After big sales gains a couple years ago, the market has suddenly crashed.

Oils are a major contributor of fat to our diets. However, though doctors seem to agree that different types of fat affect our health in different ways, not only does the debate rage over what those effects are, but the general consensus on what is healthy and what isn’t has shifted significantly over the decades. (An obvious example is the move from butter to margarine and back again.) Now, it appears that coconut oil has been the latest fat to get caught up in this hype rollercoaster. Insights firm SPINS says that after a boom as recently as 2015, sales of coconut oil came back to earth last year.

Across most retail markets, U.S. sales of coconut oil were up a whopping 38.8 percent in 2015, but then fell 5.2 percent in 2016 before crashing last year to the tune of a 25.9 percent decline, according to SPINS data recently published by FoodNavigator-USA. Needless to say, for coconut oil brands, the big question is why – but apparently there’s no single answer.

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SPINS senior nutrition researcher and insights lead Kimberly Kawa suggests that the press surrounding coconut oil has changed. “Perhaps, Medium Chain Triglycerides (aka MCTs), which are a component of coconut oil, have been in the spotlight more [than the oil itself],” she wrote. However, she also speculates that the trend-focused crowd that embraced coconut oil a couple years ago could have moved on to hipper fats like beef tallow and pork lard.

Meanwhile, evidence also suggests that whatever health halo coconut oil might have been riding is starting to wane. Kawa mentioned that “holistic professionals” may be turning against the once-hip oil. And Debbie Shandel, chief marketing officer at Carrington Farms, pointed out that news reports were behind the drop in her brand’s sales. “Negative press this past summer has caused some of the fall off of sales on the virgin coconut oil,” she told FoodNavigator, though she also said these claims have “since been debunked.” Indeed, last June, the American Heart Association came out against the oil.

Overall, the health experts that FoodNavigator spoke with seemed skeptical of coconut oil. “[The] growth in the popularity of coconut oil came almost entirely from the marketing community and not the science community,” said Tom Sanders, emeritus professor of nutrition and dietetics at King’s College in London. Sounds like consumers may simply be putting their coconut oil jar next to their old tub of margarine.