Breastfeeding controversy offers lesson to researchers about conflicts of interest

New and controversial recommendations regarding breastfeeding point out how financial conflicts of interest by researchers can muddy the scientific waters.

Those recommendations, published last week in BMJ (once known as the British Medical Journal) suggest that breast milk should be supplemented with solid foods starting around the age of four months, two months earlier than currently recommended by the World Health Organization (WHO). According to the reviewers, delaying the introduction of solid foods increases a baby’s risk of developing anemia, food allergies and celiac disease.

Not true, according to a response from WHO [PDF]. The organization’s decade-long no-solid-foods-until-six-months recommendation is “based on evidence that the early introduction of solid food to babies increases the risk of infection and disease,” the response says — and then picks apart the BMJ reviewers’ arguments one by one.  

This challenge to the WHO recommendation is a bigger official issue in Great Britain than here in the United States. We never adopted the WHO recommendation, but the U.K. did in 2003. Ironically, however, it seems that more American than British moms are following it. The BMJ review says that less than 1 percent of British mothers exclusively breastfeed their babies for six months. That compares to 13 percent here in the United States, as reported by the Centers for Disease Control and Prevention.

It seems to me that both sides — the authors of the BMJ review and WHO — are relying too much on observational studies, which can show only possible associations between two things (say, breastfeeding and food allergies), not cause and effect. Many observational findings, such as those that claimed that menopausal hormone therapy protected women against heart disease, have infamously turned out to be wrong once randomized, controlled trials (considered the gold standard in research) were conducted.

But the authors of the new BMJ review have an additional problem: Three of the four authors acknowledge that they have received funding within the past three years from companies that manufacture infant formula and baby food.

They, of course, claim that their industry connections have nothing to do with their new recommendation. “My colleagues and I are independent pediatricians and scientists, funded by universities or hospitals, and we received no funding for doing this review other than our normal salaries,” the review’s lead author, Mary Fewtrell, a child nutritionist at University College London, told NatureNews reporter Natasha Gilbert. “All of us have had links with industry at some point. We are making no comment in our paper about what type of solid foods should be introduced — this could be home-prepared or commercial depending on the mum’s choice — the main issue is that the food should be nutritionally adequate and safe.”

But the connection between the authors and the baby food industry has to raise questions about the independence of their findings. Indeed, the review itself points to a strong motivation within the baby food industry to get British health officials to change their current advice to mothers to breastfeed exclusively until six months if possible. British moms (or mums) are slowly pushing back the age at which they introduce solids to their babies:

Successive surveys since the 1970s showed that nearly all [British] infants received solids by four months (for example, 85% in the 2000 survey), but in 2005 the figure dropped to 51% and the mean age of introduction of solids was 19 weeks, a rise from 15 weeks in 2000. … In view of the higher reported rates of exclusive breast feeding to six months elsewhere in the West (more than 30% in Hungary and Portugal, for example), it seems likely that the impact of the UK recommendation will be greater in 2010 than in 2005. It is timely to consider whether such trends could influence health outcomes.

It would also seem extremely timely, therefore, for baby food companies to consider whether such trends are going to damage their bottom line — and to financially support, even if not always directly, the research efforts of “friendly” academics.

And that’s why researchers who accept money from industry shouldn’t be surprised to find their studies and recommendations — and, yes, their motives — questioned.