[log in to unmask] wrote:
>
> Has anyone had any experience with the nutrition program called Biozone? I
> have been told it is the rage in California, but I have not seen it before.
> The program is a high energy program. I have been told the Stanford swim
> team is on it.
Alan and all,
A colleague of mine has written a review of this diet, and because I
believe persons with PD could be especially at risk on such a plan, I
believe it is in the best interests of the group to post this review;
both Ms. Coleman and I feel that both the severe calorie restriction and
the very high amount of protein could adversely affect persons in any
stage of PD.
****************
The BioZone Nutrition System -- a Dietary Panacea?
A currently popular sports nutrition fad revolves around a dietary
regimen proposed by Barry Sears, Ph.D., the author of The Zone
(ReganBooks, 1995) and creator of BioZone nutrition bars. The Zone is
defined as the seemingly effortless, euphoric state where body and mind
work at peak efficiency. While in the Zone, athletes will allegedly
reach their maximum athletic performance. Sears' book attributes these
benefits to altering the production of eicosanoids with the Zone diet.
The Zone claims that eicosanoids are the most powerful of all hormone
systems and have ultimate control over all physiological functions.
An understanding of the function and formation of eicosanoids is
necessary to evaluate the performance and health claims made for the
Zone diet. Eicosanoids are the biologically-active, hormone-like
compounds known as prostaglandins, thromboxanes, and leukotrienes that
are synthesized from 20-carbon (hence the name) unsaturated fatty acids.
They have diverse and often antagonistic effects and are produced in
response to stimulatory events such as infection, trauma, allergy, or
toxin exposure. A balanced production of eicosanoids regulates the local
tissue response to stimulatory events (10).
The production of eicosanoids may be manipulated by the type of
dietary fat eaten, since different kinds of eicosanoids are synthesized
from omega-6 compared to omega-3 fatty acids. Consumption of omega-3
fatty acids (found predominantly in fish oils) is associated with a
greater depression in thromboxane relative to prostacyclin levels, which
reduces platelet aggregation and increases bleeding time (5). The low
incidence of heart disease in Greenland Eskimos has been attributed to
their high intake of fish oils (5,10).
Optimal athletic performance and health according to The Zone means
that the body makes more "good" eicosanoids than "bad" ones. In fact,
The Zone's definition of disease is that the body makes more "bad"
eicosanoids than "good" ones.
The Zone classifies prostaglandin E1 and prostoglandin I2
(prostacyclin) as "good" because they inhibit platelet aggregation,
promote vasodilation, and are anti-inflammatory. Prostaglandin E2,
thromboxanes and leukotrienes are classified as "bad" because they
promote platelet aggregation, vasoconstriction, and are
pro-inflammatory.
To control eicosanoids and so enter the Zone, The Zone advises a
dietary regimen of 30% protein, 40% carbohydrate, and 30% fat at each
meal and snack. Three small meals (not over 500 calories) and two snacks
(not over 100 calories) are recommended. The protein to carbohydrate
ratio of the Zone diet and BioZone nutrition bar allegedly maintain the
proper balance between the hormones insulin and glucagon.
The correct insulin-glucagon balance in turn supposedly increases
the production of "good" eicosanoids which bring about the Zone.
According to Sears, high carbohydrate diets impair athletic performance
and make athletes fat. The Zone recommends limiting carbohydrate to keep
the body from producing too much insulin, because high insulin levels
allegedly increase the production of "bad" eicosanoids. "Bad"
eicosanoids purportedly impair athletic performance by reducing oxygen
transfer to the cells, lowering blood glucose levels, and interfering
with body fat utilization. The Zone asserts that "bad" eicosanoids
ultimately even cause heart disease, cancer, and autoimmune diseases.
The protein content of the Zone diet supposedly increases glucagon
levels, thereby maintaining the appropriate balance between insulin and
glucagon. The Zone claims that glucagon helps to increase the production
of "good" eicosanoids by opposing the effect of insulin. Sears'
"glucagon favorable diet" supposedly maintains blood glucose, increases
endurance by increasing fatty acid utilization, and reduces body fat by
increasing the utilization of stored fat.
The lay reader may be impressed and intimidated by the
scientific-sounding information presented in The Zone. However, the
scientific basis for the Zone diet can be faulted on many fronts. I'll
begin with the claim that high carbohydrate diets increase insulin
levels, thereby causing low blood glucose and suppressing fat
mobilization.
Carbohydrate feedings 30-60 minutes before exercise do raise
insulin levels and lower blood glucose, but these responses are
temporary and will not harm performance (3). This insulin response does
not impair fat mobilization or cause accelerated glycogen depletion (3).
