French toast anyone?

Still, a man hears what he wants to hearAnd disregards the rest.              Simon & Garfunkel The Boxer 1969

When we had our first baby nearly thirty years ago, we were told to always put her face down in her cot to sleep. Eighteen months later, when we had our second, the nurses at the maternity told us never to put him face down to sleep, but always on his side. Two years later we had our third child; we were firmly told to always put him on his back to sleep, never on his side (because he could roll over), and never face down (because he could suffocate). By the time our fourth child was born we were back to square one. The nurses at the maternity firmly told us to always put him face down to sleep. (I don’t know the current recommendations.)

Marketing can play a role as well. When our first baby was born we bought standard paper nappies (diapers). By the second child we had a choice between boys’ nappies (in a blue box) and girls’ nappies (in a pink box). By our fourth child the nappy company was massively marketing a new breakthrough: “Unisex” nappies!

Food—what is healthy and what isn’t—is subject to even stronger trends (and fads).

I can remember as a young teenager being sent out by my mother to search the local shops for grapefruit. A “study” at that time had found that certain compounds in grapefruit burned body fat; eating it regularly could promote fat loss. My mother, along with half of the UK population, started to eat half a grapefruit before every meal. Within a couple of weeks there wasn’t a single grapefruit left in the country. Supply couldn’t keep up with the sudden spike in demand.

It may be that the water in grapefruit helps you feel full, and then you eat less. But if you’re hoping that grapefruit will melt fat, you’re going to be disappointed.

Back in 2014, two enterprising German journalists carried out a “scientific” study that “proved” that eating chocolate helps you to lose weight. The whole thing was a hoax, but they managed to get the study published in a scientific journal, and sent out press releases to all the media. Within a week it was on the front page of all the newspapers. None of those newspapers verified the story or checked on how vigorous and exhaustive the study was; they based their stories entirely on the press release.

In 1984 the US government published the results of what Time magazine described as “the broadest and most expensive research project in medical history”. The Time story introduced cholesterol to the world and was accompanied by its infamous cover photo of bacon and eggs. The study behind the article is now considered to be seriously flawed, but it led to millions of people around the world changing to a low-fat diet.

Thirty years later, Time put butter on their front cover, telling their readers, “Scientists labeled fat the enemy. Why they were wrong.” However, the study highlighted in the article also appears to be seriously flawed. The Harvard School of Public Health wrote,

“What the headlines miss is that in a meta-analysis such as this, there is no specific comparison (i.e. butter vs. olive oil), so the default comparison becomes butter vs. the rest of the diet. That means butter is being compared to a largely unhealthy mix of refined grains, soda, other sources of sugar, potatoes, and red meat…Here is the most important takeaway from this study not making headlines: Butter, a concentrated source of saturated fat, is still a worse choice than sources of healthy unsaturated fats such as extra virgin olive, soybean, or canola oils.”

An article published last week in the Journal of the American Medical Association (JAMA) adds to the criticism by arguing that many published meta-analyses have combined the findings of studies that differ in important ways, mixing apples and oranges—“and sometimes “apples, lice, and killer whales”—yielding meaningless conclusions.” Far from increasing statistical power, these meta-studies are reducing it or causing real correlations to disappear.

One of the meta-analyses they discuss was the 2014 study examining the connection between saturated fat and coronary artery disease. The authors of that study combined data from vegetarians in Oxford with meat eaters in Sweden, diluting its results with what probably amounts to a big false-negative.

In an article earlier this week, New Food Economy argues, “Journals are mostly interested in studies with new and striking results—results that go against the conventional wisdom, even if that wisdom is correct. Add in the influence of industry and you get a situation where the published research turns one-sided.

New Food Economy went on to explain that according to a US lawsuit filed in early 2016 (that was dismissed), the egg industry funded 29 percent of studies on dietary cholesterol in 1992—but 92 percent in 2013. It seems to be working. Not only is butter back, eggs are too!

Next week: The great butter shortage—how can the food industry cope with sudden demand shifts?

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