Why would anyone question the validity of consuming an invigorating and savory cup of coffee or tea? Especially since nearly every culture in the world does, in fact, consume a caffeinated beverage on a daily or almost daily basis. With all the potential benefits the public is hearing about–increased concentration anti- oxidants, aid for fat metabolism, ergogenic aid for improving cardiovascular sports performance, decreased risk for Alzheimer’s disease–what could possibly be a downside to these beverages (and now foods) containing caffeine? Try a decreased blood flow to the heart.
A 2006 Swiss study published in the Journal of American College of Cardiology showed that caffeine reduced the blood flow to the heart because it partially blocks a substance called adenosine that opens the arteries to increased blood flow. Those in the study who received 200 mg of caffeine (about two cups of coffee) experienced a 22 percent decrease in blood flow to the heart during exercise. However, later that same year, a study in the Journal of Sports Science reported that caffeine had a positive impact on the performance of male distance runners. The same positive results were seen with cyclists in a later study published in the same journal. Other reasons why some might exercise caution about drinking a cup of Joe are the commonly known side effects of caffeine: anxiety, insomnia, tremor and irregular heartbeat, digestive system and irritation of the bladder/prostate. The real issue in my opinion is quantity and noting how your body responds to caffeine.
First, let’s look at quantity. There seems to be some consensus that caffeine taken in amounts greater than 300-500 mg per day may produce some of the negative side effects. That is the equivalent of 3 to 5, eight-ounce cups of drip-brewed coffee. Andrew Weil suggests that individuals get no more than 300 mg per day, partly to avert the negative side effects and also to assure adequate hydration. While you may still get some benefit from the water in your coffee and tea, you have to drink three cups of either to achieve a net two cups of water because of the diuretic effect of caffeine. Note to teens and energy drink or Starbucks junkies. Check out the following website to find out just how much caffeine you are consuming: www.energyfiend.com. It even includes a “death by caffeine” tab that enables you to plug in your favorite caffeinated beverage and your weight to determine how many you could drink before you croak. When I plugged in Starbucks grande coffee, it said I could drink 24.82 servings before dying. Coffee drinkers, beware…you may not want to know this information!
Enough of caffeine’s dark side. Let’s talk about more reasons to keep the java flowing. Some of the most interesting research about caffeine’s positive effects focuses on the possibility of coffee and caffeine keeping your mind sharp and even preventing that dreaded disease of old age, Alzheimer’s. A study published in the august 2007 issue of Neurology found that women who drank three or more cups of coffee daily were 30 percent less likely to have memory problems at age 65 than women who drank a single cup or less. This improvement increased with age, showing that memory decline among women over 80 was about 70 percent less likely among those who consumed three or more cups of coffee compared to those who drank one cup or less. The researchers explain that caffeine acts as a cognitive stimulant and helps reduce a substance called beta amyloid protein in the brain. Alzheimer’s disease (ad) is a neurodegenerative disease
Characterized by severe cognitive impairment and elevated beta amyloid protein. While men didn’t show any neurological benefits from drinking coffee in the study, a 2006 study in the European Journal of Clinical Nutrition showed that male coffee drinkers in the study had lower rates of age-related cognitive decline than men who didn’t drink coffee.
Possibly the strongest evidence in favor of caffeine reducing the risk for comes from a well-controlled longitudinal study involving mice reported in a 2006 issue of Neuroscience. The treated mice were given the human equivalent of 500 mg of caffeine (or five cups of coffee) with the following outcomes: 1) the treated mice showed lower levels of hippocampal beta amyloid protein levels and 2) the treated mice performed much better than controls across multiple cognitive tasks involving learning, working memory and recognition. The authors of the study suggest that if these results could be applied to humans, it would mean that caffeine may delay or reduce the risk of ad. The reason this study is so significant is that the study design was well done. Rather than looking at humans who were drinking varying levels of caffeine in their regular living environments, this study looked at the incidence of cognitive decline in mice, that were genetically prone to develop age-related neurodegenerative disease. Combine that fact with the short life span of mice and researchers can make some conclusions easier than they can with humans.
Take-home message: If you already drink coffee, tea or other caffeinated beverages on a regular basis, and you are not experiencing negative side effects, you probably do not need to stop. In fact, you may use some of the above information as reasons to continue your afternoon latte. The key questions would be: 1) are you healthy? If you are not, and if you have heart dis- ease, you might want to reconsider your caffeine habits and 2) How much caffeine are you consuming? Even if you are not having side effects at this time, if you are consuming more than 300 to 500 mg per day, it would likely benefit you to cut down.
Did You Know?
In the U.S., the average per capita daily intake among adult caffeine consumers is 280 mg (which is equivalent to 17 oz of brewed coffee).
One cup of brewed/drip coffee (6 oz) contains an average of 100 mg of caffeine; a Starbucks Venti (20 oz) contains 415 mg caffeine.
Studies show that 30 mg or less of caffeine can alter mood and affect behavior (according to self reports).