Dr. Gabe Mirkin's Fitness and Health E-Zine
April 24, 2011
Caffeine: Good When You Exercise, Bad When You Rest
CAFFEINE INCREASES SUGAR ABSORPTION FROM THE GUT.
Taking caffeine when you eat carbohydrate-containing
foods can double your rise in blood sugar (Journal of
Caffeine Research, April 16, 2011). Since more than
35 percent of North Americans will become diabetic and
have high rises in blood sugar levels after meals, most
people should not take caffeinated drinks with meals
that contain carbohydrates: bread, spaghetti, or
sugared foods and drinks. If you are already diabetic,
your blood sugar levels rise even higher and you suffer
cell damage from it. A high rise in blood sugar causes
all the horrible side effects of diabetes: blindness,
deafness, heart attacks, strokes and so forth.
However, during exercise, caffeine can increase
endurance (Medicine & Science in Sports & Exercise,
July, 2010) by increasing the absorption of sugar from
your intestines and by increasing the uptake of sugar by
your exercising muscles by as much as 26 percent
(Journal of Applied Physiology, June 2006). Caffeine
is found in coffee, tea, chocolate, and cocoa.
SUGARED DRINKS CAUSE HIGHER RISES IN BLOOD SUGAR THAN
SUGARED FOODS. No solid food is allowed to pass into
your intestines. After food enters your stomach, the
pyloric sphincter closes. Food is kept in the stomach
until it is turned into a liquid soup. Then the stomach
muscles squeeze the soup through the pyloric sphincter
into the intestines. An orange can be kept in your
stomach for up to five hours before it passes into your
intestines. Since fruit juice is a liquid, it passes
into your intestines immediately. So orange juice causes
an immediate high rise in blood sugar, while an orange
does not. Studies show that fruits decrease diabetes risk,
while fruit juices increase risk (Diabetes Care, July 2008).
CAFFEINE DRIVES BLOOD SUGAR LEVELS EVEN HIGHER. Adding
caffeine to sugar in a drink causes blood sugar levels
to rise even higher than drinks that have only sugar.
FRUIT JUICE IS AS DAMAGING AS HIGH FRUCTOSE CORN SYRUP OR
TABLE SUGAR. High Fructose Corn Syrup (HFCS) has been
blamed for the ever-increasing rates of obesity and
diabetes in North America over the last forty years.
However, HFCS appears to be no more damaging than fruit
juice or drinks sweetened with table sugar. Most soft
drinks are sweetened with HFCS. Both HFCS and conventional
sugar (sucrose) contain a mixture of two sugars, glucose
and fructose, in nearly the same concentrations: HFCS has
55 percent fructose/42 percent glucose, while sucrose is
a 50/50 mixture. These numbers are so close that most
researchers feel that the slight increase in the
concentration of fructose in not important enough to cause
disease in itself. The fructose in orange juice, table
sugar and HFCS are equally damaging to your health.
HOW FRUCTOSE HARMS: Fructose is far more damaging to
the liver than glucose and is thought by many physicians
to be the main cause of the fatty liver that causes
insulin insensitivity and type II diabetes. When your
blood sugar rises too high, the pancreas releases large
amounts of insulin. Insulin converts sugar to
triglycerides. Since high levels of blood triglycerides
increase risk for clots, your good HDL cholesterol
carries the triglycerides from your blood to your liver
to fill up the liver with fat to cause a fatty liver.
Fructose causes far higher blood and liver levels of
triglycerides than glucose does, so fructose is a more
potent cause of a fatty liver. Having a fatty liver
prevents the body from responding to insulin and blood
sugar levels rise to increase diabetes risk and all the
harmful cell damage that diabetes causes.
DURING EXERCISE, MUSCLES PROTECT YOU. Resting muscles
are inactive. They need insulin to remove sugar from
your bloodstream. On the other hand, contracting
muscles can remove sugar from your bloodstream without
even needing insulin (American Journal of Clinical
Nutrition, July 2008). The maximum effect is during
exercise and continues maximally for up to one hour
afterward and disappears at around 17 hours (Journal of
Applied Physiology, February 2010).
