A systematic review of international trials of baby formula suggests the findings were not reliable, and the studies may even have discouraged the women taking part from continuing to breastfeed.
The paper, led by Drs Bartosz Helfer and Robert Boyle at Imperial College London was published in the British Medical Journal.
Dr Zhaoli Joy Dai-Keller is an epidemiologist at the Australian Institute of Health Innovation at Macquarie University and the Charles Perkins Centre at the University of Sydney, where she specialises in chronic disease prevention and management.
She is part of the Australian research team for the paper, contributing to the study design and critically reviewing the evidence.
"The formula industry is very closely involved in most of these trials," Dr Dai-Keller said.
"We found 84 per cent of the trials received support from the formula milk industry.
"Findings are almost always reported as favourable, and there is little transparency about the aims of the trial or the reporting of results.
"Our findings support the need for a substantial change in the conduct and reporting of formula trials to ensure participants are being protected from harm and consumers shielded from misleading information."
The release of the findings coincided with the health talk series for Nutrition for Growth Summit organised by the World Health Organisation and UNICEF the week of October 11-14.
Formula feeding is common globally for children under the age of three, and it has been increasing in recent years.
It has been associated with a range of health risks compared to breastmilk, including colic, constipation, various infections, and fatal diarrhoea in developed and developing nations.
The study evaluated the conduct and reporting of 307 infant formula trials between 2006 and 2020, with a detailed analysis of 125 trials between 2015 and 2020.
Dr Dai-Keller said the findings were worrying.
"About 80pc of the trials had a high risk of bias, mainly because of inappropriate exclusions from analysis and selective reporting," she said.
"Most of the recent trials did not have clearly defined study aims, and just 14pc were conducted independently of formula companies.
"Primary outcomes were reported as favourable in 69pc of these trials, with 92pc reporting favourable abstract conclusions.
"Of great concern was the fact that the trials were not protecting breastfeeding in their participants.
"Just one of 38 trials in partially breastfed infants reported adequate support for breastfeeding, and out of 87 trials in non-breastfed infants, only 14 confirmed the decision not to breastfeed had been firmly established before enrolment in the trial."
Dr Dai-Keller said that in Australia, just under a third of children aged between six months and three years had been exclusively breastfed to six months in 2017/18.
"We hope the findings of this study will act as a wake-up call to researchers involved in formula milk trials and parents' feeding decisions for their young children," she said.
"A number of organisations, including the Australian government and the World Health Organisation, recommend breastfeeding as the optimal feeding method for babies."
Want to read more stories like this?
Sign up below to receive our e-newsletter delivered fresh to your email in-box twice a week.
