Improvement of glucose metabolism and safety of acacia bark-derived proanthocyanidins in healthy Japanese adults: A Randomized, Double-blind, Placebo-controlled, Parallel-group Trial

Abstract

Objective: Acacia bark-derived proanthocyanidins exhibit antioxidant, anti-inflammatory, anti-diabetic, hypotensive effects, and improving skin condition, in addition to beneficial effects on blood glucose. Herein, we evaluated the effects of acacia bark-derived proanthocyanidins on fasting and postprandial blood glucose levels in healthy Japanese adults with fasting blood glucose (FBG) levels between 110–125 mg/dL.Methods: Subjects were randomly allocated into 2 groups (n = 33 per group) and consumed 6 tablets/day of either tablets of acacia bark extract containing proanthocyanidins (Acacia group) or placebo for 12 weeks. Evaluation points were at the screening, and after 4-week (4w), 8-week (8w), and 12-week intervention (12w). The primary outcome was FBG level at 12 w, whereas the secondary outcomes were FBG level at 4w and 8w, the FBG changes from Scr to each-week intervention, the percentage of subjects with FBG levels below 110 mg/dL after 12 w, the measured value and the change value from Scr to each-week intervention of HbA1c, the measured value and the change value from Scr to each-week intervention of postprandial blood glucose levels.Results: A total of 33 subjects (18 men, 15 women) from each group were analyzed. The Acacia group had significantly lower FBG levels at 8 and 12 w than the placebo group (P = 0.030 and P = 0.014, respectively). The percentage of subjects with FBG <110 mg/dL at 12 w was marginally higher in the Acacia group than in the placebo group (P = 0.079). HbA1c at 12 w was significantly lowered in the Acacia group compared to the placebo group (P = 0.015).Conclusions: Acacia bark-derived proanthocyanidins were confirmed to have FBG-lowering effects.Trial registration: UMIN000039414Foundation: Acacia-No-Ki Co.,Ltd.Keywords: Acacia bark extract, Proanthocyanidins, Fasting blood glucose level, HbA1c

Effect of proanthocyanidins on blood lipids: A systematic review and meta‐analysis

“…The meta‐analysis included data from 17 studies comprising 1138 participants (Aihong, 2011; Akazome et al, 2010; Baba et al, 2021; Baba, Natsume, et al, 2007; Baba, Osakabe, et al, 2007; Dianjuan, 2008; Giovannelli et al, 2011; Gupta et al, 2012; Hailin, 2018; Hollands et al, 2018; Hoshino et al, 2019; Jingru, 2012; Novotny et al, 2015; Rodriguez‐Mateos et al, 2018; Sano et al, 2007; Valls et al, 2016; Vigna et al, 2003). These studies were published from 2003 to 2021 and were conducted in the following countries: six in Japan (Akazome et al, 2010; Baba et al, 2021; Baba, Natsume, et al, 2007; Baba, Osakabe, et al, 2007; Hoshino et al, 2019; Sano et al, 2007), four in China (Aihong, 2011; Dianjuan, 2008; Hailin, 2018; Jingru, 2012), two in Italy (Giovannelli et al, 2011; Vigna et al, 2003), and one each (total of five studies) in Spain (Valls et al, 2016), India (Gupta et al, 2012), the United States (Novotny et al, 2015), Germany (Rodriguez‐Mateos et al, 2018), and England (Hollands et al, 2018). The intervention duration with PCs was 4 to 96 weeks, and the PC dosage ranged from 100 to 1134 mg/day.…”

“…The sources of the PCs were mostly grape seeds (seven studies), but also included cocoa (three studies), apple polyphenols (two studies), bark (three studies), and beverages (two studies). Most studies (15 studies) assessed both sexes (Aihong, 2011; Akazome et al, 2010; Baba et al, 2021; Baba, Natsume, et al, 2007; Dianjuan, 2008; Gupta et al, 2012; Hailin, 2018; Hollands et al, 2018; Hoshino et al, 2019; Jingru, 2012; Novotny et al, 2015; Rodriguez‐Mateos et al, 2018; Sano et al, 2007; Valls et al, 2016), whereas two assessed only male participants (Baba, Osakabe, et al, 2007; Vigna et al, 2003), and one assessed only female participants (Giovannelli et al, 2011). The 17 studies all adopted the principle of random allocation, 10 were double‐blinded (Akazome et al, 2010; Baba et al, 2021; Gupta et al, 2012; Hailin, 2018; Hollands et al, 2018; Hoshino et al, 2019; Novotny et al, 2015; Rodriguez‐Mateos et al, 2018; Valls et al, 2016; Vigna et al, 2003), three were single‐blinded (Baba, Natsume, et al, 2007; Giovannelli et al, 2011; Sano et al, 2007), and the remaining four did not mention blinding (Aihong, 2011; Baba, Osakabe, et al, 2007; Dianjuan, 2008; Jingru, 2012).…”

“…No adverse events were reported in 17 studies. Thirteen studies were parallel (Aihong, 2011; Akazome et al, 2010; Baba et al, 2021; Baba, Natsume, et al, 2007; Baba, Osakabe, et al, 2007; Dianjuan, 2008; Gupta et al, 2012; Hailin, 2018; Hoshino et al, 2019; Jingru, 2012; Novotny et al, 2015; Rodriguez‐Mateos et al, 2018; Sano et al, 2007), and the other four were cross‐sectional (Giovannelli et al, 2011; Hollands et al, 2018; Valls et al, 2016; Vigna et al, 2003). In addition, Table S1 shows baseline anthropometric measurements, such as sex, age, BMI, and hemodynamic characteristics (TC, TG, HDL‐C, and LDL‐C).…”

“…Animal experiments have confirmed the benefit of PCs in regulating blood lipids (Li et al, 2019; Rodríguez‐Pérez et al, 2019; Rong et al, 2018). Moreover, several prospective studies (Anderson et al, 2015; Koutsos et al, 2020) and randomized controlled clinical trials (RCTs) (Aihong, 2011; Akazome et al, 2010; Baba et al, 2021; Baba, Natsume, et al, 2007; Baba, Osakabe, et al, 2007; Dianjuan, 2008; Giovannelli et al, 2011; Gupta et al, 2012; Hailin, 2018; Hollands et al, 2018; Hoshino et al, 2019; Jingru, 2012; Novotny et al, 2015; Rodriguez‐Mateos et al, 2018; Sano et al, 2007; Valls et al, 2016; Vigna et al, 2003) have investigated the effect of PCs on blood lipids in normal and mildly hyperlipidemic populations. Some RCTs have demonstrated the regulation of blood lipids by PCs (Baba, Natsume, et al, 2007; Baba, Osakabe, et al, 2007; Gupta et al, 2012; Novotny et al, 2015; Rodriguez‐Mateos et al, 2018; Sano et al, 2007; Valls et al, 2016), whereas others found no significant effect or the opposite effect (Akazome et al, 2010; Hoshino et al, 2019).…”

A “PAKU-PAKU KOUBO-KUN” containing yeast and mulberry extract postprandial glycemic control in healthy Japanese men and women: a randomized, placebo-controlled, crossover study

“…Subjects: Table 1 shows the inclusion and exclusion criteria (TRIAL-1 and TRIAL-2). The inclusion and exclusion criteria were slightly modified based on the reports of Hashizume et al [20] and Baba et al [21].…”