I wake up most morning feeling exhausted. I can blame that on sleeping late at night trying to do one thing or the other. I usually feel reluctant to leave my bed and just want to sleep all day. But not when I can get a cup of coffee. I love everything about it. The taste, the colours, and even the aroma. The enticing aroma of the coffee makes me want to drink it every day. My brother once told me to stop taking coffee that it is bad for my health. When I refused to stop, he reported me to my mum because they both believed it was bad. I'm not sure I can stop taking it so I have to make some findings myself. Is coffee good for my health or is it killing me?
What is coffee?
Impact of coffee on human healthCoffee is one of the most consumed beverages in the world. According to this source, the average consumption rate of coffee worldwide is 1.6 cups per day. While the average consumption rate of coffee in the United States is 3.2 cups per day. With this high consumption rate, it is important to know the relationship between the consumption of coffee and the subsequent health impact it may have.
This article is a literature review of researches that have been conducted on this topic. I got a lot of information which I think may be too much for a single post if I don't want to scare my readers away. This post will be limited to the relationships between drinking coffee and cardiovascular disease and subsequently, I will be reviewing other impacts that drinking coffee has on our health.
Drinking Coffee and cardiovascular disease
According to European Cardiovascular Disease Statistics 2017, CVD accounts for 45% of all deaths in Europe and 37% of all deaths in the European Union. WHO also reported that more people die of CVDs every year than from any other cause. While the risk factors of CVD include consumption of unhealthy diet, lack of exercise and physical activity, and also excessive use of tobacco and alcohol.
Coffee contains Caffeine which is responsible for the stimulating effect it has. It also contains some other components like the phenolic compound, potassium and magnesium, niacin and its precursor trigonelline, and lignans. This may be the reason why there have been several kinds of research to know if there is any risk of taking it. Now that you know what CVD is, let's talk about the effect that drinking coffee has with CVDs.
There are a number of researches that have been conducted to find out whether there are any relationships between consuming coffee and CVDs. However, there are variations in the results of such researches. While many reported that there is no relationship between consumption of coffee and the risk of CVD, some think otherwise. Some think there are good relationships (like protection against CVDs) and not-too-good relationships (increasing the risk of CVD).
What is Meta-analysis?
Meta analysis is simply a statistical analysis which involves a thorough literature search of individual researches and combine their various results to arrive at a conclusion.
Example of a good relationship...
Long-Term Coffee Consumption and Risk of Cardiovascular Disease. A Systematic Review and a Dose-Response Meta-Analysis of Prospective Cohort Studies
This meta-analysis was conducted by Ming et al. They searched PubMed and EMBASE databases for studies conducted between January 1966 - March 2013 that evaluated relationship between coffee and risk of CVD. They filtered the studies they found based on some criteria such as the design of the study. All the studies must include exposure to coffee of all type and the outcome was the risk of CVD, eg., heart attack. Those that were filtered out include estimates presented without standard errors. 36 studies were selected and the total study participants averaged ≈1283685 with 47779 CVD cases. They reported a nonlinear(U-shaped) relationship between coffee consumption and risk of CVDs. That is, drinking coffee does not increase the risk of CVD.
The analysis defined moderate consumption to be 3 to 5 cups/day and this level was associated with lower CVD risk. The lowest risk of CVD, however, was found with those who take approximately 3 cups/day. Also, heavy consumption of 6 cups and above per day was not associated with risk of CVD.
Example of a not-too-good relationship...
This study was conducted by Liu et al to find out the association between coffee consumption and mortality from all causes and from CVD in the Aerobics Center Longitudinal Study (ACLS) cohort. The duration of the study was between February 1971, and December 2002. 44963 people between the ages of 20 - 87 years participated in the study and 43,727 people were examined with 699,632 person-years of follow up. Some were excluded from the study because of the history of some CVDs, cancer, underweight, abnormal heart activities, etc.
(Person-years is useful in finding out incidence rate by expressing the total number of cases over the person-years of observation. For instance, if 100 participants in a study were followed up for a year, they make 100 person-years. If the same number were followed up for two years, it will become 200 person-years.)
The study had a median follow up of 17 years. 2512 people died and they were 2198 men (87.5%) and 317 women (12.5%). A total of 804 death was caused by CVD which represents 32% of the total death.
They reported that men and women who consumed a higher amount of coffee were likely to smoke and had low cardiorespiratory fitness.
The result of the study showed that young men and women lesser than 55 years who drank more than 28 cups of coffee per week or more than 4 cups of coffee per day are at higher risk of dying. Although, there was no association between mortality and consumption of coffee for both men and women above the age of 55 years.
They, therefore, suggested that younger people should not be heavy drinkers of coffee.
Some author think Liu might be wrong.
In response to the above study by Liu et al, James J. DiNicolantonio made some observation in the study. He thinks there are several reasons to believes that the association is not causal. That is, the effect which is mortality may not have been caused by the exposure, which is the consumption of coffee. The adjusted models did not include some important confounders (some independent factors that can affect the result. eg., smoking may cause mortality and heavy coffee drinkers tend to smoke). For instance, some people might consume a higher quantity of coffee because of some medical issue related to fatigue. The benefit may be the stimulation for alertness. These people have a higher risk of early mortality. Also, drinking coffee may be associated with other unhealthy food intakes. Like adding extra sugar or with a serving of donuts, or other sugary snacks.
And he has the following to say "It would be a shame to brew up concern about this beloved beverage owing to analyses flawed in part by confounding from unmeasured disease states and unaddressed dietary intake."
In this article, Alan R. Katz wrote that he disagree with the conclusion of the study's findings.
He acknowledged the author for an excellent job but he also pointed out a limitation of the study. There might still be the residual confounding effect of smoking which may be the reason why mortality risk is linked with coffee.
Alan said moderation in all things has always been a good advice but he thinks Liu's conclusion on coffee consumption is not well supported by the data he presented.
A little note from me...
In my findings, I've found out that there is no major risk associated with drinking coffee and CVDs but I found out that the major causes of CVDs stem from unhealthy behaviors. Risk factors for CVD include consumption of unhealthy diet, lack of exercise and physical activity, and also excessive use of tobacco and alcohol.
CVD can be avoided by maintaining a healthy behavior. Eat fruits and vegetables as much as you can. Cut out sugar if you can. Workout because it's good for your health and even your look. You may want to have some fun but don't ever forget to stop taking too much of alcohol.
This is purely a literature review and not my opinion if you have any contributions difficult from mine I'll like to hear. Is coffee good for your health or bad? What are your reactions to drinking coffee?