Pro- and Antioxidant Effect of Food Items and Matrices during Simulated In Vitro Digestion

Abstract

The digestive tract can be considered a bioreactor. High levels of reactive oxygen species (ROS) during digestion may predispose for local and/or systemic oxidative stress and inflammation, e.g., inflammatory bowel diseases. Food items rich in antioxidants may prevent such aggravation. This investigation analyzed pro-and antioxidant patterns of food matrices/items following in vitro digestion. Gastrointestinal digestion reflecting typically consumed quantities was performed on nine food items (orange and tomato juice, soda, coffee, white chocolate, sausage, vitamin C and E, and curcumin) and their combinations (n = 24), using the INFOGEST model. Antioxidant potential was measured by FRAP, DPPH, and ABTS, and pro-oxidant aspects by MDA (malondialdehyde) and peroxide formation. An anti-pro-oxidant score was developed, combining the five assays. Liquid food items showed moderately high antioxidant values, except for coffee and orange juice, which exhibited a high antioxidant potential. Solid matrices, e.g., white chocolate and sausage, showed both high pro-oxidant (up to 22 mg/L MDA) and high antioxidant potential (up to 336 mg/L vitamin C equivalents) at the same time. Individual vitamins (C and E) at physiological levels (achievable from food items) showed a moderate antioxidant potential (<220 mg/L vitamin C equivalents). Overall, both antioxidant and pro-oxidant assays correlated well, with correlation coefficients of up to 0.894. The effects of food combinations were generally additive, i.e., non-synergistic, except for combinations with sausage, where strong quenching effects for MDA were observed, e.g., with orange juice. In conclusion, as especially highlighted by complex matrices demonstrating both pro- and antioxidant potential, only measuring one aspect would result in physiological misinterpretations. Therefore, it is imperative to employ a combination of assays to evaluate both pro- and antioxidant properties of food digesta to ensure physiological relevance.

Simulated Gastrointestinal Digestion of Chestnut (Castanea sativa Mill.) Shell Extract Prepared by Subcritical Water Extraction: Bioaccessibility, Bioactivity, and Intestinal Permeability by In Vitro Assays

“…Hence, the decrease in phenolic concentrations (attested by spectrophotometric assays and phenolic profiling by LC-DAD-ESI/MS) upon digestion may prompt a decrease in the radical scavenging efficiency, suggesting that most of the phenolic compounds from the CS extract were degraded after digestion and/or metabolized into phenolic metabolites, with reduced bioactivity compared to the parent compounds that originate them [6,37]. In addition, previous studies on the in vitro digestion of foods and by-products obtained similar outcomes, highlighting lower antiradical properties after digestion [38][39][40].…”

Effect of Digested Selected Food Items on Markers of Oxidative Stress and Inflammation in a Caco-2-Based Human Gut Epithelial Model

“…The present study investigated oxidative stress and inflammatory markers of digested food items and their combinations at the interface of the gut and the host, i.e., in a model of the small intestinal epithelium, where most macro-and micronutrients are absorbed [24]. Previous studies have suggested that ROS and pro-oxidant food compounds could especially negatively impact the gut epithelium, as ROS levels post-digestion could be high [9,16], i.e., higher than in native food items or in other body compartments that are under tight homeostatic ROS control, though surprisingly little knowledge exists in this area. As ROS is tightly linked to inflammation, food items rich in ROS or increasing ROS during digestion could also increase systemic inflammation [25].…”

“…For example, sugar-rich beverages such as sodas have been reported to increase ROS production in the short term in animal experiments [14], downregulating the body's own antioxidant defense mechanisms, while the consumption of meat can produce lipid peroxides [15]. In a previous study of ours, we have shown that lipid-rich food matrices such as white chocolate and sausage indeed result in the production of malondialdehyde (MDA), a downstream product of peroxidation during digestion, which, however, could be quenched by simultaneous ingestion of orange juice [16].…”

“…In the present study, different food items and their combinations (Table 1) were tested following simulated gastro-intestinal digestion on a model of the human gut epithelium (Caco-2) in order to investigate their pro-and antioxidant effects, as well as their inflammatory effects. Food items were selected based on a previous study [16] covering a broad range of frequently consumed food items regarding their effect on oxidative stress following gastro-intestinal digestion in the digestive fluids.…”

“…The MDA assay was performed on lysed cell material, as described earlier [16], using a Cayman kit (art. No.…”