By Anjali Athavaley NEW YORK (Reuters) - General Mills Inc said on Tuesday that it had reduced sodium by at least 20 percent in seven product categories, fewer than it had targeted, as part of the food industry's effort to cut back on an ingredient said to increase the risk of serious illnesses. The maker of brands like Cheerios cereal and Yoplait yogurt said in 2010 that it was targeting a 20 percent reduction in 10 product categories by 2015. According to the American Heart Association, excess sodium consumption can increase risk of stroke, heart disease and other health problems.