Caffeine: Pain reliever,
Performance Enhancer, Fat-burner and Anti-cancer
Compound
Caffeine is a naturally
occurring stimulant found in coffee. Caffeine is the most socially acceptable
drug in the world. Coffee is second only to tea (another caffeine-containing
brew) as the most popular beverage in the world. Despite this, very little is
known about how caffeine works, that is, its intracellular mechanism of action.
However, recent studies have unveiled many important benefits of caffeine and
coffee consumption, particularly for athletes. Many of these benefits have never
previously been considered.
At the cellular level, caffeine owes its
psycho-stimulant action to the inhibition of the adenosine A2A receptors.
(Adenosine is one of the four building blocks of DNA and an important signaling
molecule in the brain.) At concentrations equivalent to a few cups of coffee a
day, caffeine binds and blocks nerve cells that normally inhibit voluntary
movements in the brain’s movement centre, (the striatum). This creates that
subtle but very cool “wired” feeling from a jolt of caffeine.
Most
athletes know that caffeine gives a workout a serious boost. However, caffeine
has recently been shown to be effective at reducing muscle pain produced during
exercise [1].
Drinking a cup of coffee is more likely to reduce muscle
pain during a workout than taking aspirin . . .
Although aspirin is
commonly used to treat muscle pain, a team of researchers at the University of
Georgia have previously showed that aspirin does not reduce muscle pain produced
during vigorous exercise. Muscle contraction produces a host of biochemicals
that can stimulate pain. It was discovered that aspirin blocks only one of those
chemicals. Apparently, the biochemical blocked by aspirin has no role in
exercise-induced muscle pain.
Now, the same team of scientists discovered
that a shot of caffeine before training actually reduced thigh muscle pain
during intense exercise [1]. In this study, 16 healthy men cycled intensely for
30 minutes on two separate days. The exercise intensity was the same on both
days and purposefully set to make the riders' thigh muscles hurt. Participants
in the study took either caffeine (10 milligrams per kilogram of body weight) or
a placebo one hour before the exercise.
The participants reported feeling
substantially less pain in their thigh muscles after taking caffeine compared to
taking the placebo. Prior reports show that caffeine improves exercise
performance. The researchers suggest that caffeine’s ability to reduce leg
muscle pain during exercise might be explained partially by its hypoalgesic
properties.
Not all analgesics or combinations (acetaminophine and
caffeine) are effective for every type of pain or every individual. Much of this
is due to biological variation among people in receptors for the drugs as well
as variation in pain receptors in different body tissues. For instance, brain
tissue has no pain receptors so surgery can be done on the brain without
anesthesia. Obviously, it will hurt getting through the skin and
cranium.
The next step is to learn how caffeine helps athletes feel less
muscle pain during exercise. Scientists don't know yet whether the caffeine is
acting on muscles or the brain.
Coffee compounds alter glucose
absorption . . .
For effective fat loss and lean mass gains, a low
glycemic response (controlled blood glucose and insulin levels) needs to be
maintained. A small study carried out in the Great Britain has shown that coffee
consumption may delay gastric emptying of glucose from the stomach and slow the
absorption of glucose into the blood stream [2]. These researchers showed that
not only caffeine but another compound in coffee, chlorogenic acid, lowers the
glycemic response of carbohydrate consumption [2].
In a three-way,
randomized, crossover study, nine healthy volunteers consumed either a control
glucose solution, or 25 grams of glucose in a 400 milliliter caffeinated or
decaffeinated coffee after fasting. Blood was tested frequently over the
following three hours.
Both caffeinated and decaffeinated coffee
significantly slowed secretion of glucose-dependent insulinotropic polypeptides
compared with the control group. Glucose and insulin profiles were consistently
lower with coffee consumption and gastrointestinal hormone profiles revealed
delayed intestinal glucose absorption. The differences in plasma glucose,
insulin, and gastrointestinal hormone profiles shown in this research confirm
the potent biological action of coffee on glucose transport. The researchers
suggest that a novel function of coffee consumption maybe to slow intestinal
glucose absorption rates into the blood as well as shift the site of glucose
absorption to more distal parts of the intestine.
Some reports in the
media have suggested that coffee consumption negatively affects insulin
metabolism and glucose transport into muscle. However, the latest research that
has specifically examined this aspect demonstrates that caffeine has a minimal
(if any) impact on glucose transport into muscles [3]. Results from other
studies have shown that the components with coffee could be beneficial for
glucose metabolism and may even help prevent type-2 diabetes [4].
