Thursday, May 26, 2011

DrMirkin's eZine: Nitrates, mitochondria, more . . .

Dr. Gabe Mirkin's Fitness and Health E-Zine
May 29, 2011

Nitrates Make You Faster and Stronger

Drinking a half-liter of beetroot juice before a
time trial helped male bicycle racers ride an incredible 2.8
percent faster over both 4- and 16-kilometer courses
(Medicine & Science in Sports & Exercise, June 2011). This
is an extremely well-performed study because all of the
bicycle racers in the study rode faster after drinking a half-
liter of normal beetroot juice (6.2 mmol nitrate) than they
did after taking the same volume of beetroot juice that had
had the nitrates removed (0.0047 mmol nitrate). Furthermore,
the authors measured blood levels of nitrates and showed that
the nitrate-rich beet juice raised blood levels of nitrates
from 241 to 575 nm and reduced the oxygen cost of the
exercising muscles. The dose of nitrate used in the study
(6.2 mmol) is 4 to 12 times greater than what the average
person takes in each day. None of the subjects consumed
dietary supplements.
Beetroot juice is high in nitrates which have been shown in
many studies to reduce the amount of oxygen needed to fuel
muscles during exercise and to improve an athlete's ability
to tolerate high-intensity exercise. How fast you can race
on a bike is limited by the time it takes to bring oxygen
into exercising muscles to turn food into fuel for contracting
muscles. Since nitrates bring oxygen faster into muscles,
eating any food that is high in nitrates can help you ride
HOW NITRATES MAKE YOU FASTER: Inorganic nitrate is
converted to active nitrite and, subsequently, to nitric oxide
(Nat Med. 2003;9:1498-505). The most efficient form of energy
for exercising muscles comes from your mitochondria in muscles
which require less oxygen after a person takes nitrates
(Free Radic Biol Med. 2010;49:S109).
has been shown to reduce the oxygen cost of cycling (J Appl
Physiol. 2009;107:1144-55), increase power of knee extensor
exercise (J Appl Physiol. 2010;109:135-48), and help athletes
run faster (J Appl Physiol. 2011;110:591-600)
the racers were given liquids because liquids pass through their
stomachs and into their bloodstreams much faster than solid foods
do. You can get large amounts of nitrates from celery, cress,
lettuce, radishes, beets, spinach, Chinese cabbage, endive,
kohlrabi, leeks, parsley and many other vegetables (Am J Clin
Nutr. 2009 Jul;90(1):1-10). Almost all of the nitrates in
vegetables are absorbed into the bloodstream.
and healthful when eaten in vegetables and fruits. However,
nitrates can be converted to nitrites which can combine with amino
acids in foods to form nitrosamines which are potent
cancer-causing agents. Nitrates (with an A) in plants are
healthful. Too much nitrites (with an I) can be harmful.
AVOIDING NITRITES: Bacteria convert the healthful
nitrates to the harmful nitrites in vegetables. Fresh
vegetables are usually resistant to bacterial infections.
However, once a vegetable is cooked, bacteria reduce nitrates
to nitrites. Therefore, cook only the amount of a vegetable
that you plan to eat right away. Leftovers should be stored
for no more than a day or two in the refrigerator. Freezing
inactivates bacteria, so commercially frozen cooked vegetables
usually have low levels of nitrites. Pureed foods are much
higher in nitrites. Boiling vegetables reduces nitrate content
(Toxicol Lett. 2008(Oct 1);181(3):177-81).
Excessive nitrates in grass and grains have killed ruminant
animals. Bacteria in the stomachs of ruminant animals
rapidly reduce nitrates (with an A) to nitrites (with an I).
Normally, the nitrites are converted to ammonia to be used by
bacteria as a source of nitrogen, but nitrites can convert
hemoglobin in blood to methemoglobin, which cannot carry
oxygen and the animal can smother to death.
In humans, excessive nitrites can accumulate also
and prevent oxygen from attaching to red blood cells. This
is called methemoglobinemia which can prevent you from even
being able to move, and has killed some infants and adults.
This condition can be caused by drinking very large amounts
of stale juice from cooked spinach or other vegetables high
in nitrates. On the other hand, you should not worry about
nitrates in fresh vegetables harming you.
THE TIME? So far, nobody has proven that a high vegetable
diet will make you a better athlete. It was relatively easy to
set up a study in which a single dose of nitrates is given
before a time trial. However, it takes far more planning and
work to set up studies in which athletes are on long-term,
high-vegetable diets and compare them to other athletes on
low-vegetable diets. We have to await further research to
prove that a high-plant diet will make you a better athlete.
I think it will.
that you eat a high-vegetable diet anyway because it can prolong
your life and help to prevent certain cancers, heart attacks and
many other diseases. The Mediterranean Diet and the DASH Diet
have both been shown to lower cholesterol and blood pressure,
and help to prevent heart attacks. These diets are high in
fruits and vegetables that are rich sources of nitrates.
Many studies show that nitrates in vegetables lower high
blood pressure. (Hypertension. 2010;56:274-81). They do this
by widening blood vessels to increase oxygen availability to
muscles. Nitrates also help prevent heart attacks during
intense exercise (Cardiovasc Res. 2011(Feb 15);89(3):499-506).


