Urban pollution can trigger subtle changes linked to heart disease in young, healthy adults, according to a study of students at Fu-Jen Catholic University in Taipei. Exposure of one to three days is enough to adversely effect four key heart disease indicators, including coagulation in blood vessels, the National Taiwan University study found. 'They can hardly feel the effects,' says team leader Chan Chang-Chuan. 'But there are changes.' The pollution levels involved were typical of major cities, Reuters reports.

School's out for obese children

Obese primary schoolchildren miss about two more days of school a year on average than their normal-weight classmates, a University of Pennsylvania study has found - putting them at risk of problems later such as drugs and teen pregnancy. Socioeconomic status, age and gender were assumed to be the key predictors of absenteeism, but researchers say weight tops them all, AP reports. 'Missing school is such a major set-up for big-time problems,' says team leader Andrew Geier. It's not clear why, but underweight children are absent significantly less often.

If at first you don't succeed ...

Most picky eating is inherited, according to a University College London study of more than 10,700 twins which found that food fear, or neophobia, is 78 per cent genetic. The researchers say despairing parents shouldn't worry, WebMD reports: most picky eating can be overcome in time 'with repeated presentation'. But they say bribery or punishment usually fails.

Something to chew over

There's growing evidence of a strong link between stress and gum disease, an analysis by researchers at the State University of Campinas in Brazil has found - although it's not clear why. The researchers say elevated levels of the stress hormone cortisol may be a factor. And people under stress tend to have poorer health and use more nicotine, alcohol and drugs, WebMD reports.

Jason Sankey is a tennis professional