Interpreting Oxidative Stress Markers

Six out of every ten adults in the United States experience a chronic health condition, while four in ten manage two or more. Among these conditions, the leading causes of disability and death are cardiovascular disease (CVD), chronic obstructive pulmonary disease (COPD), chronic kidney disease (CKD), Alzheimer’s disease, type 2 diabetes, and cancer. Underlying these conditions is oxidative stress. It is also involved in the aging process and associated with age-related changes such as sarcopenia and frailty. Functional medicine may use oxidative stress markers to assess the balance between antioxidants and free radicals within the body and identify potential imbalances. 

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What is Oxidative Stress? 

Oxidative stress is a condition that may occur when there is an imbalance between the production of free radicals and the body’s ability to neutralize them with antioxidants. Free radicals, or reactive oxygen species (ROS), are highly reactive molecules with one or more unpaired electron(s) formed when oxygen interacts with specific molecules. They serve bodily functions, including cellular signaling and supporting the immune system. Antioxidants help manage free radicals to maintain cellular balance. When there is excessive production of free radicals or the antioxidant systems are overwhelmed, an imbalance may occur, potentially leading to oxidative stress. Free radicals can trigger reactions, including lipid peroxidation, protein oxidation, and DNA changes, which may affect cellular structures and functions. 

As cells experience cumulative changes from reactive oxygen species (ROS), they may undergo cellular senescence, a process in which cells experience growth arrest. This phenomenon may contribute to the aging process by affecting cellular function and promoting the secretion of certain molecules. Oxidative stress is also thought to play a role in the development of various non-communicable diseases (NCDs), potentially contributing to their initiation and progression. In cardiovascular diseases, oxidative stress may influence endothelial function, lipid peroxidation, and inflammation, which are factors in the development of atherosclerosis. Chronic respiratory diseases, particularly COPD, may exhibit heightened oxidative stress due to environmental factors like cigarette smoke, potentially leading to lung inflammation and tissue changes. The progression of kidney disease is thought to be linked to oxidative stress, as reactive oxygen species may contribute to renal cell changes and inflammation. 

Neurodegenerative diseases, such as Alzheimer's and Parkinson's, are characterized by oxidative changes to neurons and the accumulation of abnormal protein aggregates. Oxidative stress is also thought to play a role in cancer, potentially influencing genetic mutations and cell proliferation. Additionally, in metabolic disorders like type 2 diabetes, there may be a connection between oxidative stress and insulin resistance (IR), contributing to chronic low-grade inflammation.  

Common Causes of Oxidative Stress 

Free radicals can arise from sources within the body (endogenous) as well as from external sources (exogenous). Specific cellular processes naturally produce free radicals as byproducts. For instance, the electron transport chain in mitochondria, the process by which cells generate energy from adenosine triphosphate (ATP), is a significant endogenous source. Immune cells also release ROS to support the immune system. At low or moderate levels, ROS may benefit cellular responses and immune function. However, at high concentrations, they may contribute to oxidative stress and subsequent changes to proteins, lipids, and DNA. When the body's antioxidant systems function optimally, they maintain a balance with ROS, potentially preventing excessive oxidative changes. However, poor function or an imbalance in these systems can lead to oxidative stress. A deficiency in essential nutrients, particularly antioxidants, obtained through the diet can affect the body's ability to manage ROS. Genetic variations can influence the efficiency of antioxidant enzymes and other defense mechanisms, impacting an individual's susceptibility to oxidative stress. The natural aging process is associated with a decline in the efficiency of antioxidant systems, making older individuals more susceptible to oxidative stress.

Exogenous sources of free radicals significantly contribute to increased oxidative stress. Smoking, alcohol consumption, exposure to heavy metals, and air pollution all increase free radical generation. Cooking methods, especially those involving high temperatures and fats, produce compounds that may contribute to oxidative stress. Ionizing radiation from sources like X-rays and nuclear materials can directly affect cellular components, increasing the production of free radicals. Certain drugs, like cyclosporine, tacrolimus, and gentamicin, can also increase oxidative stress. Ultraviolet (UV) light exposure increases the generation of ROS in the skin.

