Hormesis

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Possibilities of biological effectiveness

Hormesis (Greek: "stimulation, impulse", English: adaptive response ) is the hypothesis already formulated by Paracelsus that small doses of harmful or toxic substances can have a positive effect on organisms. Today it is given a broader definition. In the case of medically active substances, such a dose-dependent reverse effect can easily be demonstrated (e.g. digitalis , colchicine or opium ). With a number of other compounds and the effects of ionizing radiation on the environment and living beings , the hypothesis is very controversial among experts.

Hormetic effects are characterized by a J- or U-shaped dose-effect curve that opens up or down (e.g. red curve in the picture on the right). Hormetic effects occur in different contexts and have different underlying mechanisms.

In recent times, the concept or hypothesis has mainly been represented by Edward Calabrese .

Radiation hormesis

Hormetic effects of ionizing radiation (radioactivity) could occasionally be detected. Here is also Strahlenhormesis (Engl. Radiation hormesis or radiation homeostasis ) spoken.

Cancer mortality among nuclear workers with an average workplace-related radiation exposure that was only a small multiple of the natural background radiation was 15 to 20% lower in some studies than that in the general population. However, it is known that a working population is generally healthier than the general population average, as this also includes all people unable to work for physical reasons, which is known as the healthy worker effect .

Inhaling radioactive radon or drinking water containing radon ( radon balneology ) should also stimulate the immune system and thus promote health. Epidemiological and animal studies have so far yielded contradicting results. The extremely low effects of small doses of radiation are difficult to interpret because they are difficult to distinguish from natural radiation exposure and from other carcinogenic factors from diet and air pollution.

Linear no-threshold model

Experts for radiation protection therefore expect conservative (in the sense of "the safe side") from a linear dose-response relationship (engl. Linear no-threshold model , LNT model ) non-threshold and thus a depletion potential even at any low radiation doses from . The findings on a stimulatory or hormonal effect of small doses are considered insufficient by many international bodies such as the International Commission on Radiation (ICRP), the BEIR Committee of the US Academy of Sciences and the United Nations Committee on the Effects of Atomic Radiation (UNSCEAR) considered convincing to deviate from the linear dose-response relationship without a threshold value. However, it is doubted that the LNT method gives the correct estimate; For radiation protection reasons, this should rather be viewed as an overestimation of the risks. The LNT model not only ignores the eventual radiation hormesis, but also the well-known ability of cells to repair genetic damage, as well as to remove damaged cells from the organism. These two mechanisms mean that a small dose over a long period is less dangerous than a large dose over a short period of time.

Mitohormesis

Mitochondrial Hormesis or Mitohormesis for short is a biochemical process in which the activation of mitochondria leads to an increased formation of free radicals in the cell, which ultimately leads to an activation of the cell's own defense against oxygen radicals .

The concept of mitohormesis was established and proven by Michael Ristow . This unexpected observation was subsequently reproduced in many other model organisms and by other working groups.

Building on this, Ristow was able to show for the first time that the health-promoting and life-prolonging effect of endurance sports, which has long been known, is also based on the effect of free radicals or reactive oxygen species (ROS). Together with Matthias Blüher in Leipzig , he was able to prove that antioxidants counteract the diabetes- preventive effect of sport or prevent it completely by counteracting the formation of free radicals.

The resulting questionability of antioxidant food supplements with possible harmful effects in humans was also discussed in detail in the international press.

In analogy to this, several meta-analyzes independently of Ristow came to the conclusion that the administration of certain antioxidants ( beta-carotene , vitamin A and vitamin E ) promotes the development of diseases including cancer in humans.

Related concepts

  • Immune stimulants (e.g. Echinacea products) are supposed to activate the body's immune system unspecifically in order to ward off infections. This is a hormetic effect in the narrower sense, but the effects are usually not scientifically proven.
  • The homeopathy used toxins in extremely diluted form as a remedy against diseases that have apparently the same symptoms, such as caused by the undiluted toxins in healthy individuals. However, the founder of homeopathy, Samuel Hahnemann , attributed the healing effect to a “spirit-like power hidden in the inner essence of medicines”. Most homeopaths believe that potentising only reduces the unwanted effects of the substance, but not the desired effects. Many homeopaths also believe that the preparation process enhances the desired effect. In practice, such high dilutions (“high potencies”) are often used that hardly any molecule of the original substance is contained in a drug dose. To justify the high potencies, Hahnemann assumed that "the matter [...] of raw medicinal substances [...] finally dissolves completely into its individual spiritual being". Today protagonists of homeopathy claim a “memory effect” of the water used as a diluent. Critics attribute any therapeutic success to the placebo effect .

