WASHINGTON — Consumption of high-fructose corn syrup, used to sweeten products from Coca-Cola to HJ Heinz ketchup and linked to obesity, is falling in the United States as health-conscious consumers drink less soda and the cost of corn soars.

The amount of corn devoted to the sweetener this year will fall to its lowest level since 1997, according to a Jan. 15 projection by the U.S. Department of Agriculture.

“A lot of attention has been paid to obesity, and that’s hurt high-fructose corn syrup,” said Marion Nestle, a public-health and nutrition expert at New York University.

Americans consumed an average of 131 calories of the corn sweetener each day in 2011, down 16 percent since 2007, according to the most recent USDA data. Meanwhile, consumption of sugar rose 8.8 percent to 185 calories daily.