Oxidative stress can cause many different diseases – cancer, brain disorders, heart problems, and more. Read more below to learn about how you can protect your body againt its negative effects.

Introduction

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http://journal.publications.chestnet.org/article.aspx?articleid=1699493

Scientists widely use the term “oxidative stress”. It refers to a serious imbalance between the production of free radicals and antioxidant defense, leading to potential tissue damage (R).

‘Free radical species’ summarizes a variety of highly reactive molecules that can be divided into different categories. The most prominent members of such categories include superoxide O2·−, hydroxyl radical OH·, and peroxy radical ROO· (R).

Under normal conditions, the rate and magnitude of oxidant formation are balanced by the rate of oxidant elimination. However, an imbalance between prooxidants and antioxidants results in oxidative stress(R).

Oxidative stress can cause either a positive response (cell proliferation) or a negative cell response (growth arrest or cell death). (R).

What Are Free Radicals?

Reactive oxygen species (ROS) are produced by all vascular cell types, including endothelial, smooth muscle, and connective tissue cells, and can be formed by numerous enzymes (R).

Oxidants are also generated by different types of radiation, with X-irradiation generating the hydroxyl radical (R, R2).

Irradiation with ultraviolet light generates electronically excited states with the subsequent radical formation (R,R2).

Ultrasound and microwave radiation can also generate reactive oxygen species (R).

Metal-catalyzed reactions produce reactive oxidant species(R).

They are present as pollutants in the atmosphere (R).

ROS are produced by neutrophils and macrophages during inflammation (R).

They are also by-products of mitochondria-catalyzed electron transport reactions and other mechanisms (R).

Benefits of Free Radicals

It has become apparent that plants actively produce ROS as signaling molecules to control processes such as programmed cell death, stress responses, pathogen defense and systemic signaling (R).

Free radical reactions are essential for host defense mechanisms as with neutrophils, macrophages and other cells of the immune system. However, if the body overproduces free radicals, they cause tissue injury and cell death (R).

ROS within cells act as secondary messengers in intracellular signaling cascades, and can induce cell death, functioning as anti-tumorigenic species (R).

O2 and H2O2 function as second messengers activating numerous signaling molecules, which play an important role in vascular biology and cardiovascular disease (R).

One further beneficial example of ROS at low concentrations is the induction of a mitogenic response, meaning they can trigger cell growth and differentiation (R).

Low concentrations of superoxide radical and hydrogen peroxide, in fact, stimulate cell reproduction and enhanced survival in a wide variety of cell types (R).

Other roles include regulation of the cellular calcium concentration, regulation of protein phosphorylation, and activation of certain transcription factors (R).

Bad Aspects of Free Radicals:

As many as 200 human diseases have been associated with increased levels of oxidative stress (R).

Reactive oxygen species (ROS) influence many physiological processes including host defense and cellular signaling and their increased production through oxidative stress plays a role in many diseases (R).

These diseases include:

  • Cancer (R).
  • Vascular diseases (R).
  • High cholesterol (R, R2).
  • Hypertension (R, R2).
  • Parkinson’s disease (R).
  • Alzheimer’s disease (R).
  • Diabetes (R).
  • Kidney disease (R).
  • Cardiac hypertrophy (R).
  • Heart failure (R).
  • Stroke (R).

1) Free Radicals Damage Cells

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At high concentrations, ROS can be important mediators of damage to cell structures, including lipids and membranes, proteins and nucleic acids (R).

Oxidative damage accumulates during the life cycle, and it plays a key role in the development of age-dependent diseases such as cancer, arthritis, brain disorders and other conditions (R).

2) Oxidative Damage Helps Cause Diabetes

Both types of diabetics display increased levels of reactive oxygen species such as free radicals; for this reason, the onset of diabetes is closely associated with oxidative stress (R).

Damaged protein is a contributing factor to the mechanism by which oxidative stress accelerates diabetes complications (R).

Additionally, it appears that oxidative stress byproducts contribute to insulin resistance, the basis of diabetes (R).

