Health Alert: How Much Caffeine Is Too Much


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If you are sipping a double latte or enjoying a cup of green tea while you’re reading this magazine, you’re not alone. An estimated 80 percent of Americans regularly consume caffeinated beverages. We brew more than 45 million pounds of coffee beans every year, to say nothing of the green and black tea, chocolate, yerba maté and all of the soda pops, herbal products and over-the-counter and prescription drugs that contain this fascinating chemical.

Consumers of herbs need to know about caffeine, its effects on the body and the plants that contain it. Caffeine-containing herbs often show up in products marketed for weight loss and energy enhancement. Because the U.S. Food and Drug Administration does not require labeling of caffeine content in products, you may not realize you’re using it. And even if you know how many espressos you need to get through your day, do you know all the ways your favorite drink might be affecting your health?

Caffeine-containing Plants

Coffee (Coffea arabica, C. canephora). The fruits of this evergreen shrub are fermented, washed, hulled and roasted prior to use in beverages. Coffee beans contain hundreds of other substances in addition to caffeine, including volatile oils and aromatic compounds that contribute to its fragrance and appealing taste. The amount of caffeine in a cup depends on the species used, the processing techniques and how the coffee is prepared. Here are some estimates for a 7.5-ounce cup:

Drip coffee: 115 to 175 mg caffeine
Brewed coffee: 80 to 135 mg caffeine
Instant coffee: 65 to 100 mg caffeine
Decaffeinated coffee: 3 to 4 mg caffeine

Tea (Camellia sinensis). This plant has been used as a beverage for as many as 500,000 years, according to archeological data. Green tea is made from unfermented young shoots, which are pan fried or steamed to stop the fermentation process. Green tea contains approximately 25 mg of caffeine per cup. Black tea is created by fermentation and oxidation of the rolled leaf. Brewed for three minutes, black tea contains 30 to 45 mg of caffeine per cup; brewed for five minutes, it contains 60 to 90 mg per cup.

In addition to caffeine and related substances, tea contains many other chemicals, some of which are highly beneficial to health and are the subject of much current research. These include catechins, proanthocyanidins, flavonols and theanine.

Yerba maté (Ilex paraguariensis and other species). Maté is a traditional beverage in South America and is gaining popularity in the United States and Europe. It contains caffeine in widely varying amounts, depending upon the species used, growing conditions and how long the herb is steeped for. Maté also contains antioxidants, phenolic substances, saponins, flavonoids and acids similar to those found in coffee. This herb is high in minerals, including iron, potassium, magnesium and manganese. Although some of these non-caffeine constituents may be beneficial, studies from South America suggest that high doses of the beverage may contribute to the risk of certain cancers, especially when consumed very hot and when combined with smoking, alcohol and red meat consumption.

Kola nut (Cola nitida). Kola is a North African native, grown throughout the tropics; the ripe nuts of the plant are used, and constituents in addition to caffeine include theobromine, tannins, phenolics and anthocyanins.

Guarana (Paullinia cupana). Another South American herb, this one contains more caffeine by weight than coffee beans.

Chocolate (Theobroma cacao). The Latin name of this plant means “food of the gods,” from the name the ancient Aztecs gave it. Those of us who love chocolate can only sigh in agreement. Chocolate’s caffeine content is small (one ounce of bittersweet chocolate contains 5 to 10 mg of caffeine; milk chocolate has about 5 mg per ounce). Now for the really good news: Chocolate might be good for you. It is antioxidant-rich, primarily in the form of polyphenols. Forty grams of milk chocolate contain about 300 mg of antioxidants, the equivalent of five servings of fruits and vegetables. Dark chocolate contains nearly twice that much.

But, there’s a downside: Chocolate may trigger migraines in susceptible individuals, and it increases gastroesophageal reflux (heartburn). As we all know, it’s fattening, since we tend to like it best with sugar and fats added — such as in brownies.

Biochemistry, Physiology and Potential Health Effects of Caffeine

Caffeine belongs to a group of chemicals called methylxanthines. Other chemicals in this group include theophylline and theobromine. Most caffeine-containing herbs include these substances, which may be converted to caffeine in the body. Caffeine’s chemical name is 1,3,7-trimethylxanthine. This doesn’t sound like something we’d want for breakfast. So why do we like it so much?

The story of caffeine’s effects in the body is a complex one. It starts with adenosine, a behind-the-scenes workhorse hormone that facilitates and modulates the actions of other hormones and body chemicals. Some effects of adenosine include vasodilation, inhibition of adrenal hormone production, decrease in platelet aggregation, decrease in lipolysis and increase in relaxing neurochemicals. Caffeine binds on the same receptor sites as adenosine and blocks or prevents its action — therefore, caffeine has the opposite effects of adenosine. Believe it or not, that’s why your big cup of French roast helps you wake up in the morning.

