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Flu News for Senior Citizens
Feed a Cold, Feed a Fever is Best Advice for Senior
Citizens; Calories Needed to Fight Flu
Research shows having a body ready to fight a virus
leads to a faster recovery and less-severe effects than if calories
restricted
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Elizabeth Gardner |
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Nov. 25, 2008 - Dieters or those who consume fewer
calories during flu season could have a harder time fighting off the flu
virus, according to research by Michigan State University nutritional
immunology professor Elizabeth Gardner. Her advice applies particularly
to senior citizens.
In a study published in the November issue of the
Journal of Nutrition, Gardner showed that mice with a
calorie-restricted diet were more likely to die during the first few
days of infection than mice with a normal diet.
Caloric restriction is the practice of reducing the
intake of calories to 40 percent of a normal diet, while maintaining
adequate vitamins and minerals.
“If you are exposed to a new strain of influenza,
to which your body has not made adequate antibodies to protect you from
infection, your body must rely on cells that will kill the virus,”
Gardner said.
“The natural killer cells are important in
controlling the early stages of virus infection, because they act
quickly once they encounter virus-infected cells. Our studies show that
calorically restricted mice have increased susceptibility to influenza,
and their bodies are not prepared to produce the amount of natural
killer cells needed to combat the stress of fighting an infection.”
In Gardner’s research, both regularly fed mice and
calorically restricted mice exposed to the virus exhibited decreased
food intake as they tried to fight off the infection.
Yet the mice on calorically restricted diets took
longer to recover and exhibited increased mortality, weight loss and
other negative effects. Even though both sets of mice had a diet
fortified with appropriate vitamins, the mice consuming normal amounts
of food had their appetites back sooner and recovered faster.
“Our research shows that having a body ready to
fight a virus will lead to a faster recovery and less-severe effects
than if it is calorically restricted,” Gardner said.
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Myth or Fact: Feed a Cold, Starve
a Fever
By Eric Bishop
Although a few small-scale
studies have suggested that “feed a cold, starve a fever”
loosely represents sound medical advice, Duke medical experts
caution against putting too much faith in the adage.
“I think it was always
pretty much dismissed as folklore,” says Denise Snyder, a
nutrition scientist and clinical trials manager at the Duke
University School of Nursing. “If you break it out and really
think about it, there is some immune response if you eat less
during a fever. But as a nutritionist, I certainly wouldn’t tell
people to starve themselves.”
Snyder points out that you
probably won’t feel like eating anyway -- loss of appetite is
your body’s natural defense mechanism for fevers, as it helps
the immune system focus its energy on fighting pathogens.
“You shouldn’t overconsume,
but if you’re hungry you should eat,” she says, adding that
fluids can only help fight the fever.
As for “feed a cold,” it’s
simply a matter of keeping your nutrient levels up while the
virus runs its course.
“Colds usually last longer
than fevers,” Snyder says. “You need to be consuming food so you
can fight it off -- especially fruit and vegetable juices and
warm broths.”
Joy doesn’t want patients to
get hung up on unproven treatments. “It’s important to stress
what we know makes a difference, which is getting plenty of
rest,” he says.
“Drinking plenty of fluids
also makes a difference because it helps keep the secretions
thinner and allows patients to get them out of their system lot
quicker, alleviating symptoms such as a cough or nasal
drainage.”
Joy also emphasizes the need
to practice good hygiene when you’re sick -- whether it’s a cold
or a fever. “Washing your hands often, covering your mouth when
you cough -- those are great ways to reduce the spread of
infection that are underappreciated.”
>> More at
DukeHealth.org |
“Adults can calorically restrict their diet eight
months out for the year, but during the four months of flu season they
need to bump it up to be ready. You need the reserves so your body is
ready for any additional stress, including fighting a virus.”
Calorically restricted diets in general have been
shown to increase lifespan in everything from yeast to primates,
acknowledges Gardner. But, she says, the model used in her research can
be extended to more vulnerable groups including children and the
elderly, who don’t eat as much but often take vitamin supplements.
Flu shots can’t guarantee protection, in any case,
since they are formulated months in advance and only can target a small
handful of the many flu virus strains that might infect the population.
“If the strain of flu a person is infected with is
different from the strain included in the flu vaccination, then your
body sees this as a primary infection and must produce the antibodies to
fight it off. A calorically restricted body is not as well prepared to
do this and cannot control early infection, which impedes recovery,”
Gardner added.
Gardner, an associate professor in the Department
of Food Science and Human Nutrition, now is investigating the mechanisms
responsible for decreased immune function during caloric restriction.
Her research in nutritional immunology will lead to a better
understanding of how a diet affects the immune system and the best
conditions for a body to quickly and successfully fight infections.
Research Interests: Nutritional Immunology
'Major emphasis of our lab is the response of
young and aged mice to primary influenza infection'
By Elizabeth Gardner, associate professor in the
Department of Food Science and Human Nutrition
Immunity decreases in aging, most well documented
as an impaired cell-mediated response to antigen, i.e., reduced T cell
proliferation and altered cytokine production. Aged mice also exhibit
altered innate immunity, including a decrease in inducible natural
killer (NK) cell activity, although such changes have not been
consistent in humans. Influenza is perhaps the best characterized model
for studying the immune response to virus, and influenza and its
secondary pneumonias represent a major public health concern in the
U.S., particularly among the elderly.
We and others have shown that the immune response
to influenza vaccine is reduced in the elderly as evidenced by lower
antibody titers, decreased T cell proliferative responses, reducted
cytotoxic T cell activity, and altered cytokine production compared to
young controls.
However, the study of immunity, particularly in the
elderly, can no longer be limited to efficacy of vaccination, given the
emergence of new viral strains of common viruses, such as avian
influenza, and the threat of using viruses to which there are no current
vaccines as agents of bioterrorism.
Therefore, a major emphasis of our lab is the
response of young and aged mice to primary influenza infection at the
site of infection, i.e., the lung, with a particular interest in innate
(NK cell function) and cell-mediated immunity. We also study the effects
of nutritional interventions, including antioxidants and nutraceuticals,
on outcome to primary influenza infection or as adjuvants to
vaccination.
Caloric restriction (CR) without malnutrition
decreases oxidative stress and extends mean and maximal lifespan in
mice. While elderly CR mice have been reported to have an increased
response to influenza vaccination, the response to CR mice to primary
infection is not known.
Our data suggest that a defect in NK cell function
decreases survival of CR mice in response to primary influenza
infection.
Michigan State University has been advancing
knowledge and transforming lives through innovative teaching, research
and outreach for more than 150 years. MSU is known internationally as a
major public university with global reach and extraordinary impact. Its
17 degree-granting colleges attract scholars worldwide who are
interested in combining education with practical problem solving.
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