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Coffee: Health Drink or Health Hazard?

Nina Nelson

9/24/07

 

 

With the rapid increase of coffee shops and specialty coffee drinks, more and more of the United States population is drinking coffee, even beginning at a younger age. Coffee sellers like Starbucks and Dunkin Donuts are brewing their way into consumers’ wallets and making the big bucks on a drink that in the past has largely been criticized for its adverse health effects. The BBC News website reports that “one cup of coffee a day is risky” (http://news.bbc.co.uk/1/hi/health/3759948.stm). Another website, Times Online, heads their article warning readers to “Enjoy that next cup of coffee: it may be your last,” reporting that those who drink more than three cups of coffee a day are seriously increasing their risk of a heart attack (http://www.timesonline.co.uk/tol/news/world/us_and_americas/article738667.ece). Many have warned that coffee will stunt your growth, cause the shakes, or make you more vulnerable to having a heart attack or other serious health conditions. However, a recent article from Oprah’s magazine raves that “one of the most widely consumed – and maligned – beverages in the world is good for you” (http://www.oprah.com/omagazine/200708/omag_200708_coffee.jhtml). The article suggests that the negative sentiment toward coffee was established when other lifestyle associations with drinking coffee, such as smoking, were not considered. Peter Martin, MD, professor of psychiatry and pharmacology at Vanderbilt University, is quoted in the Oprah.com article asserting that “coffee is an extremely healthful drink” (http://www.oprah.com/omagazine/200708/omag_200708_coffee.jhtml).

What’s so great about coffee, anyway?

            Aside from an extra jolt of energy in the morning (or afternoon), the caffeine in coffee “stimulates the brain and nervous system, and may lower your risk of diabetes, Parkinson’s disease, mood problems, headaches, and even cavities” (http://www.oprah.com/health/webmd/slide/slide_health_5foods_350_105.jhtml).

 

A brief list of the claimed health benefits in this popular media publication are:

 

 However, this popular media source still throws in the caveat that researchers are not necessarily recommending large doses of coffee for these great health benefits. It does consider that drinking coffee is associated with less healthy lifestyles and habits such as smoking and lack of sleep. It isn’t until you read further down in the article that you read that adding in cream, sugar, or any other syrup flavoring will undermine the health benefits with the added fat and calories (http://www.oprah.com/health/webmd/slide/slide_health_5foods_350_105.jhtml). So how legitimate are these claims and can we trust Oprah’s publication to give us the real truth about such a popular and comforting habit? Let’s look at more credible sources to compare some of the health claims related to the more popular diseases such as Cardiovascular Disease, Parkinson’s, and Diabetes, with grounded research to see if coffee really is the latest health drink.

 

Coffee and Cardiovascular Health

            A population based study combined data from the Health Professionals Follow-up Study (n = 44,005), which began in 1986, and the Nurses’ Health Study (n= 84,488), which began in 1976, to look at the risk of developing heart disease from drinking coffee. None of the participants had coronary artery disease at the beginning of the study. Participants filled out these surveys every four years, recording their daily caffeine consumption. The primary outcome was a nonfatal myocardial infarction (heart attack) or fatal coronary artery disease (CAD) before June 1, 2000. The relative risks for experiencing the primary outcome (myocardial infarction or fatal CAD) for men after controlling for age, smoking and other risk factors, were not deemed statistically significant. Similar results were recorded for women, as well. The conclusion from this study was that “there is no evidence that coffee consumption increases the likelihood of developing heart disease” (Ebell, 2006). Though this is a valid research design and study, more reliable results might be considered from studies that do not depend on self-report measures like surveys, where accuracy in participants’ responses is often questionable. Experimental studies would suggest more credible results, as they are able to determine causal relationships; however, when a presumed risk for disease is in the cards, these types of studies are usually deemed unethical.