Types of Oxidative Stress Markers 

Several testing methods can be employed to assess oxidative stress levels. These tests help healthcare professionals understand the extent of oxidative changes and the balance between reactive oxygen species (ROS) and antioxidants. The oxidative changes that free radicals cause to lipids, proteins, and nucleic acids of the cells can be measured. Enzyme activity assays are utilized to assess the activity of antioxidant enzymes involved in the defense against ROS. These assays provide insights into the cellular capacity to manage harmful radicals and oxidative stress. Redox assays, using a free radical generating system and seeing how well the cells resist changes, measure the cells’ resistance to oxidative stress and their overall antioxidant capacity. Additionally, levels of important antioxidants can also be measured to assess the body’s antioxidant potential.

Testing for Oxidative Stress Markers 

Functional medicine labs assist in assessing oxidative stress, providing an understanding of an individual's biochemical status. The information gathered from functional medicine labs may help in tailoring targeted interventions to address specific imbalances and support antioxidant defense.

Oxidative Stress 2.0

The Oxidative Stress 2.0 by Genova Diagnostics is a urine test measuring levels of 8-hydroxy-2'-deoxyguanosine (8-OHdg) and lipid peroxides. 8-OHdG is a modified nucleoside and a biomarker for oxidative DNA changes. It is formed when ROS reacts with guanine, one of the DNA bases. Lipid peroxides, including malondialdehyde, are products of lipid peroxidation, a process initiated by the interaction of ROS with cellular lipids. Urinary measurements of lipid peroxides and 8-OHdG, therefore, provide valuable information on the overall oxidative stress status in the body, offering a non-invasive and easily accessible means of assessing cellular changes associated with ROS. Elevated levels of these biomarkers may indicate increased oxidative stress and potential cellular changes. 

Advanced Oxidative Stress

The Advanced Ox Stress test by Precision Point is a urine test that not only measures 8-OHdg, but also includes F2-isoprostane, reduced glutathione, oxidized glutathione, and total glutathione. F2-isoprostanes are prostaglandin-like compounds that are formed through the peroxidation of arachidonic acid, a polyunsaturated fatty acid present in cell membranes. Glutathione is a crucial antioxidant that plays a central role in the cellular defense against oxidative changes. GSH is the active, reduced form of glutathione that can help manage ROS. GSH can become oxidized to GSSG during the process of managing ROS. Assessing the levels of reduced glutathione, oxidized glutathione, and total glutathione, along with calculating the GSH/GSSG ratio, provides a comprehensive understanding of the redox status within cells (24). High levels of 8-OHdg and F2-isoprostane are associated with increased oxidative stress. A balanced and healthy redox state is characterized by a relatively high level of GSH and a low level of GSSG. A decrease in the GSH: GSSG ratio suggests an imbalance between antioxidants and oxidants, indicating increased oxidative stress.

Full Cellular Nutrition Assay

The Full Cellular Nutrition Assay by Cell Science Systems combines the Cellular Micronutrient Assay and the Redox/Antioxidant Protection Assay to provide a personalized assessment of a patient's nutritional needs. The body requires micronutrients to help support cellular metabolism and function. A cellular micronutrient assay (CMA) measures metabolic activity in cells after specific micronutrients are provided. The nutrients that enhance cellular function are reported as nutrient insufficiency. The Redox Assay is a measurement of the cells’ resistance to oxidative stress and its overall antioxidant capacity. A free radical generating system is added to cells, and their growth rates and/or changes are assessed. The cells’ ability to resist oxidative changes and prevent further changes to cells is determined and compared to that of the general population, creating a redox score. A low redox score is associated with an increased risk of oxidative stress. In the Antioxidant Protection Assay, single antioxidants are added to the patient’s cells in the presence of oxidative stress molecules. This process is repeated for each individual antioxidant. Specific antioxidants that support the recovery of patients’ cells from the effect of oxidative stress are reported as highly protective or protective. 

