Hard evidence

Pollution, too much fat, thicken your arteries

 
Published: Tuesday 31 January 2006

Reality check scientists in the us have found that air pollution and a high-fat diet can together cause atherosclerosis (hardening of arteries) in laboratory mice. The findings are significant as the fine particulate concentrations used in the study were well within the range found in metropolitan areas.

Conducted by the Mount Sinai School and the New York School of Medicine, the study involved 28 mice divided into two equal groups. One group was fed regular diet (normal chow) and the other a high-fat diet (high-fat chow).

Some mice from both groups were then exposed to concentrated ambient particles measuring less than 2.5 microns (one micron equals a millionth of a metre) and some to filtered air in Tuxedo, New York for six hours per day, five days per week, for six months. The average particle exposure during the study was 15 microgrammes per cubic metre, which was well below the federal air quality standard of 65 microgrammes per cubic metre in a 24-hour period. After the exposure, the researchers measured the plaque (a fatty deposit in blood vessels which can cause heart attacks and strokes) formation in the aorta.

The results showed that mice fed on a high-fat diet and exposed to fine particles had 1.5 times more plaque formation than others, which were fed the same diet but were exposed to clean filtered air. The study has been published in the December 21, 2005 issue of the Journal of American Medical Association (Vol 294, No 23).

The study also showed that amongst the high-fat diet group, the artery walls of the mice exposed to fine particulates were significantly more inflamed than their cleaner-air counterparts. This implies that fine particulate exposure accelerates the development of atherosclerosis in the high-fat group.

However, no significant differences in plaque formation and artery wall inflammation were noticed in mice fed on a regular diet and exposed to fine particulates.

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