Caffeine is highly absorbed into the bloodstream and penetrates all biological membranes, easily crossing the blood-brain barrier, across the placenta and into breast milk. Caffeine is metabolized by the liver. Its half-life (the time it takes for half of your morning maté to be eliminated from your body) is highly individualized and ranges from two to 12 hours.

Caffeine in the Body

Caffeine affects our bodies in many ways. Following is an explanation of what happens in different areas of the body when we consume caffeine.

Central nervous system: Caffeine is a brain stimulant. It reduces the calming neurotransmitter GABA and increases the excitatory norepinephrine. This is how caffeine gives us that energy jolt when we need it. Beware, though: Excessive and chronic use may actually reduce energy. Also on the dark side, caffeine can contribute to insomnia, anxiety disorder, panic attacks and depression. It causes the blood vessels in the brain to constrict and reduces levels of melatonin, a brain hormone involved in sleep cycles and immune and endocrine function.

Cardiovascular system: Caffeine can cause increased heart rate and blood pressure, constriction of blood vessels, increased tendency to blood clotting, depletion of calcium and magnesium (minerals essential to cardiovascular health) and an increase in homocysteine levels. Homocysteine is a chemical implicated in heart disease and stroke.

Respiratory system: Caffeine increases respiratory rate (it is sometimes used to stimulate respiration in premature babies) and dilates the bronchioles (or breathing tubes). An old-fashioned drug for asthma, theophylline, a close chemical relative of caffeine, works in a similar fashion. While caffeine may ease an asthma attack, better herbs are available.

Adrenal glands: A 250-mg dose of caffeine has been shown to increase adrenal output of epinephrine by more than 200 percent. Norepinephrine is also increased. These are the “fight or flight” hormones secreted during periods of acute stress. Cortisol, the “chronic stress” hormone, is increased with regular use of caffeine. In one study, individuals who drank 300 mg of caffeine per day had elevated cortisol levels for 18 out of 24 hours. Elevated cortisol levels suppress the immune system, affect mood, may cause fatigue and interfere with sleep. High cortisol levels may suppress DHEA, a precursor hormone. Low levels of DHEA are associated with fatigue, aging and a variety of medical conditions. Overall, the adrenal effects of high caffeine consumption mimic those of acute and chronic stress.

Insulin and blood sugar: In some people, caffeine may increase blood sugar and exacerbate insulin resistance, a condition implicated in several chronic degenerative diseases.

Female hormones: High caffeine consumption is associated with premenstrual syndrome, fibrocystic breast disease and increased estrogen levels. In menopausal women, caffeine may be a trigger for hot flashes.

Headaches: Caffeine contributes to tension headaches by causing muscle spasm and vasoconstriction in scalp muscles. In an acute migraine headache, caffeine is often used as a treatment. It works by constricting the dilated blood vessels that cause migraine. Regular caffeine use, however, can trigger migraines; during caffeine withdrawal, when blood levels drop below a certain level, rebound vasodilation can occur. Individuals with migraine should use caffeine only when an acute migraine occurs and not on a daily basis.

Gastrointestinal tract: Caffeine increases stomach acid and esophageal sphincter tone, thus potentially contributing to gastritis, ulcers and reflux. In the large intestine, caffeine has a laxative effect. This is a popular “medicinal” use of caffeine. It may slow emptying of the stomach and increase gallbladder contractions, thus causing symptoms in gallbladder disease.

Kidneys and bladder: Caffeine is a fairly strong diuretic, increasing urine output two- to fourfold. This may lead to frequent urination and even dehydration. For some people, caffeine is a bladder irritant, exacerbating conditions such as interstitial cystitis.

Musculoskeletal system: Muscle tension is increased with caffeine consumption, thus contributing to muscle pain and spasm associated with acute or chronic injury. Caffeine is also a known risk factor for osteoporosis (decreased mineralization of the bones).

Cancer: Many studies have evaluated cancer risks associated with caffeine. Results are controversial and inconsistent. Cancers of the pancreas, bladder, kidney, ovary, breast and digestive tract have been shown to be increased in some but not all studies.

Weight loss: Caffeine-containing herbs are frequently used in herbal weight-loss products. The presumed mechanism of action is thermogenesis, or an increase in metabolic rate and lipolysis (breakdown of fats). Caffeine also delays gastric emptying, leading to feelings of satiety with less food. Some studies do show weight loss with caffeine consumption. However, the benefit is debatable, and the possibility of unwanted side effects such as rapid heart rate, anxiety, insomnia and increased feelings of stress should be considered, especially if the herb ephedra (Ephedra sinica) is included in the product.

