Caffeine FAQ

This is an excerpt of a longer FAQ including more coffee-related information which can be found here. The primary author of this document is Alex López-Ortiz. For a list of contributors, see end of page.

Since the FAQ doesn’t cover some issues related to home roasting, I have been so bold as to add some discussion from the HomeRoast List on this topic at the bottom of the page.

The Chemistry of Caffeine and related products

How much caffeine is there in [drink/food/pill]?

According to the National Soft Drink Association, the following is the caffeine content in mgs per 12 oz can of soda:

   Jolt Cola               71.2
   Sugar-Free Mr. Pibb     58.8
   Mountain Dew            55.0  (no caffeine in Canada)
   Diet Mountain Dew       55.0
   Kick citrus             54    (36mg per 8oz can, caffeine from guarana) 
   Mello Yellow            52.8
   Surge                   51.0
   Tab                     46.8
   Battery  energy drink -- 140mg/l = 46.7mg/can
   Coca-Cola               45.6
   Diet Cola               45.6
   Shasta Cola             44.4
   Shasta Cherry Cola      44.4
   Shasta Diet Cola        44.4
   Mr. Pibb                40.8
   OK Soda                 40.5
   Dr. Pepper              39.6
   Pepsi Cola              37.2
   Aspen                   36.0
   Diet Pepsi              35.4
   RC Cola                 36.0
   Diet RC                 36.0
   Diet Rite               36.0
   Canada Dry Cola         30.0
   Canada Dry Diet Cola    1.2
   7 Up                    0

Krank2o     sample 1     97.7mg/500ml sample 2    101.6mg/500ml
Lab: Ameritech Labs, College Pt, NY; tested Sep 03, 96

Krank2o    middle          96.4mg/500ml
Lab: Ameritech Labs, tested Aug 29, 96

By means of comparison, a 7 oz cup of coffee has the following caffeine (mg) amounts, according to Bunker and McWilliams in J. Am. Diet. 74:28-32, 1979:

   Drip                    115-175
   Espresso                100mg of caffeine   
   1 serving (1.5-2oz) 
   Brewed                  80-135
   Instant                 65-100
   Decaf, brewed           3-4
   Decaf, instant          2-3
   Tea, iced (12 ozs.)     70
   Tea, brewed, imported   60
   Tea, brewed, U.S.       40
   Tea, instant            30
   Mate                    25-150mg

The variability in the amount of caffeine in a cup of coffee or tea is relatively large even if prepared by the same person using the same equipment and ingredients day after day.

Reference Variability in caffeine consumption from coffee and tea: Possible significance for epidemiological studies by B. Stavric, R. Klassen, B. Watkinson, K. Karpinski, R. Stapley, and P. Fried in “Foundations of Chemical Toxicology”, Volume 26, number 2, pp. 111-118, 1988 and an easy to read overview, Looking for the Perfect Brew by S. Eisenberg, “Science News”, Volume 133, April 16, 1988, pp. 252-253.

Quote from the lab manual:

Caffeine is present in tea leaves and in coffee to the extent of about 4%. Tea also contains two other alkaloids, theobromine and theophylline. These last two relax the smooth muscles where caffeine stimulates the heart and respiratory systems.

The effects of theobromine are, compared to caffeine and theophylline, relatively moderate. However, cocoa contains eight times more theophylline than caffeine. As well, caffeine has been shown to combine with other substances for added potency. Thus the effects of theobromine might be enhanced by the caffeine in chocolate.

Theobromine is highly toxic to dogs and kills many canids/year via chocolate poisoning. It takes quite a dose to reach fatal levels (more than 200 mg/kg bodyweight) but some dogs have a bad habit of eating out of garbage cans and some owners have a bad habit of feeding dogs candy. A few oreos won’t hurt a dog, but a pound of chocolate can do considerable damage.

Clinical signs of theobromine toxicity in canids usually manifest 8 hours after ingestion and can include: thirst, vomiting, diarrhea, urinary incontinence, nervousness, clonic muscle spasms, seizures and coma. Any dog thought to have ingested a large quantity of chocolate should be brought to an emergency clinic asap, where treatment usually includes the use of emetics and activated charcoal. The dog will thus need to be monitored to maintain proper fluid and electrolyte balance.

