A front-page Washington Post article claims that the animal fat in milk and cheese may not be bad for your heart, after all. “Repeated research on milk, not funded by the industry but by public institutions, has provided evidence that the fats in milk are, for some reason, different,” the newspaper said.
That would be impressive…if it were true.
“In 2013, New Zealand researchers led by Jocelyne R. Benatar collected the results of nine randomized controlled trials on dairy products,” the article explained. “In tallying the tests on 702 subjects, researchers could detect no significant connection between consuming more dairy fat and levels of ‘bad’ cholesterol.”
The article went on to note that four of the nine studies included in the tally were funded by industry and that those results were consistent with those of trials funded by government entities.
the reality behind this research
Five of the nine studies assembled by the New Zealand researchers urged people to eat low-fat dairy, so it’s no surprise that their bad cholesterol didn’t climb.
Only one study—Benatar’s—tested high-fat dairy and had no industry funding or industry co-author. And in her study, people who were told to eat more high-fat dairy had higher LDL than those who didn’t change their diets.
“When studies are funded by the dairy industry, the results are predictable,” says Martijn Katan, emeritus professor of nutrition at Vrije University in Amsterdam. “They almost always have an answer that is useful for dairy marketing.” Katan is one of the world’s leading experts on dietary fat and cardiovascular disease.
how can industry funding influence the results?
“There are a number of ways to work toward the answer that you want,” explains Katan. “It depends on what kind of question exactly you ask, how many people are in your study, your statistical analyses, how carefully you do the study. If you have a small number of people and a sloppy study, you’ll get a zero answer.”
That may explain why the studies cited by Benatar found zero effect.
“For some 70 years now, studies have very consistently found that saturated fat raises cholesterol and polyunsaturated fats lower it,” says Katan. “There have been hundreds of trials, very high quality, done without influence by the industries like the meat and dairy industry that have a stake in the results.”
we’ve seen this tactic before
Dairy fat may indeed be different, but so far, the evidence is skimpy.
“If you want to say that dairy or that certain dairy foods have negligible effect on cholesterol, you need extraordinary evidence for such a claim,” notes Katan. “The evidence that we have is very weak and fragmentary. It doesn’t meet the regular standards in the field of diet and blood lipids.”
There’s a sense of déjà vu, he adds. “It’s a pattern with the dairy industry, that every five or ten years they’ll come out with some new intriguing component of dairy which their research shows is good for you and neutralizes the known effects of saturated fat.
“After a while the component is tested by independent researchers and shown to be not effective. And then it’s just a matter of time before the dairy industry comes up with something else. It’s not great science.”
Bottom line: The best studies don’t justify a switch from low-fat to high-fat dairy.
Sources: Washington Post October 6, 2015; PLoS One 8:e76480, 2013; Eur. J. Prev. Cardiol. 21: 1376, 2014.
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