Multiple studies have shown that coffee can be healthy – at least for some and at some doses. But other research has shown that too much coffee can cause early death for some age groups. And tea may well be healthier than coffee at least for men.
Let’s review the science on this ‘hot’ topic, starting from the latest positive results on coffee.
Coffee reduces risk of death for many
A 2017 review from the UK’s University of Southampton conducted a review of meta-analyses of coffee research to date. This used 201 meta-analyses and collected their total outcomes.
This analysis showed that three to four cups of coffee per day. The researchers found this level of coffee drinking reduced the incidence of death by around 15 percent and death from heart disease at 19 percent. Deaths from cancers, liver disease and neurological conditions were also reduced with coffee drinking.
The researchers also found that low birth weight risk and preterm births incidences were both increased, up to about a third, by coffee drinking at three to four cups a day. There was also an increased incidence of fractures in women who drank these levels of coffee.
A 2014 review of research from Harvard found that up to five to six cups of coffee a day yielded greater reductions in risk than two to three cups of coffee a day, to the tune of some 14 percent for all causes of death.
Confirming this finding was a large 2015 study from Harvard that followed over 160,000 women and more than 40,000 men. This found that those who drank from one to five cups of coffee a day saw reductions of 12 percent of early death for those who drank three to five cups, compared to non-coffee drinkers.
This study and some others found no associations between coffee drinking and cancer.
But all of these showed that drinking decaffeinated coffee resulted in similar reductions in early death.
Much of the research has followed more women than men for some reason. Then in most cases, the results were combined.
A 2018 study from The Netherlands’ Maastricht University medical school studied 120,852 men and women, following them over a ten-year period. This study tracked men and women together and separately.
The researchers found that higher coffee drinking was associated with a lower incidence of early death in women from all causes. However, higher coffee consumption increased the incidence of cancer and heart disease deaths in men. It did reduce deaths from other causes, however.
Tea proves better than coffee for men
This 2018 study also showed, however, that men who replaced coffee with tea saw their incidence of death from cardiovascular disease decrease. And those who drank at least 30-50 percent tea instead of coffee had even a lower incidence of death from all causes.
Women, however, had greater reductions in death incidence when they drank more coffee than tea. Exclusive women coffee drinkers fared better than exclusive tea drinkers.
What all this means that it appears that most of the benefits of coffee drinking appear to be more for women than men. Men who drink more coffee don’t seem to get the same benefits as women.
Long-term study on coffee focuses on accuracy
Contradicting the results of several previous studies, a large study published in the Journal Mayo Clinic Proceedings has found that heavy coffee drinking speeds up early death – especially among those under the age of 55.
The study followed 43,727 adults through a span of seventeen years – equating to 699,632 person-years. The data was collected by direct medical examination together with questionnaires. The medical exams consisted of blood chemistry, blood pressure, electrocardiography (EKG) together with exercise testing.
During the 17-year follow-up period, 2,512 people died, and 804 of them were from cardiovascular disease. Those who drank more than 28 cups of coffee a week were 21% more likely to die during the study period.
The 28 cups per week equates to four cups a day. The research found that three cups of coffee per day or less had little effect on health but those with four cups or more a day had the noticeable increase in early death incidence.
More alarming is that among men under the age of 55 there was an increased incidence of death by 56%. And among women under 55 the incidence of death doubled.
The concept of increased risk of death translates to increased risk of early death because during that 17 years – after canceling out other factors like smoking – more people who drank 4+ cups of coffee a day died, and fewer died who drank 3 or less cups a day.
Other studies estimate that 400 million cups of coffee are drank per day in the U.S. – an average of 3.1 cups per day for adults. And about 60% of adults are heavy coffee drinkers.
The researchers eliminated from the data other potential comingling effects such as smoking. However, they could not eliminate related lifestyle factors such as sleep. In other words, heavy coffee drinking is also associated with increased incidence of insomnia and insomnia is related to higher risk of chronic diseases.
Dr. Carl Lavie, one of the study’s authors, pointed out that the association was not with caffeine because the early death was not associated with heart disease – which is specific to caffeine use. He also added that fewer than four cups did not add or decrease mortality risk.
In their conclusion the authors added:
“On the basis of these findings, it seems appropriate to suggest that younger people avoid heavy coffee consumption (ie, averaging more than four cups per day).”
Previous coffee studies contradicted?
This study is specific for those under the age of 55. Other research such as that discussed earlier have either focused on or included those over 55. For example, a 2012 study by the National Institutes of Health followed 400,000 people between 50 and 71 years old for 12 years. They found that drinking three or more cups of coffee a day reduced the risk of death by about 10% – and less for those drinking fewer cups a day.
This result, by most evidence standards, is not considered very significant. Furthermore, the study only assessed coffee consumption through a survey on one occasion – so did not determine if the heavy coffee consumption was ongoing.
However, this study also found that heavy coffee drinking slightly increased the risk of cancer among the men.
Isn’t coffee a source of antioxidants?
Yes, coffee can be a source of antioxidants, and this is likely the reason for some of the benefits, especially for women who may not be getting good sources of antioxidants from other parts of their diets.
But as coffee beans are over-roasted – as they are in many commercial facilities – a number of these antioxidants are lost, and unhealthy metabolites are produced. These include acrylamide and others.
Acrylamide is formed when starches combined with the asparagine amino acid are overcooked. This is typically achieved with frying, roasting and other high heat cooking.
Acrylamide has been linked with cancer in animal studies, but there have been few studies confirming this in humans. Acrylamide has, however, been linked with nerve damage in humans.
Green coffee beans are loaded with antioxidants – with little acrylamide.
This relationship between overprocessing and chronic diseases exists nearly across the board with many different foods – foods that are healthy in their natural states but unhealthy in their over-processed state.
Other considerations, including sleep
Another consideration is that heavy coffee drinking has been shown to interrupt sleep – and a lack of sleep is associated with early mortality.
There has also been some indication that coffee may interfere with maintaining healthy homocysteine levels.
Certainly, the evidence is confusing – and perhaps there is a dichotomy regarding the difference between types of coffee. And the effects upon women versus men. And the age of the coffee drinker.
Then there is also the issue of adding junk to coffee such as sugar. Those who drink black coffee are probably getting better benefits than those who add lots of refined sugar.
As mentioned, some coffees are produced with fewer acrylamides.
Part of the issue may be related to the fact that smoking and coffee drinking had to be separated in all of the studies reviewed. This may well be shifting the data towards those who have more healthier, active lifestyles in general as they age – those who drink coffee but do not smoke.
While the results of these studies offer different conclusions, there is still more to learn about coffee.
Meanwhile, the data showing green tea – considered a coffee substitute – has been clear: Green tea is a great source of antioxidants, and is clearly anti-carcinogenic as well. And we’ve shown other research showing that chamomile tea reduces cancer incidence, and also increases longevity. These are in addition to chamomile’s reducing depression and anxiety.
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Case Adams is a California Naturopath and a Board Certified Alternative Medicine Practitioner with a PhD in Natural Health Sciences, and diplomas in Homeopathy, Aromatherapy, Bach Flower Remedies, Blood Chemistry, Clinical Nutritional Counseling and Colon Hydrotherapy. He has authored 26 books on natural healing strategies.