Pathogenesis of theobromine toxicity: evidently large quantities of theobromine have a diuretic effect, relax smooth muscles, and stimulate the heart and cns.


Fraser, Clarence M., et al, eds. The Merck Veterinary Manual, 7th ed. Rahway, NJ: Merck & Co., Inc. 1991. pp. 1643-44.

On humans caffeine acts particularly on the brain and skeletal muscles while theophylline targets heart, bronchia, and kidneys.

Other data on caffeine:

Cup of coffee    90-150mg
Instant coffee   60-80mg
Tea              30-70mg
Mate             25-150mg
Cola             30-45mg
Chocolate bar    30mg
Stay-awake pill  100mg
Vivarin          200mg  
Cold relief tablet  30mg

The following information is from Bowes and Church’s Food values of portions commonly used, by Anna De Planter Bowes. Lippincott, Phila. 1989. Pages 261-2: Caffeine.


Chocolate                               mg caffeine
  baking choc, unsweetened, Bakers--1 oz(28 g) 25
  german sweet, Bakers -- 1 oz (28 g)           8
  semi-sweet, Bakers -- 1 oz (28 g)            13

Choc chips
  Bakers -- 1/4 cup (43 g)                     13
  german sweet, Bakers -- 1/4 cup (43 g)       15

Chocolate bar, Cadbury  -- 1 oz (28 g)         15
Chocolate milk  8oz                             8

Jello Pudding Pops, Choc (47 g)                 2
Choc mousse from Jell-O mix (95 g)              6
Jello choc fudge mousse (86 g)                 12

3 heaping teaspoons of choc powder mix          8
2 tablespoons choc syrup                        5
1 envelope hot cocoa mix                        5

Dietary formulas
ensure, plus, choc, Ross Labs -- 8 oz (259 g)  10
Cadbury Milk Chocolate Bar

More stuff:

Guarana "Magic Power" (quite common in Germany),
15 ml alcohol with
5g Guarana Seeds        250.0 mg
Guarana capsules with
500 mg G. seeds          25.0 mg / capsule

(assuming 5% caffeine in seeds as stated in literature)

Guarana soda pop is ubiquitous in Brazil and often available at tropical groceries here. It’s really tasty and packs a wallop. Guarana wakes you up like crazy, but it doesn’t cause coffee jitters.

It is possible that in addition to caffeine, there is some other substance in guarana that also produces an effect, since it ‘feels’ different than coffee. Same goes for mate.

How much caffeine there is in blend X?

Caffeine Content in beans and blends

(Source: Newsletter–Mountanos Bros. Coffee Co., San Francisco)

Brazil Bourbons  1.20%
Celebes Kalossi  1.22
Colombia Excelso  1.37
Colombia Supremo  1.37
Costa Rica Tarrazu  1.35
Ethiopian Harrar-Moka  1.13
Guatemala Antigua  1.32
Indian Mysore  1.37
Jamaican Blue Mtn/Wallensford Estate  1.24
Java Estate Kuyumas  1.20
Kenya AA  1.36
Kona Extra Prime  1.32
Mexico Pluma Altura  1.17
Mocha Mattari (Yemen)  1.01
New Guinea  1.30
Panama Organic  1.34
Sumatra Mandheling-Lintong  1.30
Tanzania Peaberry  1.42
Zimbabwe  1.10

Colombia Supremo Dark  1.37%
Espresso Roast  1.32
French Roast  1.22
Vienna Roast  1.27
Mocha-Java  1.17

DECAFS--all @ .02% with Swiss Water Process

Chemically speaking, what is caffeine?

Caffeine is an alkaloid. There are numerous compounds called alkaloids, among them we have the methylxanthines, with three distinguished compounds: caffeine, theophylline, and theobromine, found in cola nuts, coffee, tea, cacao beans, mate and other plants. These compounds have different biochemical effects, and are present in different ratios in the different plant sources. These compounds are very similar and differ only by the presence of methyl groups in two positions of the chemical structure. They are easily oxidized to uric acid and other methyluric acids which are also similar in chemical structure.

Sources: Coffee, tea, cola nuts, mate, guarana.
Effects: Stimulant of central nervous system, cardiac muscle, and
respiratory system, diuretic Delays fatigue.

