Coffee may protect against cardiovascular disease


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Coffee drinking was first recorded in the Middle East over 500 years ago.  Today, coffee is one of the most popular beverages in the world, with over 70 countries supplying it and nearly every country in the world consuming it.  Thanks to its popularity, it is not surprising that coffee and its components have been the subjects of a wide range of studies that assess the risks and benefits of consumption.

Findings on the association of coffee consumption and cardiovascular disease (CVD) risk have been contradictory, with some studies revealing an increased risk for CVD, others showing no risk, and some finding benefits against it (1,2,3). Gender differences, types and amounts of coffee consumed, genetic factors, a tendency to focus on caffeine alone, lengths of studies, and a host of other confounders can make findings appear contradictory. Yet, in spite of these somewhat conflicting results, recent findings appear to offer some support to the hypothesis that low to moderate consumption of coffee may offer protection against some of the risk factors for CVD over the long term.

INFLAMMATION

Inflammation is a normal response to injury and plays an important role in tissue repair and restoration of tissue function.  However, prolonged inflammation can be too much of a good thing, in no small part due to its involvement in oxidative stress – chronic inflammation is a major contributor to a host of degenerative diseases, including CVD (2,3).  A 2008 study of 459 Japanese women revealed a significant, independent, inverse correlation between coffee consumption and serum C-reactive protein (CRP) levels (2).  This is an important finding because CRP has been recognized as a marker for systemic inflammation and has been shown to have predictive value for CVD, stroke, and death (4). Similarly, the Iowa Women’s Health Study provides additional support through its finding of an inverse association of coffee consumption with death attributed to inflammatory diseases (3).

LDL AND OXIDATIVE STRESS

Oxidized LDL plays a key role in the pathogenesis of atherosclerosis (5).  It has a number of atherogenic properties, so, the body uses a complex defense system to rapidly remove it from circulation.  Dietary and genetic factors can aid or overwhelm this system. The susceptibility of LDL to oxidation is dependent upon serum concentrations of conjugated dienes, lipid hydroperoxides, and antioxidant species (5). Diets high in fruits and vegetables confer protection against this susceptibility, in part, by providing a consistent, dependable source of antioxidants.  Data from a study on the effects of caffeic acid on LDL indicates that the consumption of just one cup of coffee (200 ml) per day significantly improves oxidative resistance in humans (5).

Several studies have shown a J-shaped association between coffee consumption and CVD risk (5). This is similar to the association seen with wine consumption – drinking a small amount each day improves your odds of avoiding CVD, but overdoing it swiftly swings those odds against you and adds a number of other health and social problems to your tab.

The correlation with lowered CVD risk may be a result of protection conferred by polyphenols, volatile aroma compounds, and eterocyclic compounds found in coffee, all of which contribute to its antioxidant capacity (3).  Since plasma antioxidants increase after its consumption, coffee has been associated with reduced oxidative stress (3).   The consumption of coffee for a period of just seven days has been shown to significantly decrease LDL serum concentrations and LDL susceptibility to oxidation (5).

INSTANT, FILTERED AND UNFILTERED COFFEE

The above mentioned anti-oxidative effect of coffee consumption on LDL has not been replicated in filtered coffee studies (5).  This may be due, in part, to the ability of paper filters to keep some of coffee’s antioxidants from passing through, and, thus, from being consumed.  However, paper filtered and instant coffee do not raise LDL levels after consumption, whereas, LDL serum concentrations have been shown to increase in the wake of drinking unfiltered coffee (6). Consumption of 6 cups of boiled coffee (i.e. French press, espresso) per day was estimated to increase serum LDL levels by 17.8 mg/dL (6).  Diterpene cafestol is the likely cause of this increase. So, on one hand unfiltered coffee improves LDL oxidative resistance (which is good), but raises LDL levels (which is bad).

BLOOD PRESSURE

Caffeine has been shown to increase blood pressure in people who are not habitual caffeine consumers (6).  The key word here is “habitual”.  Partial tolerance to caffeine’s effects on blood pressure takes place in as little as one week in most people (6).  Thus, it is difficult to extrapolate the findings on increased blood pressure to long term use of coffee.  In addition, trials comparing the effects of caffeine capsules vs. placebo capsules have shown much stronger effects than trials looking at caffeinated coffee vs decaffeinated coffee consumption (6).  This is likely due to the fact that coffee is not comprised of caffeine alone.  Instead, coffee, whether caffeinated or decaffeinated, contains a number of antioxidants and other compounds which confer protection against the detrimental effects of its caffeine component (6).

Perhaps most telling of the importance of these other components in coffee was the finding that caffeinated cola consumption is associated with a higher incidence of hypertension than caffeinated coffee consumption (6).  Something to keep in mind the next time you feel like frowning when you see a teenager, or even a child, sipping a Cafe Misto. Furthermore, chlorogenic acid, a component of coffee, has been shown to reduce blood pressure in hypertensive rats (6).  And, in humans, green coffee bean extracts, which are low in caffeine, were shown to reduce hypertension in a randomized, Japanese trial (6).

BOTTOM LINE

Instant coffee and filtered coffee can protect against CVD if consumed in quantities of up to 4 cups (not mugs!) per day.  Unfiltered coffee does not and can have detrimental effects in the long run if it is consumed on a regular basis.  All caffeinated coffee, regardless of how it is prepared, is contraindicated for persons who already have CVD and/or high blood pressure.

So, put away the soda, espresso, and espresso mixed drinks (i.e. latte, cappuccino) and reach for instant or filtered coffee instead.  Your heart will thank you.  I’m not suggesting you must swear off the aforementioned concoctions for the rest of your days. I certainly haven’t.  But if you are drinking unfiltered coffee on a daily basis, you may want to reconsider and train your palate to enjoy the many other varieties of roasts available that are prepared with paper filters.  Or you can rig your espresso machine to brew using paper.

Let me know how that works out.  🙂

REFERENCES

1)    Balk L, Hockstra T, Twisk J.  Relationship between long-term coffee consumption and components of the metabolic syndrome:  the Amsterdam Growth and Health Longitudinal Study.  Eur J Epidimiol 2009; 24: 203-209.

2)    Kotani K, Tsuzaki K, Sano Y, Maekawa M, Fujiwara S, Hamada T, Sakane N.   The relationship between usual coffee consumption and serum C-reactive protein level in a Japanese female population.  Clin Chem Lab Med 2008; 46(10): 1434-1437.

3)    Andersen L, Jacobs D, Carlsen M, Blomhoff R.  Consumption of coffee is associated with reduced risk of death attributed to inflammatory and cardiovascular diseases in the Iowa Women’s Health Study.  Am J Clin Nutr 2006; 83: 1039-1046.

4)    American Heart Association.  Inflammation, heart disease and stroke:  the role of C-reactive protein.  2010.  Available at: http://www.americanheart.org/presenter.jhtml?identifier=4648.  Accessed May 9, 2010.

5)    Natella F, Nardini M, Belelli F, Scaccini C.  Coffee drinking induces incorporation of phenolic acids into LDL and increases the resistance of LDL to ex vivo oxidation in humans.  Am J Clin Nutr 2007; 86: 604-609.

6)    Van Dam R M.  Coffee consumption and risk of type 2 diabetes, cardiovascular diseases, and cancer.   Appl Physiol Nutr Metab 2008; 33: 1269-1283.

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