McDonald's has admitted that its French fries contain a third more artery-clogging fat than it previously thought, citing results of a new testing method.
That means the level of so-called 'trans fat' in a portion of large fries is 8 grams, up from 6 grams, with total fat increasing to 30 grams from 25 grams.
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.
The disclosure comes as McDonald's starts rolling out packaging in the US containing facts about menu items' nutritional content - a move made voluntarily but with the fast-food industry under pressure from consumer groups and the government to provide more information.
McDonald's said it updated the nutrition information on its website last month as soon as it discovered the new level of trans fat. It announced the discovery only on Wednesday, saying an improvement in the testing process has made results more accurate.
'As part of our ongoing voluntary efforts to provide our customers with the best science-based information, we continually enhance our testing,' said Cathy Kapica, global nutrition director for Oak Brook, Illinois-based McDonald's.