Susanna C. Larsson, Ph.D. of Karolinska Institutet in Stockholm, Sweden and colleagues on Dec 16, 2010 published a study online in the journal Stroke suggesting that eating processed meat may boost risk of stroke.

Dr. Larsson is a veteran researcher at Karolinska Institutet, a medical university that is one of the best universities in the world.  

For the study, Larsson and colleagues prospectively followed for 10.4 years 34,670 women who were free of cardiovascular disease and cancer at baseline. In 1997, all participants completed a questionnaire on diet and other risk factors for cardiovascular disease.

During the follow-up, the researchers identified 1680 incident cases of stroke of which 1310 cerebral infarction, 154 intracerebral hemorrhage, 79 subarachnoid hemorrhage and 137 strokes with their types unidentified.

Consumption of total red meat and processed meat was correlated with significantly increased risk of cerebral  infarction, but not of total stroke, intracerebral hemorrhage or subarachnoid hemorrhage.

To be specific, those whose intakes of red meat and processed meat was in the highest quintile, compared with those in the lowest quintile, were 22 percent and 24 percent more likely to suffer cerebral infarction, respectively.

However, the researchers found consumption of  unprocessed or fresh meat was not correlated with total stroke or with any subtype of stroke.

Renata Micha RD, Ph.D. of Harvard School of public Health and colleagues on May 17, 2010 published a review article online in Circulation suggesting processed meat, but not red meat may boost risk of coronary heart disease and diabetes mellitus.

Micha et al. reviewed previous studies and did not found any association between consumption of red meat and processed meat with stroke. But they acknowledged that only three studies evaluated the correlation.

Larsson et al. also published another study in March, 2011 in the journal of Stroke suggesting that drinking coffee more than 1 cup per day may help cut risk of stroke by 20 to 25 percent compared with those who drank less.

Apparently Larsson' findings were based on the same set of data derived from the same study population.

Larsson et al. suggested that coffee may act as an antioxidant to help mitigate inflammation and neutralize oxidation, which may otherwise increase risk of stroke. 

But they also found caffeinated tea was not associated with any reduced risk of stroke.  This suggests that caffeine may not be the constituent in coffee that is responsible for the reduction in the risk of stroke.

It is unknown why consumption of processed meat including red meat was linked to increased risk of stroke.

Leila Azadbakht and Ahmad Esmaillzadeh of Isfahan University of Medical Sciences in Isfahan, Iran on Dec 11, 2008 published a study in the Journal of Nutrition saying that high intake of red meat was associated with increased risk of metabolic syndrome and inflammation.

Could the increase in the stroke risk have something to do with the preservatives used in the processed meat or some carcinogenic chemicals like nitrosoamines that are produced in the processed meat?

It should be noted that all the studies that have been done are observational, meaning that the results are suggestive of a possibility only.

David Liu