Blood and Chocolate

Theobroma cacao.  Food of the Gods. Xocoatl.

Origins of chocolate are traced back to before the Aztecs, who believed chocolate had divine properties and had even used cacao beans as currency.  Before sacrifices to the gods, victims were given chocolate to drink and when the Spanish arrived, mistaking Cortes for the snake god, Quetzalcoatl, Montezuma served them chocolate.

The legend of Quetzalcoatl has since been immortalized in Downtown San Jose’s Cesar Chavez park.  My brother was patient enough to pose for me next to it on my last trip home.

Chocolate has since been adopted by cultures and civilizations throughout the world, and while we may not still be feeding it to our victims before sacrifice, our love of chocolate has driven intrigue and research into closer examination of its delicious properties.  

In vogue today is the effects of chocolate on blood pressure.  Chemical components in dark chocolate have been shown to have preventative effects on stroke and trials have consistently shown that consumption of cocoa daily can lower systolic blood pressure up to 4.5 mmHg. 

Why do we care about high blood pressure? High blood pressure is treated to prevent a heart attack or stroke and to prevent other complications, like heart or kidney failure.

A review of the literature by Desch et al was published at the beginning of the year in the American Journal of Hypertension.  Desch sites that interest in the effects of chocolate on blood pressure originated from observation of the Kuna indians, who consumed large amounts of chocolate and who had low rates of high blood pressure.  Closer examination revealed that chocolate contains a lot of plant flavanols, which have been previously shown to have beneficial effects on blood pressure. 

If chocolate is to be recommended for blood pressure, it needs to be eaten daily to keep blood pressure consistently down.  Additionally, the 4.5 mmHg drop seen is not going to be enough for the majority of patients diagnosed with hypertension; traditional medications and other lifestyle modifications will be needed.  Not to be forgotten either, is that this is the era of obesity; when scientists are seriously considering putting statins into fast food orders, is encouraging increased consumption of dark chocolate to treat blood pressure really the answer?

Another interesting area regarding hypertension treatment is that every patient really is a unique and beautiful snowflake, meaning high blood pressure is driven through different mechanisms in different patients, especially patients of different ethnic backgrounds.  

Umscheild et al site that while African-American patients are more likely to have a better understanding and awareness of hypertension, they are less likely to have controlled blood pressure despite treatment.  African-Americans are also significantly more likely to have strokes and kidney failure, compared with the rest of the population.  Umscheild’s research on disparity published in January 2010 showed that providers were just as likely to intensify blood pressure therapy for African-Americans as they were for other patients, indicating that there is another reason for disparity than negligence in the health care system.

Most concerning to me is the increasing amount of evidence showing that fluctuations in blood pressure place patients at risk of cardiovascular events.  An analysis by Rothwell et al published in the Lancet in March 2010 found that fluctuations in blood pressure between office visits was a predictor of cardiovascular events and stroke independent of mean blood pressure.

I can hardly remember to take my multivitamin daily; how many patients with high blood pressure are unable to successfully adopt taking their blood pressure medications daily into their routine?  For patients with high blood pressure who don’t feel sick and are now told that they will have to take a daily (or twice daily) pill for the rest of their life to treat a risk that is poorly understood by the patient, it must be difficult to work up the motivation to take as directed.  

Evidence from trials like Rothwell's really show where a pharmacist can step up to play a role in reducing risk.  For patients consistently late in filling prescription for blood pressure medications, pharmacists have the opportunity to talk to the patient about risks, help them to better understand the benefit of taking the medication, and the risks associated with non-compliance.  

One last final shout out to Mr. Ghirardelli, who arrived in San Francisco, CA during the gold rush and discovered that he could make more money selling hot chocolate to crusty miners than actually panning for gold.  His chocolate remains awesome and delicious to this day.

References:

Bensen A.  A brief history of chocolate.  Smithsonian.com 2008.

Shah ZA et al.  The flavanol (-)-epicatechin prevents stroke damage through the Nrf2/HO1 pathway.  Journal of Cerebral Blood Flow & Metabolism 2010.

Desch S et al.  Effect of cocoa products on blood pressure: systematic review and meta-analysis.  American Journal of Hypertension 2010;23(1):97-103.

O'Riordan M.  The "MacStatin": Fast food with some ketchup, salt, and a statin to go.  theheart.org 2010.

Umscheild CA et al.  Racial disparities in hypertension control, but not treatment intensification.  American Journal of Hypertension 2010;23(1):54-61.

Rothwell PM et al.  Prognostic significance of visit-to-visit variability, maximum systolic blood pressure, and episodic hypertension.  The Lancet 2010;375:895-905.