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As well as having negative effects, caffeine does possess some positive attributes.
Present knowledge indicates that moderate intakes of caffeine should not be harmful to most people, and that caffeine may even have positive effects in preventing some diseases. As is so often the case, moderation in caffeine consumption seems to be the sensible path to follow.
Source
The amount of caffeine in some common foods and beverages is as follows:
| Coffee, brewed | 40 to 180mg per cup | | Coffee, instant | 30 to 120mg per cup | | Coffee, decaffeinated | 3 to 5mg per cup | | Tea, brewed American | 20 to 90mg per cup | | Tea, brewed imported | 25 to 110mg per cup | | Tea, instant | 28mg per cup | | Tea, canned iced | 22 to 36mg per 12 ounces | | Cola and other soft drinks, caffeine-containing | 36 to 90mg per 12 ounces | | Cola and other soft drinks, decaffeinated | 0mg per 12 ounces | | Cocoa | 4mg per cup | | Chocolate, milk | 3 to 6mg per ounce | | Chocolate, bittersweet | 25mg per ounce |
Reasons For Use
Research indicates that caffeine intake can reduce the risk of developing Parkinson's disease and possibly also liver cancer. There are indications that caffeine may decrease liver damage.
Another positive effect is that caffeine can increase the resting metabolic rate in lean and obese people, which is why it is often included in slimming pills and products, including herbal diet pills. There are many studies that document the slimming effects of caffeine. Unfortunately, most of these studies used slimming mixtures that contained caffeine in combination with compounds such as ephedrine or green tea extract. This makes it difficult to judge how much of the observed weight loss was due to caffeine and how much was due to one of the other ingredients. Some researchers do maintain that "high caffeine intake was associated with thermogenesis and fat oxidation and with suppressed leptin in women." [Westerterp-Platenga & coworkers, 2005]
150mg of caffeine a day may promote slimming: Do not increase coffee and/or tea intake to absurd levels such as 10 cups per day to promote weight loss. Excessive caffeine intake may cause pronounced side-effects like palpitations, insomnia, irritability etc.
Drink tea or coffee in moderate quantities when you are trying to lose weight, but keep in mind that you also need to reduce your energy intake with a sensible, balanced, low-energy diet, and increase your energy output by doing daily exercise for at least 30 minutes or more per day.
Research indicates that intakes of caffeine exceeding 9mg/kg of body weight (e.g. a 70kg athlete ingesting more than 630mg of caffeine per day) do not increase athletic performance more than having about 6mg/kg of body weight (e.g. the 70kg athlete would only have to ingest 420mg of caffeine per day). The optimal dose for improving athletic performance according to Burke and Deakin (2000) is, therefore, 5-6mg per kg body weight. Too high a caffeine intake by sportsmen and women can cause negative side-effects such as the shakes, palpitations, headaches etc. It may also cause dehydration. Furthermore, it has been found that some athletes do not respond to caffeine stimulation by increasing their performance, so you need to experiment before a big event to see if caffeine supplementation does improve your performance or not.
Caffeine is known to enhance athletic performance, reduce fatigue and improve recovery in athletes. The following physiological effects of caffeine may enhance athletic performance:- stimulation of the central nervous system, which leads to reduced perception of effort (reduced fatigue), or enhanced use of muscles
- stimulation of the heart muscle
- stimulation of diuresis (excretion of water by the kidneys)
- stimulation of the release of epinephrine by the body (the "fight-or-flight" hormone), which releases fats for muscle activity.
In view of the above, caffeine has been used for many years by sportsmen and women to enhance their performance, prevent fatigue and give athletes a "lift".
Because of its stimulant properties, caffeine can also help people stay awake and be more alert in situations where they are required to concentrate.
Directions
Experts agree that moderate intakes of caffeine should not be harmful to the general population.
The UK Food Standards Agency has, for example, recommended that the general population and pregnant women should not have more than 300mg of caffeine per day (e.g. four cups of instant coffee or six cups of regular tea).
When calculating daily caffeine intake, remember to include caffeine arising from any medications you may be taking: having three headache pills would contribute 150mg of caffeine to your intake.
Counter-Indicators and Warnings
Caffeine stimulates diuresis or excretion of water by the kidneys, leading possibly to dehydration. Intake of caffeine should therefore be balanced by good hydration.
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GLOSSARY
Adrenaline (Epinephrin, Epinephrine)
A hormone secreted by the adrenal medulla that is released into the bloodstream in response to physical or mental stress, as from fear or injury. It initiates many bodily responses, including the stimulation of heart action and an increase in blood pressure, metabolic rate, and blood glucose concentration.
