Beneficial and Detrimental Effects of Reactive Oxygen Species on Lifespan: A Comprehensive Review of Comparative and Experimental Studies

Abstract

Aging is the greatest risk factor for a multitude of diseases including cardiovascular disease, neurodegeneration and cancer. Despite decades of research dedicated to understanding aging, the mechanisms underlying the aging process remain incompletely understood. The widely-accepted free radical theory of aging (FRTA) proposes that the accumulation of oxidative damage caused by reactive oxygen species (ROS) is one of the primary causes of aging. To define the relationship between ROS and aging, there have been two main approaches: comparative studies that measure outcomes related to ROS across species with different lifespans, and experimental studies that modulate ROS levels within a single species using either a genetic or pharmacologic approach. Comparative studies have shown that levels of ROS and oxidative damage are inversely correlated with lifespan. While these studies in general support the FRTA, this type of experiment can only demonstrate correlation, not causation. Experimental studies involving the manipulation of ROS levels in model organisms have generally shown that interventions that increase ROS tend to decrease lifespan, while interventions that decrease ROS tend to increase lifespan. However, there are also multiple examples in which the opposite is observed: increasing ROS levels results in extended longevity, and decreasing ROS levels results in shortened lifespan. While these studies contradict the predictions of the FRTA, these experiments have been performed in a very limited number of species, all of which have a relatively short lifespan. Overall, the data suggest that the relationship between ROS and lifespan is complex, and that ROS can have both beneficial or detrimental effects on longevity depending on the species and conditions. Accordingly, the relationship between ROS and aging is difficult to generalize across the tree of life.

The Hyperfunction Theory: An Emerging Paradigm for the Biology of Aging

“…The wide net of Blagosklonny's conceptual research led him to conclude that scientific evidence does not generally support the ROS theory (Blagosklonny, 2006a;Blagosklonny, 2008b), a suspicion shared by de Magalhães and I (de Magalhães, 2005;Keaney and Gems, 2003;Keaney et al, 2004). The crisis in the ROS theory that culminated in 2008-09 has been reviewed extensively elsewhere (Gems and Doonan, 2009;Perez et al, 2009;Shields et al, 2021;Van Raamsdonk and Hekimi, 2010). It is true that there is a correlation between aging and accumulation of molecular damage.…”

Kombucha tea from seagrapes (Caulerpa racemosa) potential as a functional anti-ageing food: in vitro and in vivo study

“…Ageing is a process by which structural and functional changes are accumulated in an organism as a result of many factors, such as changes due to oxidative damage caused by reactive oxygen species (ROS) [1]. ROS is defined as a reactive molecule that contains oxygen from molecular oxygen reduction in the cell [2].…”

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