Which Plants Contain Caffeine?

Gayle Nicholas Scott, PharmD

Disclosures

March 13, 2013

Question

I've heard that some energy drinks and weight loss products contain unlabeled caffeine. What plants contain caffeine?

Response from Gayle Nicholas Scott, PharmD
Assistant Professor, Eastern Virginia Medical School, Norfolk, Virginia; Clinical Pharmacist, Chesapeake Regional Medical Center, Chesapeake, Virginia

Caffeine holds the unusual distinction of being regulated as a food additive, drug, and dietary supplement. Caffeine use in cola-type beverages is allowed by the US Food and Drug Administration as a flavoring agent in a 0.02% concentration, which is equivalent to 20 mg per 100-mL beverage, or 71 mg per 355-mL (12-oz) beverage.[1] Colas are labeled with caffeine content. Caffeine is also an ingredient in both prescription (eg, Fioricet®, Cafergot®) and nonprescription (eg, NoDoz®, Excedrin® Extra Strength) medicines. Energy drinks (eg, Red Bull® Energy Drink, Monster Energy Drink®) are regulated as dietary supplements, which exempts manufacturers from mandatory disclosure of the caffeine content on the product label. Unlike soft drinks, the caffeine content of dietary supplements and energy drinks marketed as dietary supplements is not subject to a maximum dose limit. Additionally, energy drinks as well as dietary supplements for weight loss or body building often contain herbs with substantial caffeine content, a fact that may not be readily apparent to the consumer.

The ubiquitous caffeine sources, coffee and tea, are among the more than 60 caffeine-containing plant species. (Of note, caffeine acts as a pesticide, protecting the plant from predators.) Other less well-known plants may not be recognized as caffeine sources. The following is a description of some caffeine-containing herbs found in energy drinks and other products regulated as dietary supplements.

Guaraná

Guaraná (Paullinia cupana), also known as Brazilian cocoa, grows as a shrub or woody vine in Brazil. Guaraná seeds have the highest caffeine content (2.5%-5%) of any known plant and are used as a soft drink flavoring in Brazil. Guaraná appears to have stimulant and ergogenic properties, but whether guaraná has caffeine-independent pharmacologic effects is not clear.[2,3]

Yerba Maté

Yerba maté (Ilex paraguariensis), also known as maté, terere, and chimarrão, is native to South America. The leaves and branches are prepared as a tea, which contains about 70 mg/100 mL of caffeine (compared with coffee at 57 mg/100 mL). Like guaraná, caffeine is thought to be responsible for the pharmacologic effect of yerba maté.[4] Chronic ingestion of yerba maté has been associated with esophageal and other cancers.[5,6,7]

Cola Nut

Cola nut (Cola acuminata), also known as kola nut, bissy nut, and guru nut, is cultivated in Africa and Central and South America. Cola nut, which is about the size of a chestnut, is prepared as an extract containing about 1.5%-2.5% caffeine for flavoring foods and cola beverages. The caffeine content is likely responsible for the pharmacologic effects of cola nut.[8]

Cacao

Cacao (Theobroma cacao), also known as cocoa and chocolate, contains various smaller amounts of caffeine.[9] For example, a 1.55-oz Hershey's® milk chocolate bar contains about 9 mg of caffeine per serving.[10] Compared with coffee, tea, and the plants above, cacao is a minor contributor to total caffeine consumption.

The average US adult consumes about 168 mg/day of caffeine, mostly from coffee, tea, and soft drinks.[11] Consumers of energy drinks may ingest much more caffeine. For example, 1 liquid oz of the energy shot 51FIFTY Energy Juice Regular Formula contains 500 mg of caffeine.[12] The caffeine content may or may not appear on the label of energy drinks and other products such as weight-loss or body-building supplements. Additionally, products regulated as dietary supplements may label a group of ingredients such as guaraná as a "proprietary blend," for which the total weight of several ingredients is listed instead of the amount of each ingredient, further obscuring caffeine content.

Consumption of greater than 250-300 mg of caffeine per day can cause adverse effects such as sleep disturbances and tachycardia.[13] Doses less than 500 mg per day are generally considered safe for people without medical conditions such as heart or liver disease.[14] Genetic polymorphisms and drug interactions may also affect individual response to caffeine, which is metabolized by CYP1A2.[15] Pregnant women should avoid high amounts of caffeine, which has been associated with small-for-gestational-age infants, late miscarriages, and stillbirths.[16]

Advise patients, particularly consumers of energy drinks and dietary supplements that may contain caffeine, to consider monitoring caffeine intake. Caffeine content may not appear on the product label but may be obtainable by searching product Websites. Educate patients about occult sources of caffeine such as guaraná and maté.

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