            Another study, a long-term longitudinal study, found evidence that the relation between coffee intake and incidence of hypertension is not a strong one. In this study, there were 2985 men and 3383 women assessed at baseline and follow-up visits after six and eleven years. Baseline questionnaires measured the average coffee intake. Hypertension was defined as “a mean systolic blood pressure (SBP) ≥ 140 mm Hg over both follow-up measurements, a mean diastolic blood pressure (DBP) ≥ 90 mm Hg over both follow-up measurements, or the use of antihypertensive medication at any follow-up measurement” (Uiterwaal et. al, 2007). The results indicated that those participants that did not drink coffee at baseline measures were at lower risk of hypertension than those who did drink coffee, and women who drank more than six cups of coffee per day had a lower risk than women who drank more than 0-3 cups per day. Conclusions from this study indicate that those who do not drink coffee are at lower risk for developing hypertension than those who consume small amounts. An interesting result, however, is that women (only women) who were heavy drinkers (more than six cups) were at lower risk of hypertension than were women who drank fewer cups each day, but typically only after middle age.

 

Coffee and Parkinson’s Disease

            To investigate the possible relationship between coffee consumption and risk for Parkinson’s disease, a family-based case-control study was done looking at protective factors of caffeine, smoking, and nonsteroidal anti-inflammatory drugs. There were 356 case subjects and 317 family controls who self-reported environmental exposures, such as history, status, dosage, duration, and intensity of smoking, caffeine, and nonsteroidal anti-inflammatory drugs. Participants answered telephone questionnaires assessing their environmental risk factor exposure. Cases and family controls were “matched on unmeasured genetic and environmental factors that may predispose to exposure behaviors and to disease” (Hancock et. al, 2007). The results of this study indicate that smoking and caffeine consumption are inversely associated with Parkinson’s disease. The data suggests that “increasing dosage of caffeinated coffee was not significantly associated with a lower PD risk, whereas increasing intensity was marginally significantly associated with a decreasing risk of PD” (Hancock et. al, 2007). These trends did become significant, however, when considering total caffeine consumption, not just from coffee, which suggests that multiple caffeine sources must be considered when assessing the relationship between caffeine and Parkinson’s disease. The study report acknowledges that, due to the matching and controlling for confounding variables like age, sex, and race, the sample may not be representative of all Parkinson’s disease cases and may not be generalizable to the population level. Therefore, it is necessary to consider the results of several studies to verify the assumption that coffee consumption may be a protective factor for Parkinson’s disease.

            A prospective cohort study was done to examine the prediction of coffee consumption on the incidence of Parkinson’s disease. There were 6710 participants between the ages of 50-79. Baseline measures were taken to indicate the absence of Parkinson’s disease and the participants’ daily average coffee consumption. In the 22 year follow up, 101 incident cases were reported from the participant sample. Adjustments were made for various factors such as age, sex, marital status, leisure-time physical activity, etc. The results indicated a weak association between coffee consumption and Parkinson’s disease, though those participants who drank at least 10 cups of coffee per day were at a statistically significantly lower risk for PD compared to those who did not drink coffee at all.

            In assessing the results of these studies, it is necessary to note that inconsistent results could be related to a number of things. For example, the various studies may not have a standard “cup of coffee” size. Also, the strength of coffee and other caffeine sources in the participants’ diet need to be considered when examining the protective effects of coffee consumption on the risk for Parkinson’s disease.

 

Coffee and Type 2 Diabetes

            A prospective cohort study was done to examine the association between coffee intake and incident diabetes based on the oral glucose tolerance test (OGTT). Also, the study examined coffee drinking habits in participants with impaired glucose versus those with normal glucose at baseline. The baseline measures were taken from 1984-1987 in 910 adults over 50 years old without diabetes. The participants were followed until 1992-1996, which gave an average of eight years from baseline. Adjustments were made to account for confounds such as sex, physical activity, smoking, alcohol, and hypertension. The results indicated that “past and current coffee drinkers had a reduced risk of incident diabetes…compared with those who never drank coffee” (Smith et. al, 2006). Also the 317 participants who had impaired glucose at baseline that drank coffee (past or current) were at lower risk for developing incident diabetes. It can be concluded from this study that caffeinated coffee has a “striking protective effect against incident diabetes” (Smith et. al, 2006).

            The first study mentioned previously in relation to cardiovascular disease and coffee drinking also examined data from the Nurses’ Health Study and Health Professionals’ Follow-up Study in relation to the risk for type 2 diabetes mellitus. Results indicated that “total caffeine intake from coffee and other sources was associated with a statistically significantly lower risk for diabetes in both men and women” (Salaazar-Martinez et. al, 2004).

