Energy Drink

Frequently Asked Questions about Caffeine

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:

   Afri-Cola 		   100.0  (?)
   Jolt                    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?

  1. 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-dione, 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.

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