CHICAGO - Food and fuel prices have boosted U.S. inflation by only a small amount in recent years, despite two unprecedented commodity price spikes, according to a study published Monday by the San Francisco Federal Reserve Bank.

The finding suggests that concern over the inflationary effects of commodity price increases may be overdone.

Oil, natural gas and agricultural crops accounted for only one percentage point of the 10-percent cumulative rise in personal consumption expenditures prices from January 2007 to December 2011, the researchers showed in the most recent issue of the San Francisco Fed's Economic Letter.

"We estimate that crops, oil,and natural gas make up about 5 percent of the cost of consumer goods and services, mostly through their direct consumption as food and fuels," wrote senior economist Galina Hale, senior reseach advisor Bart Hobijn, and Harvard University undergraduate Rachna Raina.

"When commodity price movements are taken into account, we find that their contribution to overall inflation is limited."