## 4 Discussion
In vivo antioxidant activities of dietary polyphenols are much lower due to their relatively low bioavailability and fast clearance [55; 65]. Probiotics are live microorganisms that can have beneficial effects on the body when administered in sufficient amounts [10; 18; 22; 67; 68; 69; 70]. These microorganisms do not colonize the gut permanently and must remain alive all through the digestive system [52; 71; 72]. They reach the colon temporarily and grow, influencing the composition of the gut microbiota and the production of beneficial metabolites derived from fermentation [72; 73]. The most frequent probiotic genera contained in various functional foods and nutritional supplements are Bifidobacterium and Lactobacillus strains [7; 18; 22; 52; 70]. The main probiotic bacteria found in dairy products are _Lactobacillus casei_, _Lactobacillus acidophilus_ and _Biflodobacterium_[3]. The biological mechanisms through which they exert their effects on health are discussed in [10; 18; 22; 49; 52; 67; 68; 70; 71; 74; 75] and are as follows:  
1. Antagonistic adherence to epithelium and mucosa with pro-inflammatory microbes;
2. Adjustment of the gut-associated lymphoid immune system over intestinal cell pattern recognition receptors (Toll-like receptors) or through the release of metabolites;
3. Bile acid deconjugation by _Lactobacillus_ strains, which reduce lipid absorption and calorie absorption;
4. Initiation of lipolysis;
5. Obliteration of fat deposition, because of an increase in angiopoietin (inhibitor lipoprotein lipase);
6. Stimulation of genes linked to \(\beta\)-oxidation of fatty acids in the liver and in the muscles;
7. Obliteration of fatty acid synthetase in the liver;
8. Ameliorating insulin sensitivity and glucose tolerance through the production of SCFA and diminishing LPS translocation;
9. Ameliorating the function of the intestinal barrier through SCFA production;
10. Regulation of appetite. The traditional Mediterranean diet is followed in Mediterranean countries, where the moderate climate supports the production of fruits and vegetables all through the year. It is a nutritionally recommended pattern rich in fruits and vegetables, legumes, nuts, whole grains, and herbs, where olive oil is the main source of fat [5; 5; 73; 76; 77]. Furthermore, there is limited consumption of dairy products (mostly fermented products such as cheese and yogurt), fish, and eggs, and red wine is consumed in small proportions along with meals. This type of diet presents a limited meat consumption once a week, mostly lean meats (chicken, turkey, rabbit) [51; 56; 73; 77]. Onion and garlic (abundant in prebiotics) are used, as well as aromatic herbs (oregano, rosemary, basil) and spices (cinnamon, pepper, cumin, saffron), rich in antioxidant and anti-inflammatory components. Greater consumption of plant-origin proteins (mainly from legumes and whole grains), rather than animal proteins, increase the beneficial effects of the Mediterranean diet [4; 73; 77]. A Mediterranean-type diet present a different microbiome than that associated with a Western-type diet. The microflora, associated with a Mediterranean-type diet, present higher diversity (i.e., a greater number of bacterial species), which exert a positive impact on human health. Mediterranean diet adherence protects against dysbiosis, and is associated with higher SCFA levels, decreased TMAO levels, and the enhancement of fiber-degrading Prevotella and Firmicutes [2; 73]. The limited number of studies considered in this review is a limitation; therefore, further analysis of the existed bibliography is needed for more clear results.