Source: Tufts University

January 22, 2001

Introduction

Coffee consumption is an oft-studied consumer health habit, with much of the research focused on a possible connection between coffee intake and risk of cardiovascular disease. But, in spite of a substantial body of research on the subject, scientists do not yet have a clear picture of what effect, if any, regular coffee has on heart health. A study published in a recent issue of the Archives of Internal Medicine provides more food for thought about the relationship of coffee to heart disease in both men and women.

Assessing coffee consumption in Finland

In this latest analysis, Finnish researchers used information gathered during a national health survey to assess the usual coffee intake, smoking habits, and medical history of more than 20,000 men and women aged 30 to 59. They then followed the subjects for up to ten years, documenting the number of people who suffered a non-fatal myocardial infarction (MI) or died from any cause during that time.

After adjusting for age, smoking status, serum cholesterol level, blood pressure, and history of MI, the researchers found a U-shaped association between coffee consumption and total mortality in men, with the lowest risk among those who consumed 4 to 7 cups of coffee a day. (In this study, one cup was equal to 1.1 dL, or slightly less than 4 oz. Each cup contained 100 mg of caffeine, about the amount in 6 oz. of the type of coffee commonly consumed in the US.) In women, risk of death from all causes decreased as coffee consumption increased. There was no association between coffee intake and non-fatal MI or death from cardiovascular disease in either men or women.

Scores of studies have investigated a possible link between coffee and coronary heart disease (CHD) risk, with mixed results. Most cohort studies do not show a connection between coffee intake and heart disease, but many case-control studies have reported a positive correlation. Why the discrepancy?

Limitations of study designs limit its conclusions

The authors point out that cohort studies are conducted over extended periods of time, and are meant to capture the eventual consequence of a particular behavior on a health outcome. Case-control studies, on the other hand, often capture shorter-term associations. The researchers speculate that coffee intake may be a "triggering event" that precipitates an MI in those with existing CHD. In that instance, a case-control study would pick up on a transient effect that would be missed in a long-range cohort study. Another problem with case-control studies is that those with a diagnosis may tend to exaggerate their recall of events associated with the health problem, while those without the diagnosis may tend to under-report.

Also, in spite of researchers' efforts to control for confounders, it is difficult to separate one particular habit--like coffee consumption--from all the other lifestyle factors that can have an effect on health. This study and others have shown that high coffee consumption is positively correlated with heavy cigarette use and elevated serum cholesterol, both potent risk factors for heart disease. (Lipid-rich components in boiled coffee, once a mainstay of Finnish meals but now largely replaced by filtered coffee, may have contributed to an increase in total and LDL cholesterol levels in earlier studies. It is not known if intake of boiled coffee had a significant impact on the serum cholesterol levels of the people in this study.)

Should recommendations change?

Although interesting to read, these research findings don't warrant any new recommendations about coffee consumption. Rather, they reinforce the current advice that coffee, like all other food and drink, is best consumed in moderation - which in the United States, translates to about 2 to 3 cups of filter-brewed coffee a day.

Source

Coffee And Parkinson's Disease

In the past 30 years, nine studies have shown that regular coffee consumption over time may reduce the risk of Parkinson's Disease. PD is an incurable and debilitating disease affecting 1 million Americans, including actor Michael J. Fox and former Attorney General Janet Reno. Sufferers develop tremors and have difficulty in moving their arms and legs.

Six retrospective studies found that people who drank coffee on a regular basis were 50% - 80% less likely to develop Parkinson's disease than those who did not consume coffee. (1-6) Three of the studies showed a dose-response relationship-strong support that the more one consumes coffee, the less likely the risk of developing Parkinson's Disease (1-3).

Further, in a prospective study covering 30 years, the more coffee consumed by men during the late 1960s, the lower their risk of Parkinson's disease when they were examined in the 1990s (7). The finding was consistent whether coffee intake was determined by 24-hour recall or by food frequency questionnaire. The association was also observed for coffee intake measured at different examinations six years apart. Similar significant relationships were observed for total caffeine intake and caffeine from non-coffee sources. The authors of this study concluded, "it appears caffeine may be the responsible constituent."

Alberto Ascherio, associate professor of nutrition and epidemiology at Harvard School of Public Health, led a team in conducting a second large prospective study that followed women and men from the Nurses' Health Study and the Heath Professionals Follow-up Study. In their study, 47,000 male health professionals were followed for 10 years and 88,000 female health professionals were followed for 16 years (8).

