White bread ‘healthier’ than whole grain? Why readers should avoid these half-baked stories

File this under definitely NOT the best thing since sliced bread.

Headlines claiming that “Whole Grain Bread Might Not Actually Be Healthier Than White Bread.” 

It’s the latest turn of the clickbait merry-go-round powered by preliminary studies whose conclusions may change from week to week.

Despite the ephemeral nature of the findings, some journalists breathlessly cover these studies with overblown “good for you/bad for you” headlines and superficial reporting.

It’s a trend that does real harm to the public’s understanding of nutrition, according to Yoni Freedhoff, MD, director of the Bariatric Medical Institute in Ottawa and a contributor to HealthNewsReview.org.

“If a study even remotely infers a dietary outcome that people want to hear it would seem that many journalists, in their mad rush for clicks, check their integrity at the door and produce the most idiotic of headlines – all at the expense of the consequently ever-more-confused public,” he says.

As usual, it starts with a news release

Take this Men’s Fitness story headlined “Could white bread be better for you than whole wheat? It depends on your gut.”

It leans heavily on a news release put out by the study authors’ institution and includes no comment from an independent expert. Unsurprisingly, given the source material, it features no warning about the limitations of research that involved just 20 participants who were studied for a mere two weeks.

Ditto for this fluffy Newsweek piece, which references the same news release, and which pins white bread’s apparent healthiness to its impact on glycemic response — a measure of blood sugar levels two hours after eating.

The gist is that differences in gut bacteria between individuals might determine how we process specific foods, and that people with certain bacterial profiles might metabolize white bread just fine.

That’s an intriguing hypothesis. But let’s remember that this is just one lab value, measured for two weeks, out of potentially dozens that might contribute to a food’s overall “healthiness” over the long term. Not to mention the vitamins, minerals, and other nutrients that may play a role in determining a food’s health effects.

Some journalists were more thorough

Ed Yong, writing in The Atlantic, had one of the only stories that I’d describe as more than a Wonder Bread take on the study. He reached out to Tufts University nutrition professor Susan Roberts, who cautioned not to make too much of the study’s findings on various health markers like cholesterol and blood pressure.

“Of course you wouldn’t expect to see significant effects in one week, with a small amount of bread, in 20 people,” she says. “That doesn’t mean there isn’t an effect. It just means this study was underpowered.” Susan Jebb, a professor of diet and population health at the University of Oxford, concurs. “It’s a weak study design, and I wouldn’t want to draw any conclusion from this analysis,” she says.

Moreover, among the stories that I read, Yong’s was the only one that adequately conveyed that this tiny study doesn’t exist in an evidence vacuum.

A single study like this also cannot refute a large body of epidemiological evidence showing that people who eat more whole-grains tend to have lower risks of cancer, heart disease, type 2 diabetes, and other conditions. If you assume that these effects are causal, rather than just correlational, it may be that you need to eat a lot of whole grains, over long periods of time, to experience any benefits. Alternatively, large population-wide studies might mask the fact that only some people would benefit from these foods.

Is there money to be made on this story?

I’ll conclude with one last item that journalists could have done a better job on: identifying a conflict of interest.

Several news stories gave prominent play to this quote, cribbed from the news release, from one of the study authors, Eran Elinav: “These findings could lead to a more rational approach for telling people which foods are a better fit for them, based on their microbiomes.”

But again, among those stories that I read, Yong’s was the only one that informed readers that Elinav consults for a company called Day Two that claims to offer personalized nutrition recommendations via a mobile app. The company’s pitch sounds pretty much the same as the idea that Elinav was selling in the news release.

“What’s healthy for others may not be healthy for you. Discover which foods help balance your blood sugar, based on your gut microbiome.”

Take home points for consumers

To summarize, here’s the context that more journalists covering the story could have provided:

• This is one study, with only 20 people, studied for a grand total of two weeks. In short, weak evidence.
• The conclusions are based on differences in one lab value, not a health outcome that anyone should care about.
• The headlines are contradicted by a large body of evidence which may also have limitations, but is much stronger than this single tiny study.
• The study authors have a financial interest in promoting the concept conveyed in these news stories — that dietary recommendations should be personalized based on one’s gut microbiome.

We offer resources for journalists to do better. Readers deserve more than half a loaf.

This post has been revised to reflect that Ed Yong’s piece in The Atlantic acknowledged the researchers’ relationship with Day Two.