Bittersweet: Coffee – friend or foe?

If you’re anything like me, you truly appreciate  worship that little cup of onyx goodness in the mornings.


For the entirety of my university life I’ve turned to coffee, a pungent smelling pick-me-up that guarantees within 30 minutes to work it’s magic in the body and make me actually seem interested in the lives of people around me.


But, like anything that seems to good to be true – there’s a darker side to coffee that isn’t just in the roast of it’s beans.

And it’s  all  in the mechanism of action.

In doing some weekly readings (#unilife), I’ve stumbled across a few articles detailing cardiovascular disease (CVD) -the leading killer of developed and developing nations worldwide.

According to the Heart Foundation’s ‘Summary of Evidence’ report 2010:  Habitual Coffee consumption has always been a topic of hot debate when it comes to heart health.

===== Caution: fancy words ahead =====

Whilst phenolic chemical compounds in coffee including; Caffeine, diterpene alcohols, and chlorogenic acid (a polyphenolic acid) have been shown to be strong antioxidants (opposite of oxidants -aka bad)  in vitro (outside of the human body), population studies have commonly seen an association with coffee consumption and increased risk in the development of certain CVD markers 



Mixed evidence regarding the subject has been the topic of recent debate; a study by  this chick named Sofia (1) suggested that a positive association (a link exists) between habitual coffee consumption (i.e living and breathing coffee) and Coronary Heart Disease using 13 case-control studies, but several meta-analyses (meshed analysis) of cohort studies (a study where researchers practically follow people around for a few years and annoy them) have found no effect of coffee drinking on the risk of CHD.


Another  study involving 200,000 participants (2) suggested a significant inverse association (opposite relationship) between coffee consumption and the risk of type 2 diabetes. This means that Individuals who drank four to six cups per day and more than six cups per day had a 28 and 35% lower risk of type 2 diabetes than those who drank no coffee or less than two cups per day- 

So could this mean that to avoid the T2DM epidemic we simply… drink more coffee?

BUT WAIT, Before you rush to your nearest Starbucks/Zarraffas/insertbrandnamecoffeestorehere and rip up your Dietitian’s orders to eat healthily and exercise, there’s more…

You may know that Coffee is a stimulant, a vasoconstrictive agent if you will (constricts your arteries so blood flows at a pressure used rate), so consuming caffeine has (as you would expect), an effect on blood pressure.

So this researcher called Jee, and his mates (3) decided to look into coffee consumption and it’s effect on Blood pressure. They found that after 56 days with an average of consuming 5 coffees a day , the guinea pigs (humans) had an increased systolic pressure of 2.4mmol/Hg  and diastolic 1.2mmol/Hg. 

Now this might not sound like much, but if you’re slightly overweight and  your blood pressure is borderline hypertensive (140/90) – habitual coffee consumption could just step you over the line into deep hypertension territory (aka bad).

Hypertension goes hand in hand with more cardiovascular diseases than I am bothered to type out. And  all this information seems really quite counterintuitive.

So far the research suggests;

1) Drinking coffee constantly was associated with increased CVD risk

2)drinking 5 cups or more of  coffee associated with decreased incidence of type 2 diabetes (good)

3) BUT drinking 5 cups or more of coffee increases blood pressure (bad)

Not looking so good for coffee is it?

So what if coffee slightly raised blood pressure or is associated with increased CVD risk? It doesn’t have an effect on cholesterol right?

Well, It depends.

Christensen and coworkers  (4) hypothesised that terpenoid (cholesterol) fractions (found in very high amounts in unfiltered coffee), mainly cafestol and kahweol, in coffee oil raise blood cholesterol levels. 

It has been shown that boiled coffee contains a lipid fraction that can be removed during filtration though paper, and once filtered, does not raise blood cholesterol levels 

And Instant coffee has very low levels of cafestol and kahweol, and is unlikely to raise blood cholesterol levels. Both Robusta and Arabica coffee beans contain kahweol and cafestol.

A comparison of diterpenes in various coffee brews found that Turkish/Greek-style coffee contains the highest cafestol levels per cup (mean: 3.9 -3.2 mg), while plunger/cafetierestyle coffee contained 3.5 -1.2 mg. Five cups per day of either of these styles of coffee would raise serum cholesterol by about 8–10 mg/dL or 0.2–0.25 mmol/L. 

So take home message to my fellow caffeinated mates: don’t drink too much, too often and defenatly not the Turkish boiled or plunger coffee! 

I’m unsure of the levels of cafestrol in decaf coffee but seriously, who drinks coffee without the intention of reaping the benefits of sweet, sweet (but actually quite bitter) caffeine? 

Have a lovely week,

Stay caffeinated, ( but not too much)

===Anna Freeman==

===student Dietitian===


(1) . Sofi F, Conti AA, Gori AM, et al. Coffee consumption and risk of coronary heart disease: a meta-analysis. Nutr Metab Cardiovasc Dis 2007; 17: 209–223.

(2)  van Dam RM, Hu FB. Coffee consumption and risk of type 2 diabetes: a systematic review. JAMA 2005; 294: 97–104.

(3) Jee SH, He J, Whelton PK, et al. The effect of chronic coffee drinking on blood pressure: a meta-analysis of controlled clinical trials. Hypertension 1999; 33: 647–652.

(4) Christensen B, Mosdol A, Retterstol L, et al. Abstention from filtered coffee reduces the concentrations of plasma homocysteine and serum cholesterol––a randomized controlled trial. Am J Clin Nutr 2001; 74: 302–307.