Millions of people start their day with a cup of coffee to get that caffeine “hit.” But what many don’t know is that this beverage may actually promote longevity and improve health outcomes.
A 2017 umbrella review of existing meta-analyses found that coffee consumption was more often associated with benefit than harm for a number of health outcomes including cancer, type 2 diabetes and cardiovascular disease.
Caffeine
The caffeine in coffee affects adenosine receptors in the brain and has stimulating effects. Some studies have also shown that the polyphenol antioxidants in coffee can help boost memory and prevent cognitive decline. However, it’s important to keep in mind that caffeine can interfere with sleep and increase heart rate. While the evidence suggests a moderate amount of caffeine (about three 8-ounce cups a day providing about 300 mg of caffeine) is safe for most people, too much can cause side effects such as nervousness, stomach upset and high blood pressure.
It’s also worth noting that most of the research on coffee and health has been observational studies, and not experimental. This means that we don’t know for sure whether the benefits of coffee are due to the caffeine or other plant compounds in the drink. It would be great if we could have a randomized controlled trial where people drank coffee for two weeks and were then followed for five years to see whether they had the same results as those in the observational studies.
In the most recent meta-analysis that compared high versus low or any versus no coffee consumption, researchers found that even one extra cup of coffee a day was associated with lower all-cause mortality. They also conducted a non-linear dose-response analysis and found that the highest exposure category, seven cups of coffee per day, was associated with a reduced risk of all-cause mortality by four percent.
The uproar in 2018 over cancer warnings on coffee stemmed from the fact that the chemical acrylamide is formed when coffee beans are roasted, and it can also be found in starchy foods cooked with high heat such as French fries, cookies, crackers and potato chips. The US National Toxicology Program classifies acrylamide as a probable human carcinogen. Several epidemiological studies, as well as the one randomized controlled trial that analyzed coffee and lung cancer, have not shown an association between acrylamide exposure and cancer in humans.
Antioxidants
The antioxidants in coffee are thought to play a role in helping the body prevent and fight against free radical damage. Studies have shown that people who drink more coffee may have a reduced risk of developing type 2 diabetes, liver diseases and Alzheimer’s disease. In the US, beverages are the largest source of dietary antioxidants, with coffee being the top drink. Other sources include tea and fruits.
Despite earlier research that suggested an association between coffee consumption and a range of negative health outcomes, including gynecologic cancers and a higher risk of respiratory disease, more recent studies have found that drinking a moderate amount of coffee is not harmful. However, this is probably in part due to improved adjustment for smoking, which has been shown to be both a confounder and effect modifier in previous meta-analyses.
A 2018 uproar over warning labels placed on coffee stemmed from a chemical called acrylamide, which is formed when starchy foods are cooked at high temperatures. The chemical has been shown to be carcinogenic in lab animals. Although the FDA does not regulate acrylamide levels in food, the World Health Organization classifies it as a probable human carcinogen.
Interestingly, a new umbrella review of existing meta-analyses found that while consuming a cup of coffee per day is associated with some adverse effects (such as increased risk of death from heart disease), there are many health benefits linked to a moderate intake of coffee. These include a decreased risk of death from digestive tract disease in women and men, as well as a decreased risk of mortality from respiratory conditions.
Heart Health
Some people avoid coffee because they worry that it can lead to heart problems, but a large 2017 umbrella review of studies found that moderate coffee consumption is associated with lower risks of heart disease and death than non-drinkers. In fact, drinking two to three cups of coffee per day was linked with a lower risk of heart failure and a lower death rate, even after accounting for many other factors that influence health, such as smoking, alcohol intake, BMI, diabetes, obstructive sleep apnea, and diet.
This was true whether the study participants were men or women and regardless of their age, sex, family history of heart disease, or other medical conditions, such as high cholesterol or depression. The researchers also looked at the results of more than 200 other studies and found that coffee was beneficially associated with a range of health outcomes, including mortality from digestive tract disease in men and women; circulatory and cerebrovascular diseases in both genders; and cancers.
Moreover, in a second study from the UK Biobank database that included 34,279 people with some form of cardiovascular disease at baseline, Kistler and colleagues found that consuming two to three cups of coffee per day was associated with a lower death rate than not drinking coffee. This was independent of the amount of other beverages a person drank and was true even for people who had been diagnosed with arrhythmias like atrial fibrillation or flutter at baseline. In addition, they found that consuming any level of coffee did not seem to increase a person’s risk of developing these rhythm issues in the future. This finding is particularly important because these types of arrhythmias are what clinicians often worry about in patients with heart disease.
Bone Health
Coffee is widely known for being a great source of energy and can help improve moods. However, less is known about the effects of daily coffee consumption on bone health. Osteoporosis is a disease that can lead to decreased bone density, increased risk of bone fractures, and a reduced quality of life.
While some studies have linked osteoporosis and coffee drinking, other studies have found no association. This inconsistency led researchers to identify and evaluate the role of coffee-associated metabolites on bone mineral density (BMD). The authors found that BMD was significantly higher in regular coffee drinkers than in non-coffee consumers. The higher BMD was attributed to the high concentration of coffee-associated metabolites in serum samples.
The study was conducted among 6152 adults who had completed questionnaires on lifestyle factors, including coffee consumption, in 2006 and 2014. T-scores, which are used to measure BMD, were correlated with both dietary and non-dietary variables. The results showed that the higher T-scores were associated with higher BMD, and a lower risk of osteoporosis in both men and premenopausal women.
The authors of the study emphasized that their findings were observational, and thus the association was not causal. They also pointed out that some of the factors that were associated with bone loss were modifiable, including low calcium intake, and suggested that the positive associations observed with coffee consumption were due to a combination of caffeine and other chemicals in the beverage. However, a cross sectional study showed a significant inverse association between tea consumption and hip bone density, and this may have been because it is not as highly caffeinated as coffee.
Mental Health
A few cups of coffee each day can help you focus, but beware that caffeine can also increase your anxiety and cause mood fluctuations. It’s important to monitor your caffeine intake, pick a different coffee or brew in a different way, and to avoid it at certain times of the day, particularly right before bedtime.
Caffeine is a central nervous system stimulant that’s the most commonly used drug in the world. Besides coffee, people also consume it in the form of tea, soda, chocolate and energy drinks. People who habitually drink caffeine, whether it’s coffee or another source, can develop a physical and emotional dependence on it.
In a recent study, researchers looked at data from 146,566 participants from the UK Biobank. They asked participants to report their coffee consumption, and compared this to information from their electronic medical records. Initially, positive relationships were observed between total weekly caffeine intake and stress, depression and anxiety. However, after adjusting for dietary, demographic and lifestyle covariates, the effect on stress and anxiety disappeared. However, consuming >1000 mg/w was still associated with high anxiety and with an increased risk of depression compared to non-consumption.
The results indicate that high levels of caffeine are associated with symptoms of mental illness in college students. However, the research was not designed to prove whether the association is causal. This requires further prospective and experimental studies aimed at exploring the role of caffeine intake in the development of psychiatric disorders.
The bottom line is that, for most healthy adults, moderate coffee consumption seems to be OK. It is important to note that coffee contains other chemicals besides caffeine, and these are important to consider when evaluating the health impact of your beverage.
