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Two Studies Indicate We Can Live Longer, Better With Proper
Diets
Reducing calories
worked in one, DASH diet with exercise in the second
April 5, 2006 – Two studies released this week
indicates that diets – one reducing calories and the other using the
DASH diet – can make a significant contribution to longer life. Reducing
calories, even without more physical activity, over six months resulted
in a decrease in fasting insulin levels and body temperature, two
biomarkers of longevity. The DASH study was of people with elevated
blood pressure who increased physical activity while eating on the DASH
plan, resulting in much lower hypertension and less risk of the major
killers – heart disease and stroke.
Reducing Calories and Longevity
Prolonged calorie restriction increases life span
in rodents and other shorter-lived species. Whether this occurs in
humans is unknown, according to background information in the article.
One theory concerning the antiaging effects of calorie restriction is
its impact on metabolism, including alterations in insulin sensitivity
and signaling, neuroendocrine function, stress response, or a
combination of these.
Leonie K. Heilbronn, Ph.D., of Louisiana State
University, Baton Rouge, La., and colleagues conducted a study to
determine the effects of prolonged calorie restriction, with or without
exercise, in overweight men and women.
The randomized trial, conducted between March 2002
and August 2004, included 48 healthy, sedentary men and women.
Participants were randomized to 1 of 4 groups for 6
months:
● control (weight maintenance diet);
● calorie restriction (25 percent calorie restriction of baseline
energy requirements);
● calorie restriction with exercise (12.5 percent calorie restriction
plus 12.5 percent increase in energy expenditure by structured
exercise);
● very low-calorie diet (890 kcal/d until 15 percent weight
reduction, followed by a weight maintenance diet).
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Editorial on Calorie Reduction Study |
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Editorial: Excessive Adiposity, Calorie Restriction, and Aging
in Humans
In an accompanying editorial,
Luigi Fontana, M.D., Ph.D., of the Washington University School
of Medicine, St. Louis, comments on the findings of Heilbronn et
al.
“The most important
contributions from this study for enhancing current
understanding of the effects of calorie restriction on aging
relate to the calorie restriction–mediated reductions in core
body temperature, serum T3 levels, and oxidative damage to DNA,
as reflected by a reduction in DNA fragmentation. The oxidative
stress hypothesis of aging is currently one of the most accepted
explanations for how aging occurs at the biochemical and
cellular level,” Dr. Fontana writes. “The study by Heilbronn et
al is the first to report a significant decline in DNA damage in
response to calorie restriction in humans.”
“Although is it not likely that
many individuals would adopt a calorie-restricted diet, the
value of these studies is that they suggest possible mechanisms
of aging in humans and suggest points of intervention to modify
the effects of aging. Further elucidating the mechanisms that
control longevity will be a major step in understanding the age
dependency of a range of chronic human diseases and will help to
improve the quality of life in old age.” |
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After six months…
● the control group had experienced an average
weight loss of 1.0 percent;
● the calorie restriction group, 10.4 percent;
● calorie restriction with exercise, 10.0 percent; and
● very low-calorie diet, 13.9 percent.
Other findings:
● Fasting insulin levels were significantly
reduced at month 6 in all intervention groups.
● There were no significant changes in fasting glucose or
dehydroepiandrosterone sulfate (DHEAS) levels in any group.
● Participants randomized to calorie restriction and calorie
restriction with exercise had reduced average core body temperature at 6
months.
● There was no change in core body temperature in the control or very
low-calorie diet groups.
● A technique to measure DNA fragmentation indicated reductions of
DNA damage from baseline in all intervention groups.
After adjustment for changes in body composition,
sedentary 24-hour energy expenditure was unchanged in controls, but
decreased in the calorie restriction, calorie restriction with exercise,
and very low-calorie diet groups. These “metabolic adaptations” were
statistically different from controls.
“Our results indicate that prolonged calorie
restriction caused:
(1) a reversal in 2 of 3 previously
reported biomarkers of longevity (fasting insulin level and core body
temperature);
(2) a metabolic adaptation (decrease in energy expenditure
larger than expected on the basis of loss of metabolic mass) associated
with lower thyroid hormone concentrations; and
(3) a reduction in DNA fragmentation, reflecting less DNA
damage,” the authors write.