Caffeine
A member of the family of chemicals that are called methyl xanthines. It is variously classified as a stimulant, an addictive substance, a performance-enhancing drug and a slimming aid. Sources of caffeine include drinks, foods and medications. Examples include coffee, tea, cola drinks, the new generation 'energy' drinks, chocolate, and many over-the-counter and prescription medications.
Cancer
Refers to the various types of malignant neoplasms that contain cells growing out of control and invading adjacent tissues, which may metastasize to distant tissues.
Central Nervous System (CNS)
A collective term for the brain, spinal cord, their nerves, and the sensory end organs. More broadly, this can even include the
neurotransmitting hormones instigated by the CNS that control the chemical nervous system, the endocrine glands.
Cup (Cups)
A unit of volume measurement equal to 8 fluid oz, or roughly 250ml. It also equals 1/2 pint, 1/4 quart and 1/16 gallon.
Diuresis
Excessive discharge of urine.
Herbs (Herb, Herbal)
Herbs may be used as dried extracts (capsules, powders, teas), glycerites (glycerine extracts), or tinctures (alcohol extracts). Unless otherwise indicated, teas should be made with one teaspoon herb per cup of hot water. Steep covered 5 to 10 minutes for leaf or flowers, and 10 to 20 minutes for roots. Tinctures may be used singly or in combination as noted. The high doses of single herbs suggested may be best taken as dried extracts (in capsules), although tinctures (60 drops four times per day) and teas (4 to 6 cups per day) may also be used.
Hormones (Hormone)
Chemical substances secreted by a variety of body organs that are carried by the bloodstream and usually influence cells some distance from the source of production. Hormones signal certain enzymes to perform their functions and, in this way, regulate such body functions as blood sugar levels, insulin levels, the menstrual cycle, and growth. These can be prescription, over-the-counter, synthetic or natural agents. Examples include adrenal hormones such as corticosteroids and aldosterone; glucagon, growth hormone, insulin, testosterone, estrogens, progestins, progesterone, DHEA, melatonin, and thyroid hormones such as thyroxine and calcitonin.
Kidneys (Kidney, Renal)
Bean-shaped organs, each about the size of a fist. They are located near the middle of the back, just below the rib cage. The kidneys are sophisticated reprocessing machines, each day handling about 50 gallons of blood to sift out about half a gallon of waste products and extra water. The waste and extra water become urine, which flows to the bladder through tubes called ureters. The actual filtering occurs in tiny units inside the kidneys called nephrons. Every kidney has about a million nephrons. In a nephron, a glomerulus -- which is a tiny blood vessel, or capillary -- intertwines with a tiny urine-collecting tube called a tubule. A complicated chemical exchange takes place, as waste materials and water leave your blood and enter your urinary system. The kidneys recycle chemicals such as sodium, phosphorus, and potassium and thus regulate their levels. Renal: Pertaining to the kidneys.
Kilogram (kg, kgs, Kilogramme, Kilogrammes, Kilograms)
1000 grams, 2.2lbs.
Liver (Hepatic)
The largest and one of the most complex organs of the body, the liver is responsible for much of the metabolism of fats, proteins and carbohydrates. It is the site of much of the body's detoxification. It is connected very closely with digestion and the regulation of blood sugar, among many other functions. Found behind the ribs on the right side of the abdomen, it has many important functions such as removing harmful material from the blood, making enzymes and bile that help digest food, and converting food into substances needed for life and growth. Hepatic: Pertaining to the liver.
Metabolism (Metabolic, Metabolize, Metabolizes, Metabolizing)
The chemical processes of living cells in which energy is produced in order to replace and repair tissues and maintain a healthy body. Responsible for the production of energy, biosynthesis of important substances, and degradation of various compounds. Also defined as the sum total of changes in an organism in order to achieve a balance (homeostasis): Catabolic burns up, anabolic stores and builds up; the sum of their work is metabolism.
Milligram (mg, Milligrams)
0.001 or a thousandth of a gram.
Ounce (Ounces, oz)
Approximately 28 grams.
Parkinson's Disease (Parkinson's)
A chronic, slowly-progressing disease of the nervous system characterized clinically by the combination of tremor, rigidity, extreme slowness of movement, and stooped posture. It is characterized pathologically by loss of dopamine in the substantia nigra.
Last updated: May 04, 2009
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