ALBUQUERQUE, N.M. — Ninety percent of Americans consume caffeine daily, and the average daily intake is about 280-300 mg of caffeine (2-4 cups). From 20 percent to 30 percent of us consume more than a whopping 600 mg per day.
Older adults obtain their caffeine mostly from coffee, whereas children, teens, young adults, athletes and military personnel have a higher proportion of their caffeine coming from soda or energy drinks.
Starbucks Coffee is high octane fuel: A 20-ounce Venti has 415 mg of caffeine, a 16-ounce Grande has 330 mg, and a 2-ounce Starbucks Espresso doppio has 150 mg of caffeine.
Meanwhile, a Dunkin’ Donuts medium 14-ounce coffee has 178 mg of caffeine, a 16-ounce Einstein Bros. Coffee contains 206 mg caffeine, a 16.8-ounce Panera coffee has 189 mg, and a McDonald’s large 16-ounce coffee has 133 mg.
Even decaf coffee contains some caffeine (Dunkin’ Donuts, Panera or Starbucks Decaf Coffee 16-ounce servings have 15-25 mg).
Black tea generally contains more caffeine compared to other teas, between 40-120 mg caffeine per 8-ounce serving, while green tea contains 30-50 mg.
And the amount of caffeine in some of our beverages may surprise us – for example A&W Cream Soda (currently in my house!) contains 29 mg caffeine per can (dpsgproductfacts.com) and Sunkist Orange soda (a mistake in my house long ago) contains 41 mg per can (sunkistsoda.com/product.php).
I was also surprised to discover that dark roast coffee has less caffeine than light roast.
Energy drinks have been linked to the deaths of several teens and young adults in recent years. In one highly publicized case, a 14-year-old girl died after consuming two 24-ounce Monster Energy drinks in 24 hours (480 mg caffeine).
Energy drinks should not be confused with sports drinks, which contain sugar and electrolytes and can play an important role in maintaining hydration in extreme heat or long bouts of exercise.
In contrast, energy drinks contain high amounts of caffeine (much higher than soda, where the caffeine content is regulated by the FDA) and sometimes additional ingredients (such as yerba mate, taurine, carnitine, kola nut or guarana) that may exacerbate the stimulating effects of caffeine.
For example, a 16-ounce Monster Energy contains 160 mg caffeine and a 1.9-ounce 5-Hour Energy has 208 mg caffeine.
Poison Control reports numerous cases of caffeine overdose each year (almost half in children younger than 6 years old) but few fatalities. In rare cases where teens have died after consuming energy drinks, the teens appear to have had underlying heart or other medical conditions, which may have made them more susceptible to caffeine intakes well below the level that would normally be fatal.
So is caffeine truly dangerous? Why is it so hard to kick a caffeine habit? Is a moderate intake of caffeine or coffee good or bad for us? Today’s article will review caffeine’s pros and cons.
How caffeine works
Caffeine (trimethylxanthine) is a naturally occurring central nervous system stimulant that can be found in coffee, tea, soda, energy drinks, cocoa, other food items and in medications.
Caffeine is a drug that is rapidly absorbed from the stomach and small intestines and reaches peak levels in 30-60 minutes after ingestion. Caffeine is metabolized in the liver; its half-life is 3-10 hours (ncbi.nlm.nih.gov/pmc/articles/PMC4163805/).
Caffeine passes through the blood-brain barrier and binds to adenosine receptors in the brain, thereby blocking adenosine’s actions. This results in an increase in neural activity, vasoconstriction of blood vessels in the brain and a surge of adrenaline throughout the body, which helps us feel energized.
Caffeine also increases the levels of the neurotransmitter dopamine, which activates the pleasure center in the brain in a similar but weaker manner to that of heroin and cocaine.
Moderate consumption (20-200 mg per day) results in enhanced mood, increased energy, alertness and concentration. However, these effects diminish as the consumer becomes habituated.
Fortunately for us caffeine aficionados, the daily consumption of up to six cups (but not 20-ounce Ventis), about 600 mg, does not appear to be harmful for most people. The Harvard Nurse’s Health Study and the Health Professionals Follow-Up Study followed 130,000 middle-aged adults for 18-24 years and found no serious adverse effects even with six cups per day.
Regular coffee or decaffeinated coffee consumption is associated with a lower risk of Type 2 diabetes. Coffee consumption has also been found to reduce the risk of liver cancer, liver disease, Parkinson’s disease and Alzheimer’s disease.
However, some research has shown that caffeine can raise blood sugar in patients with diabetes. Individuals who have trouble controlling their blood sugar levels may want to try switching to decaffeinated coffee.
It’s also worth noting that coffee contains numerous chemicals besides caffeine, which may explain some of the mixed findings. For example, caffeine in coffee results in less of an increase in blood pressure than the same amount of caffeine in other beverages. Also, while caffeine enhances exercise performance in unhabituated individuals (non-caffeine users), coffee provides less benefit than other caffeine sources.
A major concern is caffeine intake during pregnancy. Caffeine is much more slowly metabolized by the liver during pregnancy. High intakes of caffeine have been associated with an increased risk of miscarriage.
Most health organizations, including the March of Dimes, have suggested that it is safe for pregnant women to consume caffeine in moderation (below 200 mg per day); however, this is currently under debate.
The Dietary Guidelines Advisory Committee has been reviewing the research on caffeine for the next edition of the U.S. Dietary Guidelines, due out in 2015. The Center for Science in the Public Interest has argued that this level is too high and increases the risks of spontaneous abortion, stillbirth, preterm delivery and childhood leukemia. Read comments at health.gov/dietaryguidelines/dga2015/comments/readcomments.aspx.
Unfiltered coffee (boiled coffee consumed in Scandinavia, French press and Turkish coffee) contains chemicals (diterpenes, such as cafestol and kahweol) that can raise bad (LDL) cholesterol. Instant coffee is low in cafestol, whereas espresso has intermediate levels.
Paper filters appear to be the most effective type of filter for reducing the amount of these chemicals in coffee. (So much for my gold filters!)
These findings help explain conflicting data: Some studies have found that European coffee raises cholesterol, but others found no relationship between coffee intake and cholesterol levels.
As little as one small cup of coffee daily (100 mg caffeine) can result in dependence and in withdrawal within 24 hours after stopping. Withdrawal can last two to nine days and severity increases with the amount habitually consumed. Symptoms include fatigue and severe headache, which explains why so many of us remain addicted to caffeine.
Too much caffeine (300-600 mg/day) can result in side effects such as insomnia, anxiety, feeling jittery or an upset stomach. Higher doses (more than 600 mg per day) can cause seizures and cardiovascular events.
However, some individuals who are sensitive to caffeine may suffer side effects with as little as 100 mg. Children and teenagers may be more susceptible to caffeine toxicity than adults and should avoid energy drinks.
Those with high blood pressure may want to avoid caffeine to see if that helps lower their blood pressure. Individuals with heart conditions should avoid it.
The bottom line is that caffeine (in semi-moderation) is safe and perhaps even good for most of us. I think I’ll go get another cup of coffee …
Sharon Himmelstein, Ph.D., M.N.S., R.D.N, is a member of the Academy of Nutrition and Dietetics (eatright.org) and the New Mexico Academy of Nutrition and Dietetics (eatright-nm.org). She teaches nutrition at Central New Mexico Community College (CNM) in Albuquerque.