How Coffee Can Help Fight Bad Breath

If you’ve ever worried your morning coffee might make your breath worse—or been told to avoid it for that reason—you’re not alone. But what if your daily cup could actually help fight bad breath instead?

Yes—according to Israeli scientists, coffee contains natural compounds that can significantly reduce the production of foul-smelling gases in the mouth. In some lab tests, coffee inhibited up to 90% of bad breath causing emissions.

What Causes Bad Breath?

Bad breath, or halitosis, starts in your mouth. Bacteria on the tongue, in the gums, and especially in dental plaque, produce volatile sulfur compounds (VSCs)—the primary culprits behind unpleasant mouth odors. These compounds are released when bacteria break down proteins in food particles, dead cells, and other organic debris in the oral cavity.

Certain foods like onions and garlic can worsen the issue. When you eat them, their sulfur-rich components enter your bloodstream, travel to your lungs, and are exhaled, prolonging the odor. Even healthy people often wake up with noticeable morning breath due to reduced saliva flow overnight, allowing bacteria to thrive.

The Surprising Coffee Discovery

Contrary to common belief, coffee may help combat bad breath. Researchers at Tel Aviv University, led by Professor Mel Rosenberg—a leading expert on halitosis—made an unexpected discovery while testing the effects of coffee on saliva.

In their experiment, they introduced various types of coffee—including two locally produced Israeli coffees and a Nestlé instant coffee—into test tubes containing human saliva. Initially, they expected the coffee to increase the production of foul-smelling gases. Instead, they found that coffee actively suppressed the formation of these gases. In several trials, coffee reduced VSC production by as much as 90%.

"We thought coffee caused bad breath," said Professor Rosenberg, "but we found that certain components in coffee actually inhibit it. It’s quite magical."

Why the Old Belief Is Wrong

It’s true that coffee can sometimes contribute to bad breath—but not for the reason most assume. When coffee is mixed with milk, the combination can dry out the mouth’s tissues and promote bacterial fermentation, leading to unpleasant smells. However, black coffee itself contains elements that counteract the very bacteria responsible for VSCs.

This means that while a milky latte might leave you with less-than-fresh breath, black coffee has properties that could help keep your mouth cleaner.

Future Applications in Oral Care

Professor Rosenberg and his team aim to isolate the specific compounds in coffee that suppress VSC production. Their goal is to develop new formulations for mouthwash, chewing gum, and breath sprays that don’t just mask bad breath but prevent it at the source.

Unlike traditional products that rely on mint or other flavorings to temporarily cover odors, these new solutions could contain coffee-derived agents that inhibit the formation of odor-causing bacteria and plaque. This could mark a shift from masking to preventing bad breath altogether.

Frequently Asked Questions

Does coffee really reduce bad breath?

Yes. Research by Tel Aviv University found that certain compounds in coffee can suppress the production of volatile sulfur compounds (VSCs) by up to 90% in lab tests using saliva samples, meaning it can reduce bad breath at the source.

Why do people think coffee causes bad breath?

Coffee is often blamed for bad breath because it can dry out the mouth and, when mixed with milk, may promote bacterial fermentation. However, black coffee itself contains elements that inhibit the bacteria responsible for foul-smelling compounds.

What bacteria cause bad breath?

Bad breath is primarily caused by volatile sulfur compounds (VSCs) produced by oral bacteria, especially on the tongue, in dental plaque, and along the gumline. These bacteria break down proteins and food particles, releasing foul-smelling gases.

Can coffee replace mouthwash or gum?

Not yet—but researchers aim to extract the active anti-VSC compounds in coffee to create new, more effective mouthwash, gum, or breath spray formulations that prevent bad breath rather than just masking it.

Does milk in coffee make bad breath worse?

Yes. Mixing coffee with milk can dry out the mouth and promote bacterial activity, which may worsen breath. Black coffee, however, has shown potential to reduce bad breath causing compounds.

What did the experiment with coffee and saliva show?

In lab tests, coffee—when mixed with saliva—reduced the production of foul-smelling gases by up to 90%. The initial hypothesis was that coffee would increase bad breath, but the results showed the opposite effect.

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