The reduced calorie study is published in today's
issue of JAMA, and does say longer studies are required to determine if
calorie restriction changes the aging process in humans. This work was
supported by a research grant from the National Institutes of Health.
Using DASH and Exercise in Lowering High
Blood Pressure
 In
the second study, men and women with elevated blood pressure who made
healthy lifestyle changes and sustained them for up to a year and a half
were able to substantially reduce their rates of high blood pressure and
potentially decrease their heart disease risk.
With behavioral counseling, increases in physical
activity, and adoption of a healthy eating plan called DASH, rates of
high blood pressure dropped from 37 to 22 percent among participants in
a study conducted by the National Heart, Lung, and Blood Institute (NHLBI)
of the National Institutes of Health.
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Related Stories |
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New Dietary Guidelines Emphasize Physical Fitness,
Nutrition
Jan. 12, 2005 – The Dietary Guidelines for
Americans 2005 were officially released today after being drafted early
last year and going through a long approval process. As much of what has
been suggested about better health in the last few years, the report
emphasizes physical fitness and nutrition.
More...
Boomers, Seniors High Risk for High Blood Pressure
Dairy Products Making Comeback During Stroke Month
New studies show lowered risk for stroke, heart
disease with milk, low-fat dairy
May 26, 2005 - A diet rich in milk does not
increase the risk of heart disease and stroke, and may even be
protective, says one study. While another suggests that increased intake
of low-fat dairy foods, as part of a DASH-based eating plan, may lower
blood pressure more effectively than a conventional low-fat diet -- a
significant finding for the millions of Baby Boomers and Senior Citizens
who suffer from high blood pressure, a major risk factor for stroke and
heart attack.
Read
more...
Study of Postmenopausal Women
Low-Fat Diet with Fruit, Veggies, Grains Does NOT
Reduce Heart, Breast Cancer or Colon Cancer Risks
Study findings send shock waves through health
care community - Feb. 6, 2006 –
Read more...
Low-Fat, High-Carb Diets Don't Cause Weight Gain in
Older Women
Another blow for promoters of the low carbohydrate
diets
Jan. 4, 2006 – A very large study of older women
has concluded that low-fat, high-carb diets do not result in excessive
weight gain. This strikes a blow against those who have promoted
low-carbohydrate diets as the answer to the countries highly hyped
"obesity crisis."
Read more...
Read more
on
Health & Medicine
or
Nutrition & Vitamins |
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High blood pressure is a major risk factor for
heart disease and the chief risk factor for stroke. About 65 million
American adults, one in three, have high blood pressure. An additional
59 million adults have pre-hypertension, a level that is above normal,
and increases risk of heart disease and stroke. Results of the study,
called PREMIER, appear in the April 4, 2006 issue of Annals of Internal
Medicine.
“This study underscores the value of lifestyle
changes — namely improving diet and increasing physical activity — in
reducing high blood pressure, an important public health problem,” said
NHLBI Director Elizabeth G. Nabel, M.D. “For the millions of Americans
with pre-hypertension and hypertension, this shows that individuals can
make healthy lifestyle changes to keep blood pressure under control
without the use of medications.”
A total of 810 men and women ages 25 and older with
either pre-hypertension (120-139mmHg/80-89mmHg) or stage 1 hypertension
(140-159mmHg/90-95mmHg) but who were not taking medications to control
blood pressure were randomly assigned to three groups.
Participants in two of the groups attended 18
counseling sessions during the first six months — 14 group meetings and
4 individual sessions. During the last 12 months they attended 12 group
meetings and 3 individual sessions. They were prescribed goals for
weight loss, physical activity, and given sodium and alcohol intake
limits.
One of these groups also received guidance on
implementing the Dietary Approaches to Stop Hypertension diet (DASH), an
eating plan rich in fruits and vegetables, low-fat dairy products and
low in saturated, total fat and dietary cholesterol. DASH is used as an
example of a healthy eating plan by the U.S. Dietary Guidelines for
Americans, and has been shown to lower blood pressure in previous NHLBI
studies.
