Recently, two different results have indicated why intermittent fasting
(aka alternate day fasting) can be so effective for autoimmune
disorders. It reduces T cells in humans and now we have evidence from
animal research it may also reduce B cell counts. B cells produce the
antibodies that T cells attack (although it's a little more complicated
than that). Regulatory T cells are known to benefit directly from mTOR
inhibition so part of the benefits of fasting might occur from a
reduction in protein synthesis. Unfortunately, whatever benefit fasting
offers autoimmunity, it comes at the expense of general immunity, thus
leaving practitioners at greater risk for infection.
<http://www.sciencedaily.com/releases/2008/04/080401091210.htm>
Immune System Needs Food To Function Well, So Feed That Cold
ScienceDaily (Apr. 4, 2008) ‹ Researchers studying deer mice have
discovered evidence to sup****t what mothers everywhere have long
suspected: the immune system needs food to function properly. In a new
study Lynn Martin and coauthors find that reduced food intake leads to a
decline in immune function in their subjects. The findings could have
profound implications for human health.
Why immune activity is variable in many wild animals is a question that
has long puzzled researchers. "Animals live different lifestyles, so
they may use different types of defenses against infection depending on
the situation. Perhaps this is why immune defenses vary seasonally in
most species; some may be too expensive to use all the time," Martin
said, referring to previous work on Peromyscus and other small mammals
and birds.
While it is known that the immune system expends energy when it gears up
to fight a virus or an infection--a fever, for example--the researchers
found that restricting their subjects' diet by 30% significantly
decreased the amount of available B cells, which produce antibodies and
maintain immune memory. Without these cells, the immune system must
relearn how to fight a threat if it reappears.
Research on the relation****p between food and the immune system could
have profound implications for humans. Martin and fellow researchers
cite previous studies that have found that infections are "more frequent
and tend to be chronic in malnourished children." Vaccines, in order to
work effectively, must provoke B cells to produce sufficient antibodies
for immune memory.
Previous studies have found that vaccines such as those for measles have
a significantly lower rate of efficacy among the malnourished. "A 30%
restriction in food intake doesn't affect body mass and only minimally
reduces activity in deer mice, but it eliminates the long-term immune
protection provided by antibodies. One wonders whether similar moderate
food restriction has comparable immune effects in humans," Martin asked.
Although other variables may be at work, the authors propose that for
both wild animals and humans, food availability impinges on immunity and
future research should determine what specific components of a diet
(calories, protein, micronutrients) are responsible.
The article "Food Restriction Compromises Immune Memory in Deer Mice
(Peromyscus maniculatus) By Reducing Spleen-Derived Antibody-Producing
B-Cell Numbers," will be published in the May/June 2008 issue of
Physiological and Biochemical Zoology.
Adapted from materials provided by University of Chicago Press Journals,
via EurekAlert!, a service of AAAS.
FASEB J. 2008 Jan 9; [Epub ahead of print] Related Articles, LinkOut
Modified alternate-day fasting regimens reduce cell proliferation rates
to a similar extent as daily calorie restriction in mice.
Varady KA, Roohk DJ, McEvoy-Hein BK, Gaylinn BD, Thorner MO, Hellerstein
MK.
*Department of Nutritional Sciences and Toxicology, University of
California at Berkeley, Berkeley, California, USA; andDivision of
Endocrinology and Metabolism, Department of Internal Medicine,
University of Virginia, Charlottesville, Virginia, USA.
Calorie restriction (CR) and alternate-day fasting (ADF) reduce cancer
risk and reduce cell proliferation rates. Whether modified ADF regimens
(i.e., allowing a ****tion of energy needs to be consumed on the fast
day) work, as well as true ADF or CR to reduce global cell proliferation
rates, remains unresolved. Here, we measured the effects of true ADF,
modified ADF, and daily CR on cell proliferation rates in mice. Thirty
female C57BL/6J mice were randomized to one of five interventions for 4
wk: 1) CR-25% (25% reduction in daily energy intake), 2) ADF-75% (75%
reduction on fast day), 3) ADF-85% (85% reduction on fast day), 4)
ADF-100% (100% reduction on fast day), and 5) control (ad libitum
intake). Body weights of the ADF groups did not differ from controls,
whereas the CR-25% group weighed less than all other groups
posttreatment. Epidermal cell proliferation decreased (P<0.01) by 29,
20, and 31% in the CR-25%, ADF-85% and ADF-100% groups, respectively,
relative to controls. Proliferation rates of splenic T cells were
reduced (P<0.01) by 37, 32, and 31% in the CR-25%, ADF-85%, and ADF-100%
groups, respectively, and mammary epithelial cell proliferation was 70,
65, and 62% lower (P<0.01), compared with controls. Insulin-like growth
factor-1 levels were reduced (P<0.05) in the CR-25% and ADF-100% groups
only. In summary, modified ADF, allowing the consumption of 15% of
energy needs on the restricted intake day, decreases global cell
proliferation similarly as true ADF and daily CR without reducing body
weight.-Varady, K. A., Roohk, D. J., McEvoy-Hein, B. K., Gaylinn, B. D.,
Thorner, M. O., Hellersteinm M. K. Modified alternate-day fasting
regimens reduce cell proliferation rates to a similar extent as daily
calorie restriction in mice.
PMID: 18184721
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