Twenty‐five years of total antioxidant capacity measurement of foods and biological fluids: merits and limitations

Abstract

This review summarises 25 years of investigations on antioxidants research in foods and biological fluids and critically analyses the merits and limitations of using the total antioxidant capacity (TAC) measurement in the metabolomic era. An enormous bulk of knowledge was produced regarding the antioxidant capacity of foods and large TAC databases were developed. A direct link between a food TAC value and any health benefit is erroneous and has led to several cases of consumer deception. However, the striking epidemiological evidence associating a high dietary TAC with some disease prevention and the availability of well-constructed TAC databases deserve attention and must be taken into account to establish the usefulness of measuring TAC in both foods and biological samples. The in vivo TAC measurement, usually performed in plasma, is influenced by many external factors, such as dietary habits, as well as environmental and behavioural factors, which are integrated towards homeostatic control by fine physiological mechanisms with high inter-individual variability. Therefore, plasma TAC cannot be considered as a unique biomarker of individual antioxidant status. However, the combined evaluation of plasma TAC with known markers of disease, individual metabolism, inflammation and genetics, as well as with markers of gut microbiota composition and activity, may lead to the identification of populations that are more responsive to food/diet TAC. In this framework, the appropriate use of TAC measurement both in food and in vivo can still provide support for the interpretation of complex phenomena and be a tool for sample screening when making a quick decision toward in-depth research investigations.

Plasma Non-Enzymatic Antioxidant Capacity (NEAC) in Relation to Dietary NEAC, Nutrient Antioxidants and Inflammation-Related Biomarkers

“…With regard to nutrient antioxidant biomarkers, high P-NEAC as FRAP was associated with high levels of almost all antioxidants, including TP. While this marker seems to not reflect the amount of phenolic compounds contained in food [45], we observed positive associations between all P-NEAC assays and TP. D-NEAC was also positively associated with dietary intake (all carotenoids and flavonoids) and plasma antioxidant levels (lutein and α-tocopherol) in a study of 60 healthy non-smoking subjects [3].…”

“…D-NEAC has been associated with health outcomes in several epidemiological studies [44]. However, it has been argued that the in vitro antioxidant capacity may not reflect the real in vivo antioxidant potential of the body [2,5,45]. Studies assessing the relationship between D-NEAC and P-NEAC have reported, at best, moderately-weak correlations for some NEAC assays [4,14,15], while others did not support a correlation [46].…”

“…Another possible reason for the seemingly weak correlation between the two is that P-NEAC is affected by many lifestyle factors including dietary habits, the individual´s physiological state, genetic variation and gut microbiome composition and function [47]. All of them have a well-known direct impact on the mechanisms of digestion, absorption and metabolism of dietary antioxidants, resulting in a high inter-individual variability of P-NEAC [45]. For instance, P-NEAC has been found to be higher in smokers compared to non-smokers [5], in men [18] and in overweight/obese individuals [12].…”

ABTS/PP Decolorization Assay of Antioxidant Capacity Reaction Pathways

“…Two ions with m/z 259 and 259.1 assigned to ABTS •+ degradation products were detected as well. The two adducts of the catechin/ABTS •+ reaction had m/z values of 803 and 560, the coupling reaction product (10) and hydrazinediylidene-like derivative (12), respectively (Figure 5b). Small amounts of the imine-like adduct (11) were also presumably detected on the preparative HPLC chromatogram, but its quantity was not enough for characterization.…”

Parameters of Oxidative Stress in Reproductive and Postmenopausal Mexican Women

“…Total antioxidant capacity (TAC) includes the synergic and redox interactions between the different molecules present in foods and biological fluids [16]. However, the results regarding TAC are not clear; in some studies, TAC was increased [6,14], but in other studies, TAC was decreased in PMW [11,13,15,17].…”