CHICAGO -- McDonald's french fries just got fatter _ by nutritional measurement. The world's largest restaurant chain said Wednesday its fries contain a third more trans fats than it previously knew, citing results of a new testing method it began using in December.

That means the level of potentially artery-clogging trans fat in a portion of large fries is eight grams, up from six, with total fat increasing to 30 grams from 25.

Often used by restaurants and in packaged foods, trans fats are thought to cause cholesterol problems and increase the risk of heart disease. The dietary guidelines for Americans that were issued by a government panel last year said people should consume as little trans fat as possible.

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