“Just a cup a day” is a phrase I hear frequently from patients when I ask them if they drink coffee. People take comfort in this phrase-they even take pride in it. They have a concept that “just a cup a day” means that they are not like their friends, who drink thermos-fulls a day, and that they are safe from any disease-producing effects. Any recommendation of cutting down coffee consumption and it is as if the patient has been asked to strike down their own kin, or to stuff their favorite pet. The truth is there are pros and cons to the drink—rather you will experience the pros or the cons may depend greatly on who your parents were, as I will discuss later in this article.
Indeed, attachments to the aromatic coffee bean are strong; there is a supposedly true story that when coffee was introduced to the Italian markets the wine merchants appealed to the Pope to ban it, fearing it would impact wine sales. The Pope asked that some of the beverage be brought to him so that he could try it. After smelling, then tasting it, he proceeded to baptize coffee and proclaimed it a Christian beverage.
Unfortunately, recent research shows that even a cup of coffee has deleterious effects on the body. The study, published in the American Journal of Clinical Nutrition (AJCN), sought to evaluate the effects of coffee on several metabolic markers, including cholesterol levels and inflammatory markers.
Inflammatory markers have been shown in several studies to be better predictors of heart disease than cholesterol. This means that as inflammatory markers in your blood stream rise, your chance of having a heart attack (or other vascular disease such as stroke) goes up in a linear fashion. This is truer of inflammatory markers than it is for cholesterol, which actually has a comparatively weak relationship to heart disease. The most commonly clinically tested marker of inflammation is called C-Reactive Protein, or CRP.
The study revealed that just 1-2 cups of coffee per day raises CRP levels by 30%! The paper also stated that in addition to its role in cardiovascular disease, long-term low-grade inflammation participates in the development of obesity, insulin resistance, metabolic syndrome X, and abnormal coagulation processes. Other studies have shown strong associations between CRP levels and cancer. A recent study in the Journal of the American Medical Association (JAMA) found that “CRP concentrations are elevated among persons who subsequently develop colon cancer. These data support the hypothesis that inflammation is a risk factor for the development of colon cancer…”
A linear relationship was also found in cholesterol levels and the amount of coffee consumed; the more coffee one drinks, the higher the cholesterol. That’s the bad news. The good news is that research was cited showing that while unfiltered coffee raises cholesterol, filtered coffee does not. Apparently two cholesterol-raising substances, cafestolkahweol, are removed during the filtration process.
Coffee consumption is also associated with increased rates of osteoporosis—probably due to its acidifying effect on the body. When the body becomes acidic, minerals are “robbed” from the body to buffer the acid and maintain a neutral environment.
Other recent research has shown that regular coffee consumption is associated with increased homocysteine levels (Journal of Nutrition, 2006). Homocysteine, like CRP, is a reliable marker for heart disease risk.
Thus we find that coffee may play a contributory role in the development of all of the diseases that represent the greatest causes of death and suffering in the Western world (cardiovascular disease, diabetes, cancer, and osteoporosis). Coffee is also the world’s second most valuable legal commodity (oil is the first) with over 10 billion pounds of coffee beans exported from over 70 countries annually. About one quarter of this product is consumed in the US (we also are a leading country in the incidence of colon cancer, heart disease, and osteoporosis).
Now for the conundrum part; other research demonstrates a beneficial role for coffee on human health. Here are the highlights:
- A 2006 study in the journal Neuroscience found that moderate coffee consumption had a protective effect against Alzheimer’s disease.
- A new study (American Journal of Clinical Nutrition, 2007) found that women who drink no coffee have lower risk for high blood pressure than women who drink up to three cups per day. Then it gets weird--women who had more than 6 cups per day had less risk than women drinking up to 3 cups per day, and only slightly higher risk than women drinking none at all!
- A 2004 study from the Annals of Internal Medicine concluded “caffeine intake from coffee and other sources was associated with a statistically significantly lower risk for diabetes in both men and women.”
- A 2007 research review in Current Opinion in Lipidology found some of the chemicals present in unfiltered coffee increase heart attack rates, but also found that many moderate coffee drinkers have lower heart disease rates. They concluded that in some people the antioxidants in the coffee lower heart disease risk.
A Plausible Answer to the Conundrum
The answer to this conundrum may be in our genes. A study in the March 2006 edition of JAMA looked specifically at coffee consumption and heart disease rates among 2 populations with genetic differences known to affect caffeine metabolism. Group 1 were “fast caffeine metabolizers”, and group 2 were “slow caffeine metabolizers”. It was consistently found that the slow metabolizers had increased risk of heart attack with coffee consumption, whereas the fast metabolizers had decreased risk of heart attack with coffee consumption! This study is so important that I’m including a link to it--here it is. The relevance of this study to you is this; if you are at risk for heart disease and are addicted to coffee, I think you should be tested for this gene (print the study from the link above and bring it to your cardiologist). If you are a “fast metabolizer” (homozygous for the CYP1A2*1A allele in your genetic code), then coffee is therapeutic for you! If you are a “slow metabolizer” (you carry the variant variant CYP1A2*1F), then coffee is a poison!
One last coffee fact—shortly after its introduction to Constantinople in 1475, Turkish law made it legal for a woman to divorce her husband if he did not supply her with her daily coffee. I think that if a 15th century Turk were imported to a modern day Starbucks, he would observe that the law is still in effect!