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Latest coffee health report not up to snuff.

Latest coffee health report not up to snuff

In the New England Journal of Medicine (323:1026-1032) of October 11, 1990, Dr. Walter Willet of the Department of Epidemiology at Harvard School of Public Health, and five colleagues published a report supported by a research grant from the National Institute of Health. The paper was entitled: "Coffee, Caffeine and Cardiovascular Diseases in Man."

The major conclusion of this report is extremely gratifying to both coffee roasters and consumers. It states: "Findings do not support the hypothesis that coffee or caffeine consumption increases the risk of coronary heart disease or stroke".

It is one of the minor results of this study wherein lies the mystery. Among the men drinking four or more cups of regular coffee daily, risk of heart trouble was practically the same as that for drinking no coffee or one cup or less per day. However, among men drinking four or more cups of decaffeinated coffee daily, the incidence of heart trouble or stroke was twice as great as among those who drank the same amount or less of regular coffee or no coffee. The authors concluded that this was statistically significant.

On the other hand, common sense tells us that this is unbelievable. How can decaffeinated coffee, with its potent active ingredient removed, be hazardous to health while regular coffee is not? It is almost like assembling data from a large group of beer drinkers, demonstrating that non-alcoholic beer is more intoxicating than the regular six-pack, or that low tar, low nicotine cigarettes are more unhealthy than the full flavor brands.

Could it be the type of coffee used? No data was presented as to how frequently soluble decaffeinated was used versus fresh brewed. Could it be the blends? Again there were no details as to the proportion of Brazilians, Milds or Africans. If solubles were the coffees of choice, could it be the solvent used for removal of caffeine? Still no data was presented in this area, but in any event, current solvents such as water or carbon dioxide are undoubtedly free from hazard; and other solvents used, such as ethyl acetate or even chlorinated hydrocarbons, have been determined to leave insufficient residue to be potentially harmful.

I examined the details of this study to see if there were any obvious flaws. Somewhat over 50,000 men, age 40 to 75 in 1986, were involved. These included about 30,000 dentists, almost 4,000 optometrists, 2,000 osteopathic physicians and 10,000 veterinarians. They all returned mailed questionnaires on their medical history, smoking habits, and family history of heart disease and strokes. About 5,000 individuals were eliminated from the study because of previous medical problems or they did not provide complete information on diet, height and weight, etc.

As part of the initial survey, the participants provided food frequency data on their average intake of 131 foods and beverages from memory during the previous year. Questions about caffeinated and decaffeinated coffee and tea divided them into frequency categories of none; one cup per day or less; two to three cups per day; and four or more daily. Total caffeine consumption was calculated by the addition of the amounts from coffee, tea, cola beverage along with that from chocolate candies, cakes and cookies.

Since memory of what you ate last week, last month, or last year is often unreliable, the validity of the reported consumption of these and other dietary factors were verified. A total of 127 participants weighed and recorded all foods and beverages consumed at each meal for two one-week periods, six months apart. Later they completed another questionnaire from memory, identical to the initial one. Memory data was accurate to within 10-15% of actual results.

Biennial follow-up was completed in 1988. After six mailings, 96% return was achieved. Results were all in the same experimental range with the exception for those drinking four or more cups of decaffeinated coffee daily.

Among the 45,000 participants, 83% drank coffee; and 69% reported the use of regular caffeinated type. Those that did not drink coffee were slightly younger and leaner than those who did. Coffee imbibers were twice as likely to smoke than the others, but proportion of smokers in the entire group was only about 10%. Other characteristics were broadly similar throughout the population.

The report concludes: "Men drinking caffeinated coffee exhibited no increase in risk of cardiovascular disease or stroke with higher intake. Rather the estimate of relative risks were below 1.0 for total coronary disease or total cardiovascular difficulties in those drinking four or more cups per day. There was a positive trend, however, toward an association between a higher consumption of decaffeinated type and a marginally significant increase in the risk of coronary heart disease and total cardiovascular disease with increased consumption. Because fewer participants drank decaffeinated than caffeinated coffee, the confidence interval for the estimates for decaffeinated were wider. Multivariate analysis changed the risk estimate only slightly. No apparent association was observed between consumption of tea and the risk of cardiovascular endpoint; however, only 664 men drank four or more cups of tea per day."

"In this study of multivariate analysis, relative risk is adjusted for age, smoking habits, history of diabetes, parental history of heart trouble, specific health profession, dietary intake of energy, cholesterol and fat types and total caffeine consumption. For reliable conclusions, 664 tea drinkers are considered too few."

A possible solution to the mystery of why decaffeinated should present a greater risk than regular coffee was immediately suggested by a coffee-loving psychologist: People who have switched from regular to decaffeinated coffee, drinking four or more cups per day are not your run-of-the-mill healthy individuals. Usually they are serious coffee fanatics who forego their caffeine with the greatest reluctance. In this group of well educated, trained, health care workers, most are not swayed by the deluge of anti-caffeine propaganda that has caused many of the lay public to switch. This group consists of individuals who recognize the many benefits they receive from the stimulant in their beverage. On the other hand, they are first to recognize in themselves possibly some incipient symptom which they can attribute to their caffeine ingestion. These may not be serious enough yet to necessitate medical attention, but they hope that these physiological reactions, often the result of aging or genetic defects, may be delayed, postponed or even banished by abstention from caffeine. It is little wonder, that in a group like this, there should occur a greater incidence of heart or stroke problems, where coffee is the marker or indicator of this effect and not the cause. In other words, the problem may be with the group and not with the decaffeinated coffee.

131 dietary components were assessed quantitatively in 45,000 individual men, only one component of which was coffee. Could not one of the other components bear equal or possibly greater responsibility in causing heart trouble, stroke, or circulation problems?
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Title Annotation:Harvard School of Public Health report "Coffee, Caffeine and Cardiovascular Diseases in Man"
Author:Lee, Samuel
Publication:Tea & Coffee Trade Journal
Article Type:column
Date:Feb 1, 1991
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