Coffee continues to grab headlines. Being an avid coffee drinker, it would suggest that I’m doing myself no harm whatsoever if I drink at least three cups a day. The latest research is suggesting that ‘moderate’ drinking i.e. 3 and 5 cups of coffee apparently reduces the early onset of atherosclerosis because it prevents calcium build-up in the arteries. This has lead to headline grabbing claims that it might reduce the risk of stroke and heart attacks which compete with other studies that claim the opposite.
Studies of any kind which can lead to bold statements or controversy always need to be examined carefully. The NHS quite rightly is more cautious than the newspapers over the latest research and it pays to examine their interpretation in the light of more sensationalist articles. However, it is always interesting to see not just the study but to witness an increasing body of clinical research into coffee and its benefits. One study had looked at the reduction in type 2 diabetes and improvements to insulin sensitivity with drinking coffee and another study with multiple sclerosis, endometrial cancer and melanoma skin cancer.
This recent study examined 25,000 people in middle-age and their coffee drinking habits. It suggested that those who drank little or too much coffee were at greatest risk from calcium deposition in the coronary arteries. Any clogging up of these major blood vessels is a sure sign that heart disease is possible if not probable. A meta-analysis of 36 clinical studies suggested that drinking the beverage in moderation could actually protect the heart and the optimum benefit was imbibing three to five cups per day.
Generally, a lot of earlier studies had indicated that drinking coffee had a negative impact, that it did promote heart attacks because it raised levels of cholesterol in the blood stream and increased blood pressure i.e. hypertension. It was the conflicting evidence that prompted a further look at moderate coffee drinking.
The studies conducted at the Kangbuk Samsung Hospital in Seoul assessed thousands of patients attending for health screening with an average age of 41 and no heart disease, for the presence of coronary artery calcium (CAC). They conducted food frequency questioning and CT scanning. This aspect of mineral deposition is one of the earliest signs of blockage of an artery because it promotes hardening and narrowing of these vessels. Continued blockage ultimately leads to heart disease, stroke and attacks. This study also included a questionnaire on their diet and smoking history.
The idea of ‘moderation’ is the most interesting. The Korean researchers grouped the patents in the study into those drank no coffee, less than one cup a day, one to three cups, three to five cups and over five cups per day. The group belonging to the three to five cups category had the least amount of coronary artery calcium (CAC). The next lowest group for CAC were those in the one to three cups per day grouping. Those drinking less than one cup a day appeared to have calcium levels as high as those drinking five cups a day hence the conclusions. There was a U-shaped association !
A number of confounding factors were also examined. These are factors that need to be taken into account when assessing multifactorial impacts on conditions like diabetes and heart health. So, education, smoking, exercise and physical activity, family histories, the body mass index, diet, consumption of fresh vegetables and fruits versus processed foods and meat for example etc. were all assessed. None of these factors were directly linked to the findings save they had no impact on the final significance of the findings.
The link to diabetes is an interesting feature of coffee because that condition increases the risk of arteries becoming harder. If there is a strong association between coffee and diabetes reduction which is linked to an absence of artery hardening then coffee drinking would be a benefit. The other aspect might be an improvement in insulin sensitivity and beta-cell function. The next questions might be determining exactly how much and what the components responsible happen to be. Good guesses look at the various acids such as chlorogenic acid for example and then there is caffeine and there is always the genetic question.