Kale Bar on Type 2 Diabetes Patients: A Randomized, Double-Blinded, Placebo-Controlled Clinical Trial

Per Bendix Jeppesen  1 , Amanda Dorner  1 , Yuan Yue  2 , Nikolaj Poulsen  1 , Sofie Korsgaard Andersen  1 , Fie Breenfeldt Aalykke  1 , Max Norman Tandrup Lambert  1
Affiliations
Randomized Controlled Trial

Beneficial Effects of a Freeze-Dried Kale Bar on Type 2 Diabetes Patients: A Randomized, Double-Blinded, Placebo-Controlled Clinical Trial

Per Bendix Jeppesen et al. Nutrients. .

Abstract

Background/objectives: Type 2 diabetes (T2D) is one of the most common global diseases, with an ever-growing need for prevention and treatment solutions. Kale (Brassica oleracea L. var. acephala) offers a good source of fiber, minerals, bioavailable calcium, unsaturated fatty acids, prebiotic carbohydrates, vitamins, health-promoting secondary plant metabolites, as well as higher amounts of proteins and essential amino acids compared to other vegetables. The objective of this study was to investigate whether daily intake of freeze-dried kale powder can provide health benefits for T2D patients vs. placebo.

Methods: This study was designed as a 12-week, blinded, randomized, controlled trial. Thirty T2D patients were randomly assigned to either a placebo bar (control) or a kale bar (intervention). Participants in the intervention group were instructed to consume three bars/day, each containing 26.25 g of freeze-dried kale (corresponding to approx. 341 g fresh kale/day). At baseline and 12 weeks, all participants underwent an oral glucose tolerance test (OGTT), 24 h blood pressure measurements, DEXA scans, and fasted blood samples were taken.

Results: A significant reduction in HbA1c, insulin resistance, body weight, and calorie intake was observed in the intervention group compared to control. Positive trends were detected in fasted blood glucose and LDL-cholesterol for those in the kale intervention group. No significant differences were found in total body fat mass and area under the curve glucose 240 min OGTT.

Conclusions: Given the positive effects of high daily kale intake observed in this study, further research with a larger sample size is needed to better understand the health benefits of kale bars. This could potentially lead to new dietary recommendations for patients with T2D.

Keywords: calorie intake; essential AA; kale; type 2 diabetes; vegetables.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Study timeline.
Figure 2
Figure 2
Study flow diagram.
Figure 3
Figure 3
Change (Δ) in plasma glucose OneTouch for the control and intervention groups over the 12- week study period. The data are presented as mean ± SEM.
Figure 4
Figure 4
Change (Δ) in hemoglobin A1c for the control and intervention groups over the 12-week study period. The data are presented as mean ± SEM. * p < 0.05.
Figure 5
Figure 5
(A,B). 5A: Results of oral glucose tolerance test. Change in total area under the curve (AUC) values for the control and intervention groups at the start (week 0) and end (week 12) of this study are shown. 5B: HOMA-IR levels in the intervention group showed a significant decrease from the start to the end of this study (−0.95 ± 0.34) compared to the control group (0.15 ± 0.28) The data are presented as mean ± SEM. * p < 0.05; ns: not significant.
Figure 6
Figure 6
Changes (Δ) in body weight for the control and intervention groups over the 12-week study period. The data are presented as mean ± SEM. (*) p ≤ 0.05.
Figure 7
Figure 7
Change (Δ) in waist circumference for the control and intervention groups over the 12-week study period. The data are presented as mean ± SEM; NS, not significant.
Figure 8
Figure 8
Change (Δ) in plasma lipid ((A) Tg, (B) TC, (C) LDL-C, (D) HDL-C) levels for the control and intervention groups over 12 weeks. The data are presented as mean ± SEM; NS, not significant.
Figure 9
Figure 9
Change (Δ) in caloric intake for the control and intervention groups over 12 weeks. The data are presented as mean ± SEM. * p ≤ 0.05.
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