## 2 Materials and Methods
### Clinical Trial
#### 2.2.3 Study Design  
The clinical trial was a randomized, placebo-controlled, double-blind crossover with 13 individuals with dyslipidemia. The trial consisted of three stages with a washout period of 1 week. At the end of the study, all volunteers received all treatments, and thus, each group was composed of 13 individuals. Using the R (sample) function of the R statistical software, the volunteers were initially randomly assigned to three experimental groups by an independent statistician: the control group, which received water plus flavoring (rum essence), the low dose group, which received the beet leaves and stalk juice containing 32 mg of polyphenols (319.67 mg/L) and the high dose group, which received the beet leaves and stalk juice containing 77.5 mg of polyphenols (775.2 mg/L). As there were no studies carried out in humans using beet leaves and stalks, the concentrations were based on the number of leaves that was considered viable for daily human consumption. Amounts higher than those used conferred difficulty in preparation and an unpleasant taste.  
The protocol followed the same pattern at each stage and was previously described by [PERSON] et al., (2019) [19]. The individuals were instructed not to perform vigorous physical exercises 24 h before the data collection, not to drink alcohol or eat foods rich in polyphenols 72 h before. To guarantee that, a list containing antioxidant-rich food was provided, and possible alterations in dietary intake were monitored by 24-h recall throughout the clinical trial.  
First, blood was collected from the peripheral vein after a 12-h fast (T0). Then, the volunteers received a breakfast containing a pastry filled with pepperoni sausage, bacon and cheddar cheese accompanied by an industrialized coconut candy (conventional condensed milk and coconut). The meal had a total energy content of 720.6 kcal, with 38.5 g (21%) of carbohydrates, 19.7 g (11%) of protein and 54.2 g (68%) of total fats, including 17.7 g of saturated fat. The volunteers were instructed to eat the entire meal within a maximum period of 15 min.  
Five min after the end of the meal, flavored water with rum essence (without phenolic compounds) or beet leaves and stalk juice was provided in a black disposable cup, capped and encoded. The black cups had the same appearance for all groups and were distributed by a researcher not involved in the study. Thus, the volunteers and staff were blinded.  
Then, new blood samples were taken at times of 30 (T30), 60 (T60), 120 (T120) and 180 (T180) min after the first blood collection. The blood samples were immediately processed in a refrigated centrifuge (Hitachi(r), CF16-RN Series) at 117\(\times\)\(g\) for 15 min for the separation of plasma and erythrocytes, which were lysed with a buffer containing 0.32 M sucrose, 10 mM Tris-HCl buffer (pH 7.4), 5 mM MgCl2 and 1% Triton X-100 according to the protocol of [PERSON] et al., (2006) [21] and stored in an ultra-freezer at -80 \({}^{\circ}\)C until the moment of the analyses. The following biomarkers were analyzed: triglycerides, total polyphenols, malondialdehydedehyde, TNF\(\alpha\) and the activity of catalase and glutathione peroxidase.  
Anthropometric assessment of the participants was performed during screening. The weight, height and waist circumference were collected according to the work of [PERSON] and [PERSON] (2000) [22] by using a digital anthropometric scale (Filizola, Brazil) and an inextensible and inelastic millimeter tape. The percentage of body fat was assessed at the last week of data collection by dual-energy X-ray absorptiometry (DXA) (in DPX NT, GE model equipment) to characterize the studied population.