Sources: Tea
Effects: Cariac stimulant, smooth muscle relaxant, diuretic, vasodilator

Sources: Principle alkaloid of the cocoa bean (1.5-3%) Cola nuts and tea
Effects: Diuretic, smooth muscle relaxant, cardiac stimulant, vasodilator.

(Info from Merck Index)

The presence of the other alkaloids in colas and tea may explain why these sometimes have a stronger kick than coffee. Colas, which have lower caffeine contents than coffee are, reportedly, sometimes more active. Tea seems the strongest for some. Coffee seems more lasting for mental alertness and offers fewer jitters than the others.

A search in CAS and produced these names and synonyms:

RN   58-08-2  REGISTRY
CN   1H-Purine-2,6-dione, 3,7-dihydro-1,3,7-trimethyl- (9CI)  (CA INDEX NAME)
CN   Caffeine (8CI)
CN   1,3,7-Trimethyl-2,6-dioxopurine
CN   1,3,7-Trimethylxanthine
CN   7-Methyltheophylline
CN   Alert-Pep
CN   Cafeina
CN   Caffein
CN   Cafipel
CN   Guaranine
CN   Koffein
CN   Mateina
CN   Methyltheobromine
CN   No-Doz
CN   Refresh'n
CN   Stim
CN   Thein
CN   Theine
CN   Tri-Aqua

MF   C8 H10 N4 O2

The correct name is the first one, 1H-Purine-2,6-diione,3,7-dihydro-1,3,7-trimethyl- (This is the “inverted name”) The “uninverted name” is 3,7-Dihydro-1,3,7-trimethyl-1H-purine-2,6-dione

Merck Index excerpt…

Caffeine: 3,7-dihydro- 1,3,7-trimethyl- 1H-purine- 2,6-dione; 1,3,7-trimethylxanthine; 1,3,7-trimethyl- 2,6-dioxopurine; coffeine; thein; guaranine; methyltheobromine; No-Doz.

C8H10N4O2; mol wt 194.19. C 49.48%, H 5.19%, N 28.85%, O 16.48%.

Occurs in tea, coffee, mate leaves; also in guarana paste and cola nuts: Shuman, U.S. pat. 2,508,545 (1950 to General Foods). Obtained as a by-product from the manuf of caffeine-free coffee: Barch, U.S. pat. 2,817,588 (1957 to Standard Brands); Nutting, U.S. pat. 2,802,739 (1957 to Hill Bros. Coffee); Adler, Earle, U.S. pat. 2,933,395 (1960 to General Foods).

Crystal structure: Sutor, Acta Cryst. 11, 453, (1958). Synthesis: Fischer, Ach, Ber. 28, 2473, 3135 (1895); Gepner, Kreps, J. Gen. Chem. USSR 16, 179 (1946); Bredereck et al., Ber. 83, 201 (1950); Crippa, Crippa, Farmaco Ed. Sci. 10, 616 (1955); Swidinsky, Baizer, U.S. pats. 2,785,162 and 2,785,163 (1957 to Quinine Chem. Works); Bredereck, Gotsmann, Ber. 95, 1902 (1962).

Hexagonal prisms by sublimation, mp 238 C. Sublimes 178 C. Fast sublimation is obtained at 160-165 C under 1mm press. at 5 mm distance. d 1.23. Kb at 19 C: 0.7 x 10^(-14). Ka at 25 C: <1.0 x 10^(-14). pH of 1% soln 6.9. Aq solns of caffeine salts dissociate quickly. Absorption spectrum: Hartley, J. Chem. Soc. 87, 1802 (1905). One gram dissolves in 46 ml water, 5.5 ml water at 80 C, 1.5 ml boiling water, 66 ml alcohol, 22 ml alcohol at 60 C, 50 ml acetone, 5.5 ml chloroform, 530 ml ether, 100 ml benzene, 22 ml boiling benzene. Freely sol in pyrrole; in tetrahydrofuran contg about 4% water; also sol in ethyl acetate; slightly in petr ether. Soly in water is increased by alkali benzoates, cinnamates, citrates, or salicylates.

Monohydrate, felted needles, contg 8.5% H2O. Efflorescent in air; complete dehydration takes place at 80 C. LD50 orally in rats: 200 mg/kg.