Organic Acids

The Organic Acids test (OAT) from Mosaic Diagnostics provides a comprehensive metabolic analysis, including information about yeast and bacteria levels, vitamins and minerals, oxidative stress, and neurotransmitters. Metabolic processes in the body produce organic acids as by-products, which can then be measured in the urine. The OAT includes markers that reflect the efficiency of mitochondrial function, such as citric acid cycle intermediates. High levels of these intermediates can indicate mitochondrial dysfunction, which is often associated with increased oxidative stress. It also measures specific markers related to oxidative stress, including products of lipid peroxidation. Elevated levels of these markers are suggestive of oxidative stress and changes. It provides information about the levels of essential nutrients and antioxidants, like glutathione and CoQ10. Deficiencies in these nutrients can affect the body’s ability to manage oxidative stress effectively. Pyroglutamic acid is a metabolite of glutathione, and elevated values are most commonly caused by glutathione deficiency. 3-Hydroxy-3-methylglutaric Acid (HMG) is a precursor of coenzyme Q10, and an increase in urine HMG may indicate decreased synthesis of coenzyme Q10.

Micronutrients

The Micronutrient Test by SpectraCell Laboratories measures 31 vitamins, minerals, and other nutrients. Many nutrients, such as Vitamin E, vitamin C, selenium, and glutathione, play important roles as antioxidants in the body. Low levels can increase the risk of oxidative stress (25, 29).

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Interpreting Oxidative Stress Marker Results 

Interpreting oxidative stress markers requires an understanding of which type of marker is being evaluated. Elevated markers of oxidative changes, such as 8-OHdg, malondialdehyde, and F2-isoprostane, are associated with increased oxidative stress and changes. If directly measuring levels of antioxidants, such as Vitamin C, E, and glutathione, low levels are associated with deficiencies that can lower the body’s antioxidant potential and increase the risk of oxidative stress.  

When confronted with imbalanced levels, healthcare professionals should further investigate root causes, such as environmental exposures, nutritional deficiencies, or chronic inflammation. Depending on the causes, interventions may involve lifestyle modifications, dietary changes, or targeted antioxidant supplementation to help manage oxidative stress and support overall well-being. The interpretation of these results is a crucial step in developing personalized strategies for health optimization and wellness. 

Managing Oxidative Stress 

A multifaceted approach that includes dietary adjustments, lifestyle modifications, and the strategic incorporation of antioxidants when needed can help to manage oxidative stress. Embracing this type of comprehensive strategy empowers individuals to take charge of their health, potentially reducing the future health risks associated with oxidative stress. 

Nutrition

Western diets are characterized by excess consumption of saturated fats, refined sugars, and sodium and low consumption of plant-based fiber. People who regularly eat Western diets have been shown to have higher levels of oxidative stress and a greater risk of chronic disease. High-calorie, high-fat, and/or high-carbohydrate diets have been associated with increased oxidative stress. Fruits and vegetables, on the other hand, are rich in polyphenols and antioxidants that help to manage ROS. The Mediterranean diet is rich in vegetables, unrefined cereals, fruits, legumes, fish, olive oil, and nuts. Its higher intake of phytonutrients, as well as anti-inflammatory fats, such as omega-3 fatty acids in fish and nuts, make it a smart choice for supporting balanced oxidative stress levels. Studies have shown that the Mediterranean diet may support weight management and overall health, potentially reducing the risk of conditions like type 2 diabetes, stroke, CVD, cognitive changes, Alzheimer’s disease, metabolic syndrome, and other chronic conditions associated with inflammation and oxidative stress (13).

Stress Management

Chronic stress triggers the activation of the neuroendocrine system, influencing a number of physiological responses and potentially contributing to an elevation in oxidative stress. The sympathetic nervous system (SNS) and hypothalamic-pituitary-adrenal (HPA) axis release catecholamines and glucocorticoids, like cortisol. Prolonged exposure to elevated levels of glucocorticoids can affect mitochondrial electron transport chain activity, potentially leading to the formation of ROS. Catecholamines may influence the activity of enzymes responsible for redox in the cell, potentially increasing mitochondrial function changes and ROS production. Implementing mind-body practices may assist in restoring equilibrium to the nervous system and alleviating feelings of stress. Mind-body therapies are known to activate the parasympathetic nervous system, often referred to as the "rest and digest" system, which counterbalances the sympathetic nervous system's "fight or flight" response triggered during stress. Specific practices such as meditation, yoga, and diaphragmatic breathing have all been shown to help manage oxidative stress. 

