8-hydroxy-2'-deoxyguanosine or 8-hydroxy-deoxyguanosine (8-OH-dG or 8-oxo-dG) is a new biomarker that measures the effect of oxidative stress on cell DNA. The 8-OH-dG measurement is used to assess the relative risk of cancer and degenerative diseases due to DNA damage. The use of the right treatments and lifestyle adjustments can minimize the presence of 8-OH-dG, taking an important step toward optimal health and longevity.
Oxidative stress affects many of the body's normal processes and is responsible for or involved in the onset of more than 100 diseases, including aging and cancer. DNA oxidation occurs easily at guanosine bases, so measuring urine 8-hydroxy-deoxyguanosine provides a quantitative estimate of the continuing oxidative damage due to oxidative stress in the body. When 8-OHdG levels are elevated, it is important to identify the sources of oxidative stress and also to assess glutathione levels in the body.
Free radicals and other active molecules are continuously produced in vivo and cause oxidative damage to biomolecules, a process controlled only by the existence of multiple antioxidant systems and the replacement of damaged nucleic acids, proteins, and lipids. DNA is perhaps the most important biological target of oxidative damage and it is believed that persistent oxidative damage to DNA contributes significantly to the development of cancers, such as colon, breast, rectal, and prostate cancer.
8-hydroxy-deoxyguanosine is an oxidized derivative of deoxyguanosine and is produced when Reactive Oxygen Species (ROS) and other oxidants act on cellular DNA. As a modified nucleoside base, 8-OH-dG is important not only because of its abundance but also because of its mutagenic activity in DNA replication. 8-OH-dG is widely accepted as a sensitive indicator of oxidative DNA damage and oxidative stress. Evidence shows that elevated levels of 8-OH-dG are closely associated with exposure to harmful environmental factors such as ionizing radiation, industrial chemicals, air pollution, smoking, and chemotherapy.
Who should test for 8-Hydroxy-Deoxyguanosine?
Measurement of urine 8-hydroxy-deoxyguanosine is an important indicator in the control and etiological treatment of the following pathological conditions:
- Oxidative stress
- Metabolic syndrome
- Alzheimer's disease
- Parkinson's disease
- Diabetes mellitus, diabetic nephropathy, and diabetic retinopathy
- Various cancers
- Chronic hepatitis
- Inflammatory bowel disease (Crohn's disease and ulcerative colitis)
- Cystic fibrosis
- Atopic dermatitis and other skin diseases
- Rheumatoid arthritis and other autoimmune diseases
- Adrenal exhaustion
The 8-OH-dG measurement can also be used to assess DNA damage in humans after exposure to carcinogens such as tobacco, asbestos fibers, heavy metals, polycyclic aromatic hydrocarbons, ionizing radiations, and more.
Measurement of 8-hydroxy-deoxyguanosine (8-OH-dG) in the urine is an excellent biomarker of oxidative stress and at the same time an important risk factor for many diseases, including cancer. Reactive oxygen species (ROS) are produced as a result of normal aerobic metabolism or exposure to exogenous factors (xenobiotics). The large increase in oxygen free radicals (oxidative stress) results in oxidative damage of lipids, proteins, and DNA. Oxidative damage to nuclear and mitochondrial DNA occurs easily at guanosine bases which are removed by DNA repair mechanisms and excreted in the urine. 8-OH-dG is the best-studied oxidized nucleotide of DNA and is considered a pre-mutagenic agent. Bladder, prostate, and breast cancer have been associated with elevated 8-OH-dG levels.
Oxidative stress and the induced increase in 8-OH-dG by oxygen-free radicals have been associated with numerous pathological conditions. Environmental factors, lifestyle choices such as smoking and drug use as well as certain medications have also been associated with elevated 8-OH-dG levels. Known environmental factors include exposure to ionizing radiation, asbestos, toxic heavy metals, smoke from burning oil and coal, benzene, styrene, toluene, and xylene.
Moderately elevated 8-OH-dG levels have been associated with inadequate carotenoid intake, decreased intake of antioxidant-rich foods, and inadequate use or inadequate intake of antioxidant supplements. Detection of elevated levels of 8-hydroxy-2-deoxyguanosine requires the search for sources of oxidative stress or inflammation and the evaluation of the body's antioxidant defense systems such as glutathione. The effectiveness of the therapeutic intervention to improve oxidative stress should be monitored by reviewing urinary 8-OH-dG levels.
What can be done when 8-OH-dG is elevated?
- Dealing with the cause of its elevation. Reduction of oxidative stress and avoidance of exogenous factors
- Increase consumption of fruits and vegetables
- Taking the right antioxidant supplements (vitamins C & E, melatonin, etc.)
- Evaluation and enhancement of endogenous glutathione
Orange juice (but not pomegranate, apple, grapefruit, or cranberry juice) can reduce the effects of oxidative stress as measured by the 8-OH-dG assay. Orange juice, regardless of its polyphenol content, can lower 8-OHdG levels and help with weight loss in obese people with metabolic syndrome. Smokers with high 8-OH-dG levels can lower their levels by consuming moderate amounts of fish oils.