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19 avril 2015 7 19 /04 /avril /2015 00:21

Jeûner trois jours renouvelle totalement le système immunitaire


Repéré par Eric Leser
Science & santé
mis à jour le 18.04.2015


Des chercheurs d'une équipe de l'Université de Californie du sud (USC) affirment avoir trouvé le moyen de contraindre le corps humain à se régénérer. Une découverte annoncée comme «capitale». Jeûner pendant 72 heures peut permettre de reconstruire l’ensemble du système immunitaire même chez les personnes âgées ou gravement malades telle est la conclusion de cette nouvelle étude scientifique.
Si jeûner est considéré comme néfaste pour l’organisme par les nutritionnistes, priver le corps de nourriture pendant trois jours contraindrait ensuite la moelle osseuse à produire de grandes quantités de globules blancs qui combattent les infections. Cette découverte peut être particulièrement utile aux malades dont le système immunitaire a été affaibli, par exemple les cancéreux traités par des chimiothérapies.
Selon les chercheurs d’USC, jeûner lance un processus de régénération. «Cela donne le feu vert à la moelle osseuse pour reconstruire l’ensemble du système immunitaire» explique Valter Longo, professeur de gérontologie et de biologie à l’Université de Californie du sud. «Et la bonne nouvelle est que le corps se débarrasse des parties du système immunitaire abîmées ou âgées et inefficaces, pendant le jeun. Et si vous partez d’un système fortement endommagé par une chimiothérapie ou le vieillissement, les cycles de jeûne peuvent permettre de créer, littéralement, un nouveau système immunitaire».
Les jeûnes prolongés contraignent en fait le corps à consommer ces réserves de glucoses et de graisses mais aussi détruisent une proportion importante des globules blancs. «Quand vous vous privez de nourriture, le corps essaye d’économiser l’énergie dépensée et pour cela recycle un grand nombre de cellules du système immunitaire qui ne sont pas indispensables, notamment celles qui sont abimées». Ainsi, pendant le jeûne, le nombre de globules blancs baisse fortement et augmente rapidement quand la personne s’alimente à nouveau. Le jeûne a aussi un autre effet bénéfique, il réduit la présence dans le corps de l’enzyme PKA qui est liée au vieillissement et augmente les risques de cancer et de croissance des tumeurs.


«Il n’y a pas de preuve que jeûner soit dangereux mais il y a de grandes preuves que ce soit bénéfique», résume Valter Longo.


Fasting for three days renews entire immune system, protects cancer patients, ‘remarkable’ new study finds




Sarah Knapton, The Daily Telegraph, National Post Wire Services
Thursday, Jun. 5, 2014




While most nutrition experts frown on the idea, medical researchers say that a short fast — lasting just three days — may have benefits for the body's ability to renew its immune system, with minimal downside risks to health. Fotolia


Fasting for three days can regenerate the entire immune system, even in the elderly, scientists have found in a breakthrough described as “remarkable.”


Although fasting diets have been criticized by nutritionists, research suggests that starving the body kick-starts stem cells into producing more white blood cells, which fight off infection.


Scientists at the University of Southern California (USC) say the discovery could be particularly beneficial for those suffering from damaged immune systems, such as cancer patients on chemotherapy. It could also help the elderly whose immune systems become less effective.


The researchers say fasting “flips a regenerative switch” that prompts stem cells to create white blood cells, essentially restoring the immune system.


“It gives the OK for stem cells to go ahead and begin proliferating and rebuild the entire system,” said Valter Longo, professor of gerontology and biological sciences at the university.


“And the good news is that the body got rid of the parts of the system that might be damaged or old, the inefficient parts, during the fasting. Now, if you start with a system heavily damaged by chemotherapy or aging, fasting cycles can generate, literally, a new immune system.”


‘Fasting cycles can generate, literally, a new immune system’


Prolonged fasting forces the body to use stores of glucose and fat but also breaks down a significant portion of white blood cells. During each cycle of fasting, this depletion induces changes that trigger stem cell-based regeneration of immune system cells.


In trials, volunteers were asked to fast regularly for between two and four days over a six-month period. Scientists found that prolonged fasting also reduced the enzyme PKA, which is linked to aging and a hormone which increases cancer risk and tumour growth.


“We could not predict that prolonged fasting would have such a remarkable effect in promoting stem cell-based regeneration of the hematopoietic [formation of stem cells] system,” added Longo. “When you starve, the system tries to save energy, and one of the things it can do to save energy is to recycle a lot of the immune cells that are not needed, especially those that may be damaged.


‘There is no evidence at all that fasting would be dangerous while there is strong evidence that it is beneficial’


“What we started noticing in both our human work and animal work is that the white blood cell count goes down with prolonged fasting. Then when you re-feed, the blood cells come back.”


Fasting for 72 hours also protected cancer patients against the toxic impact of chemotherapy.


“The results of this study suggest that fasting may mitigate some of the harmful effects of chemotherapy,” said co-author Tanya Dorff, assistant professor of clinical medicine at the USC Norris Comprehensive Cancer Center and Hospital.


Referring to the 72-hour fasting period, Chris Mason, professor of regenerative medicine at University College London, said: “That could be potentially useful because that is not such a long time that it would be terribly harmful to someone with cancer. But I think the most sensible way forward would be to synthesize this effect with drugs. I am not sure fasting is the best idea. People are better eating on a regular basis.”


Longo added: “There is no evidence at all that fasting would be dangerous while there is strong evidence that it is beneficial.”


Posted in: News Tags: Health, Cancer, Chemotherapy, Clinical Immunology, Diet And Nutrition, Fasting, Immune System, Medical Breakthroughs, Medical Research

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Published by Jean-Pierre LABLANCHY - CHRONIMED - dans Nutrition
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commentaires

asmaa yacoubi 24/05/2015 23:21

Ça a l'air très intéressant. Je aimerais avoir plus d informations sur le type de jeûne.

Gilles 26/04/2015 19:46

J'ai moi même jeuner plusieurs fois et mon corps est plus jeune de au moins 5 ans.