## 4 Discussion
Blood samples were taken at fasting, 3 h after the drink, over 5 h after the standard meal, and at fasting the day after to measure plasma concentrations of glucose and triglyceride levels. The acute consumption of the drink rich in polyphenols from red grape pomace followed after 3 h by a standard meal elicited similar glycemic and triglyceride post-mean responses compared to a control drink in these healthy individuals [50]. This finding is in accordance with our intervention outcome, as the consumption of the novel grape seed flour crackers led to similar postprandial glucose levels and maintained serum lipid concentrations similar to (regarding triglyceride and HDL concentrations) or lower than (regarding total and LDL cholesterol concentrations) baseline values. The energy intake of functional meal 1, which comprised the grape seed flour crackers, was lower than that of the standard meal offered in the previous study, and the polyphenol-rich drink was administered 3 h before the consumption of the meal, whereas, in our study, the enriched crackers were part of the meal administered. Furthermore, the time points of blood sampling differed from those of our study as the final time point was 2 h after meal consumption, whereas, in the previous study, it was the next day after overnight fasting. Even with the different parameters between our study and the one retrieved, grape polyphenols and their metabolites when consumed daily in a meal in the usual diet could potentially improve glucose homeostasis and lipid metabolism long-term. In our study, even if non-significant differences were observed, the post-prandial levels of lipids and glucose after enriched cracker consumption were retained close or lower to baseline levels, suggesting a possible protective role in lipid and glucose metabolism after a high-fat and high-carbohydrate meal. Furthermore, as our study and the study retrieved employed healthy individuals, a statistically significant difference in lipidemic and glycemic profiles would require long-term supplementation in high doses. The acute consumption of 40% barley flour crackers enriched with \(\beta\)-glucan elicited a slightly lower glycemic response and retained post-prandial lipid levels similar to the baseline values, as observed in the case of triglyceride and total and HDL cholesterol concentrations, whereas, in respect to LDL cholesterol, lower levels compared to baseline were detected. These findings suggest a possible role of barley flour-enriched products in the regulation of postprandial hyperglycemia and hyperlipidemia after a high-fat and high-carbohydrate meal. Furthermore, plasma levels of FRAP as a measure of total antioxidant capacity did not change. Studies in the literature have investigated the effect of barley flour and \(\beta\)-glucan on post-prandial metabolic markers following the acute consumption of a variety of bakery products; some of them elicited lower glycemic and lipid responses, whereas others observed higher levels or no effect of the intervention, especially in the case of antioxidant measures. The acute consumption of 17.5% barley flour bread containing 2.5 g \(\beta\)-glucan along with two subsequent standard meals by 23 healthy participants aged 20-30 years resulted in a significantly lower glucose concentration 60 and 90 min post-prandially comparedto refined wheat flour bread. Compared to our study, the participants the day before the trial consumed an energy-adjusted meal between 19:00 and 20:00. After 20:00, their access to food and drink, apart from water, was restricted, similarly to our study. Furthermore, the meals were adjusted to contain 50 g of carbohydrates without dietary fiber and were consumed with 180 mL of lactose-free milk; this is in contrast to our study, where dietary fiber was present and only water was allowed. Participants were instructed to consume each meal during a 10-15 min period, similar to our study instructions, and to drink milk after swallowing.