An overview on antioxidant supplements: the current situation situation from a scientific point of view. (original) (raw)
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An overview on antioxidant supplements. The current situation from a scientific point of view
Agro Food Industry Hi Tech, 2012
Accumulating evidence demonstrates that damage to cellular components from reactive oxygen species (ROS) plays an integral role in the age-related deterioration of biochemical and physiologic processes and in the incidence of age-related disease. In the late 1980s, many in vitro studies and early observational studies have suggested a role of antioxidants in the prevention of the ROS-induced damage involved in the etiopathogenesis of coronary artery disease. This led to a substantial increase in the use of antioxidant supplements for the prevention of c a r d i o v a s c u l a r d i s e a s e s a n d o t h e r a g e-r e l a t e d pathologies. Unexpectedly, recent more rigorous scientific evaluation did not support a causational relationship between antioxidant supplements and lowering the risk of c o r o n a r y a r t e r y d i s e a s e a n d o t h e r a g e-r e l a t e d pathologies (1). Moreover, supplementation with antioxidants has been linked to increased incidence of a number of diseases with adverse effects on human longevity (2, 3). Recent advances in the comprehension of the complex interaction between ROS and antioxidants in vivo and the role of mitochondria in the adaptive response to oxidative stress can help in understanding these seemingly contradictory data. Oxidative stress-i.e., an excessive production of ROS outstripping endogenous antioxidant defence capacity-is implicated in oxidative damage to nucleic acids, proteins, carbohydrates, and lipids. It is well known that mitochondria are the primary site for ROS generation as a by-product of aerobic metabolism, and that the accumulation of mitochondrial oxidative damage over time diminishes t h e c e l l u l a r e f f i c i e n c y i n e n e r g y production. ROS-induced damage is complex and frequently irreversible, and it further impairs mitochondrial function, rendering them prone to further ROS generation. This feedforward relationship between mitochondrial ROS generation and damage was hypothesized to be responsible for oxidative stress and accelerated ageing (4).
Frontiers in Physiology, 2020
Oxidative stress plays an essential role in the pathogenesis of chronic diseases such as cardiovascular diseases, diabetes, neurodegenerative diseases, and cancer. Long term exposure to increased levels of pro-oxidant factors can cause structural defects at a mitochondrial DNA level, as well as functional alteration of several enzymes and cellular structures leading to aberrations in gene expression. The modern lifestyle associated with processed food, exposure to a wide range of chemicals and lack of exercise plays an important role in oxidative stress induction. However, the use of medicinal plants with antioxidant properties has been exploited for their ability to treat or prevent several human pathologies in which oxidative stress seems to be one of the causes. In this review we discuss the diseases in which oxidative stress is one of the triggers and the plant-derived antioxidant compounds with their mechanisms of antioxidant defenses that can help in the prevention of these diseases. Finally, both the beneficial and detrimental effects of antioxidant molecules that are used to reduce oxidative stress in several human conditions are discussed.
A review of the interaction among dietary antioxidants and reactive oxygen species
The Journal of Nutritional Biochemistry, 2007
During normal cellular activities, various processes inside of cells produce reactive oxygen species (ROS). Some of the most common ROS are hydrogen peroxide (H 2 O 2 ), superoxide ion (O 2 À ), and hydroxide radical (OH À ). These compounds, when present in a high enough concentration, can damage cellular proteins and lipids or form DNA adducts that may promote carcinogenic activity. The purpose of antioxidants in a physiological setting is to prevent ROS concentrations from reaching a high-enough level within a cell that damage may occur. Cellular antioxidants may be enzymatic (catalase, glutathione peroxidase, superoxide dismutase) or nonenzymatic (glutathione, thiols, some vitamins and metals, or phytochemicals such as isoflavones, polyphenols, and flavanoids).