In fact, consuming carbohydrate an hour before exercise has been shown
to improve performance (7). Carbohydrate feedings three to four hours
before exercise also enhance performance by "topping off" muscle and
liver glycogen stores (8). Lastly, carbohydrate feedings during exercise
improve performance (2) and improve glycogen repletion following
exercise (4).
The Zone's claim that a high carbohydrate diet promotes greater
body fat storage is also unfounded. Carbohydrates, not fatty acids, are
used preferentially for energy during exercise at or above 70% of V02Max
-- the intensity at which most athletes train and compete (2). Athletes
don't usually work out long enough to burn significant amounts of fat
during exercise. Rather, it is the caloric deficit resulting from the
exercise session that promotes body fat utilization. Carbohydrates will
be converted to fat only if they are eaten in excess of calorie
requirements. However, when compared to dietary fat, dietary
carbohydrate is more likely to be burned for energy than stored as fat
(9).
The metabolic pathways presented in The Zone which supposedly
connect diet, insulin-glucagon, and eicosanoids do not exist in standard
nutrition or biochemistry texts (5,10). The idea that the Zone diet (or
any diet) completely controls the secretion of insulin and glucagon is
not supported by the relationship between nutrition and endocrinology
(10). Next, the notion that the insulin-glucagon axis controls the
production of eicosanoids is not supported by biochemistry (5). And
finally, the belief that eicosanoids control all physiological functions
(including athletic performance, health, and disease) is not only
unfounded (5,10), it is an appalling over-simplification of complex
physiological processes.
In science, no hypothesis is presumed to be true until it has been
clearly demonstrated. Responsible health professionals should actively
oppose the Zone diet because nutrition recommendations must be supported
by scientific research. The Zone, however, abounds with unproven claims
based on case histories, testimonials, and unpublished, poorly
controlled studies. The Zone also ridicules double-blind,
placebo-controlled, peer-reviewed published research and attacks current
nutrition recommendations based on this research.
The Zone promotes the fundamental nutrition misbelief that "you are
what you eat" -- that everything from health to physical and mental
performance is determined by diet (6). Many people want to believe that
there are simple cures for ailments and easy paths to perfection.
Unfortunately, in spite of what The Zone claims, a dietary panacea does
not exist.
At the very least, following the Zone diet may impair athletic
performance due to inadequate dietary carbohydrate (1), and possibly,
calorie intake. However, I feel that The Zone's deceptive health claims
are particularly insidious because they create false hope for desperate
people who seek a cure for life-threatening illnesses such as heart
disease and cancer.
References
1. Coleman, E. Debunking the "Eicotec" Myth. Sports Med. Dig. 15:6-7,
1993.
2. Coyle, E.F., A.R. Coggan, M.K. Hemmert, and J.L. Ivy. Muscle glycogen
utilization during prolonged strenuous exercise when fed carbohydrate.
J. Appl. Physiol. 61: 165-172, 1986.
3. Hargreaves, M., D.L. Costill, W.J. Fink, D.S. King, and R.A.
Fielding. Effect of pre-exercise carbohydrate feedings on endurance
cycling performance. Med. Sci. Sports Exerc. 19: 33-36, 1987.
4. Ivy, J.L. A.L. Katz, C.L. Cutler, W.M. Sherman, and E.F. Coyle.
Muscle glycogen synthesis after exercise: Effect of time of carbohydrate
ingestion. J. Appl. Physiol. 64: 1480-1485, 1988.
5. Mayes, P.A. Metabolism of unsaturated fatty acids & eicosanoids. In:
Harper's Biochemistry 23rd ed. Appleton & Lange, Norwalk, CT, 1993.
6. Position of the American Dietetic Association: Food and nutrition
misinformation. J. Am. Diet. Assoc. 95: 705-707, 1995.
7. Sherman, W.M., M.C. Peden, and D.A. Wright. Carbohydrate feedings 1
hr before exercise improves cycling performance. Am. J. Clin. Nutr. 54:
866-870, 1991.
8. Sherman, W.M. G. Brodowicz, D.A. Wright, W.K. Allen, J. Simonsen, and
A. Dernbach. Effects of 4 hr preexercise carbohydrate feedings on
cycling performance. Med. Sci. Sports Exerc. 21: 598-604, 1989.
9. Sims, E.A.H. and E. Danforth. Expenditure and storage of energy in
man. J. Clin. Invest. 79: 1019-1025, 1987.
10. Zeman, F.J. Clinical Nutrition and Dietetics 2nd ed. Macmillan
Publishing Company, New York, NY, 1991.
--
Kathrynne Holden, MS, RD
Editor-in-Chief,
"Spotlight on Food--nutrition news for people 60-plus"
Tel: 970-493-6532 Fax: 970-493-6538
http://www.fortnet.org/~fivstar
You may wish to contact:
Better Business Bureau of the Mountain States,
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for further information.
