Thursday, August 4, 2011

DrMirkin's eZine: Chocolate for endurance, more . . .

Dr. Gabe Mirkin's Fitness and Health E-Zine
August 7, 2011

Chocolate Increases Endurance

A recent symposium at the American College of Sports
Medicine 58th Annual Meeting June 2, 2011 and other recent
studies show that chocolate improves endurance training in mice
and humans. Taking small amounts of a chocolate extract, called
epicatechin, twice a day for two weeks shortened recovery from
intense exercise and increased endurance in mice (Journal of
Physiology, July 25, 2011). Drinking chocolate milk after all-
out exercising helped athletes recover faster and cycle faster
afterwards (Journal of Strength Conditioning Research, May 2011).
These studies do not encourage you to take chocolate
just before competitions. They show that chocolate helps you to
recover faster from hard exercise, and that you may benefit from
taking small amounts of chocolate daily during hard training.
All athletic training is done by taking a harder workout on one
day, feeling sore on the next and taking easier workouts for as
many days as it takes for the soreness to go away. If you can
recover faster, you can do more intense training and be a better
Your body requires oxygen to convert food to energy to
power your muscles during exercise. The limiting factor to how
fast you can run or cycle, and how much force your muscles can
generate, is the time it takes to move oxygen from your lungs
into your muscles. The aim of all athletic training is to
increase your body's ability to convert food to energy with the
least amount of oxygen. Anything that increases oxygen supply
or decreases oxygen needs will make you faster and stronger.
Your muscles convert food to energy primarily in your
mitochondria, small chambers numbering from a few to thousands
inside your muscles. Anything that grows new mitochondria or
enlarges existing ones will make you faster and stronger. The
cocoa bean contains chemicals called epicatechins that stimulate
your muscles to grow and produce mitochondria. It takes only
small amounts, taken regularly, to do this.
However, pure chocolate is very bitter, so manufacturers
add huge amounts of sugar and saturated fats that should not be
taken when you are not exercising. Eating refined sugar when you
are not exercising causes a high rise in blood sugar that can
damage every cell in your body and saturated fats from animals
block insulin receptors to prevent insulin from clearing sugar
from your bloodstream to raise blood sugar levels even higher.
*You can eat small amounts of sweetened chocolate when
you are exercising.
*You should not eat sweetened chocolate when you are not
*You can eat chocolate every day that you exercise,
particularly on your intense exercise days.
*You should take only small amounts as more is not more
effective in hastening recovery. A reasonable daily amount would
be about five grams of dark chocolate (1/6th of an ounce) per day.


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Dear Dr. Mirkin: How could eating meat cause diabetes?

There are several theories. The most widely-accepted
theory is that saturated fat in animal products blocks insulin
receptors (American Journal of Physiology. May, 2011). Since
insulin cannot attach on its receptor on cells, it cannot do its
job of driving sugar from the bloodstream inside cells. Then,
blood sugar levels rise causing sugar to stick on and damage
every cell in your body.


Dear Dr. Mirkin: Why does sugar increase risk for heart
attacks and diabetes?

Most sugars that you eat contain two sugars called
glucose and fructose. Fruit sugar and table sugar from cane or
beets contain sucrose: glucose and fructose bound together in a
single molecule. High fructose corn syrup (HFCS) in most soft
drinks contains glucose and fructose separately. Only single
sugars can be absorbed from your intestines into your bloodstream.
Of all sugars, only four (glucose, fructose, galactose and
mannose) can pass from your intestines into your bloodstream.
Only glucose is allowed to circulate in your bloodstream. The
other three are converted to glucose in the intestines or pass
to the liver and do not reach the general circulation.
WHY FRUCTOSE IS HARMFUL: In just two weeks, high doses
of fructose markedly increase blood levels of the bad LDL
cholesterol, triglycerides and apolipoprotein-B (a protein that
causes plaques to form in arteries). These are blood markers of
increased risk for diabetes and heart attacks. Those taking
comparable amounts of glucose do not suffer these changes
(Journal of Clinical Endocrinology & Metabolism, October, 2011).
GLYCOGEN. Fructose is not allowed to circulate in the
bloodstream. It is first converted in the liver to a stored
sugar called glycogen and when your liver fills with glycogen,
it is then converted to triglycerides to cause high blood levels
that increase heart attack risk.
limited amount of glycogen that can be stored in the liver, so
when you take in high levels of fructose, almost all is
converted to triglycerides. Then your liver takes 1500
triglyceride molecules and a lesser number of cholesterol
molecules to form the bad LDL cholesterol that causes plaques to
form in arteries. So fructose is a major player in the formation
of plaques that can eventually break off from arteries to cause
heart attacks.
exercising, fructose is not harmful. The first fructose is
stored in your liver as glycogen which can be released as
glucose into your bloodstream. Your brain depends on glucose for
more than 98 percent of its energy. Your muscles depend on
glucose as an energy source also. There is only enough sugar in
your bloodstream to last about three minutes, so your liver has
to constantly release sugar from its glycogen stores into your
When you start to exercise, your muscles draw sugar
rapidly from your bloodstream. To maintain blood sugar levels,
your liver markedly increase its release of sugar from its
glycogen stores. So most of the fructose you take in during
exercise is converted to liver glycogen and then glucose to be
used by your exercising muscles for energy.
CAN BE HARMFUL. When you are not exercising, all sugared drinks
are equally damaging to your arteries. Fruit and cane sugars
contain glucose and fructose in 50/50 proportions. HFCS contains
about 55 percent fructose and a lesser amount of glucose.
Fructose from any source is harmful only when it is converted
into large amounts of triglycerides.
1) Avoid all sugared drinks, including fruit juices and those
sweetened with HFCS, when you are not exercising. All are
sources of fructose and are equally damaging to your health.
3) Restrict foods with added sugars when you are not exercising.
4) Eat large amounts of vegetables and fruits.


Recipe of the Week:

Cioppino (Italian Seafood Stew)

You'll find lots of recipes and helpful tips in
The Good Food Book


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