Reconvene and reconnect the antioxidant hypothesis in human health and disease
Indian Journal of Clinical Biochemistry, 2010
The antioxidants are essential molecules in human system but are not miracle molecules. They are neither performance enhancers nor can prevent or cure diseases when taken in excess. Their supplemental value is debateable. In fact, many high quality clinical trials on antioxidant supplement have shown no effect or adverse outcomes ranging from morbidity to all cause mortality. Several Chochrane Meta-analysis and Markov Model techniques, which are presently best available statistical models to derive conclusive answers for comparing large number of trials, support these claims. Nevertheless none of these statistical techniques are flawless. Hence, more efforts are needed to develop perfect statistical model to analyze the pooled data and further double blind, placebo controlled interventional clinical trials, which are gold standard, should be implicitly conducted to get explicit answers. Superoxide dismutase (SOD), glutathione peroxidase and catalase are termed as primary antioxidants as these scavenge superoxide anion and hydrogen peroxide. All these three enzymes are inducible enzymes, thereby inherently meaning that body increases or decreases their activity as per requirement. Hence there is no need to attempt to manipulate their activity nor have such efforts been clinically useful. SOD administration has been tried in some conditions especially in cancer and myocardial infarction but has largely failed, probably because SOD is a large molecule and can not cross cell membrane. The dietary antioxidants, including nutrient antioxidants are chain breaking antioxidants and in tandem with enzyme antioxidants temper the reactive oxygen species (ROS) and reactive nitrogen species (RNS) within physiological limits. Since body is able to regulate its own requirements of enzyme antioxidants, the diet must provide adequate quantity of non-enzymic antioxidants to meet the normal requirements and provide protection in exigent condition. So far, there is no evidence that human tissues ever experience the torrent of reactive species and that in chronic conditions with mildly enhanced generation of reactive species, the body can meet them squarely if antioxidants defense system in tissues is biochemically optimized. We are not yet certain about optimal levels of antioxidants in tissues. Two ways have been used to assess them: first by dietary intake and second by measuring plasma levels. Lately determination of plasma/serum level of antioxidants is considered better index for diagnostic and prognostic purposes. The recommended levels for vitamin A, E and C and beta carotene are 2.2-2.8 lmol/l; 27.5-30 lmol/l; 40-50 lmol/l and 0.4-0.5 lmol/l, respectively. The requirement and recommended blood levels of other dietary antioxidants are not established. The resolved issues are (1) essential to scavenge excess of radical species (2) participants in redox homeostasis (3) selective antioxidants activity against radical species (4) there is no universal antioxidant and 5) therapeutic value in case of deficiency. The overarching issues are (1) therapeutic value as adjuvant therapy in management of diseases (2) supplemental value in developing population (3) selective interactivity of antioxidant in different tissues and on different substrates (4) quantitative contribution in redox balance (5) mechanisms of adverse action on excess supplementation (6) advantages and disadvantages of prooxidant behavior of antioxidants (7) behavior in cohorts with polymorphic differences (8) interaction and intervention in radiotherapy, diabetes and diabetic complications and cardiovascular diseases (9) preventive behavior in neurological disorders (10) benefits of non-nutrient dietary antioxidants (11) markers to assess optimized antioxidants status (12) assessment of benefits of supplementation in alcoholics and heavy smokers. The unresolved and intriguing issues are (1) many compounds such as vitamin A and many others possessing both antioxidant and non-antioxidant properties contribute to both the activities in vivo or exclusively only to non-antioxidant activity and (2) since human tissues do not experience the surge of FR, whether there is any need to develop stronger synthetic antioxidants. Theoretically such antioxidants may do more harm than good.
Oxidized forms of dietary antioxidants: Friends or foes?
Trends in Food Science & Technology
Many clinical trials in which individuals received one or more dietary antioxidants failed to demonstrate conclusive effects of antioxidant supplementation. Antioxidant supplements do not seem to protect sufficiently against oxidative stress, oxidative damage or to increase lifespan. Some recent studies implied that antioxidant therapy can even increase mortality. In this paper, the idea is presented that antioxidants in their oxidative forms may have more health-beneficial effects than their reduced forms. It seems that it is not the anti-oxidative potential of the antioxidants that has the major role in health-improvement, but rather their involvement in cell signaling processes, regulation of transcription factor activities and other determinants of gene expression. Although oxidized forms of dietary antioxidants may be toxic, their low concentrations might trigger an adaptive stress response (hormesis) and provoke an increased endogenous antioxidant protection and an activation ...
