How do you take your tea? One lump of sugar, two or maybe some milk? Unless you're adding salt, one U.S. scientist says, your cup won't be perfect — a notion so controversial in the U.K. that even the American embassy is involved. 

Author and chemist Michelle Francl's push for salt in tea came to light with the release of her new book, "Steeped: The Chemistry of Tea," published Wednesday by the Royal Society of Chemistry. In the book, Francl argues that adding a pinch of salt to tea — not enough to taste — can make it seem less bitter, as the sodium helps "block the bitter receptors in our mouths," according to the Associated Press.

Brits were quick to react to the suggestion — and it didn't go well. 

"This feels like a crime," "Good Morning Britain" posted on social media Wednesday, sharing a video of one of its anchors saying such an addition is "absolute craziness." 

"I mean I've never heard anything like it," the anchor said. " ... Don't mess with a cup of tea. You can't add salt and warm the milk. I don't know what she's thinking." 

Popular social media account VeryBritishProblems said the book created a "bad day for special relations." 

"What will America recommend today, we wonder?" the account posted on Thursday. "Onions in a bowl of cereal? Mustard on Jaffa Cakes?"

Adding salt to tea is seemingly so scandalous that even the American embassy got involved. The U.S. Embassy in London issued a statement on Wednesday, saying that Francl's "'perfect' cup" recipe landed the embassy's relationship with the U.K. "in hot water."

"Tea is the elixir of camaraderie, a sacred bond that unites our nations. We cannot stand idly by as such an outrageous proposal threatens the very foundation of our Special Relationship," the embassy said. "...the unthinkable notion of adding salt to Britain's national drink is not official United States policy. And never will be." 

The embassy continued to say that it intends to show "steeped solidarity" with the people of Britain. 

"When it comes to tea, we stand as one," they said before quipping, "The U.S. Embassy will continue to make tea in the proper way – by microwaving it." 

An important statement on the latest tea controversy. 🇺🇸🇬🇧 pic.twitter.com/HZFfSCl9sD

— U.S. Embassy London (@USAinUK) January 24, 2024

Francl herself responded to the embassy's statement, writing on social media she didn't know her writing "would brew up such a storm." 

"If that's what it takes to shed light on the importance of chemistry, then I'm not bitter," she said. "Add that grain of salt and make that tea in the microwave and see!" 

How do you make the perfect cup of tea? 

Tea is a serious beverage across the U.K. One local company, The Kent and Sussex Tea and Coffee Company, conducted a survey in 2021 to determine what exactly people feel is the tried and true way of creating the beverage. 

Of the 2,000 people surveyed, the company found that 70% agreed that the right way to make tea is to place the tea bag to your cup, boil the water and then add milk — no salt to be found. 

While Francl argues in her book that tea should be made in a pre-warmed pot and served in a short and stout mug, the addition of milk at the end of the tea-making process is at least something she and Brits agreed on. But there is one more commonality: never heat the water in the microwave. 

"A white film can form," Francl told The New York Times. "Tea scum, like the scum in your bathtub, making a less scented, less tasty cup of tea." 

And if you do decide to make your tea via microwave and it develops a scummy surface, she said you can add "a little lemon." 

Salted tea isn't as odd as it sounds

While Brits are having trouble with Francl's recipe, adding salt to tea isn't as taboo elsewhere in the world. In fact, it's a practice that in some places has dated back centuries. 

Lancaster University virology professor Muhammad Munir said that adding salt to tea is "not a surprise." 

"A tiny pinch of salt in a kettle of tea is a norm in South East Asia," he wrote on social media, "and we grew up with a tiny bite of salt in bread, tea, on cut pieces of apple and watermelons."

In an article she wrote for Chemistry World that was published on Wednesday, Francl said that she's read hundreds of papers on the chemistry of what creates the perfect cup of tea, including a "famously extraordinary cup" that was outlined in an 8th century Chinese manuscript. 

In 2019, the South China Morning Post published an opinion piece on tea drinking traditions. One of those traditions dates back to China's Tang dynasty, which lasted from 618 to 907. During that time, the Post said tea leaves were crushed into powder, which then was compressed into blocks. When people would use those blocks to brew a pot of tea, they would add salt. 

Salt is a staple for making some teas in Tibet today, as well. One popular recipe, known as yak butter tea, involves brewing a dark fermented tea with a lot of salt and then serving it with yak butter and milk. 

"This is a funny US vs UK spat about tea, but just remember, it was always people in Central and East Asia which knew how to make tea, long before the British Empire arrived," writer and journalist Ramin Skibba posted on social media.

In:
• Food & Drink
• Science
• United Kingdom

Li Cohen

Li Cohen is a social media producer and trending content writer for CBS News.