# Effects of _Gynura bicolor_ on Glycemic Control and Antioxidant Ability in Predicates
## 4 Discussion
They concluded that improving insulin sensitivity and glucose homeostasis on a plant-based diet is more effective than other commonly used diets, because plant-based diets contain fiber, micronutrients (potassium, folate and magnesium) and phytochemicals such as anthocyanins, flavonoids and chlorophyll [33; 34; 35]. The PREDIMED study (PREvencio'n con DIetaMEDiterra'nea) conducted a 3-month clinical trial. It showed increasing dietary fiber intake with natural food (22 g per day) on risk factors for CVD in subjects at high risk decreased FPG, TC and increased HDL-C, which is associated with CVD risk factors [36]. Another randomized clinical trial suggested that a moderate amount of dietary fiber intake (7 g per day) may be beneficial for managing the FPG but no effects on weight and BMI in Japanese men with hyperglycemia and visceral fat obesity [37]. According to \"2005-2008 Nutrition and Health Survey in Taiwan (NAHSIT)\", the dietary fiber intake in men was 13.7 g and 14 g in women, both of which were less than 25-35 g, the recommended intake from the Ministry of Health and Welfare (MHW). In our study, the dietary intake (13-14 g) in the control and GB groups was no different at baseline. After an 8-week intervention of GB, the dietary intake in the GB group was increased 6 g/day and FPG was decreased when compared with baseline. One exchange of GB contained dietary fiber (3.1 g). Although not reaching the recommended intake from the MHW, it did indeed raise the dietary intake. We speculated that decreased FPG was associated with an increasing intake of dietary fiber, which is from GB. In addition, total polyphenols and total anthocyanins of GB extract were 25.54 \(\pm\) 1.77 mg GAE/g DW and 1.53 \(\pm\) 0.15 mg CGE/g DW, respectively. A previous study showed that the main chemical components of GB are phenolic acids, flavonoids, carotenoids and anthocyanins [38]. Using UPLC-MS/MS analysis, 53 phenolics were identified [39]. Most polyphenols exist in the form of glycosylated derivatives in GB. These polyphenols must undergo digestive enzymes and intestinal microbiota metabolism to become bioactive in the human body [40]. Clinical study in obese healthy subjects did not support the use of dietary supplementation with dried purple carrot (259.2 mg/day of phenolic acids) to achieve weight loss, improvements in body composition, LDL-C and blood pressure [41]. The same results were also observed in our study, because the total polyphenol was much lower. Several antioxidants exist in plasma, such as ascorbic acid, vitamin E, carotenoid and polyphenols. The ability of dietary polyphenols to reduce inflammation is related to acting as antioxidants, interfering with oxidative stress signaling, suppressing the proinflammatory signaling transductions. The biological significance of phenolic compounds is not only in direct reaction with ROS, but also in activation of cell signaling pathways [42]. FRAP is presented as a method for assessing total antioxidant power. Ferric ferrous ion (Fe\({}^{3+}\)) reduction at low pH causes a navy blue ferrous-tripyridyltriazine (Fe\({}^{2+}\)-TPTZ) complex form. The deeper the color, the better the antioxidant power [43]. We observed that FRAP both in the GB group and control group were increased after an 8-week experimental period. It meant that total antioxidant power was both enhanced. Moreover, the change between baseline and Week 8 in the GB group was more significant than in the control group. MDA is an intermediate product of lipid peroxidation, which usually uses thiobarbituric acid-reactive substances (TBARS) to quantify. One study showed that smoking and alcohol consumption were confounding factors of MDA [44]. GSH-Px is the important enzyme of the cell defense system. GSH-Px could breakdown peroxide to oxygen and water. The activity of GSH-Px would decrease when peroxididant increases [45].