Don't read this before lunch. Diners are finding cockroaches, flies and human hair in their food, and complaints are piling up.

There were 19,094 complaints about inedible items in food in stores or served in restaurants in the nearly six years since fiscal 2009, the National Consumer Affairs Center of Japan said Monday.

In the period from last April to Jan. 10 this year, consumer affairs offices nationwide received 1,852 complaints. Of them, 345 were about insects, 253 referred to pieces of metal, and 202 were human in origin: hair and teeth found in food, for example.

In all, 104 complaints related to boxed food, 90 concerned rice, and there were 88 complaints about frozen products.

The figures come after a series of revelations of tainted food served in McDonald's Holdings Co. (Japan) outlets, including bits of plastic found in cooked products such as Chicken McNuggets.

The number of complaints is roughly steady at about 2,000 every year, although there was a spike of 6,477 in fiscal 2013, after a worker laced frozen food products with pesticide at a factory of Aqlifoods Co. The incident led to a criminal case.

The number of complaints about problems such as mouth injury and stomachache reached 3,191 in the period.

"If you find a foreign object, report the case to retailers and request surveys," an official of the center said.