Acetate, C8H10N4O2.(CH3COOH)2, granules or powder; acetic acid odor; acid reaction. Loses acetic acid on exposure to air. Soluble in water or alcohol with hydrolysis into caffeine and acetic acid. Keep well stoppered.

Hydrochloride dihydrate, C8H10N4O2.HCl.2H2O, crystals, dec 80-100 C with loss of water and HCl. Sol in water and in alcohol with dec.

Therap Cat: Central stimulant.

Therap Cat (Vet): Has been used as a cardiac and respiratory stimulant and as a diuretic.

Is it true that tea has no caffeine/What is theine, theobromine, etc?

From “Principles of biochemistry”, Horton and al, 1993.

Caffeine is sometimes called “theine” when it’s in tea. This is probably due to an ancient misconception that the active constituent is different. Theophylline is present only in trace amounts. It is more diuretic, more toxic and less speedy.


Coffee and tea contain caffeine and theophylline, respectively, which are methylated purine derivatives that inhibit cAMP phosphodiesterase. In the presence of these inhibitors, the effects of cAMP, and thus the stimulatory effects of the hormones that lead to its production, are prolonged and intensified.

Theobromine and theophylline are two dimethylxanthines that have two rather than three methyl groups. Theobromine is considerably weaker than caffeine and theophylline, having about one tenth the stimulating effect of either.

Theobromine is found in cocoa products, tea (only in very small amounts) and kola nuts, but is not found in coffee. In cocoa, its concentration is generally about 7 times as great as caffeine. Although, caffeine is relatively scarce in cocoa, its mainly because of theobromine that cocoa is “stimulating”.

Theophylline is found in very small amounts in tea, but has a stronger effect on the heart and breathing than caffeine. For this reason it is often the drug of choice in home remedies for treating asthma bronchitis and emphysema. The theophylline found in medicine is made from extracts from coffee or tea.

Where can I find a gif of the caffeine molecule?

Caffeine = 1,3,7-Trimethylxanthine

The Department of Chemistry at Jamaica of the University of Western Indies has made available an avi and an mpeg of a rotation of the caffeine molecule, among other molecules and chemical processes. The index page contains more information and the links to the clips.

           N----C   C==O
          ||   ||   |
          ||   ||   |
          CH    C   N--CH3
              /  /
             N    C
             |   ||
            CH3   O

There is a gif picture at the ftp site or any of its mirror sites under



Theobromine is also a common component of coffee, tea, chocolate, and mate (particularly in these last two).



           N----C   C==O
          ||   ||   |
          ||   ||   |
          CH    C   N--H
              /  /
             N    C
             |   ||
            CH3   O

Theophylline was once thought to be a major component of tea. This is not correct. Tea contains significantly more amounts of caffeine than of theophylline.


           N----C   C==O
          ||   ||   |
          ||   ||   |
          CH    C   N--CH3
              /  /
             N    C
             |   ||
             H    O

Is it true that espresso has less caffeine than regular coffee?

Yes and no. An espresso cup has about as much caffeine as a cup of dark brew. But servings for espresso are much smaller. Which means that the content of caffeine per millilitre are much higher than with a regular brew. Moreover, caffeine is more quickly assimilated when taken in concentrated dosages, such as an espresso cup.

The myth of lower caffeine espresso comes comes from the fact that the darker roast beans used for espresso do have less caffeine than regularly roasted beans as roasting is supposed to break up or sublimate the caffeine in the beans (I have read this quote on research articles, but found no scientific studies supporting it. Anybody out there?). But espresso is prepared using pressurized water through significantly more ground (twice as much?) than regular drip coffee, resulting in a higher percentage of caffeine per millilitre.

Here’s the caffeine content of Drip/Espresso/Brewed Coffee:

Drip            115-175
Espresso        100         1 serving (1.5-2oz)
Brewed          80-135

How does caffeine taste?

Caffeine is very bitter. Barq’s Root Beer contains caffeine and the company says that it has “12.78mg per 6oz” and that they “add it as a flavouring agent for the sharp bitterness”

How much theobromine/theophylline there is in …?

Sources: Physicians Desk Reference and Institute of Food Technologies from Pafai and Jankiewicz (1991) DRUGS AND HUMAN BEHAVIOUR

cocoa                      250mg theobromine
bittersweet choc. bar      130mg theobromine
5 oz cup brewed coffee     no theobromine
tea 5oz cup brewed 3min 
with teabag                3-4 mg theophylline
Diet Coke                  no theobromine or theophylline

Caffeine and your Health

Important: This information was excerpted from several sources, no claims are made to its accuracy. The FAQ mantainer is not a medical doctor and cannot vouch for the accuracy of this information.

