Claims made by a Japanese TV channel about the slimming powers of natto, or fermented soya beans, have led to a broadcasting row.
Newspapers have criticised TV shows for exaggerating health claims
Kansai Television Corporation aired a show this month that said eating natto morning and night had helped people lose up to 3.5kg.
The programme triggered a buying frenzy, emptying shelves of the sticky beans in shops across Japan.
But the show's producers have admitted that some of the data was false.
They said that the US professor shown in the programme was not the one who did the original research. He was also misquoted.
KTV said it still believed the diet could help people slim.
But its president, Soichiro Chugusa, said he was sorry his company had damaged viewers' trust over the mistakes that were made.
Japanese newspapers vented their anger at the programme, whose name in English is Encyclopaedic Discovery.
The top-selling Yomiuri Shimbun said the show had harmed the credibility of the television media sector as a whole.
It said the loss of trust was incalculable.
The Mainichi Shimbun said in an editorial commentary that popular media tended to exaggerate or give misleading information to keep their ratings high when reporting on weight loss or other health issues.