The Japanese government has set up a comprehensive plan and system to monitor food from affected areas. The WHO and FAO are keeping track of the situation, and the FAO has praised government efforts to keep the food supply safe.
The fears of radiation have decreased purchases of fresh foods, both agricultural and marine.
Produce from Ibaraki Prefecture, to the northeast, has been hard hit because of the discovery of spinach with unacceptable levels of radiation.

Markets have plenty of fresh fish and vegetables from unaffected areas, despite the devastation of part of the Tohoku area, including farms and small fishing villages.

Food exports from Japan are small, less than 0.5% of total exports (seafood about half of this).

Alarmist blogs are being printed in the U. S. by vehicles such as the Majirox News, staffed by former underground writers, and in UK by their large yellow press.

MSN News, April 3, 2011; "Radiation Discovery Fans Food Fears in Japan."