(2023-04-13) What If Ice Cream Is Actually Good For You

What If Ice Cream Is Actually Good for You? Back in 2018, a Harvard doctoral student named Andres Ardisson Korat was presenting his research on the relationship between dairy foods and chronic disease to his thesis committee. One of his studies had led him to an unusual conclusion: Among diabetics, eating half a cup of ice cream a day was associated with a lower risk of heart problems

This was obviously not what a budding nutrition expert or his super-credentialed committee members were hoping to discover. “He and his committee had done, like, every type of analysis—they had thrown every possible test at this finding to try to make it go away. And there was nothing they could do to make it go away.”

The dissertation explained that he’d hardly been the first to observe the shimmer of a health halo around ice cream.

Pereira and his co-authors tested these old ideas using data from a study, begun in 1985

Pretty much across the board—low-fat, high-fat, milk, cheese—dairy foods appeared to help prevent overweight people from developing insulin-resistance syndrome, a precursor to diabetes

But the international media coverage didn’t mention what I’d seen in Table 5. According to the numbers, tucking into a “dairy-based dessert”—a category that included foods such as pudding but consisted, according to Pereira, mainly of ice cream—was associated for overweight people with dramatically reduced odds of developing insulin-resistance syndrome. It was by far the biggest effect seen in the study, 2.5 times the size of what they’d found for milk.

The results of Harvard’s first observational study of dairy and type 2 diabetes came out in 2005. Based on data collected from just one of their three cohorts, following men between 1986 and 1998, the authors reported that higher dairy intake, and higher low-fat-dairy intake in particular, was associated with a lower risk of diabetes. “The risk reduction was almost exclusively associated with low-fat or non-fat dairy foods,”

Yes, according to that table, men who consumed two or more servings of skim or low-fat milk a day had a 22 percent lower risk of diabetes. But so did men who ate two or more servings of ice cream every week

The Harvard researchers didn’t like the ice-cream finding: It seemed wrong. But the same paper had given them another result that they liked much better. The team was going all in on yogurt.

“Higher intake of yogurt is associated with a reduced risk” of type 2 diabetes, “whereas other dairy foods and consumption of total dairy are not,” the 2014 paper said. “The conclusions weren’t exactly accurately written,” acknowledged Dariush Mozaffarian, the dean of policy at Tufts’s nutrition school and a co-author of the paper, when he revisited the data with me in an interview. “Saying no foods were associated—ice cream was associated.”

So how did the Harvard team explain away the ice-cream finding?

it wouldn’t be that ice cream prevented diabetes, but that being at risk of developing diabetes caused people to not eat ice cream.

To test this idea, Hu and his co-authors set aside dietary data collected after people received these sorts of diagnoses, and then redid their calculations. The ice-cream effect shrank by half, though it was still statistically significant, and still bigger than the low-fat-dairy effect that Harvard had publicized in 2005.

“We didn’t believe in it,”

Hu, the Harvard nutritionist, said that deciding what a study means requires looking beyond the numbers to what is already known about dietary science: “You need to interpret the data in the context of the rest of the literature.” Mozaffarian, Hu’s co-author, echoed this view. Still, he noted, “you’re raising a really, really important point, which is that when, as scientists, we find things that don’t fit our hypotheses, we shouldn’t just dismiss them. We should step back and say, ‘You know, could this actually be true?’ ”

there are at least a few points in its favor. For one, ice cream’s glycemic index, a measure of how rapidly a food boosts blood sugar, is lower than that of brown rice.

In 2017, the YouTuber Anthony Howard-Crow launched what Men’s Health called “a diet that would make the American Dietetic Association shit bricks”: 2,000 calories a day of ice cream plus 500 calories of protein supplements plus booze. After 100 days on the ice-cream diet, he’d lost 32 pounds and had better blood work than before. (2017-05-04-ThisGuyLost32PoundsOnTheIceCreamDiet)

To be clear, none of the experts interviewed for this article is inclined to believe that the ice-cream effect is real, although sometimes for reasons that differ from Hu’s.

once you start contemplating all the ways that cultural biases can seep into the science, it doesn’t stop at dairy-based desserts. If the ice-cream effect can be set aside, how should we think about other signals produced by the same research tools?

Many stories can be told about any given scientific inquiry, and choosing one is a messy, value-laden process

If there’s a lesson to be drawn from the parable of the diet world’s most inconvenient truth, it’s that scientific knowledge is itself a packaged good. The data, whatever they show, are just ingredients.