HOW CAFFEINE AND SUGAR HELP YOU DURING EXERCISE:
Caffeine increases endurance by helping the body use
more sugar from drinks that you take during exercise
(Journal of Applied Physiology, June, 2005). The limiting
factor to how fast you can move over distance is the time
it takes to get oxygen into muscles. Since sugar requires
less oxygen than fat or protein do, muscle move faster with
more power when they burn sugar. Those who took sugared
drinks with caffeine were able to absorb and use 26 percent
more of the ingested sugar than those who took the same
drinks without caffeine. Caffeine-laced drinks help
improve endurance even more in hot weather (International
Journal of Sport Nutrition and Exercise Metabolism,
February 2011).
CAUTION! You should take caffeinated sugared drinks only
when you exercise and for up to an hour after you finish.
Taking sugared drinks, with or without caffeine, when you
are not exercising causes higher rises in blood sugars that
increase risk for diabetes and cell damage.
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Dear Dr. Mirkin: What can prevent dementia in older
people as they start to forget things?
Older people suffering from mild memory and
cognition problems are far less likely to progress to
Alzheimer's disease if they are treated to protect their
blood vessels: for high blood pressure, high triglycerides
and cholesterol, low good HDL cholesterol, abdominal
obesity, diabetes and heart disease (Neurology, published
online April 13, 2011).
In 2004, researchers started to follow 837 people,
ages 55 and older, who were forgetful but did not have
dementia. More than half had the signs of blood vessel
disease listed above. After five years, 35 percent
developed Alzheimer's and the majority were from the
group who had signs of blood vessel disease. Those
with blood vessel disease who received treatment were 40
percent less likely to develop Alzheimer's. Slightly
less than ten percent of people with cognitive
impairment progress to Alzheimer's each year.
All people, whether they are forgetful or not,
should prevent blood vessel disease by getting their
bad LDL cholesterol below 100, the diabetic test HBA1C
below 5.7, blood pressure below 120/80, triglycerides
below 120, and a pinch of their abdominal flesh smaller
than one inch. They should exercise every day, lose weight
if overweight, avoid refined carbohydrates, sugared drinks
and red meat, and eat plenty of fruits, vegetable, whole
grains, beans, seeds and nuts. They should also try to
get their vitamin D3 level above 75 nmol/L.
***********************************************
Dear Dr. Mirkin: Do you recommend taking calcium
supplements to prevent osteoporosis?
No; taking calcium both with and without
vitamin D has been shown to be associated with increased
risk for heart attacks and strokes by more than 15
percent (British Journal of Medicine. April 19, 2011).
Treating 1000 people with calcium or calcium and vitamin
D for five years would cause an additional six heart
attacks or strokes and prevent only three fractures.
Calcium supplements increase risk for heart
attacks and strokes because they raise blood calcium
levels which increases chances of forming clots, a major
cause of heart attacks and strokes (J Bone Miner Res,
1997;12:1959-70), thickens neck artery plaques
(Atherosclerosis, 2007;194:426-32), calcifies main
arteries (J Bone Miner Res, 2010;25:505-12), increases
heart attack risk (Am Heart J, 2008;156:556-63) and
causes premature death (J Clin Endocrinol Metab,
1996;81:2149-53). Taking calcium without also taking
vitamin D increases heart attack risk even further
because calcium blocks the activation of vitamin D to
cause a relative deficiency of that vitamin.
***********************************************
Recipe of the Week:
Portuguese Potato-Garlic Soup
http://www.drmirkin.com/recipes/portsoup.html
You'll find lots of recipes and helpful tips in
The Good Food Book
http://www.drmirkin.com/goodfood/index.html
***********************************************
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Gabe Mirkin, M.D.
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