CAFFEINE CONTENTS

CAFFEINE CONTENTS

COFFEE

The amount of caffeine in a cup of coffee can vary greatly, depending on its origin or the composition of the blend, the method of brewing and the strength of the brew. Instant, or soluble, coffee generally contains less caffeine than roast and ground coffee, but may be consumed in greater volume. Robusta coffees have about twice as much caffeine as arabicas. A 'cup' is usually understood to contain 150 ml (5 oz in the United States) but an espresso may be as small as 40 ml.

The U.S. Food and Drug Administration gives the following ranges for caffeine contents:

(mg per 5 oz cup)

	range	average
Roast and ground -drip method -percolator	60-180 40-170	115 80
Instant coffee	30-120	65

Consumer surveys

An interesting survey of caffeine contents in cups of coffee was conducted in Canada (Stavric et al, reference below). Whether the coffee was prepared by housewives at home, for sale in commercial outlets, or by individuals at work, the mean caffeine content was about 80 mg per cup (about 350 mcg per ml). The means for roast and ground coffee, both drip and percolator brewed, were below 85 mg; for instant coffee 71 mg. However, the range of measurements was so wide that, for most individuals, it would be inaccurate to use these figures as a basis for calculating the exact amount of caffeine consumed in a day. The size of the cup/serving varied from 25 ml (Greek coffee) to 330 ml at home and from 130 ml to 280 ml in the out-of-home situation.

DECAFFEINATED COFFEE

Whatever method of decaffeination is used, the decaffeinated green coffee must contain less than 0.1% caffeine (dry weight basis) to comply with EC regulations. This corresponds to about 3 mg caffeine in a cup of decaffeinated coffee.

OTHER BEVERAGES

Tea contains more caffeine than coffee weight for weight, but less weight is used, in general, to brew a cup of tea. In the Canadian study referred to above, both the type of tea used and the steeping time affected the caffeine concentration of samples prepared in the laboratory as follows:

(mean, mcg per ml)

	2 minutes	5 minutes
Tea-bag	238	402
Loose tea	189	295

The average caffeine concentration of samples of tea prepared at home was lower, at 159 mcg per ml, but with a wide variation.

The caffeine content of a cup of tea is usually less than 60 mg, but a strong cup of tea may contain more caffeine than a weak cup of regular coffee.

Cocoa and chocolate drinks contribute 4-5mg caffeine per cup to the diet, dark chocolate and cooking chocolate 20-26mg per ounce (0.7-0.9mg per gram). Many soft drinks, including colas and "peppers", contain caffeine, which as well as being present in cola nuts is often added as a flavour ingredient. A 12-ounce serving may contain 30-60mg caffeine. The major brands of cola on sale in the UK contain about 120mg caffeine per litre.

DRUGS

Caffeine is present in many prescription and non-prescription (over-the-counter) drugs, including some taken for headache, pain relief, appetite control, staying awake, colds, asthma and fluid retention. The caffeine contents of drugs varies from 7mg to 200mg per tablet.

LEVELS OF CAFFEINE CONSUMPTION

Caffeine is generally consumed in amounts less than 300mg per day, roughly equivalent to:

3-4 cups of roast and ground coffee

5 cups of instant coffee

5 cups of tea 

6 servings of some colas or

10 tablets of some painkillers

It has been suggested that the British consume more caffeine on average than Americans, but there are no large scale studies to support the observation. The nine, normal subjects recruited by Dr M.S. Bruce and his colleagues, as habitual caffeine users, for a study in London (reference below) were found to consume on average 428mg caffeine a day, with a range from 230mg to 670mg.

Customary caffeine consumption has been classified as follows:

Low caffeine users: less than 200mg per day

Moderate caffeine users: 200-400mg per day

High caffeine users: more than 400mg per day

References

Bruce M.S. et al. British Journal of Clinical Pharmacology,22: 81-87. 1986.

Lecos C. The latest caffeine scorecard. FDA Consumer, March 1984.

Stavric B. et al. Variability in caffeine consumption from coffee and tea: possible significance for epidemiological studies. Fd Chem Toxic 26(2):111-118. 1988.