An
intervention study showed that increased coffee consumption (up to 7 cups a day)
for 14 days reduced fasting plasma glucose levels in healthy people, whereas
substitution of regular coffee for decaffeinated coffee for 20 days did not
affect plasma glucose. These results suggest that coffee and caffeine could be
beneficial for glucose metabolism [4].
Drinking strong coffee may help
prevent cancer . . .
A team of German researchers who have identified
a potent antioxidant compound in coffee have shown that coffee consumption
increased protection against colon cancer [5].
Scientists have suspected
for years that coffee could offer some protection against cancer thanks to its
high antioxidant content, but for the first time, these scientists identified a
specific, highly active anticancer compound in coffee that boosts the activity
of phase II enzymes. Activation of phase II enzymes dramatically upgrades
protection against free radical damage and this important process is thought to
protect our DNA against cancer-causing damage.
The study revealed that
coffee contains the anticancer compound methylpyridinium, not found in
significant amounts in other foods and beverages. Its anticancer activity was
unknown until now. Methylpyridinium is not present in raw coffee beans but is
formed during the roasting process from its chemical precursor, trigonellin,
which is common in raw coffee beans. It is present in both caffeinated and
decaffeinated coffee, and even in instant coffee.
Coffee consumption was
shown to boost activity levels of phase II enzymes in a dose dependent manner.
In other words, the higher the quantity of coffee, the higher the increase in
the activity level of the enzymes. Analysis of the extract showed that the most
active anticancer compound was methylpyridinium. The results provide strong
support for coffee as a cancer fighter in living systems.
Until human
studies are done, no one knows exactly how much coffee is needed to have a
protective effect against colon cancer. However, the results from these studies
suggest that drinking coffee may offer real protection, especially if the coffee
is strong! Espresso coffee contains about two to three times more of the
anticancer compound than a medium roasted coffee beverage. The researchers also
suggested that a dietary supplement could be developed to offer the benefits of
the coffee chemical to those not keen on the beverage.
The healthy
brew . . .
The results from another large study involving over 51
thousand people suggest that drinking three cups of coffee daily may reduce the
risk of mortality from liver cirrhosis [6].
Other research studies have
shown that coffee could also boost male fertility [7]. In tests on 750 men
awaiting vasectomy operations, Brazilian researchers showed that coffee drinkers
had better sperm motility. The scientists have proposed research on coffee-based
treatments for fertility problems.
Caffeine boosts fat metabolism and
stamina in athletes . . .
Bodybuilders and other athletes use
caffeine mainly for its fat-burning, performance-enhancing effects. It appears
that a relatively small dose of caffeine before your workout will boost
performance and increase the amount of fat utilized during exercise.
An
Australian team of researchers have shown that athletes who consumed a small
dose of caffeine before exercise (approx 200 milligrams) could continue to
exercise at a high capacity for up to 30% longer than those who had not taken
the stimulant. The caffeine supplement enabled the athletes to perform up to
3.5% beyond their normal capacity in a series of performance tests.
The
researchers suggested that substances in caffeine triggered the muscles to use
fat to fuel exercise instead of the usual carbohydrate stores, thus enabling
better endurance performance. In other tests performed by these scientists,
drinking Coca Cola© helped cyclists go faster for longer than those who were
given caffeine-free beverages.
Keeping habitual caffeine consumption to a
minimum appears to be important to obtaining caffeine’s performance-enhancing
effects. However, in terms of burning unwanted body fat, no research has shown a
reduced effect from frequent caffeine consumption. In other words, while
caffeine’s stimulating effects may be blunted by frequent use, caffeine’s potent
fat-burning effect may not necessarily be reduced by frequent caffeine
consumption.
References:
1. Journal of Pain, August, vol 4, no 6, 2003.
2. American
Journal of Clinical Nutrition, Vol. 78, No. 4, 728-733, 2003.
3.
Canadian Journal of Applied Physiology 28; 3; 2003
4. Lancet 360:
1477–78, 2002
5. Journal of Agricultural and Food Chemistry, No 5:
November, 2003
6. Annals of Epidemiology, July; 7: 2003.
7.
Presented at The Annual American Society for Reproductive Medicine conference;
Texas, August 2003.
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