Introduction
This is a review of a study out of the American College of Cardiology that looked at three separate studies on the effect that coffee has on heart disease.
Heart disease and Death
Drinking coffee, particularly two to three cups a day, is not only associated with a lower risk of heart disease and dangerous heart rhythms but also with actually living longer, this is according to studies being presented at the American College of Cardiology's 71st Annual Scientific Session.
These trends held true for both people with and without cardiovascular disease. Researchers said the analyses - the largest to look at coffee's potential role in heart disease and death - provided reassurance that coffee isn't tied to new or worsening heart disease but may actually be heart protective.
Statement
Professor Peter M. Kistler, MD, Head of Arrhythmia Research at the Alfred Hospital and Baker Heart Institute in Melbourne, Australia said, "Because coffee can quicken heart rate, some people worry that drinking it could trigger or worsen certain heart issues. This is where general medical advice to stop drinking coffee may come from.
But our data suggest that daily coffee intake shouldn't be discouraged, but rather included as a part of a healthy diet for people with and without heart disease.
"We found coffee drinking had either a neutral effect - meaning that it did no harm - or was associated with benefits to heart health."
The Study
Kistler and his team used data from the UK BioBank Study, a large-scale prospective database with health information from over half a million people who have been followed for at least 10 years.
Researchers looked at varying levels of coffee consumption ranging from one cup to more than six cups per day, and the relationship with heart rhythm problems, cardiovascular disease, including coronary artery disease, heart failure and stroke; and total and heart-related deaths among people both with, and without, cardiovascular disease.
The Cohort
Patients were grouped by how many cups of coffee they reported drinking, on average, each day:
- 0,
- <1,
- 1,
- 2-3,
- 4-5, and
- >5 cups/day.
Coffee drinking was assessed through questionnaires that were completed upon entry into the registry.
Overall, they found either no effect or, in many cases, significant reductions in cardiovascular risk, and this was after controlling for confounding factors that could also play a role in heart health and longevity such as exercise, alcohol, smoking, diabetes and high blood pressure.
The First Study
For the first study, researchers examined data from 382,535 individuals without known heart disease to see whether coffee drinking played a role in the development of heart disease or stroke during the 10 years of follow up, the participants' average age was 57, and half of them were women.
The results, having two to three cups of coffee a day was associated with the greatest benefit, translating to a 10%-15% lower risk of developing coronary heart disease, heart failure, a heart rhythm problem, or dying for any reason.
The risk of stroke or heart-related death was lowest among the people who reported that they drank one cup of coffee a day.
That said, researchers did observe a U-shaped relationship with coffee intake and new heart rhythm problems. The maximum benefit was seen among people drinking two to three cups of coffee a day.
The Second Study
The second study included 34,279 individuals who already had some form of cardiovascular disease. Coffee intake at two to three cups a day was associated with lower odds of dying compared with having no coffee at all.
Importantly, consuming any amount of coffee was not associated with a higher risk of heart rhythm problems, including Atrial Fibrillation (AFib) or atrial flutter, which Dr. Kistler said is often what clinicians are concerned about.
Of the 24,111 people included in the analysis who had an arrhythmia at baseline, drinking coffee was associated with a lower risk of death. For example, people with AFib who drank one cup of coffee a day were nearly 20% less likely to die than non-coffee drinkers.
Statement
Professor Kistler, the study's senior author stated that, "Clinicians generally have some apprehension about people with known cardiovascular disease or arrhythmias continuing to drink coffee, so they often err on the side of caution and advise them to stop drinking it altogether due to fears that it may trigger dangerous heart rhythms.
But our study shows that regular coffee intake is safe and could be part of a healthy diet for people with heart disease."
Dr. Kistler added, “Although two to three cups of coffee a day seemed to be the most favorable overall, people shouldn't increase their coffee intake, particularly if it makes them feel anxious or uncomfortable.
There is a whole range of mechanisms through which coffee may reduce mortality and have these favorable effects on cardiovascular disease.
Coffee drinkers should feel reassured that they can continue to enjoy coffee even if they have heart disease. Coffee is the most common cognitive enhancer - it wakes you up, makes you mentally sharper and it's a very important component of many people's daily lives."
Is it in the Caffeine?
So, how might coffee beans benefit the heart? Professor Kistler says, “People often equate coffee with caffeine, but coffee beans actually have over 100 biologically active compounds. These substances can help reduce oxidative stress and inflammation, improve insulin sensitivity, boost metabolism, inhibit the gut's absorption of fat and block receptors known to be involved with abnormal heart rhythms.”
The Third Study
In the third study, researchers looked at whether there were any differences in the relationship between coffee and cardiovascular disease depending on whether someone drank instant coffee, or ground coffee, or caffeinated or decaffeinated coffee.
They found, once again, that two to three cups a day was associated with the lowest risk of arrhythmias, blockages in the heart's arteries, stroke or heart failure regardless of whether they had ground or instant coffee.
Lower rates of death were seen across all coffee types. Decaf coffee did not have favorable effects against incident arrhythmia but did reduce cardiovascular disease, with the exception of heart failure.
Dr. Kistler said “The findings suggest caffeinated coffee is preferable across the board, and there are no cardiovascular benefits to choosing decaf over caffeinated coffees.”
Study Limitations
However, as always there are a few limitations that need to be considered.
The researchers were not unable to control for dietary factors (such as processed foods, cookies etc.) that do play a role in cardiovascular disease (which I think is a very important factor), nor were they able to adjust for the use of creamers, milk or sugar (again, something that I believe is very important).
Also, coffee intake data was based on self-reported questionnaires; the data from these types of studies are often open to flawed data being recorded, participants guessing, and/or people over or under reporting.
Current Recommendations
Most studies have come up with around a recommendation of around 2 to 4 cups a day; this number seems to be beneficial to all sorts of medical conditions from cardiovascular disease to Alzheimer’s. But what to official organizations say? A quick search on Microsoft Bing came up with this from the FDA and the Mayo clinic; 400 milligrams a day seems to be the agreed limit, the FDA say that’s about 4 or 5 cups and the Mayo Clinic say that’s roughly 4, of course there are so many variables when it comes to brew strength and cup size it would be difficult to state a single number when it comes to how many cups a day.
What is 400mg?
Although we can all generally agree that drinking coffee has tangible benefits, unless you drink too much too late in the day, and it affects your sleep, the size of the cup is still a mystery. If you buy from a regular coffee shop is 400mg 1 small, or 2 medium or 3 large cups?
It may be difficult to find out how many milligrams of caffeine your local coffee shop has in its small, medium, and large cups, and small medium and large mean different things in different places.
Scientific Studies:
https://www.acc.org/Latest-in-Cardiology/Articles/2022/03/25/17/36/Coffee-a-Day-May-Benefit-the-Heart-acc-2022
https://www.sciencedaily.com/releases/2022/03/220324104420.htm
https://www.gcrmag.com/daily-coffee-may-benefit-the-heart-new-study-says/
https://www.ajmc.com/view/coffee-s-preventive-benefits-for-cvd-heart-disease-on-display-in-study-pair
YouTube Video: