Coffee has become one of the most popular beverages in the world. A large amount of coffee research is happening right now. Scientists are looking at everything from the cancer-protective properties of coffee to its effect on bone mass and cholesterol levels to its potentially beneficial plant compounds called phytochemicals.
Here is a snapshot of what we are learning. Please note: all of the research is considered to be “in progress,” meaning relationships are being discovered between coffee drinking and health, but more study is needed to nail down cause and effect. So grab a cup, and stay tuned!
What’s in a Cup of Coffee?
In addition to caffeine, coffee is a good source of riboflavin (vitamin B2) and of several natural antioxidant phytochemicals.
Coffee and Heart Health
Studies looking at large groups of people have found that coffee consumption did not increase the risk of heart disease and may actually be associated with a lower risk of stroke and heart failure, but more study is needed.
Coffee and Diabetes
Several studies show that moderate to high consumption of caffeinated or decaffeinated coffee is associated with low risk of developing type 2 diabetes. Some researchers suggest that coffee components other than caffeine may affect the development of type 2 diabetes, so decaf coffee may work as well as caffeinated.
Coffee and Bone Health
A moderate intake of coffee does not seem to be related to an increase in bone loss. Moderate caffeine consumption—suggested to be about 300 milligrams daily—is about three 8-ounce cups of brewed coffee.
A high intake of caffeine appears to decrease calcium absorption by a small amount, but this effect seems to be blunted by getting enough calcium in your diet. You can do this by adding lots of milk or calcium-fortified beverage to your coffee. The National Osteoporosis Foundation advises that drinking more than three cups of coffee every day may be harmful to bone health.
Coffee and Dehydration
The Institute of Medicine updated the Dietary Reference Intakes for water in 2004. The studies they reviewed showed that caffeinated drinks, such as coffee, tea and soft drinks, may be counted toward the daily fluid total. They found that caffeine-containing beverages appear to contribute to the body’s daily total water intake in amounts similar to that contributed by non-caffeinated beverages. For consistent caffeinated beverage drinkers, coffee drinking has not been shown to have a diuretic effect.
Coffee and Exercise
Research suggests that both caffeine and coffee consumed one hour before exercise can improve short-term and endurance exercise performance.
How Much Coffee Is Too Much?
It depends. Your reaction to the caffeine in coffee depends on many factors, including your normal intake, age and physical condition, and anxiety level. According to the Academy of Nutrition and Dietetics, for most healthy adults, moderate amounts of caffeine — 200 to 300 milligrams a day, or about two to three 8-ounce cups of coffee — pose no physical problems. Clearly, if you’re drinking so much coffee that you are jittery, have trouble sleeping, experience heart palpitations, or feel stressed and uncomfortable, you may be consuming too much.
Other conditions that may cause you to consider lessening your coffee intake are:
Pregnancy: There are mixed research studies on the effects of caffeine during pregnancy, so recommendations vary. The March of Dimes recommends that women who are pregnant or trying to get pregnant consume no more than 200 milligrams of caffeine per day. This is the amount of caffeine in two 8-ounce cups of coffee. The Academy of Nutrition and Dietetics recommends keeping your intake below 300 milligrams per day. For some pregnant women, caffeine may cause nausea and heartburn.
Breastfeeding: The American Academy of Pediatrics says it’s safe for breastfeeding moms to have caffeine. A small amount of caffeine does get into breast milk. Breastfed babies of women who drink more than two to three cups of coffee a day may become irritable or have trouble sleeping.
GERD (gastro-esophageal reflux disease): Coffee may worsen the symptoms.
Watching Sugars and Fat: Black coffee is calorie-free. Added whole milk, whipped cream, chocolate, and sugar or syrup flavorings can turn coffee into more than a meal’s worth of liquid calories.
High Blood Pressure: The Harvard School of Public Health suggests that although coffee is not associated with a serious risk of high blood pressure, people who have a hard time controlling their blood pressure may benefit from switching to decaf coffee if they are caffeine-sensitive.
Heart Health: Unfiltered coffee such as boiled or French press coffee seems to increase total cholesterol, harmful LDL-cholesterol, and triglycerides concentrations, but filtered coffee has little effect on these measures.
If you feel that you are drinking too much coffee, but don’t want to give it up completely, here are some tips for cutting back:
- Split it up. Mix regular with decaffeinated coffee.
- Alternate a cup of decaffeinated coffee with regular coffee.
- Drink a glass of water in alternate sips with coffee.
- Switch to espresso, as it has less caffeine than a cup of coffee! One ounce of espresso (plain or in a coffee-drink) has 40 milligrams of caffeine, about half that of an 8-ounce serving of coffee.
- If you normally drink a lot of coffee, be sure to cut back slowly. For some people, cutting back quickly will cause headaches, lethargy, and drowsiness for a day or two.
For most people without the health concerns noted above, the evidence we have so far suggests that moderate amounts of coffee do not cause serious harmful health effects. The research is still emerging, so stay tuned for updated coffee information as we learn more!
For more information on the latest coffee research: