Former National Party MP Katherine Rich will not be investigated by the Health Promotion Agency after she was accused of undermining its work.
Ms Rich is chief executive of the Food and Grocery Council, which represents the food industry, and was appointed by the Government to the board of the Health Promotion Agency.
Thirty-three senior health researchers signed a letter to Prime Minister John Key in response, asking for an inquiry into Ms Rich's position with the agency.
One researcher, Professor Boyd Swinburn from Auckland University, said Ms Rich's role in lobbying for processed food and alcohol became clear in the Nicky Hager book, Dirty Politics.
The book suggested the former National MP was involved in a right-wing blogger's attacks on public health researchers and academics.
"She's sitting on the board of the Health Promotion Agency, while at the same time she's denigrating public health professionals, and undermining public health policy, when it is totally incompatible with her role as a board member," said Professor Swinburn.
But Ms Rich has denied she has been involved in any campaign to undermine public health, and has refused to resign from the agency.
And the agency's chairperson, Lee Mathias, has now reaffirmed her faith in Ms Rich.
Dr Mathias said she had not read the letter, but had no doubt about Ms Rich's integrity. She described Ms Rich as an active supporter of the agency.