**5. Remarks and Future Perspectives**

Literature shows an evident gap regarding the antioxidant mechanisms of soy in health. This discrepancy of the literature is particularly relevant taking into consideration that the antioxidant effect of soy is frequently cited but not described in depth. The causes of this phenomenon are manifold: (i) The interest is largely focused on the interaction between isoflavones and the estrogen receptors. Even if this effect is the most evident, the currently available evidence suggests that it is not sufficient to justify the effects of soy on health. Furthermore, isoflavones itself can act with multiple mechanisms, probably concerted with non-isoflavone soy phytochemicals. (ii) There are many markers of oxidative stress but there is no consensus of methods and cutoffs adequate to detect the antioxidant ability of a substance in vivo. (iii) The presence of numerous confounding factors, especially dietary ones, raises critical issues in detecting the real effects of soy against oxidation. This has frequently led to the use of animal models whose data are difficult to transfer to humans for physiological differences. For example, rodent and non-human primate differently metabolize isoflavones. Moreover, there are discrepancies between experimental animal conditions and human real life. (iv) The detection of a physiological effect could be greatly different by the type of food used (soybeans, traditional soy foods, and soy-based meat analogs and supplements) and by the population reference (healthy individuals, patients with metabolic diseases, pre or postmenopausal, athletes, etc.).
