MEXICO CITY—Congress's lower house of Congress passed late Thursday a special tax on junk food that is seen as potentially the broadest of its kind, part of an ambitious Mexican government effort to contain runaway rates of obesity and diabetes.

The House passed the proposed measure to charge a 5% tax on packaged food that contains 275 calories or more per 100 grams, on grounds that such high-calorie items typically contain large amounts of salt and sugar and few essential nutrients.

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