Caffeine and Health Problems

Caffeine Addiction and Withdrawal

Addiction to caffeine appears to be common. In physiological terms, addiction means that tolerance (a larger dose is required over time to achieve the same effect) is developed and withdrawal symptoms occur. Caffeine withdrawal symptoms include headache, depression, irritability, fatigue, decreased mental alertness or disorientation, nausea and vomiting, muscle tension and obsessive thinking about and desire for caffeine.

Individual tendencies to addiction vary widely. Some people seem to be able to drink a cup of coffee every now and then with no trouble, whereas others are hooked from their first sip. How do you know if you are addicted? Generally, the more you consume, the more likely addiction is to occur. At 100 mg per day or less, addiction is unlikely; 300 to 600 mg per day, addiction is likely; 600 to 900 mg per day, very likely; and at 900 mg per day or more, addiction is almost certain. If you experience withdrawal symptoms when you reduce your daily amount or stop altogether, you are addicted. If you know all those cappuccinos aren’t good for you and you still can’t quit, consider yourself an addict.

First, reduce caffeine consumption gradually. A “cold turkey” approach is more likely to lead to failure. Estimate as honestly as possible your total daily amount, and then come up with a planned reduction schedule. Decreasing by ¼ to ½ cup every one to two weeks will usually prevent withdrawal symptoms. For example, if you’re currently drinking 4 cups of coffee per day, your first reduction would be to 3¾ or 3½ cups per day. To improve accuracy during your withdrawal schedule, use the same size cup and measure the amount of ground beans or dried herb you use per cup.

Try using gently and safely stimulating herbal teas, such as peppermint (Mentha ¥piperita), ginger (Zingiber officinale) and licorice (Glycyrrhiza glabra) for your morning or mid-afternoon brew instead.

Address any underlying nutritional deficiencies you may have with a good multivitamin. Your adrenals, nervous system and other organ systems will benefit from safe, nourishing and balancing herbs. For example, adaptogenic herbs such as eleuthero (Eleutherococcus senticosus) and schisandra (Schisandra chinensis) can help bring your adrenal glands back into balance, and a soothing cup of chamomile (Matricaria recutita) and oat seed (Avena sativa) tea will ease your frazzled nerves.

Regular exercise is a great energizer and stress reducer. Walk around the block instead of to the coffee shop at break time.

As you confront caffeine addiction, take the time to look at the reasons for stress, fatigue and overwork that led you down the road to caffeine dependence in the first place. How can you make your life calmer, more peaceful and less driven by appointments and deadlines?

Caffeine as an Herbal Medicine

Is there ever a good time to use caffeine? Since nature has blessed us with many caffeinated plants, we should learn to use them wisely. The most obvious use would be as an occasional, brief stimulant — for example if you are feeling sleepy on a long road trip or need to stay up late to meet an important deadline. And I do mean occasional. If you succumb regularly, the beneficial effects are decreased and addiction and unwanted side effects are a risk. Caffeine is also a reasonable treatment for acute vascular headache, such as migraine, but never for daily use. I would also consider caffeine to treat an acute asthma attack, if nothing else was available.

Because of their potential preventive health benefits and low caffeine content, green or black tea and small amounts of dark chocolate are probably the best choices for regular use. How’s that for permission to indulge?

Lois Johnson, M.D., has a busy primary-care holistic practice in Santa Rosa, California.


If you decide coffee isn’t for you, several companies offer great herbal teas, as well as tasty, healthful coffee substitutes, which are usually some combination of grain and chicory.

Coffee Substitutes

Rapunzel Pure Organics
2424 SR-203
Valatie, NY 12184
(800) 207-2814

Raja’s Cup
Maharishi Ayurveda
1068 Elkton Dr.
Colorado Springs, CO 80907
(800) 345-8332

12215 Ventura Blvd. Ste. 208
Studio City, CA 91604
(866) 769-2333

PO Box 42259
Santa Barbara, CA 93140
(800) 498-3434 

Herbal Teas

Celestial Seasonings
4600 Sleepytime Dr.
Boulder, CO 80301
(800) 351-8175

Native American Herbal
PO Box 1266
Aberdeen, SD 57402
(605) 226-2006

Republic of Tea
8 Digital Dr. Ste. 100
Novato, CA 94949
(800) 298-4832

Traditional Medicinals
4515 Ross Rd.
Sebastopol, CA 95472
(800) 543-4372