In foods, these substances may have different effects. Fiber The systematic review by Hartley et al. (2016) reviewed 23 RCTs and found insufficient evidence of a patient-oriented benefit from fiber supplements.[101] Fourteen RCTs reported information on adverse events.[101] In seven studies, GI side effects including flatulence, constipation, nausea, bloating, and diarrhea were more common in the fiber intervention groups than in control groups, though rates were generally low. Few studies had an intervention duration exceeding 12 weeks. There was a wide variety of fiber sources used with little similarity between groups. The Work Group s confidence in the quality of evidence for fiber supplements was very low. Garlic A systematic review by Sahebkar et al. (2016) reviewed six RCTs and found insufficient evidence of a patient-oriented benefit from garlic supplements.[102] It found garlic supplements were well tolerated with no serious adverse events reported. An RCT by Ried et al. (2016) assessed the effect of aged garlic extract on central blood pressure and arterial stiffness in patients with uncontrolled hypertension.[103] There was no statistically significant difference in adverse events for the garlic or placebo group. The Work Group s confidence in the quality of evidence for garlic supplements was moderate.[102,103] Ginger There is no evidence of a patient-oriented benefit from ginger supplements. The systematic review by Zhu et al. (2018) reviewed 12 RCTs and assessed the effects of ginger supplements on Type 2 DM or components of the metabolic syndrome.[104] The evidence was inconclusive for increased adverse events. The Work Group s confidence in the quality of the evidence for ginger was very low.[104] Green Tea There is no evidence of a patient-oriented benefit from green tea supplements. The systematic review by Onakpoya et al. 