Reports from

Exercise bikes


Cycling cadence


Dear Dr. Mirkin: Should I take antioxidant pills as part of
my training program?

No; the current issue of Journal of the American College
of Sports Medicine shows that antioxidant pills prevent the
major mitochondrial benefits of athletic endurance training
(Medicine & Science in Sports & Exercise, June 1, 2011).
Rats that trained on a treadmill increased the enzymes that are
necessary to increase the number and size of mitochondria.
Rats who trained on a treadmill and were given two powerful
antioxidants, vitamin E and alpha lipoic acid, did not increase
the enzymes that are necessary to increase the number and size
of mitochondria.
food to energy most effectively in the mitochondria, hundreds
of small chambers inside muscle fibers. They need oxygen to
do this. The limiting factor to how fast and long you can
move is the time it takes to move oxygen into muscle fibers.
Athletic training makes you faster and gives you greater
endurance by enlarging and increasing the number of
mitochondria in muscles.
ANTIOXIDANT PILLS CAN HARM: People who take 1000 mg/day
of vitamin C and 400 IU/day of vitamin E do not gain the
benefits of increased insulin sensitivity when they exercise
(Proceedings of the National Academy of Sciences, May 12,
- When blood sugar levels rise too high, sugar sticks on
the surface of cell membranes and can never get off. The
attached sugar is converted in a series of chemical reactions
to sorbitol that destroys cells.
- Contracting muscles help to prevent this damage by
removing sugar so fast from the bloodstream that blood sugar
levels do not rise too high.
- Food is converted to energy to power your muscles by a
series of chemical reactions that shuffle electrons from
molecule to molecule.
- This occurs primarily in the mitochondria, small
energy-producing chambers in cells, that number anywhere from
a few to thousands in each cell.
- As electrons are shuffled to produce energy, extra
electrons can accumulate. They can either end on hydrogen
atoms to form water and become harmless, or they can end up on
oxygen atoms to form free radicals that can damage cells. This
can cause cancers, heart attacks and other life-shortening
- Exercise speeds up the reactions that turn food into
energy, so exercise increases the production of free radicals.
- The body responds to this increased production of free
radicals during exercise by producing tremendous numbers of
antioxidants that sop up the free radicals and render them
- Exercise prolongs life and prevents heart attacks and
cancers by causing the body to dispose of free radicals by the
increased production of antioxidants.
LET THE BUYER BEWARE: If you exercise and take
antioxidant vitamins C and E, you prevent your own body from
making large amounts of antioxidants during exercise, so more
free radicals (oxidants) accumulate in your body and more
cells are damaged.
Many studies show that:
- Taking large doses of beta carotene (pro-vitamin A)
increases risk for heart attacks in men and increase risk for
lung cancer in smokers.
- Taking large doses of vitamin C does not prevent colon
cancer, and does not prolong life in people with cancer.
- Taking large doses of vitamin E or selenium does not
prevent lung cancer, heart disease or stroke.
MY RECOMMENDATIONS: Exercise every day, and get the
antioxidant vitamins and other nutrients your body needs from
foods, not from pills. Eat a wide variety of foods including
large amounts of fruits, vegetables, whole grains, beams, nuts
and other seeds. If you want to take Recommended Dietary
Allowances of vitamins in pills, go ahead; there is little
evidence that you will harm yourself. However, when you take
large doses of any vitamin, you don't have the foggiest idea
whether you are harming or helping yourself. I do not
recommend large doses of vitamins to anyone.


Dear Dr. Mirkin: Is it harmful to drink five beers on
Saturday if I have no alcohol the rest of the week?

Yes! That is called binge drinking. Taking more than
2 drinks a day on a regular basis will shorten your life and
increase risk for certain cancers, heart attacks and strokes.
A drink is five ounces of wine, 12 ounces of beer and 2/3rds
of shot glass. Taking more than two drinks a day, just once
a week, can impair your memory. Binge drinking students
perform worse on memory tests, both on immediate and delayed
recall (Alcoholism: Clinical and Experimental Research,
published online May 16, 2011).


Recipe of the Week:

Eggplant Sauce for Whole Grains or Pasta

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