Quote

“All things are poison and nothing without poison; the dose alone makes a thing not a poison. "

- Paracelsus - The third defension for writing the new recipes

See also

literature

Web links

Wiktionary: Hormesis  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ^ H. Douglas: Science, hormesis and regulation. In: Hum Exp Toxicol 27, 2008, pp. 603-607, PMID 19029255 .
  2. ^ A b E. Calabrese et al .: HORMESIS: The Dose-Response Revolution. In: Annu Rev Pharmacol Toxicol 43, 2003, pp. 175-197, PMID 12195028 .
  3. ↑ Anderson: Effects of low-dose radiation on the immune response. In: Biological Effects of Low Level Exposures to Chemicals and Radiation. Ed. EJ Calabrese. Lewis Pub. Inc., Chelsea, Michigan, USA, 1992; 95-112.
  4. ↑ Makinodan: Cellular and subcellular alteration in immune cells induced by chronic, intermittent exposure in vivo to very low dose of ionizing radiation (ldr) and its ameliorating effects on progression of autoimmune disease and mammary tumor growth. In: Low-Dose Irradiation and Biological Defense Mechanisms. eds. Sugahara T, Sagan LA, Aoyama T. Exerpta Medica; Amsterdam, London, New York, Tokyo, Japan, 1992; 233-237.
  5. ↑ Kendall, GM, Muirhead, CR, MacGibbon, BH, O'Hagen, JA, Conquest, AJ, Goodill, AA, Butland, BK, Fell, TP, Jackson, DA, Webb, MA, Haylock, RGE, Thomas, JM , Silk, TJ: Mortality and Occupational Exposure to Radiation: First Analysis of the National Registry for Radiation Workers. Br. Med. J. 304: 220-225 (1992).
  6. ↑ Federal Office for Radiation Protection: Hormesis . Retrieved March 6, 2018.
  7. ↑ a b M. Tubiana, LE Feinendegen, C. Yang, JM Kaminski: The linear no-threshold relationship is inconsistent with radiation biologic and experimental data. In: Radiology. Volume 251, number 1, April 2009, pp. 13-22, doi: 10.1148 / radiol.2511080671 , PMID 19332842 , PMC 2663584 (free full text).
  8. ↑ The 2007 Recommendations of the International Commission on Radiological Protection , International Commission on Radiological Protection , accessed on July 31, 2015
  9. ^ Health Impacts, Chernobyl Accident Appendix 2 , World Nuclear Association, 2009. Retrieved July 31, 2015.
  10. ↑ Schulz, TJ et al. (2007): Glucose restriction extends Caenorhabditis elegans life span by inducing mitochondrial respiration and increasing oxidative stress. In: Cell Metabolism . 6 (4); 280-293; PMID 17908557
  11. ↑ Ristow, M. et al. (2011): Extending lifespan by increasing oxidative stress . In: Free Rad Biol Med 51, 327-336; PMID 21619928
  12. ↑ Yun, J & Finkel, T. (2014): Mitohormesis in: Cell Metabolism , 19, 757-766; PMID 24561260
  13. ↑ Ristow, M (2014): Unraveling the truth about antioxidants: mitohormesis explains ROS-induced health benefits. in: Nature Medicine , 20, 709-711; PMID 24999941
  14. ↑ Shadel, GS & Horvath, TL (2015): Mitochondrial ROS signaling in organismal homeostasis. in: Cell , 163, 560-569; PMID 26496603
  15. ↑ Ristow, M. et al. (2009): Antioxidants prevent health-promoting effects of physical exercise in humans . In: Proc Natl Acad Sci 106: 8865-8870; PMID 19433800
  16. ^ [1] The New York Times : Vitamins Found to Curb Exercise Benefits
  17. ↑ [2] BBC : Vitamins "undo exercise efforts"
  18. ↑ [3] Der Spiegel : Vitamin pills slow down the positive effects of sport
  19. ↑ [4] Deutsches Ärzteblatt : Why exercise only promotes health without vitamins
  20. ↑ Bjelakovic, G. et al. (2007): Mortality in randomized trials of antioxidant supplements for primary and secondary prevention: systematic review and meta-analysis . In: JAMA 299 (7); 842-857; PMID 17327526
  21. ↑ Bjelakovic, G. et al. (2012): Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases . In: Cochrane Database Syst Rev 14; CD007176; PMID 22419320
  22. ↑ Quote from Samuel Hahnemann: Organon der Heilkunst ., 6th edition, § 20 .
  23. ^ Samuel Hahnemann: Organon der Heilkunst ., 6th edition, § 270 .
  24. ^ Lionel R. Milgrom: Homeopathy, fundamentalism, and the memory of water. In: Curr Oncol 14 (2007), 221-222, PMID 18080011 , PMC 2133095 (free full text).
  25. ↑ Deutsche Apotheker Zeitung online: “Still no evidence for homeopathy” , February 22, 2016
  26. ↑ Third chapter in: Philippus Theophrastus Aureolus Bombastus von Hohenheim ("Paracelsus"): Labyrintus and mistake of the supposed doctor: Item, Siben defensiones, or umbrella speeches . Publishing house Petrus Perna, Basel 1574.