            In reviewing a previously published article by another author, Peyrin-Biroulet et. al (2007) points out that the protective effect of caffeine on risk for diabetes cannot be attributed to coffee consumption because “the inverse associations of coffee consumption with diabetes risk were stronger for decaffeinated coffee than for regular (caffeinated) coffee” (Peyrin-Biroulet et. al, 2007).  This author suggests that it is necessary to investigate the possible relationship between homocysteine-raising effects of caffeine and risk for diabetes. Homocysteine is an amino acid that is used by the body for cellular metabolism functions, as well as the manufacturing of proteins. Elevated levels are thought to be damaging to the lining of blood vessels and can increase the risk for heart disease (http://dictionary.reference.com/browse/homocysteine). This amino acid is also considered a risk factor for developing diabetes when it is at elevated levels in the body. Therefore, it can be concluded that perhaps “the lack of protective effect of regular coffee consumption against diabetes might be due to caffeine-induced hyperhomocysteinemia” (Peyrin-Biroulet et. al, 2007).

            It is evident from the discrepancy in findings of various articles that there are differences in the effect of coffee consumption and the risk for diabetes depending on type of coffee (caffeinated, decaffeinated) and also perhaps the brewing method. Those investigating the relationship between coffee and risk for diabetes must critically read articles and consider the results of more than one study to make a decision about what effects are truly relevant to their particular consumption habits.

 

Survey says…

            In looking at a number of studies on coffee consumption, it can be concluded that coffee does have some beneficial health factors to consider. However, depending on the particular benefit you are concerned with, it is important to note that many factors must be considered to determine this potential benefit. In some cases, it is very large amounts of daily coffee consumption that lead to beneficial outcomes, and in other cases it is total caffeine intake, not just from coffee. It is advised to examine studies carefully, as they often have inconsistent results with other findings or the circumstances and controlling factors from which they determine the benefits or particular health behaviors may not be relevant or directly applicable to the investigator. All health behaviors and environmental elements of a particular individual must be assessed, not just one (coffee consumption), in order to examine health risks and benefits. It may be an exaggeration to exalt coffee as the “latest health drink,” but your morning cup of coffee seems to be less harmful than many used to claim. 

           

             

            Literature Cited

 

 

Ebell, M. (2006). Coffee does not increase risk of developing heart disease.          American Family Physician, 74(8), 1408-1410.

 

Hancock, D.B., Martin, E.R., Stajich, J.M., Jewett, R., Stacy, M.A., Burton, L.S.,      et al. (2007). Smoking, caffeine, and nonsteroidal anti-inflammatory drugs     in families with Parkinson disease. Archives of Nuerology, 64, 576-580.

 

Pereira M.A., Parker E.D., Folsom, A.R. (2006). Coffee consumption and risk of   type 2 diabetes mellitus: an 11-year prospective study of 28,812           postmenopausal women. Archives of Internal Medicine, 166, 1311-1316.

 

Peyrin-Biroulet, L., Gueant, J., Roblin, X. (2007). Coffee and Diabetes: Is   homocysteine the missing             link? Archives of Internal Medicine, 167, 204.

 

Saaksjarvi, K., Knekt, P., Rissanen, H., Laaksonen, M.A., Reunanen, A.,   Mannisto, S. (2007). Prospective study of coffee consumption and risk of   Parkinson’s disease. European Journal of Clinical Nutrition, 1-8.

 

Salazar-Martinez, E., Willett, W.C., Ascherio, A., Manson, J.E., Leitzmann, M.F.,   Stampfer, M.J., Hu, F.B. (2004). Coffee consumption and risk for type 2             diabetes mellitus. Annals of Internal Medicine, 140(1), 1-8.

 

Smith, B., Wingard, D.L., Smith, T.C., Kritz-Silverstein, D., Barrett-Connor, E.        (2006). Does coffee consumption reduce the risk of type 2 diabetes in        individuals with impaired glucose? Diabetes Care, 29(11), 2385-2390.

 

Uiterwaal, C., Verschuren, W.M.M., Bueno-de-Mesquita, H.B., Ocke, M.,     Geleijnse, J.M., Boshuizen, H.C., et al. (2007). Coffee intake and       incidence of hypertension. American Journal of Clinical Nutrition, 85, 718-     723.

 

 

 

 

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