Coffee and the job: heartfelt insults?

Drinking coffee and working at a blue-collar job could be two strikes against someone fighting the leading cause of death in the United States. According to epidemiologic studies reported at last week's American Heart Association annual meeting in Washington, D.C., either of these life-style factors could contribute to heart disease.

Drinking five or more cups of coffee a day increases the risk of having heart problems 2.8 times, report researchers from Johns Hopkins Medical Institutions in Baltimore. After correcting for other factors--such as age, smoking habits and hypertenstion--they found heavy coffee drinkers still have 2.5 times the incidence of coronary heart disease compared with nondrinkers. Members of the research team say that, based on the findings, they now limit their own daily coffee intake to two cups, a decision labeled as premature by several physicians attending the meeting.

The controversy over coffee and heart disease is not new. Studies have linked coffee consumption to elevated blood cholesterol levles (SN: 6/25/83, p. 406) and heart arrhythmias (SN: 4/16/83, p. 249). The Nov. 15 JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION (JAMA) contains letters from physicians critical of research tying coffee intake to increased serum lipds, as reported in the March 8 JAMA (SN: 3/16/85, p. 173). Critics note that most studees have found no association between coffee and heart disease.

By using more subjects and a longer study period, the Johns Hopkins group says it avoided some of the flaws that critics found in earlier work. Data were collected at fiven earlier work. Data were collected at five-year intervals for up to 25 years on 1,130 male physicians, starting at their graduation from medical school between 1948 and 1964. The study also included annual surveillance for incidents of coronary heart disease.

According to co-researcher Andrea LaCroix, besides the increased incidence of heart disease in heavy coffee drinkers, other observations are worth noting. Those who drank a moderate amount (from two to four cups a day) had a twofold risk of heart disease. And the association between smoking and drinking coffee seen by others was supported by statistics LaCroix says indicate non-smokers "consistently showed lower coffee consumption throughout the 25-year study period."

Still, the Baltimore study did not collect information on the proportion of decaffeinated coffee ingested, or whether consumption was related to stress, considered by many to be another heart disease factor. Until more surveys are completed, LaCroix warns, results "should be interpreted cautiously."

Perhaps more unexpected than the coffee/heart disease results are those suggesting a blue-collar worker is 43 percent more likley to die of heart disease that the stereotypically sedentary white-collar worker. Because figures show that heart disease is more common in industrialized nations, researchers at Harvard Medical School in Boston looked at cardiac death in occupations with different physical demands. They used 568 case-control pairs in Florida found by collecting death certificates of married men who died between the age o f 30 and 70, and then selecting age-matched controls living within two blocks of the deceased. Using interviews with widows and wives about occupation and heart disease risk factors, the researchers were surprised at the results, says Harvard's Charles Hennekens. "The most plausible interpretation is an inverse relationship betwen white-collar occupations and mortality from coronary heart disease," he says.

Allowing that it would be "very premature to ascribe risks of coronary heart disease to occupation and the work place," Hennekens says epidemiologists need to determine whether something in the work place is contributing to the disease, or whether occupation is indicative of other known risk factors like diet.

The Harvard study agrees with another reported at this week's American Public Health Assocation meeting in Washington, D.C. Using Framingham (MASS.) Heart Study data from 2,292 men followed for 30 years, researchers at Boston University found men with very physical jobs had a 13.7 per 1,000 death rate from heart disease and cancer -- compared with sedentary men, who had an 8.5 per 1,000 rate.