Mrs van Dam, whose children are 2 and 4, had difficulty breastfeeding but said she was unable to get information about using formula from medical professionals.
"The restriction will have a backlash beyond just taking formula advertising from the public eye. As a consumer I have a right to as much information as reasonable, with regards to products that I choose to use."
A commission spokeswoman said there had been one formal submission against its decision. In addition, six members of the public had made complaints or given feedback.
"Some of these had the mistaken belief that a ban of infant formula was proposed, when this is not the case," she said.
No ban on either formula or its advertising had been proposed. "The absence of advertising and marketing in this space is voluntary and industry-led. The INC code has been in place since 2012."
The INC represents manufacturers and importers of brands including Karicare, Aptamil, Nurture, Nan, S-26, as well as Fonterra formula brands. The group applied for authorisation of its code of practice by the commission to protect its members from any court action under the Commerce Act, from the commission or a private individual.
Under the act, practices that could reduce competitive pressure and therefore make consumers worse off, are prohibited. This could include the INC's practice of not advertising and marketing products.
INC spokeswoman Jan Carey said the decision would not see any changes made to the current restrictions on infant formula marketing or selling in New Zealand. The application to the commission was out of concern for INC members' compliance with the Commerce Act.
In relation to Mrs van Dam's concerns, Ms Carey said the aim of the code of practice was to ensure all infants had access to safe and adequate nutrition, including infant formula when necessary.
"Health practitioners have a duty to provide information about infant formula when necessary under the Ministry of Health's Health Workers Code.
"If mothers need information about infant formula it should be readily available and no restrictions have been applied about providing this information."
A Plunket spokeswoman said the organisation supported exclusive breastfeeding for the first six months due to its health benefits.
"If breastfeeding is not possible, or if a family decides they want to use infant formula, then they are entitled to the advice they need. ... we provide relevant and accurate information to support parents to make the best choices for their baby."
The ministry also recommended exclusive breastfeeding to around 6 months. Information on formula feeding is available on the ministry's website.
Your views
Not all mothers are able to [breastfeed] and should not have alternatives restricted visually or otherwise.
Deborah FitzPatrick
It will put even more pressure on mothers who are unable, for many legitimate reasons, to breastfeed their babies.
Verna Morgan
It's hard enough to find info on formula and bottle feeding as it is.
Derryn W
I think this is a bit unfair on those mothers who can't breastfeed.
Anon