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In addition understanding the relationship between
In addition, understanding the relationship between human metabolic processes and dietary antioxidant intake would provide opportunities for altering the diet to improve health (Prior, 2015). Prior et al. (2007) emphasized that excess reactive oxygen species, which occurred during the metabolism of carbohydrate, created oxidative stress with overwhelming the antioxidant defense system and decrease the plasma antioxidant capacity. They assumed that decline in plasma antioxidant capacity might be linearly related with energy intake via the carbohydrate metabolism. For an individual consuming 2500kcal per day, antioxidant capacity needs were estimated to be 11.5mmol TE and calculated the antioxidant capacity intake per servings from different types of cereals, fruits and vegetables (Prior et al., 2007). Other researchers also examined it and reported that intakes of 5–18mmol TE per day of antioxidant capacity could be achieved with the selection of appropriate high antioxidant foods (Farvid et al., 2013, Holtan et al., 2012, Prior, 2015, Rautiainen et al., 2012). Other researchers also calculated the daily intake of antioxidant PD325901 with GAR method and GAR+ method as 1.2–7.3mmol TE and 2.3–16.1mmol TE per day, respectively (Pastoriza et al., 2011, Pérez-Burillo et al., 2018).
Last but not least, understanding the metabolism and physiological effects of antioxidants have potential importance to design functional foods having desirable properties for human health. For example, with considering their potential health benefits, insoluble fiber from cereals is a promising framework to develop new functional foods rich in bound antioxidants (Cömert & Gökmen, 2017).
Conclusion
The topic antioxidants have been intensively studied for seventy years. Although they were firstly thought as food preservative by inhibiting the rancidity, then it was noticed that they provided health benefits by preventing the oxidative stress and related diseases. Various antioxidant substances have been discovered and isolated from natural sources. Several in vitro and in vivo measurement methods have been developed to determine the antioxidant capacity of foods. Then, the physiological effects of antioxidants in human body have been recognized. Recently, understanding the metabolism and the digestion behavior of antioxidants gain the spotlight among researchers. One should also keep in mind that intestinal absorption involved biochemical events along with the physical and chemical processes in vitro models must contain all of these events. From a physiological point of view, the QUENCHER approach combined with an enzymatic digestion and bacterial transformation procedures have also been considered in in vitro digestion models to determine the antioxidant potential of dietary antioxidants. With these developments, recent studies highlighted that antioxidants bound to insoluble food matrix could not be absorbed through the intestinal digestion, reach the colon and create a reducing environment. Therefore, it has been emphasized that bound antioxidants provide a greater potential benefit for both human colon health and defense than the soluble antioxidants. In addition, when digestion tract is considered as a dynamic reactor system consisting of soluble and bound antioxidant compounds and various radicals, soluble antioxidants are able to regenerate the bound antioxidant radicals thus helping them to exert their antioxidant action longer. Understanding the physiological effects of these antioxidants on human health seems to become even more important in future studies. It is thought that these findings provide simple but important tips from a functional food design point of view. It is also worth saying that better understanding the relationship between dietary antioxidant intake and prevention of oxidative stress in the body will provide advantages to regulate human diet.
Introduction
Phenolic antioxidants are widespread in nature and can be considered the most important class of radical scavengers. In recent years many efforts have been made to produce lipophilic derivatives (phenolipids) [1], [2], [3], [4] with expected higher antioxidant performances in systems with large interface area. Food products, pharmaceuticals and cosmetic formulations – all characterized by high surface-to-volume lipid-microstructures (emulsions, micelles, lamellar phases) – are generally better protected by lipophilic than by hydrophilic antioxidants. This is the basis of the so-called ‘polar paradox theory’ of antioxidant efficiency [5], [6].