Caffeine Withdrawal: Procedures and Symptoms.

How to cut caffeine intake?

Most people report a very good success ratio by cutting down caffeine intake at the rate of 1/2 cup of coffee a day. This is known as Caffeine Fading. Alternatively you might try reducing coffee intake in discrete steps of two-five cups of coffee less per week (depending on how high is your initial intake). If you are drinking more than 10 cups of coffee a day, you should seriously consider cutting down.

The best way to proceed is to consume caffeine regularly for a week, while keeping a precise log of the times and amounts of caffeine intake (remember that chocolate, tea, soda beverages and many headache pills contain caffeine as well as coffee). At the end of the week proceed to reduce your coffee intake at the rate recommended above. Remember to have substitutes available for drinking: if you are not going to have a hot cup of coffee at your 10 minute break, you might consider having hot chocolate or herbal tea, but NOT decaff, since decaff has also been shown to be addictive. This should take you through the works without much problem.

Some other people quit cold turkey. Withdrawal symptoms are quite nasty this way (see section below) but they can usually be countered with lots of sleep and exercise. Many people report being able to stop drinking caffeine almost cold-turkey while on holidays on the beach. If quitting cold turkey is proving too hard even in the beach, drinking a coke might help.

What are the symptoms of caffeine withdrawal?

Regular caffeine consumption reduces sensitivity to caffeine. When caffeine intake is reduced, the body becomes oversensitive to adenosine. In response to this oversensitiveness, blood pressure drops dramatically, causing an excess of blood in the head (though not necessarily on the brain), leading to a headache.

This headache, well known among coffee drinkers, usually lasts from one to five days, and can be alleviated with analgesics such as aspirin. It is also alleviated with caffeine intake (in fact several analgesics contain caffeine dosages).

Often, people who are reducing caffeine intake report being irritable, unable to work, nervous, restless, and feeling sleepy, as well as having a headache. In extreme cases, nausea and vomiting has also been reported.


Caffeine and Health. J. E. James, Academic Press, 1991. Progress in Clinical and Biological Research Volume 158. G. A. Spiller, Ed. Alan R. Liss Inc, 1984.

What happens when you overdose?

From Desk Reference to the Diagnostic Criteria from DSM-3-R (American Psychiatric Association, 1987):

Caffeine-Induced Organic Mental Disorder 305.90 Caffeine Intoxication

  • Recent consumption of caffeine, usually in excess of 250 mg.
  • At least five of the following signs:
  1. restlessness
  2. nervousness
  3. excitement
  4. insomnia
  5. flushed face
  6. diuresis
  7. gastrointestinal disturbance
  8. muscle twitching
  9. rambling flow of thought and speech
  10. tachycardia or cardiac arrhythmia
  11. periods of inexhaustibility
  12. psychomotor agitation
  • Not due to any physical or other mental disorder, such as an Anxiety Disorder.

Basically, overdosing on caffeine will probably be very very unpleasant but not kill or deliver permanent damage. However, People do die from it.

    1. Toxic dose

The LD_50 of caffeine (that is the lethal dosage reported to kill 50% of the population) is estimated at 10 grams for oral administration. As it is usually the case, lethal dosage varies from individual to individual according to weight. Ingestion of 150mg/kg of caffeine seems to be the LD_50 for all people. That is, people weighting 50 kilos have an LD_50 of approx. 7.5 grams, people weighting 80 kilos have an LD_50 of about 12 grams.

In cups of coffee the LD_50 varies from 50 to 200 cups of coffee or about 50 vivarins (200mg each).

One exceptional case documents survival after ingesting 24 grams. The minimum lethal dose ever reported was 3.2 grams intravenously, this does not represent the oral MLD (minimum lethal dose).

In small children ingestion of 35 mg/kg can lead to moderate toxicity. The amount of caffeine in an average cup of coffee is 50 – 200 mg. Infants metabolize caffeine very slowly.

