## 4 Discussion
Blood glucose concentrations were measured using the glucose meter just before the consumption of the first meal (0 min) and 15, 30, 45, 60, 90, and 120 min afterwards. The standard meal, which contained three seaweed rice balls and had a higher energy yield than our functional meals (770 kcal, 7% protein, 5% fat, 88% carbohydrate), was then consumed as the second meal. Blood glucose concentration was also measured just before the second meal (0 min) and 15, 30, 45, 60, 90, and 120 min afterwards. The authors pointed out that barley has a tendency to have a first-meal effect in the form of kernels, rather than when present in processed form, such as in porridge or in foods supplemented with dietary fiber extracted from barley. This could be the reason for not observing statistically significant differences in our study [51]. Wheat flour bread containing barley fiber concentrated with 3% \(\beta\)-glucan elicited a similar response in 14 healthy individuals aged 20-29 years old. The \(\beta\)-glucan and control bread had higher fiber and carbohydrate contents and lower fat contents and energy intake compared to the meals provided in our study. Furthermore, the bread was administered with 5 g apricot jam and 125 mL semi-skimmed milk, which differed from our meal composition. Blood samples were taken at baseline (before breakfast) and at 30, 60, 120, and 180 min after breakfast. Even though the enriched bread contained 3 gr of \(\beta\)-glucan, similar to the crackers of our study, the type of food used, the subjects of the study, and the viscosity of the \(\beta\)-glucan could explain the contradictory results compared to our study [52]. However, the intake of wheat-based bread enriched with 40% barley flour elicited a lower glycemic response, but not at the significance level, compared to control wheat bread in 14 healthy individuals aged 18-65 years old. The participants had at least a 12 h overnight fast, similar to our study, and were instructed to avoid strenuous exercise, smoking, and alcohol consumption and consume a similar carbohydrate-based meal the evening before the visit; those restrictions were not included in our instructions. There was at least a 48 h washout period between the visits. The portion size of the meal was decreased to retain 25 g of available carbohydrates in the bread. Subjects had to consume the test products within 15 min with 250 mL of water, similar to our study, and blood samples were drawn at baseline and 15, 30, 45, 60, 90, 120, and 180 min after meal consumption. Those results are in accordance with our results regarding glucose levels. Fat and protein content can influence the glucose response, although their contents were low both in the trial and in our study as well. Furthermore, the authors mentioned that the EFSA criteria for the health claim of the lowering of the post-prandial glycemic response require 4 g of \(\beta\)-glucan per 30 g of available carbohydrates, a very high dose that is difficult to achieve in bread. This also applied to our product formulation, as the use of special milling fractions with elevated levels of \(\beta\)-glucan were required instead of regular barley flour. This could be a possible explanation as well for our study outcomes [53]. In another study, chapattis formulated with 15% barley flour resulted in non-significantly lower levels of glucose, total and LDL-cholesterol, and triglycerides compared to wheat flour chapattis in 18 healthy individuals aged 25-40 years old. The participants were instructed to consume two chapattis per day for 30 days and blood samples were drawn at baseline, 15 days, and 30 days. The results highlighted that the inclusion of composite flours with a high fiber content should be encouraged for long-term nutritional supplementation in order to achieve hypoglycemic and hypolipidemic effects in healthy subjects, as also indicated in our study [54].