New research from the San Francisco Fed plays down the impact the central bank’s very expansionist monetary policy stance has had on commodity prices.

The paper, written by staff economists Reuven Glick and Sylvain Leduc, sought to shed light on the critical question of the Fed’s influence over commodity prices. There has been increasing concern that zero-percent short-term rates joined with a massive program to buy long-term bonds is catalyzing a surge in all manner of commodity prices, from food stuffs, to raw material for factories, through to energy prices.

No one can doubt that over recent months, commodity prices have jumped. Fed officials have by and large argued the blame for these increases must be placed not on their shoulders, but elsewhere. Speaking Friday in Puerto Rico, New York Fed President William Dudley said commodity-price gains “have virtually nothing to do with U.S. monetary policy” and can instead be attributed to the impact of a growing world economy coupled with supply disruptions resulting from bad harvests and political unrest.

Finding an explanation is important because of what can happen to inflation. Overall price pressures are rising amid a deterioration in short-term inflation expectations, and that may mean underlying price pressures will start to rise too quickly.