Cyanide is a poison. Rattlesnake venom is a poison. Certain household products can be a poison. But coconut oil? One professor seems to think so, colliding head-on with consumers who believe it's good for them.
In her lecture at the University of Freiburg -- entirely in German and posted in July -- professor Karin Michels, of the university's Institute for Prevention and Tumor Epidemiology, calls the health claims surrounding coconut oil "absolute nonsense" and says it's "pure poison" for its saturated fat content and its threat to cardiovascular health. The video of her lecture has amassed close to a million views and counting.
"Coconut oil is one of the worst things you can eat," Michels said.
While others have taken a more measured view, they hardly buy into the ballyhoo. A 2016 survey in the New York Times suggested that 72% of Americans think coconut oil is healthy, versus only 37% of nutritionists polled.
"There are many claims being made about coconut oil being wonderful for lots of different things, but we really don't have any evidence of long-term health benefits," said Dr. Walter C. Willett, professor of epidemiology and nutrition at the Harvard T.H. Chan School of Public Health, where Michels is also an adjunct professor.
"Coconut oil is somewhere in the middle of the spectrum in terms of types of fats. It's probably better than partially hydrogenated oils, (which are) high in trans fats, but not as good as the more unsaturated plant oils that have proven health benefits, like olive and canola oil," Willett previously told CNN.
Health organizations tend to discourage the use of coconut oil, which is more than 80% saturated fat. The American Heart Association says it's better on your skin than in your food, and it recommends that no more than 5% or 6% of your daily calories come from saturated fats -- about 13 grams per day. The association also advocates replacing coconut oil with "healthy fats" such as polyunsaturated fats and monounsaturated fats, like those found in canola and olive oils, avocados and fatty fish.
Coconut oil is "probably not quite as 'bad' as butter but not as good as extra virgin olive oil," Kevin Klatt, a molecular nutrition researcher at Cornell University who is studying the metabolic effects of coconut oil, previously told CNN.
Klatt cautions that we should not develop too strong of an opinion of it without more data. "But at the same time, you have to be evidence-based ... and (currently), the evidence reflects benefits for olive oil, fish, nuts and seeds -- so that should be the focus in the diet."
Coconut oil is extracted from the meat of the fruit. It contains mostly saturated fat, which is also found in large quantities in butter and red meat. Like other saturated fats, coconut oil increases LDL cholesterol, commonly known as "bad" cholesterol, which has been associated with increased risk of heart disease.
But coconut oil also raises HDL, the "good" cholesterol, especially when replacing carbohydrates in the diet. This may be due to its high content of a fatty acid known as lauric acid. (This is also noted in Michel's statement summarizing her talk.)
"Coconut oil is half lauric acid, which is a little bit unique," Klatt said, as the acid seems to raise HDL more than other saturated fats and is rarely found in such high amounts in foods.
Still, though the increase in HDL seen with consumption of coconut oil may offset some of the disease risk, it's still not as good as consuming unsaturated oils, which not only raise HDL but lower LDL, according to Willett.
Complicating matters is the fact that we still don't know for sure what exactly a high HDL translates to in terms of health risk. "There's been debate about the role of HDL," Willett cautioned. "Partly because there are many forms of HDL which have different health consequences ... which has made the water murky."
For example, there are different forms of HDL that do different things. One role is to help take LDL cholesterol out of the bloodstream. "But some forms of HDL don't do that," Willett said, "so we don't know for sure that higher HDL is better."
While an elevated LDL level is used as a marker for predicting cardiovascular risk and doesn't always translate to heart attacks, experts say it's still cause for concern.
Research has found a mixed bag when it comes to saturated fats, and coconut oil in particular. A 2015 Cochrane review found that cutting back on saturated fats also lowered the risk of cardiovascular disease by 17% -- but it didn't change the risk of dying, and there was no benefit to replacing these fats with protein or starchy foods.
Other research specifically on coconut oil has explored its effects on metabolism, appetite and cognitive function -- but "you can't infer from ... studies what coconut oil will and will not do. We need better controlled trials," Klatt said.
"Right now, the internet is jumping the gun and going way beyond the evidence."
Like other oils, coconut oil is calorie-dense, which means consuming large amounts without reducing other calorie sources can lead to weight gain. Just one tablespoon has 120 calories, about the same as a large apple or four cups of air-popped popcorn.
"Oil is a really easy way to increase the energy density of a food. Things like almonds have a lot of fat, but it's easier to overeat pure oil than overeat pure almonds," Klatt said.
In small amounts, however, coconut oil can have a place in one's diet. But for day-to-day use, experts recommend vegetable oils such as olive, canola or soybean oil, along with nuts and seeds, as a primary source of fats in the diet.
"It's not that you have to absolutely avoid coconut oil, but rather limit coconut oil to where you really need that special flavor, like for Thai food or for baking a special dessert," Willett said.
Klatt agreed, saying that coconut oil "is certainly fine to consume occasionally, when a recipe calls for it."
'Pure poison:' Harvard professor issues warning about coconut oil