Oxidative stress causes an excessive formation of free radicals which weaken defense mechanisms against further oxidation and that increases the likelihood of more cell damage, insulin resistance, and further complications of diabetes (R).

Also, recent research has demonstrated a direct link between the imbalance of oxidative stress and antioxidants leading to impaired glucose uptake (R).

3) Oxidative Damage Causes COPD

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Oxidative stress damages and impairs the functioning of several kinds of proteins, harming lung physiology in ways that can induce COPD, a chronic lung disease (R).

The harmful effects include oxidative inactivation of cells, excessive secretion of mucus, membrane lipid peroxidation, remodeling of the extracellular matrix, and cell death (R).

Additional oxidative stress occurs in COPD patients, because oxidative stress causes inflammation, and inflammation, in turn, causes more oxidative stress (R).

This cycle occurs because oxidation causes various protein dysfunctions, and that hinders the operation of functions that restore a healthy oxidant/antioxidant balance (R).

4) Oxidative Stress Contributes to Cancer

While a high level of oxidative stress is cytotoxic to the cell and halts proliferation by inducing apoptosis or even necrosis, a low level of oxidative stress can in fact stimulate the cell division in the promotion stage and thus stimulate the promotion of tumour growth (R).

There is a link between increased levels of ROS and disturbed activities of enzymatic and non-enzymatic antioxidants in tumor cells (R).

What are Antioxidants?

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Living organisms have evolved a number of antioxidant defenses to maintain their survival against oxidative stress (R).

In order to avoid free radical overproduction from oxidative stress, antioxidants are present in tissues to neutralize these free radicals (R).

An antioxidant is a substrate which protects biological tissues from free radical damage. Biological reductants can regenerate or recycle the antioxidants (R,R2).

Antioxidant defense mechanisms involve both enzymatic and nonenzymatic strategies. (R).

Common antioxidants include the vitamins A, C, and E, glutathione, and the enzymes superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase (R).

Other antioxidants include – lipoic acid, mixed carotenoids, coenzyme Q10, several bioflavonoids, antioxidant minerals (copper, zinc, manganese, and selenium), and the cofactors (folic acid, vitamins B1, B2, B6, B12) (R).

They work in combination with each other and against different types of free radicals (R).

The most prominent of the antioxidants such as vitamins E and C, α-lipoic acid and glutathione which comprise an antioxidant network (R).

What About Antioxidant Supplements?

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Antioxidant supplements are not associated with lower all-cause mortality (R, R2).

Beta-carotene, vitamin E, and higher doses of vitamin A may actually be associated with higher all-cause mortality (R, R2)

Vitamin C (ascorbic acid) is a very important, and powerful, antioxidant that works in aqueous environments of the body, such as are present in the lungs and in the lens of the eye (R).

While intake of high doses of Vitamin C (up to 2000 mg/day) has not been consistently reported to result in side effects, the benefit of a high intake of Vitamin C has never been established (R).

The intake of Vitamin E (200 IU (international units)/day) reduced the incidence of colorectal cancer by triggered apoptosis of cancer cells (R).

Generally, the protective effect of Vitamin E is a result of the inhibition of free radical formation and activation of endonucleases (R).

In view of current data and the lack of evidence to prove the benefits of use of antioxidant vitamins to prevent cardiovascular disease (R, R2).

The general population should consume a diet emphasizing antioxidant-rich fruits and vegetables and whole grains (R).

Recent trials from the U.K. demonstrated that subjects consuming high fruit and vegetable diets had significantly reduced blood pressure (R).

Another important lifestyle modification that may have cardiovascular protective and blood pressure– lowering effects by reducing oxidative stress is exercise (R).

In experimental models of hypertension and in human patients with coronary artery disease, exercise reduced ROS production ameliorated vascular injury, and reduced blood pressure (R).

Decreasing ROS generation and increasing nitric oxide availability and antioxidants may prevent or repair organ damage by reducing vascular injury and renal dysfunction (R).

The optimal source of antioxidants seems to come from our diet, not from antioxidant supplements, especially in well-nourished populations (R).

Oxidative Stress on SelfDecode

Here are SNPs related to oxidative stress on SelfDecode.

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