    1. Symptoms
  • Acute caffeine poisoning gives early symptoms of anorexia, tremor, and restlessness. Followed by nausea, vomiting, tachycardia, and confusion. Serious intoxication may cause delirium, seizures, supraventricular and ventricular tachyarrhythmias, hypokalemia, and hyperglycemia.
  • Chronic high-dose caffeine intake can lead to nervousness, irritability, anxiety, tremulousness, muscle twitching, insomnia, palpitations and hyperreflexia. For blood testing, cross-reaction with theophylline assays will detect toxic amounts. (Method IA) Blood concentration of 1-10 mg/L is normal in coffee drinkers, while 80 mg/L has been associated with death.
    1. Treatment
  • Emergency Measures
  • Maintain the airway and assist ventilation. (See Appendix A)
  • Treat seizures & hypotension if they occur.
  • Hypokalemia usually goes away by itself.
  • Monitor Vital Signs.
  • Specific drugs & antidotes. Beta blockers effectively reverse cardiotoxic effects mediated by excessive beta-adrenergic stimulation. Treat hypotension or tachyarrhythmias with intravenous propanolol, .01 – .02 mg/kg. , or esmolol, .05 mg/kg , carefully titrated with low doses. Esmolol is preferred because of its short half life and low cardioselectivity.
  • Decontamination
  • Induce vomiting or perform gastric lavage.
  • Administer activated charcoal and cathartic.
  • Gut emptying is probably not needed if 1 2 are performed promptly.
    1. Appendix APerforming airway assistance.
  • If no neck injury is suspected, place in the “Sniffing” position by tilting the head back and extending the front of the neck.
  • Apply the “Jaw Thrust” to move the tongue out of the way without flexing the neck: Place thumb fingers from both hands under the back of the jaw and thrust the jaw forward so that the chin sticks out. This should also hurt the patient, allowing you to judge depth of coma. 🙂
  • Tilt the head to the side to allow vomit and snot to drain out.

From conversations on alt.drugs.caffeine:

The toxic dose is going to vary from person to person, depending primarily on built-up tolerance. A couple people report swallowing 10 to 13 vivarin and ending up in the hospital with their stomaches pumped, while a few say they’ve taken that many and barely stayed awake.

A symptom lacking in the clinical manual but reported by at least two people on the net is a loss of motor ability: inability to move, speak, or even blink. The experience is consistently described as very unpleasant and not fun at all, even by those very familiar with caffeine nausea and headaches.

Effects of caffeine on pregnant women.

Caffeine has long been suspect of causing mal-formations in fetus, and that it may reduce fertility rates.

These reports have proved controversial. What is known is that caffeine does causes malformations in rats, when ingested at rates comparable to 70 cups a day for humans. Many other species respond equally to such large amounts of caffeine.

Data is scant, as experimentation on humans is not feasible. In any case moderation in caffeine ingestion seems to be a prudent course for pregnant women. Recent references are Pastore and Savitz, Case-control study of caffeinated beverages and preterm delivery. American Journal of Epidemiology, Jan 1995.

On men, it has been shown that caffeine reduces rates of sperm motility which may account for some findings of reduced fertility.

Caffeine and Osteoporosis (Calcium loss)

From the Journal of AMA: (JAMA, 26 Jan. 1994, p. 280-3.)

“There was a significant association between (drinking more) caffeinated coffee and decreasing bone mineral density at both the hip and the spine, independent of age, obesity, years since menopause, and the use of tobacco, estrogen, alcohol, thiazides, and calcium supplements [in women].”

Except when:

“Bone density did not vary […] in women who reported drinking at least one glass of milk per day during most of their adult lives.”

That is, if you drink a glass of milk a day, there is no need to worry about the caffeine related loss of calcium.

Studies on the side-effects of caffeine.

OAKLAND, California (UPI) -- Coffee may be good for life. A major study has found fewer suicides among coffee drinkers than those who abstained from the hot black brew.

The study of nearly 130,000 Northern California residents and the records of 4,500 who have died looked at the effects of coffee and tea on mortality.

Cardiologist Arthur Klatsky said of the surprising results, ``This is not a fluke finding because our study was very large, involved a multiracial population, men, women, and examined closely numerous factors related to mortality such as alcohol consumption and smoking.''

The unique survey also found no link between coffee consumption and death risk. And it confirmed a ``weak'' connection of coffee or tea to heart attack risk -- but not to other cardiovascular conditions such as stroke.

