## 3 Greek Dried Grapes: Source of Bioactive Compounds
### Health Benefits of Greek Dried Grapes (In Vitro, In Vivo, and Clinical Trial Studies)  
The nutritional value of raisins and currants has been unequivocally demonstrated following several studies, implementing both in vitro and in vivo experiments but also clinical trials (Table 3), with respect to their composition but also their health benefits, addressed to healthy people, athletes, and patients suffering from various diseases [58; 59]. Raisins comprise an important source of boron, a trace element that relates to bone health, prevention of arthritis and osteoporosis in postmenopausal women [60]. Boron might also interact with normal functions including enzyme reaction, cell membrane function, and hormone metabolism, and it is also required for brain function [61]. Apart from the advantages mentioned above, raisins constitute a rich source of fructologosaccharides, specifically fructans, which exhibit prebiotic effect on modulation of the gut microbiota. For instance, [PERSON] et al. [62] conducted a pilot feeding study, where volunteers consumed sun dried raisins three times per day for fourteen days. Analysis of fecal samples indicated that overall microbiota composition was not substantially altered, although the inclusion of raisins resulted in significant increases in targeted taxa, specifically _Faecalibacterium prausnitzii_, _Bacteroidetes_ sp., and _Ruminococcus_ sp., which have the potential to exert health benefits [62]. Likewise, diets rich in fiber have been associated with a reduction in the risk of CVDs, constipation, diabetes, colon cancer, and obesity [60]. Fiber content in dried fruit along with phytochemicals like phenolic acids, are speculated to contribute in the reduction of glycemic response [63]. Guidelines directed to people diagnosed with type 2 diabetes or predisposed individuals include a low glycemic load diet. Raisins have a medium-to-low glycemic index and could stimulate the mechanisms associated with insulin levels, blood pressure, and satiety control [64]. [PERSON] et al. [63] performed a randomized acute-feeding trial to evaluate the effect of dried fruit including raisins and suitanas, on postprandial glycemia, whereby a reduction in the glycemic response was suggested whereas raisins demonstrated a GI of 54.7 [63]. In another study, [PERSON] et al. [64] also included raisins among other dried fruit, as a substitute to high carbohydrate foods \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Sub-Varieties**} & \multirow{2}{*}{**Region in Greece**} & \multicolumn{2}{c}{**Total Phenolic**} & \multirow{2}{*}{**Reference**} \\  & & **Content (mg/g) a** & \\ \hline Vostizza & northern Peloponese & 2.446  & [55] \\ Vostizza & northern Peloponese & 1.55–2.46 & [53] \\ Vostizza & northern Peloponese & 2.30–2.55 & [54] \\  & (conventional cultivation) & & \\ Vostizza & northern Peloponese & 2.61–2.66 & [54] \\ Messinia & western Peloponese & 2.41  & [55] \\ Cretan Sultanas & Crete island & 0.662  & [55] \\ Nemea & northern Peloponese & 0.592  & [55] \\ Provincial & western Peloponese & 2.01–2.05 & [53] \\ Provincial & western Peloponese & 2.28–2.64 & [54] \\ Provincial & Zante island & 2.11 & [53] \\ Provincial & Zante island & 2.17–2.43 & [54] \\ Gulf & northern Peloponese & 1.67–1.90 & [53] \\ Gulf & northern Peloponese & 2.33–2.35 & [54] \\ Zante & & & \\ (discarded during & Zante island & 1.92–3.36 & [57] \\ processing) & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Phenolic content of different Greek raisins and currants. (e.g., white bread) to investigate blood glucose concentration. The study suggested that moderate amount of fructose in dried fruit could mitigate the excess rise in blood glucose, and confer a positive effect on postprandial glycemic control, without changing the total carbohydrate intake. The inclusion of raisins in the diet has been also proposed to confer benefits on the prevention of neurodegenerative diseases. [PERSON] et al.