Total antioxidant capacity and polyphenol content of national diet and determination of some beverages' total antioxidant capacity in turkey

The aim of this study is to determine the total antioxidant capacity (TAC) and polyphenol content of the diet using national dietary consumption research data in Türkiye and to create a database by analyzing the TAC of commonly consumed soft beverages in Turkey. This study consists of two parts. In the first part, the dietary TAC content, polyphenol content, and nutrient density of individuals aged 15 and over were calculated using food consumption records from TBSA 2010 (n=9012; 3390 males, 5622 females) and 2017 (n=12318; 5516 males, 6802 females). The TAC content was assessed using 9 different methods, the polyphenol content was determined using the Phenol Explorer database, and the nutrient density was calculated using the Nutrient Rich Foods Index (NRF 9.3). The diet TAC value calculated by all methods was significantly higher in 2017 than in 2010 (p<0,05). In 2010, the dietary TAC value was higher in the Western Anatolia region compared to other regions, and in 2017, it was higher in both the Western Anatolia and Northeastern Anatolia regions (p<0,05). The Southeastern Anatolia region had the lowest dietary TAC intake in both years (p<0,05). The dietary total polyphenol intake was found to be similar in 2010 and 2017, with values of 453,02±324,05 and 445,41±314,76 mg/1000 kcal, respectively (p>0,05). In Turkey, 63,32% of the total polyphenol content in the diet comes from flavonoids. After flavonoids, the sub-group contributing the most to total dietary polyphenol intake is phenolic acids (25,14% in 2010 and 28,72% in 2017). In 2010, the Western Anatolia region had the highest dietary total polyphenol intake, while in 2017, it was the Northeastern Anatolia region. The Southeastern Anatolia region had the lowest intake in both years. Beverages, particularly tea and coffee, made the most significant contribution to both dietary TAC and total polyphenol intake in Türkiye (p<0,05). The nutrient density of the diet in 2017 was significantly higher than in 2010, with values of 667,75±587,09 and 649,90±581,17, respectively (p<0,05). Individuals aged 15-18 had the lowest dietary TAC, polyphenol intake, and nutrient density compared to other age groups (p<0,05). In the second part of the study, the TAC of a total of 394 non-alcoholic beverages, including 60 carbonated beverages, 100 non-carbonated beverages, 211 tea-coffee samples, and 23 fermented beverages, was analyzed using thethe 2,2'-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) method. The average TAC value of the analyzed non-alcoholic beverages was 3,693±1,428 mmol TE/L (ranging from 0,120 to 5,535 mmol TE/L). Among all non-alcoholic beverages, tea and coffee had the highest TAC value (4,317±0,617 mmol TE/L), while carbonated beverages had the lowest TAC value (1,434±1,484 mmol TE/L) (p<0,05). The TAC value for non-carbonated beverages was 3,760±1,332 mmol TE/L, and for fermented beverages, it was 3,567±1,102 mmol TE/L (p>0,05). It was found that the brewing time (15, 30, 60 minutes), brewing temperature, brewing method, and the type of teapot used had no significant effect on the TAC value of black tea (p>0,05). Although all non-alcoholic beverages analyzed in this study demonstrated antioxidant activity, selecting the right beverages can contribute to the diet's TAC and polyphenol values, and increase fluid intake. The study concluded that strategies should be developed to increase the consumption of foods that are important sources of antioxidants and polyphenols in the Turkish diet.