Coffee raises cholesterol, study finds, but how much depends on your sex and how it's brewed

A new development has emerged in the age-old debate as to whether the humble cup of joe is good for your heart.

Research suggests the type of coffee you consume may be impacting your heart more than others - depending on your sex. 

Coffee raises cholesterol, but to what extent depends on how the beverage is brewed and whether you are biologically a man or woman, the researchers found.

The study found that drinking espressos - a strong, black coffee made by forcing steam through ground coffee beans - will cause a more significant spike in cholesterol for men compared to women.

However, drinking filter coffee - which is made by allowing water to pass through a paper or mesh filter containing ground coffee - may see higher levels of cholestrol in women.

The study, which was conducted in Norway and involved more than 20,000 participants, found cafetière coffee - or plunger coffee - is the only brewing method that does not cause "significant sex differences" in cholesterol. 

Diterpenes, cafestol and kahweol, the naturally occurring chemicals in coffee, are known to raise the body's level of cholesterol. Cholesterol, a waxy, fat-like substance found in most body tissues, is an important constituent of cell membranes, but a high proportion in the blood of low-density lipoprotein - which transports cholesterol to the other tissues - can lead to an increased risk of coronary heart disease.

High levels of cholesterol can cause fatty deposits to develop in the blood vessels, which can make it difficult for enough blood to flow through the arteries. Sometimes, those deposits can break suddenly and form a clot that causes a heart attack or stroke.

The study found that espressos will cause a more significant spike in cholesterol for men compared to women.
The study found that espressos will cause a more significant spike in cholesterol for men compared to women. Photo credit: Getty Images

The study, which was published in the journal Open Heart and carried out by a team of researchers led by the UiT Arctic University of Norway, examined blood samples of 21,083 people over the age of 40 who lived in Tromso, Norway. 

The team examined the effects of four brewing methods - espresso, cafetière, filtered and instant coffee. Each participant was required to answer a survey regarding their coffee consumption, such as how many cups of coffee they drank each day and what type of brewing method they used. Blood samples were then taken for analysis, as well as the participants' height and weight.

The results found that people who drank three to five espressos a day were significantly more likely to have higher levels of cholesterol in the blood, compared with those who did not. But the extent of the increase differed by sex: men who drank three to five espressos saw their cholesterol rise by 0.16mmol/L, whereas women only saw their levels rise by 0.09mmol/L - almost 50 percent less.

Typically, people who score below five millimoles per litre (mmol/L) of blood on a cholesterol test are considered to have a healthy level of fat in their blood. 

Drinking six or more cups of filtered coffee did not increase male participants' levels of cholesterol, the study found - but it did increase its levels in women by 0.11mmol/L. The researchers noted that as filtered coffee passes through a filter, most of the chemicals that can raise cholesterol are removed in the process.

Participants who enjoyed six or more cups of cafetière coffee also experienced raised levels of cholesterol - 0.30mmol/L for women and 0.23mmol/L for men - but there was no significant difference between men and women.

The study did not identify a strong relationship between cholesterol and instant coffee, with the researchers noting only contains trace amounts of cholesterol-raising chemicals are found in the beverage. Instant coffee, or powdered coffee, is made by adding hot water or milk to already brewed coffee beans that are available in a crystalised or powdered form. 

The study found that women experienced higher levels of cholesterol when consuming six or more cups of filtered coffee a day - but the same wasn't observed in men.
The study found that women experienced higher levels of cholesterol when consuming six or more cups of filtered coffee a day - but the same wasn't observed in men. Photo credit: Getty Images

However, experts have stressed the findings should not be a cause for concern among those who consume a moderate one to two cups a day. 

As reported by the Daily Mail, Dr Dipender Gill - an expert in pharmacology from the University of London - warned that other factors aside from coffee preference could be impacting the results.

"Men and individuals with a preference for a certain type of coffee may also have other lifestyle factors that affect their cholesterol levels," he acknowledged, as reported by the Daily Mail.  

Professor Tom Sanders, an expert in nutrition from King's College London, also said that people don't have to worry about the kind of coffee they consume - as long as it's in moderation. 

"It doesn't 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 [than that]," he said. 

A key limitation of the study was that the participants were not drinking from the same or a standard cup size. 

Research over the years has proved contradictory and inconclusive, with other studies finding that coffee can actually lower the risk of heart-related conditions. An Australian study published in March found people who drank two to three cups of coffee per day lowered their risk of developing heart disease or dying within a decade by 10 to 15 percent.