Physical Activity

Regular physical activity may support antioxidant defenses and reduce lipid peroxidation. Engaging in moderate exercise and maintaining an active lifestyle not only aids in managing oxidative stress but also serves as support against cardiovascular conditions, type II diabetes, metabolic syndrome, and neurodegenerative conditions. Chronic exposure to high levels of ROS can be challenging, potentially overwhelming the body's antioxidant systems and affecting cellular function. Therefore, excessive exercise can be harmful, especially for untrained individuals. However, through progressive training, cells may enhance their ability to manage a greater amount of ROS. Exercise-induced ROS generation may trigger an upregulation in the activity of enzymatic antioxidants, thereby improving resistance to oxidative challenges. 

Antioxidants

The body's antioxidant system is a complex network of molecules and enzymes that work together to help manage oxidative stress. A balanced and varied diet helps to ensure the body has an abundant supply of nutrients that help to support the antioxidant system.

Glutathione is an intracellular antioxidant that also assists in managing substances that can increase oxidative stress. Additionally, it helps recycle other antioxidants in the body, such as vitamins C and E. It is a tripeptide molecule composed of three amino acids: cysteine, glutamic acid, and glycine. There are several foods that contain the thiol-rich compounds glutathione, NAC, and cysteine, including asparagus, avocado, cucumber, green beans, and spinach. N-acetyl cysteine (NAC) supplementation serves as a precursor for the synthesis of glutathione, or individuals can choose to directly supplement with liposomal glutathione. 

CoQ10 is an important cofactor for energy production in the mitochondria, a lipid antioxidant, and also helps regenerate vitamin E. CoQ10 is both produced endogenously and absorbed through the diet. Major dietary sources of CoQ10 include meats, fish, nuts, and soybeans. Many individuals can obtain sufficient amounts of CoQ10 through a balanced diet, but supplementation may be useful for individuals with particular health considerations, such as cardiovascular health and metabolic support (28, 31).

Vitamin E is a lipid-soluble antioxidant that helps to support cell membranes from oxidative changes. Naturally occurring vitamin E exists in eight chemical forms (alpha-, beta-, gamma-, and delta-tocopherol and alpha-, beta-, gamma-, and delta-tocotrienol) that have varying levels of biological activity. Alpha-tocopherol is the most biologically active form of vitamin E. Nuts, seeds, and vegetable oils are among the best sources of alpha-tocopherol. Vitamin E supplements are available in either alpha-tocopherol form or as mixed tocopherols or tocotrienols. Evidence suggests that vitamin E may help manage the formation of oxidized low-density (LDL) cholesterol and support cardiovascular health (43).

Vitamin C is a water-soluble antioxidant that helps manage free radicals in cellular fluids. Vitamin C is found in foods like bell peppers, citrus fruits, kiwi, and broccoli. Low levels of vitamin C have been associated with a number of considerations, including blood pressure management, gallbladder health, and cardiovascular support. Vitamin C supplements come in various types and forms to suit different preferences and health needs. Ascorbic acid is the most common and basic form of vitamin C. Buffered forms, such as sodium ascorbate or calcium ascorbate, are available and may be more suitable for those who experience stomach upset with ascorbic acid. Ester-C, a combination of calcium ascorbate with vitamin C metabolites, is also easier on the stomach.

Selenium is a trace mineral that is incorporated into selenoproteins, some of which serve antioxidant functions. One important selenoprotein is glutathione peroxidase. Brazil nuts and seafood are great sources of selenium. It is also available as both a stand-alone supplement and as part of multivitamin complexes. Studies have shown that selenium may help manage products of oxidative stress, like malondialdehyde, and support glutathione levels.

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Oxidative Stress Markers: Final Thoughts

Oxidative stress is thought to play a role in the aging process and the development of many chronic, inflammatory conditions. Functional medicine testing provides individuals with an opportunity to identify the signs of oxidative stress and make informed healthcare decisions to support future wellness. Embracing healthy lifestyle changes, dietary modifications, and mindfulness practices can help maintain balance, supporting our defenses against oxidative stress.