When Calgary-based food writer Julie Van Rosendaal asked followers in a social media post last month whether they too were finding butter was no longer soft at room temperature, her “buttergate” musings went viral.

“Nigella Lawson tweeted me,” Van Rosendaal told CBC, referring to the famous English food writer. “I knew we would connect over butter and we did — two times. The Times of London called the other day. I did Radio Melbourne, Australian Broadcasting Corporation. Did I mention Nigella yet?”

However, the questions Van Rosendaal raised about the chemistry of butter were perhaps just as intriguing as the media storm she unleashed. She suggested butter’s supposed new hardness could be the result of dairy farmers feeding higher levels of supplements containing palm oil by-products to cows.

Palm oil-based supplements are used in part because they increase the fat content of dairy products. Van Rosendaal suggested pandemic-fueled demand for high-fat dairy in home kitchens might have encouraged farmers to feed their cows a higher-calorie diet to meet the demand.

That suggestion is freighted because palm oil comes from the fruit of oil palms. Its widespread use in food and beauty products has led to the clearing of forests in parts of Indonesia and Malaysia for oil-palm monoculture.

The resulting biodiversity losses, including losses of endangered orangutans, has raised concerns not just among environmentalists, but also consumers. Plus, saturated fats such as palm oil are linked to an increased risk of heart disease and chronic health conditions.

It’s no surprise then that media reports raised the question of whether increased use of palm oil-derived palmitic acid in dairy cow diets was in fact causing butter to remain hard at room temperature.  The short answer – according to experts such as Dalhousie University animal physiologist Leslie MacLaren – is “unlikely, but conceivable.” The longer answer is more interesting.

What does the science say?

There has been little research on the impact of palm-oil derived supplements on milk and its products. But here is what chemists and animal health experts do know: palm oil is very high in palmitic acid, a long-chain saturated fatty acid with 16 carbon atoms. As a saturated fat, palmitic acid has a higher melting temperature than unsaturated fats and can contribute to butter’s firmness.

If more dairy farmers feed their cows palm oil-based supplements, more of the resulting milk and could potentially have a higher melting point and remain firmer at room temperature.

But two things make that unlikely, says MacLaren. The first is that for the past two decades, dairy farmers in Canada, the United States and other countries have known that feeding their cows low levels of palm-derived supplements (0.5-2% of their diet) in the early stages of lactation can provide an energy boost to the animals when they need it most – in other words, this is not a ‘new’ trend.

Some choose to include it in their rations, but many don’t. There are no data to suggest Canadian dairy farmers have increased those levels in the last few months or years.

“It works best at low levels,” says MacLaren. “The optimum level is about 1.5%. This is not a situation where more is better.”

The second thing that makes palmitic acid supplements an unlikely culprit is that about one-third of the fatty acids in milk fat (thus butter) are palmitic acid that the cow produces naturally. “The small amount of supplementation is unlikely to have a significant influence on butter hardness,” says MacLaren.

Université Laval animal scientist Rachel Gervais agrees. “Milk fat is a very complex matrix with more than 400 different naturally occurring fatty acids. The melting point of butter will depend on the combination of all these fatty acids,” says Gervais. “So, looking at the concentration of only one fatty acid is not going to give you a definite answer.”

She says while it’s true that feeding palm oil by-products to cows will slightly increase palmitic acid concentration in milk fat, it will also decrease the concentration of other saturated fatty acids.

Researchers suspect that’s because the cow’s milk-synthesizing process regulates the proportion of saturated fatty acids to ensure optimum fluidity of the milk.

But is butter actually harder now?

There is no scientific research confirming or refuting the notion that butter has become harder at room temperature. While the Dairy Farmers of Canada has expressed skepticism that butter is in fact any harder, it is sensitive to criticism over palm oil and has convened an expert committee to investigate.

In the meantime, the organization has asked dairy farmers “to consider alternatives.” Les Producteurs de lait du Québec has gone further, calling on its members to stop using them entirely.

Experts say it may be hard to single out the impact of one feed supplement because there are many factors that influence milk fat composition and thus butter characteristics.

The cow’s breed, age, feed, season, stage of lactation can all affect milk’s fat profile. Processing conditions – such as temperature and agitation – used to convert milk fat into butter can also affect the product’s hardness. Creameries can alter those conditions to optimize butter characteristics for consumers.

Like the Dairy Farmers of Canada, MacLaren is skeptical about claims that butter is harder these days.

“The butter on my counter still spreads nicely on my bread and melts into big mess when I forget to take it away from the sunny window,” she says.