Fasting Generates a New Immune System


A new study in the journal Cell Stem Cell shows that cycles of prolonged fasting prompts the human immune system to rejuvenate hematopoietic stem cells from dormancy to a state of self-renewal. Hematopoietic stem cells, which reside in bone marrow, are those from which all other blood cells are derived. The findings represent the first academic confirmation of a natural action prompting stem regeneration of an organ or system.

One of the authors of the study, Valter Longo, a professor at the University of Southern California (USC) Davis School of Gerontology, labeled the effect “remarkable.” When the human body is starved, he said, it tries to conserve energy. One of the ways it does this is to “recycle” immune cells, including those which may be damaged.

Humans in the six-month clinical trials fasted regularly for between two and four days over a six-month period. It has been known that fasting forces the body to use glucose, fat and ketones it has held in storage. Now, with the new study, it is also known that three-day fasts break down a meaningful portion of white blood cells. Longo compares the effect to ridding an airplane of extra baggage.

Not eating for long periods lowered white blood cell counts significantly. Simultaneously, it is as if “a regenerative switch” was flipped for hematopoietic stem cells, thus providing the first, important step in the generation of blood and the regeneration of immune systems. Professor Longo says that once this “OK” is issued, stem cells proliferate, and rebuilding of the entire, critically-important immune system commences.

The new discovery will likely be helpful to cancer patients who are doing chemotherapy treatments and their inevitably damaged immune systems. It could also be helpful for elderly people, whose immune systems are less effective and for whom the fighting off of common diseases is more difficult.

Longo’s team noticed that, in both humans and animals, white blood cell counts decreased when associated with fasting. Each cycle of fasting depletes white blood cells in the body, thus triggering changes that begin the stem cell-based regeneration of new immune system cells. Toxicity was also seen as being protected against with fasting.

Tanya Dorff, a co-author of the study and an assistant professor at the USC Norris Comprehensive Cancer Center and Hospital, noted that chemotherapy causes significant incidental damage to the human immune system, and the study suggests that fasting may allay some of the damage caused by the chemotherapy. More studies are needed, she cautioned, and suggested that any such attempts to fast should only happen with a physician’s supervision. Cycles of fasting can literally generate a new immune system, she said.

Some experts are skeptical of the research. “Improbable” is the opinion of Dr. Graham Rook from University College London (UCL). Although his UCL colleague, Chris Mason, concedes that fasting could be helpful, he believes “the most sensible way forward” would be to fake the body into believing it is fasting, not by starving it of food, but with drugs. “I am not sure fasting is the best idea. People are better off eating on a regular basis,” he said. Dr. Long counters, stating that no evidence exists that fasting is dangerous to chemotherapy patients while, at the same time, firm evidence now exists that it can be beneficial.

By Gregory Baskin

The Telegraph
USC News
University Herald

6 Responses to "Fasting Generates a New Immune System"

  1. ACNY   June 15, 2014 at 8:51 pm

    After 3 days Ketones begin to flow but the benefits of the fast doesn’t necessarily mean that they begin only at that moment. By stopping ingesting food, you immediately stop a flow of invading agents headed for the intestine, thus within hours start freeing portions of the immune system to work on the restoration of the rest of the body. So, you start with initially only 30% of the immune system at your disposal for body restoration to then gradually reach the full 100% benefit capacity when the intestine is completely empty. That occurs after about 33 hours from last meal (47 hours for women).

  2. Gregory Baskin   June 15, 2014 at 4:57 pm

    How many days beyond three is typically considered helpful?

  3. ACNY   June 15, 2014 at 4:47 pm

    Yes Gregory, as Prof. Ryan says, after about 72 hours of fasting you will not experience hunger pans (48 hours for women). I am not sure why during this particular study mentioned in this article they used 2 to 4 days series. If you have intention to try out 3 days series, instead of one longer fast, it seems you will be going through hunger pans repeatedly without need. In any case, any little bit that you can keep the intestines empty and 100 % of the immune system at your disposal, it will help.

  4. Prof. Bryan   June 14, 2014 at 5:16 pm

    A true fast does begin until the 2nd or 3rd day using ONLY water.

    During the first 24 – 48 hours after starting a water fast, the body is still burning off circulating blood sugar and sugar stored in the muscles and liver in the form of glycogen.

    Ultimately, the “true” metabolic fast does not begin until we fully metabolize our blood sugar which takes approximately 2 to 3 days. The body then begins to burn fat tissue for fuel and molecules named ketones begin to flow in the blood circulation. Ketones actually suppress hunger and why fasting is not a difficult process.

    To learn more about the physiological stages of fasting, check this article out:

  5. Gregory Baskin   June 14, 2014 at 11:25 am

    ACNY, I agree that learning all we can – and using that knowledge – for the sake of our own bodies is very important. There is a general need to take personal power in our own health and the simplicity (and results) that can come from a series of three-day fasts offers such an opportunity. I am excited to do this myself!

  6. ACNY   June 14, 2014 at 9:52 am

    Unless you are critically ill, although preferred, it is not true that fasting (with water) should be done only with medical supervision (trained on the subject), it is actually better to read a few books on the subject first, in order to understand what it is happening and not avoid mistakes. For instance, I had a 20 year plus, mild chronic problem with my voice. During fasting the voice went almost away for a few days, prompting panic among my family, friends and co workers. I knew that the best course of action was to do nothing and not take any medication, which would have halted the destruction of the weak cells and the construction of new ones. In fact it has been five years, and no more problems with voice.

    Dr. Rook and Dr. Mason seem to be totally unfamiliar with the subject, or even its terminology. Real starvation occurs only when all the fat content in the body is used up, and that may take months, until that moment it is called fasting. The suggestion to use drugs to trick the body into thinking it is starving, is senseless, and even dangerous. The reason the body gets gigantic steps toward full health and cellular reconstruction is because 70 % of the immune system is normally busy fighting invaders into the intestine. While fasting, the intestine gets empty, so the immune system is now 100% free to fix everything wrong with the rest of the body. If you trick the immune system to leave the intestine while eating food, the decomposing matter would rip the intestine and leak into the body, causing toxic shocks and death.

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