A third group served as a control, receiving only
two 30-minute sessions of advice to follow standard recommendations for
blood pressure control; one at study enrollment and one 6 months later.
A third session was offered at the end of the 18-month trial after
measurements were completed.
The numbers of participants with high blood
pressure declined in all three groups, but the reduction was greater in
the intervention groups and most striking in the intervention group that
included the DASH eating plan. While approximately 37 percent of
participants in all three groups had high blood pressure at the study’s
start, this was reduced to 22 percent in the group following DASH and 24
percent in the intervention group without DASH. By comparison, the rate
of hypertension fell only to 32 percent in the control group.
“Participants in the two intervention groups made
greater changes than those in the control group and saw the greatest
benefit in blood pressure status,” said Eva Obarzanek, Ph.D., research
nutritionist and study co-author. “This shows that people at risk for
heart disease can successfully and simultaneously make multiple changes
in lifestyle, for a substantial benefit.”
Goals for the intervention groups included a 15 lb
weight loss (95 percent of participants were overweight or obese), 3
hours per week of moderate physical activity, daily sodium intakes of no
more than 2300 milligrams (1 tsp salt), and limits of one alcoholic
drink per day for women, and two per day for men.
Those also following the DASH diet were asked to
increase their consumption of fruits and vegetables to 9-12 servings per
day, consume 2-3 servings of low-fat dairy products, and keep total fat
to no more than 25 percent of total daily calories.
To keep track, participants kept food diaries,
monitored calories and sodium intakes, and recorded minutes of physical
activity.
More than one-third of participants had high blood
pressure at the beginning of the study. Of these, 62 percent in the
intervention group with DASH, and 60 percent in the intervention group
without DASH successfully had their blood pressure under control after
18 months (that is, their blood pressure levels were no longer
considered high).
Comparatively, only 37 percent of the control group
with hypertension at the study’s start had their blood pressure under
control at the end of the study.
“These rates of hypertension control produced by
the two interventions are even better than the 50 percent control rates
typically found when single drug therapy is used to control high blood
pressure,” said William M. Vollmer, Ph.D., a study investigator from
Kaiser Permanente Center for Health Research.
Compared with the control group, one or both
intervention groups had:
● Greater weight loss: 5.9 lb in the DASH group
and 4.8 lb in the group without DASH.
● Greater improvement in fitness: 2 beats per minute lower heart rate
for the DASH group and 1 beat per minute lower heart rate for those
without DASH. (The greater the reduction in heart rate, the greater the
improvement in fitness.)
● Greater sodium reduction: 354 milligrams for those on the DASH
eating plan and 384 milligrams without DASH (about 1/6 tsp less salt).
● Greater reductions in calorie intake: the intervention groups
reduced their daily intake by 95 (DASH) and 130 calories (without DASH).
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For
statistics on Cardiovascular Disease for Senior
Citizens and Baby Boomers -
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In addition, 25 percent of intervention group
participants met the weight loss goal. The group following DASH also
achieved increased fruit, vegetable, dairy, fiber and mineral intakes
and decreased fat intake.
Part of the National Institutes of Health, the
National Heart, Lung, and Blood Institute (NHLBI) plans, conducts, and
supports research related to the causes, prevention, diagnosis, and
treatment of heart, blood vessel, lung, and blood diseases; and sleep
disorders. The Institute also administers national health education
campaigns on women and heart disease, healthy weight for children, and
other topics. NHLBI press releases and other materials are available
online at:
www.nhlbi.nih.gov.
The National Institutes of Health (NIH) — The
Nation's Medical Research Agency — includes 27 Institutes and Centers
and is a component of the U.S. Department of Health and Human Services.
It is the primary federal agency for conducting and supporting basic,
clinical and translational medical research, and it investigates the
causes, treatments, and cures for both common and rare diseases. For
more information about NIH and its programs, visit
http://www.nih.gov.
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