The study was conducted by the health maintenance organization Kaiser Permanente and was reported Wednesday in the Annals of Epidemiology.

Caffeine and your metabolism.

Caffeine increases the level of circulating fatty acids. This has been shown to increase the oxidation of these fuels, hence enhancing fat oxidation. Caffeine has been used for years by runners and endurance people to enhance fatty acid metabolism. It’s particularly effective in those who are not habitual users.

Caffeine is not an appetite suppressant. It does affect metabolism, though it is a good question whether its use truly makes any difference during a diet. The questionable rationale for its original inclusion in diet pills was to make a poor man’s amphetamine-like preparation from the non-stimulant sympathomimetic phenylpropanolamine and the stimulant caffeine. (That you end up with something very non-amphetamine like is neither here nor there.) The combination drugs were called “Dexatrim” or Dexa-whosis (as in Dexedrine) for a reason, namely, to assert its similarity in the minds of prospective buyers. However, caffeine has not been in OTC diet pills for many years per order of the FDA, which stated that there was no evidence of efficacy for such a combination.

From Goodman and Gilman’s The Pharmacological Basis of Therapeutics:

Caffeine in combination with an analgesic, such as aspirin, is widely used in the treatment of ordinary types of headache. There are few data to substantiate its efficacy for this purpose. Caffeine is also used in combination with an ergot alkaloid in the treatment of migrane (Chapter 39).

Ergotamine is usually administered orally (in combination with caffeine) or sublingually […] If a patient cannot tolerate ergotamine orally, rectal administration of a mixture of caffeine and ergotamine tartarate may be attempted.

The bioavailability [of ergotamine] after sublingual administration is also poor and is often inadequate for therapeutic purposes […] the concurrent administration of caffeine (50-100 mg per mg of ergotamine) improves both the rate and extent of absorption […] However, there is little correspondence between the concentration of ergotamine in plasma and the intensity or duration of therapeutic or toxic effects.

Caffeine enhances the action of the ergot alkaloids in the treatment of migrane, a discovery that must be credited to the sufferers from the disease who observed that strong coffee gave symptomatic relief, especially when combined with the ergot alkaloids. As mentioned, caffeine increases the oral and rectal absorption of ergotamine, and it is widely believed that this accounts for its enhancement of therapeutic effects.

Nowadays most of researchers believe that the stimulatory actions are attributable to the antagonism of the adenosine. Agonists at the adenosine receptors produce sedation while antagonists at these sites, like caffeine and theophylline induce stimulation, and what is even more important, the latter substance also reverse agonists-induced symptoms of sedation, thus indicating that this effects go through these receptors.

Another possibility, however, is that methylxanthines enhance release of excitatory aminoacids, like glutamate and aspartate, which are the main stimulatory neurotransmitters in the brain.

As to the side effects: methylxanthines inhibit protective activity of common antiepileptic drugs in exptl. animals in doses comparable to those used in humans when correction to the surface area is made. It should be underlined, that although tolerance develop to the stimulatory effects of theo or caffeine when administered on a chronic base, we found no tolerance to the above effects . This hazardous influence was even enhanced over time. Therefore, it should be emphasized that individuals suffering from epilepsy should avoid, or at least reduce consumption of coffee and other caffeine-containing beverages.

Author and Contributors

List of Contributors

This FAQ is a collective effort. Here’s a list of most (all?) of the contributors.


This FAQ is Copyright (C) 1994,1995 by Alex Lopez-Ortiz. This text, in whole or in part, may not be sold in any medium, including, but not limited to, electronic, CD-ROM, or published in print, without the explicit, written permission of Alex Lopez-Ortiz.

