How does oxidative damage trigger Alzheimer's disease

Oxidative stress

  1. Home
  2. Illness & Symptoms
  3. Diseases

Cell aging and oxidative stress are first and foremost completely normal biological processes. Free radicals play an important role in this. Here you will find information about the causes, symptoms and treatment of oxidative stress.


Free radicals have a bad reputation among health-conscious people. They are said to accelerate the aging process and promote cancer. In the meantime, however, there are more and more studies that put supposed truths about free radicals, oxidative stress and cell aging in a much more differentiated light. The use of artificial vitamins as antioxidants or radical scavengers is also viewed much more critically.

If you believe the advertising, free radicals are the cause of almost all health ills. Premature aging, Alzheimer's disease, cancer, stroke or arteriosclerosis: all kinds of diseases that are said to be favored, triggered or promoted by the oxygen compounds described as "aggressive". The advertising also has the antidote ready: vitamins that act as antioxidants or radical scavengers to clear up cells - and render free radicals harmless. But is that also true? Current research is moving further and further away from condemning free radicals. And refers to the sometimes even fatal risks of vitamins as radical scavengers.

What are Free Radicals?

Free radicals are particularly reactive oxygen compounds in our cells. They are by no means a foreign body or poison, but a natural component of the biochemistry of our body. Free radicals perform a variety of functions. For example, they regulate the activity of the cell power plants, the mitochondria - and thus have a significant influence on cell growth. The citric acid cycle, with which our cells in the mitochondria generate energy, is not possible without oxidation and free radicals. The immune system uses free radicals to kill cells that are growing in an uncontrolled manner or to destroy pathogens. These are just a few examples of the functions of free radicals. So they are not just the “bad” aggressive oxygen compounds they are portrayed as in many publications.

Oxidative stress from free radicals

But where does the bad reputation of free radicals come from? In addition to their important tasks in the cell, free radicals have another side: they can - like many other substances - actually burden the organism. Doctors speak of oxidative stress. They refer to a condition in which the concentration of free radicals is higher than necessary and at the same time a counterweight in the form of antioxidants is missing or not strong enough.


Oxidative stress does not have to damage the organism. For example, strong physical exertion causes oxidative stress. According to many experts, this form of oxidative stress makes sense. It sets the stimuli that stimulate muscle development in athletes, for example, or accelerate the healing process in rehab treatment after an injury or operation. This is how free radicals are involved when exercise becomes the turbo-charger for healing and prevention.

Negative symptoms of oxidative stress

If the natural balance of the metabolism in the cells is disturbed, however, the risk of free radicals and oxidative stress damaging the cell can increase. Whether lung cancer in smokers, pancreatic cancer in alcoholics or skin cancer after many sunburns: Many studies suggest a connection between the increased occurrence of free radicals, oxidative stress and cancer. Nevertheless: An actual causal connection between the free radicals and the development of cancer has not yet been proven.

Free radicals damage genetic material - is that true?

Free radicals supposedly damage the genetic material, the DNA, during cell division. This is arguably the most common supposed fact about free radicals. The American biologist Denham Harman formulated this theory as early as the 1950s. He made the free radicals responsible for the aging of the skin and organs. Almost 70 years later, however, his thesis has still not been clearly proven.


However, oxidative stress does not usually arise as if by magic. The most important causes for the oversupply of free radicals and an undersupply of antioxidants are pollution caused by diseases, behavior or environmental influences. Doctors speak of endogenous and exogenous causes of oxidative stress.

Exogenous causes for the multiplication of free radicals

The most important causes for the multiplication of free radicals and the reduction of radical scavengers are shaped by our behavior and environmental influences. These are above all:

  • Smoke
  • Substance abuse
  • Alcohol abuse and alcoholism
  • stress
  • certain medications such as antibiotics, cytostatics, or hormonal drugs
  • Smog, car exhaust, air pollution
  • UV rays, radiation exposure, x-rays
  • Environmental toxins such as pesticides, dioxins, methane, ozone, solvents, heavy metals

Endogenous cause of oxidative stress

For example, endogenous causes of oxidative stress are independent of environmental influences and behavior

  • Disorders of the immune system (immune deficiency)
  • Inflammation and infection
  • Injuries or operations
  • Allergies and autoimmune processes such as chronic rheumatic joint inflammation
  • pronounced physical (including sporting) stress

Ultimately, however, these endogenous causes are not entirely independent of behavior. A weak immune system can often be traced back to a one-sided diet and lack of exercise.


The diagnosis of oxidative stress is made primarily through blood and urine tests, which show the relationship between antioxidants and free radicals.


Antioxidants are antagonists of free radicals. So that there is no persistent oxidative stress with negative consequences, it makes perfect sense to supply the body with antioxidants. The most important antioxidants are vitamins A, C, E and the mineral zinc. It is undisputed that these micronutrients intervene in the metabolism in a wide variety of ways. It is also undisputed that they have an antioxidant function. And that they help to avoid oxidative stress and protect the organism.

The myth of the healthy radical scavengers

The undeniably positive properties of antioxidants have condensed into a true myth of healthy radical scavengers in recent years. Whether it is the aging process, cholesterol level, cancer risk, dementia or the immune system - more and more people attribute almost miraculous powers to antioxidants. Accordingly, sales of vitamin and mineral supplements are rising to ever greater heights. Germans spend a good billion euros annually on dietary supplements. 75 percent of it for self-treatment.

Complications instead of benefits from vitamins

Especially when it comes to self-treatment, many people follow the motto “a lot helps a lot”. In the best case scenario, it is just a waste of money if expensive vitamins and minerals are simply excreted in the urine. If things don't go so well, overdosing can lead to serious consequences or life-threatening complications.

No question about it: Vitamins are essential for life - and in the right dosage, they promote health. But they can also cause harm. For example, vitamin A and E advertisements repeatedly claim that the combination can lower the risk of lung cancer in smokers. On the other hand, it is correct: a large American study had to be discontinued in 1994 because the administration of vitamins A and E to smokers caused the lung cancer rate to skyrocket. Similar results came from another large review of studies on the effects of antioxidants.

Contrary to the expectations of many athletes, vitamin preparations with vitamins C and E do not have a positive effect on muscle growth and endurance. On the contrary: taking vitamin supplements can even slow down muscle growth.

Meet your antioxidant needs risk-free

If free radicals and antioxidants are in balance in the cells, there are no health risks, restrictions or premature signs of wear and tear from oxidative stress. A varied diet with fresh foods and regular exercise in the fresh air are in most cases sufficient to supply our body with sufficient vitamins and minerals.

From a medical point of view, it is perfectly clear: healthy people generally do not need any vitamin or mineral supplements. And if it does: To avoid risks, you should only use antioxidants against free radicals after consulting your doctor.

Author: Charly Kahle

Status: 07/13/2020

Our newsletter provides you with weekly news and information about health.