As with the other prospective study, it found a strong dose-response relationship, starting with one cup of coffee. At the upper limit, men consuming the equivalent of four to five cups of coffee a day had half the risk for the disease as those who consumed little or no caffeine. For women, those who had one to three cups a day had the lowest risk. Consumption of decaffeinated coffee did not lower the risk.

If regular consumption over a span of decades seems to protect, how does it do so? One of the characteristics of Parkinson's patients is the reduced amount of dopamine in certain areas of the brain. Mice whose brain dopamine content has been depleted exhibit some symptoms of Parkinson's disease. In a 1991 study, caffeine given to these mice prevented the development of Parkinsonian symptoms (9).

In a laboratory study published in 2001, mice were given a chemical that depletes dopamine in important areas of the brain. Levels of caffeine intake comparable to human consumption successfully reduced the amount of dopamine depleted in the brain as well as the physical symptoms typical of Parkinson's Disease in humans (10). These latest experiments, published in the Journal of Neuroscience and led by Michael Schwarzschild and Jiang-Fan Chen (assistant professors of neurology at Harvard Medical School), revealed caffeine's neuroprotective effect in slowing down the progression of Parkinson's Disease by its ability to block the adenosine A2A receptor.

The recent lab and epidemiology studies offer a rare convergence of scientific research addressing the same problem from two different but complementary angles. "The difference between the animal experiments and the epidemiology is that they [the animal experiments] can prove causality, but they cannot generalize to humans," Professor Ascherio told Focus newsletter, the publication of Harvard's Medical, Dental and Public Health Schools (May 18, 2001 issue). "We [epidemiologists] work directly on humans but we cannot prove causality. That's why the two papers are nicely complementary to each other, because the two together strengthen the case for a causality in humans."

References

1. Hellenbrand W, Boeing H, Robra BP, Seidler A, Vieregge P, Nischan P, et al. Diet and Parkinson's disease. II: A possible role for the past intake of specific nutrients. Results from a self-administered food-frequency questionnaire in a case-control study. Neurology 1996;47:644-50.

2. Fall PA, Fredrikson M, Axelson O, Granerus AK.Nutritional and occupational factors influencing the risk of Parkinson's disease: a case-control study in southeastern Sweden. Movement Disorders 1999;14:28-37.

3. Benedetti MD, Bower JH, Maraganore DM, McDonnell SK, Peterson BJ, Ahlskog JE, et al. Smoking, alcohol, and coffee consumption preceding Parkinson's disease: a case-control study. Neurology 2000;55:1350-8.

4. Nefzger MD, Quadfasel FA, Karl VC. A retrospective study of smoking in Parkinson's disease. American Journal of Epidemiology 1968;88:149-58.

5. Jimenez-Jimenez FJ, Mateo D, Gimenez-Roldan S. Premorbid smoking, alcohol consumption, and coffee drinking habits in Parkinson's disease: a case-control study. Moving Disorders 1992;7:339-44.

6. Morano A, Jimenez-Jimenez FJ, Molina JA, Antolin MA. Risk-factors for Parkinson's disease: case-control study in the province of Caceres, Spain. Acta Neurologica Scandinavia 1994;89:164-70.

7. Ross GW, Abbott RD, Petrovitch H, Morens DM, Grandinetti A, Tung KH, et al. Association of coffee and caffeine intake with the risk of Parkinson's disease. Journal of the American Medical Association 2000;283:2674-9.

8. Ascherio A, Zhang SM, Hern½n MA, Kawachi I, Colditz GA, Speizer FE, et al. Prospective study of caffeine consumption and risk of Parkinson's disease in men and women. Annals of Neurology 2001;in press

9. Popoli P, Caporali MG, Scotti de Carolis A. Akinesia due to catecholamine depletion in mice is prevented by caffeine. Further evidence for an involvement of adenosinergic system in the control of motility. The Journal of Pharmacy and Pharmacology 1991;43:280-1.

10. Chen JF, Xu K, Petzer JP, Staal R, Xu YH, Beilstein M, et al. Neuroprotection by Caffeine and A2A Adenosine Receptor Inactivation in a Model of Parkinson's Disease. Journal of Neuroscience 2001;21:RC143.