Every morning, long before you reach for coffee or breakfast, most of us make one of the day’s first taste choices: the sweetness in our toothpaste.
But unlike a spoonful of sugar in your coffee, the sweetness from many toothpastes doesn’t come from sugar, it often comes from artificial or low‑calorie sweeteners. And emerging research suggests this seemingly small choice may have ripple effects on metabolism, cravings, and even oral microbiome balance.
Let’s unpack why that first sweet hit might be more impactful than you realise — and why choosing the right sweeteners in oral care (like xylitol and stevioside) matters.
A sweet trigger before breakfast?
When you taste sweetness, whether from sugar or a sweetener, your body doesn’t just register flavour. It also initiates a set of physiological responses designed for when food should be entering your digestive system.
One such response is called the cephalic phase insulin response (CPIR). This is an early burst of insulin release triggered by sensory cues, especially taste, before digestion and absorption even start. The theory is that when the brain detects sweetness, it signals the pancreas to release a bit of insulin in anticipation of incoming glucose, helping with blood sugar regulation overall. (1)
This response is subtle but real: studies have shown that mouth stimulation with sweet solutions can modestly increase insulin release, even without calories being ingested. (2) That means your first taste of sweetness in the morning — from toothpaste — may send a metabolic signal before you’ve eaten a single bite!
Toothpaste sweeteners: a mixed bag
Many conventional toothpastes include artificial sweeteners such as saccharin, sucralose, or aspartame. These compounds are generally approved as safe, but they’re different from natural sweeteners and sugar alcohols in how the body and microbiome respond to them.
Research suggests that some artificial sweeteners may alter the gut microbiome and could be correlated with disrupted glucose and lipid metabolism when used persistently and in larger amounts. (3)
Meanwhile, other studies point out that artificially sweetened products often affect the body differently than simple sugars, particularly in how they interact with gut and oral microbes. (4)
But this is where toothpaste is different from eating or drinking sweetened products, the amounts ingested are tiny, and the goal is oral care, not systemic energy intake. Still, the type of sweetener used can matter greatly for how your body perceives sweetness first thing in the morning.
Why Xylitol shines (especially in toothpaste)
Xylitol isn’t just “a sweet taste with fewer calories.” It’s a sugar alcohol that behaves differently from both sugar and high‑intensity artificial sweeteners.
1. It doesn’t spike glucose or require insulin -
Xylitol has a low glycemic index and doesn’t trigger significant glucose or insulin spikes. In fact, it doesn’t require insulin for its metabolism at all. (5)
2. It fights harmful oral bacteria, rather than feeding them -
Bacteria responsible for dental caries, notably Streptococcus mutans thrive on sugars! Xylitol, however, cannot be fermented by these bacteria. Instead, when they try to use it as fuel, their energy pathways get “clogged,” which can lead to reduced bacterial growth and lower plaque acidity. A large systematic review shows that low‑intensity sweeteners like xylitol consistently reduce cariogenic bacteria in plaque and saliva, far more so than many high‑intensity artificial sweeteners. (6)
3. It may help support a healthier oral environment -
Regular exposure to xylitol (as found in toothpaste, gum, or oral rinses) has been linked with reduced plaque and lower caries rates, particularly in clinical settings where it’s used regularly. (7)
Importantly, because toothpaste use delivers small quantities topically (not large amounts swallowed), xylitol in toothpaste doesn’t come close to the oral or gastrointestinal doses that might cause digestive upset, like bloating or diarrhoea, effects that only occur with high ingestion (far above what’s in toothpaste). (8)
What about Xylitol and the gut microbiome?
Some online concerns suggest that xylitol could harm the gut microbiome. However:
Evidence in human studies does not support significant disruption of gut bacteria from small, topically applied xylitol such as that found in toothpaste (far below dietary doses). (9)
Sugar alcohols like xylitol aren’t fully absorbed in the intestine, but effects are generally dose‑dependent, and adverse outcomes are linked to large amounts consumed orally, not incidental toothpaste ingestion. (5)
In the oral cavity, xylitol’s non‑fermentability is a strength: it doesn’t feed harmful bacteria, reducing acid production and potentially lowering the risk of caries. (10)
Stevioside: a complimentary natural sweet alternative
Stevioside (a steviol glycoside from the Stevia plant) used in your toothpaste also offers sweetness without glucose metabolism. It doesn’t add calories, doesn’t feed oral bacteria, and research suggests it may even support healthy glucose responses when used as a sugar replacement in food. (11)
Stevioside and xylitol together combine favourable taste with oral health benefits, unlike many artificial sweeteners that are simply there to mask unpleasant flavours.
So, what does this all mean for your morning routine?
Your toothpaste isn’t food, but sweetness isn’t just flavour! It’s a signal. That first taste each morning can engage taste receptors and metabolic signalling pathways before breakfast begins. When that sweetness comes from xylitol and stevioside rather than sugar or artificial high‑intensity sweeteners, you’re choosing compounds that:
- Don’t spike blood sugar or insulin
- Don’t feed harmful oral bacteria
- May reduce cariogenic bacteria and plaque formation
- Are metabolised differently from sugars and many artificial sweeteners
Conventional sweeteners in toothpaste may seem insignificant, but for people focused on metabolic and oral wellbeing, they’re worth paying attention to.
After all, the first thing you put in your mouth sets the tone for the day.
