People who like to start the day with coffee and a cigarette may be doing particular damage to their arteries, new research suggests.

Among 24 healthy young adults in the study, the combination of smoking and caffeine consumption temporarily increased stiffness in the aorta - the main artery carrying blood from the heart to the rest of the body - more than either caffeine or smoking did alone.

In fact, the effect of the cigarette-caffeine combo was more than just the sum of the effects of each, according to findings published in the Journal of the American College of Cardiology.

This means that tobacco and caffeine may act interact and work in a synergistic manner to harm the arteries over the long run, the study authors conclude.

Indeed, a second phase of the study, involving 160 healthy adults, found that those who were regular smokers and caffeine consumers showed the greatest stiffness in the aorta. This suggests that the combination does pose a particular threat to the arteries over time, according to lead study author Dr. Charalambos Vlachopoulos of the Athens Medical School in Greece.

The aorta is the largest artery in the body, and stiffness in the large arteries contributes to high blood pressure and forces the heart to work harder to meet the body’s needs. Over time, this can lead to complications such as heart attack and stroke.

The main message from the new findings, Vlachopoulos told Reuters Health, is, not surprisingly, that people who smoke should quit.

For those who have yet to quit, he advised avoiding heavy caffeine consumption - and not having a cup of coffee along with that cigarette.

In addition, Vlachopoulos noted, older adults and those with high blood pressure may be especially vulnerable to the combined effects of tobacco and caffeine.

For the first phase of their study, Vlachopoulos and his colleagues used non-invasive measures to estimate aortic stiffness in 24 healthy young adults who were regular smokers and caffeine consumers.

The measures were taken before and after each of four conditions: smoking one cigarette; smoking a cigarette after taking the equivalent of two coffee cups’ worth of caffeine; puffing on a “sham” cigarette; having a sham cigarette after taking phony caffeine pills. [1912, par 2]

Aortic stiffness, the researchers found, was greatest after the cigarette-caffeine combination, and the results of the larger, population study - where participants ranged in age from 18 to 60 - confirmed a similar one-two punch in those who regularly smoked and drank coffee.

According to Vlachopoulos, the immediate effects that caffeine and smoking had on the aorta may have to do with the release of certain hormones and central nervous system chemicals that affect artery function, blood pressure and heart rate.

Whether this explains the long-term harm linked to the caffeine-cigarette combo is less clear, he added, because researchers don’t yet know how regular caffeine intake affects the health and function of the arteries over time.

SOURCE: Journal of the American College of Cardiology, November 2, 2004.