May 10, 2022

expert reaction to study looking at coffee, cholesterol, coffee drinker’s sex and coffee brewing method

A study published in Open Heart looks at self-reported consumption of coffee and cholesterol levels.

June Davison, Senior Cardiac Nurse at the British Heart Foundation, said:

“It’s important to remember that this type of study can only show an association and can’t prove cause and effect.

“We also need to be cautious in drawing firm conclusions, as the researchers didn’t use a standard definition of what an espresso is.  They also didn’t account for factors such as adding milk or sugar to coffee, which could have an impact on people’s health.  More research is needed to look into this further.

“These findings shouldn’t cause concern if you are partial to a cup of coffee – for most people, a moderate amount of coffee is fine.  But be careful if you like to add flavoured syrups or whipped cream, as these can increase your sugar and saturated fat intake.  If you are sensitive to caffeine or you experience heart palpitations (flutters or pounding), it’s best to cut down on the amount you drink.”

Dr Dipender Gill, NIHR Clinical Lecturer in Clinical Pharmacology and Therapeutics, St George’s, University of London, said:

“This is an observational study of over 20,000 participants in the Norwegian city of Tromsø, which explores the association between self-reported consumption of different forms of coffee and cholesterol levels.  While the variation in association between coffee consumption and cholesterol levels observed when stratifying the population by sex and method of brewing coffee are interesting, caution should be taken in interpreting causal effects.  For example, the observed differences could instead be explained by confounding factors giving rise to spurious associations.  Specifically, men and individuals with a preference for a certain type of coffee may happen to also have other lifestyle factors that affect their cholesterol levels.  Generally speaking, it is difficult to infer causation from such observational study designs, and randomised clinical trials are typically required for this.”

Dr Duane Mellor, Registered Dietitian and Senior Teaching Fellow, Aston Medical School, Aston University, said:

“Although this is an interesting study, it is important to note that it is cross-sectional so it does not see the effect of consuming coffee over time, just that consuming more coffee seems to be linked to a higher cholesterol.  It is important to note, as the author notes, that it is different in different countries and although they looked at espresso, plunger, filter and instant coffee the size of a cup of coffee can vary from person to person and place to place.  In this case in Norway where the study was undertaken espresso cups were noted as being larger than in other countries.  Also it is not just about how the coffee is made, it can be an effect of heat, with higher temperature of water on beans potentially extracting compounds linked to the effects seen with plunger coffee in this study and in previous studies too.

“In other studies looking at coffee consumption long term, perhaps less so with plunger type coffee, it has been linked to lower rates of heart disease and type 2 diabetes.  So, it is important to note although there was an association with total cholesterol and coffee, there were no data on the type of cholesterol or if it were linked to risk of heart disease.

“Overall, perhaps with the exemption of using very hot water to make coffee, moderate intake (up to about 3 cups per day – with a cup being 150-200ml) seems not to be linked to increased risks and other studies have suggested coffee may reduce risk of heart disease and type 2 diabetes.  It is also worth remembering, it’s often what else goes in our coffee (e.g. sugar, syrups and cream etc.) or with it in the form of snacks and cakes, which can have a greater impact on our health.”

Prof Tom Sanders, Professor Emeritus of Nutrition and Dietetics, King’s College London, said:

“It well known that terpinoids (kahweol and cafestol) found in coffee increase blood cholesterol quite substantially (more than saturated fat and cholesterol).  In the past people in Tromso used to drink large amounts of boiled coffee which was high in these compounds.  The levels are lower in expresso coffee which is often more popular in men.  Levels in coffee made in a cafetière are similar to those in boiled coffee.  The levels are low in instant coffee.  The Dutch dietary guidelines recommend drinking filtered coffee over other forms.

“It does not really matter what type of coffee you drink if you only have one or two cups a day but it is important if you drink more.

“This study reports associations with coffee drinking habits and blood cholesterol.  It is not a trial but really a follow-up on findings from the original Tromso Heart Study which showed that drinking large amounts of boiled coffee in the 1980s was linked to high blood cholesterol.  There have been many trials conducted on type of coffee consumed and they show that the coffee terpinoids raise cholesterol in both men and women.  It is likely that the differences observed between men and women are due to difference in coffee drinking behaviour rather than a physiological difference.”

‘Association between espresso coffee and serum total cholesterol: the Tromsø Study 2015–2016’ by Åsne Lirhus Svatun et al. was published in Open Heart at 23:30 UK time on Tuesday 10 May 2022.

DOI: 10.1136/openhrt-2021-001946

Declared interests

Dr Dipender Gill: “I am a physician specialising in Clinical Pharmacology and Therapeutics, and General Internal Medicine.

I am an honorary Clinical Fellow at Imperial College London.

I am employed part-time by Novo Nordisk.”

Dr Duane Mellor: “I have no conflicts of interest.”

Prof Tom Sanders: “No conflicts.”

For all other experts, no reply to our request for declarations of interest was received.