Toenails the key to the heart?
2008-06-06 07:16
New York - Toenail clippings may help to identify women who have a risk of suffering from heart disease in the future, researchers said.
Toenails grow slowly so by analysing the nicotine content in clippings scientists may get a stable and long-term estimate of a person's exposure to tobacco smoke.
Toenail analysis "could become a useful test to identify high-risk individuals in the future, especially in circumstances when smoking history is not available or is subject to bias", said Dr Wael K Al-Delaimy of the University of California in San Diego.
Scientists examine biomarkers of cigarette smoke, such as the amount of a nicotine breakdown product called cotinine, in urine or saliva. But it only reflects exposure within the past few days, according to Al-Delaimy and his team.
The researchers correlated the nicotine content in toenail clippings collected in 1982 for 62 641 women participating in the Nurses' Health Study to the risk of being diagnosed with heart disease between 1984 and 1998.
The women in the top fifth for toenail nicotine content were thinner, less active, heavier drinkers, and more likely to have high blood pressure or diabetes, as well as a family history of heart attack, compared to those with less nicotine in their toenails, the researchers found.
Also, the 905 women who had been diagnosed with heart disease had twice as much nicotine in their toenails, on average, as similar women without heart disease.
After the researchers adjusted for other risk factors, they found that women in the top fifth for toenail nicotine had nearly four times the risk of heart disease compared to those in the bottom fifth.
The findings, which are reported in the American Journal of Epidemiology, suggest that measuring nicotine levels in the toenails "may improve the assessment of exposure and therefore our understanding of tobacco-related illnesses", the researchers said.