This is an excerpt of a longer FAQ including more coffee related information which can be found here. Copyright (C) 1994, Alex López-Ortiz. [email protected] (this email seems to be defunct? -Tom 6/03)

Caffeine and Home Roasting

Since the FAQ doesn’t cover some issues related to home roasting, I have been so bold as to add some discussion from the HomeRoast List on this topic.
Tom’s email:


Q: Could the roast level be affecting the amount of caffeine?
A: Everything I have read would indicate “no”. Caffeine is very chemically stable, amazingly so since everything else in coffee changes so much in roasting.
Q: Or could it be the different types of extraction – espresso vs. drip?
A: I think it makes more sense to simply look at the amount of coffee used to brew, by whatever method. Basically, more ground coffee used means more caffeine. Caffeine washes easily out of the coffee into the cup. Only by some serious underextraction would you get less caffeine. BTW: if you measure coffee by weight, you would get more caffeine with a darker roast if my notion that there is negligible loss of caffeine in roasting since you do lose 18-23% of the weight of moisture and other compounds…

Dave’s comment:


I have no experimental data, BUT I suspect that roast level does affect the amount of caffeine remaining in the bean. My guess is that darker roasted beans have less caffeine than lighter roasts.
Way back in Organic Chemistry lab (about 45 years ago) one of the experiments we did involved purifying caffeine by sublimation. Caffeine passed from the solid state to a gas, then condensed again to give really pretty crystals, leaving impurities behind. As I recall, it didn’t take lots of heat for sublimation to occur.
So I suspect that some caffeine is vaporized during roasting, and longer/darker roasting would likely lead to a greater loss of caffeine.
Westerville, OH

Deward’s Comments:


Regarding roast level and caffeine . . .
You are correct about caffeine being quite stable (in comparison to other
coffee bean components), but it has an appreciable vapor pressure at final
roasting temperatures, so a significant amount can outgas along with CO2 and
volatile oils (water will be mostly already gone late in the roast when this
can occur). In a drum roaster with limited airflow an equilibrium will
establish, with volatilized caffeine re-condensing on the beans for little
net loss, but in an air roaster (or a drum with significant airflow)
vaporized caffeine will be carried out of the roaster (and there have been
many comments here about home roasters getting a “caffeine jangle” from the
There is also variance with extraction method. Although caffeine is very
soluble in water an espresso extraction leaves perhaps 20% of the extracting
water behind in the puck, and with it a similar percentage of the caffeine.
In other brewing methods the retained water is a smaller percentage of the
total extract, which implies less residual caffeine in the grounds.
Both mechanisms above (assuming the typically darker roast for espresso use)
would contribute to the commonly presented measurements which show less
caffeine in espresso than in press, vac or drip extractions (assuming an
equal weight of ground coffee is used per dose (serving).
All else being equal, other variables may apply, and YMMV, of course . . .
< g>

Tom’s response:


I am not sure if adequate temp.s are reached in roasting – here’s a reference:

In an article in the Jan/Feb 2005 Roast Magazine Jim Fadded wrote;
” Popular lore has always been that the darker the roast level, the lower the
caffeine content. This is not really the case, as caffeine changes very
little during the roasting process. Caffeine has a very stable crystalline
structure with a boiling point above 600 degrees Fahrenheit, far above
roasting temperatures, which rarely exceed 470 degrees Fahrenheit. This
means there is very little change to the caffeine during the roasting
process.” (Fadden)

(after this post, we were forwarded contrasting information that caffeine does not have a boiling point and that it actually subliminates at 352 degrees F. You can view this information on page 7 of this document). This is an interesting point because of the new fad of green coffee used in beverages for antioxident value. This would mean there is more caffeine content if the coffee is unroasted.

Q: Does fresh Home Roasted coffee have more caffeine – I am feeling buzzed after changing over to 100% home roasted coffee…


A: There’s no reason that it would. If you drank cheap commercial coffee (R/G -Roasted / Ground brands, like Maxwell House etc ) then you would usually be getting some Robusta in the blend, which actually means higher caffeine contents (Robusta is in the range of 2.2% and most Arabica is in the 1.1% to 1.3% caffeine range). Then again, as a matter of taste cheap coffees tend to be portioned more strictly (very strictly in the case of office coffee portion packs), or people simply brew weaker as a matter of taste. Less ground coffee used to make the cup means less caffeine. It might be that people brew home roasted coffee stronger, or simply enjoy more coffee because it smells and tastes good!

Q: Is there more caffeine in espresso than drip, or French Press?

A: Focus not on the brew method but on the amount of ground coffee used to make what you drink. Caffeine is easily percolated out of the ground coffee into the cup, so the amount of caffeine tends to be a direct result of how much coffee is used to prepare the beverage. Some people use little coffee, make weak dribbly espresso and get little caffeine. So a certain brew method isn’t necessarily stronger than another.