2012
There has been a current upsurge in the medical implications of free radicals and related species during the past several decades. These chemical species are integral components produced during normal biochemical and physiological processes but leads to oxidative stress when produce in excess and causes potential damage to cells. A wide range of non-enzymatic and enzymatic antioxidant defenses exists to counteract the damaging effects of free radicals. There exist epidemiological evidences correlating higher intake of antioxidant rich foodstuffs with greater free radical neutralizing potential to lower incidence of several human morbidities or mortalities. Gene therapy to produce more antioxidants in the body, novel biomolecules and the use of functional foods enriched with antioxidants are milestones to newer approaches to reduce free radical damage. This paper reviews the biology of reactive species, their pathways through which they relate to the pathology of various diseases and discusses the putative roles that antioxidants, from different sources, play in controlling oxidative stress and reduce the incidence of concerned diseases.
Antioxidants for Health Management
Jurnal Intelek, 2022
Antioxidants are technically reductant molecules that prevent the oxidation of other molecules. As other living systems, human biological molecules are also prone to oxidation reactions. In order to repair all of the oxidation damage, human body is naturally producing antioxidants or known as endogenous antioxidant. Unfortunately, the body’s production of antioxidants declines with age and this is found to be a strong factor in contributing to premature aging and degenerative diseases. Researchers have found that exogenous antioxidants which are obtained from foods may work together with endogenous antioxidants to maintain the redox reaction balance in the body. There are thought to be hundreds and possibly thousands of substances that can act as exogenous antioxidants including carotenoids, flavonoids, indoles, polyphenols, essential vitamins (A, C, E), and the minerals copper, zinc, manganese, and selenium. Thus, this paper intended to give insights on the endogenous and exogenou...
Role of Antioxidants in Pathophysiology
To counter the harmful effects of reactive species, antioxidant defencemechanism operates to detoxify or scavenge the reactive species. Antioxidants are able to neutralize free radical and render them harmless. It has been suggested that the extent of damage caused by the free radical might be modified by three dietary intervention strategies: (a) caloric restriction and thus a depression in free radicals arising due to normal metabolism; (b) minimizing the intake of food substance that increase the free radicals, such as poly-unsaturated fatty acids; (c) supplementation with one or more antioxidants in diet. A wide array of enzymatic antioxidants defence exists, that include superoxide dismutase, glutathione reductase, catalase etc. The interrelationship between both the activity and the intracellular levels of these substances protect them from toxicity. ABSTRACT
Antioxidants in Health, Disease and Aging
CNS & Neurological Disorders - Drug Targets, 2011
There is growing scientific agreement that antioxidants, particularly the polyphenolic forms, may help lower the incidence of disease, such as certain cancers, cardiovascular and neurodegenerative diseases, DNA damage, or even have anti-aging properties. On the other hand, questions remain as to whether some antioxidants or phytochemicals potentially could do more harm than good, as an increase in glycation-mediated protein damage (carbonyl stress) and some risk has been reported. Nevertheless, the quest for healthy aging has led to the use of antioxidants as a means to disrupt age-associated deterioration in physiological function, dysregulated metabolic processes or prevention of many age-related diseases. Although a diet rich in polyphenolic forms of antioxidants does seem to offer hope in delaying the onset of age-related disorders, it is still too early to define their exact clinical benefit for treating age-related disease. Regardless of where the debate will end, it is clear that any deficiency in antioxidant vitamins or adequate enzymatic antioxidant defenses can manifest in many disease states and shift the redox balance in some diseases. This review updated critically examines general antioxidant compounds in health, disease and aging with hope that a better understanding of the many mechanisms involved with these diverse compounds may lead to better health and novel treatment approaches for age-related diseases.