Nutrition myth buster: Are ultra-processed soft foods stopping your mouth from getting a workout?

New Zealand Listener

21 Jan, 2026 05:08 PM4 mins to read

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There are hints from emerging animal studies that a lifetime of soft-diet eating might influence jaw development and orthodontic health. Photo / Getty Images

If modern life has a texture, it might just be mush. We live in the age of ultra-processed softness: burgers so soft you barely need teeth, yoghurts and squeezable pouches for adults and snack bars that disintegrate on impact.

Even “healthy” convenience foods such as smoothies, soft
wraps and instant oats arrive pre-blended, sparing us the apparently arduous task of chewing. It’s a far cry from the foods our grandparents ate: dense breads, fibrous vegetables, crisp apples and nuts you had to crack yourself. Somewhere between convenience and rushed schedules, many of us now eat meals our teeth barely register, overlooking the fact that chewing is the first step in digestion, impacting fullness, our digestive processes and oral health.

Our mouths play an essential role in digesting fibrous food. For starters, our teeth are designed to cut, tear and pulverise solid food up into smaller particles that are then mixed together with saliva into a soft mass ready for swallowing. We produce about 1000-1500ml of saliva a day, of which 99.5% is water; the remaining 0.5% is made up of minerals and other compounds such as digestive enzymes. The water in saliva allows food molecules to dissolve so we can taste them and importantly it allows digestive reactions to occur.

Saliva contains two types of digestive enzymes; firstly, salivary amylase, which begins breaking down starches in food into smaller fragments in the mouth. This action continues for a short time in the stomach before acid inactivates the enzymes. Secondly, saliva also contains lipases that, when activated by the stomach’s acidic environment, begin breaking down dietary fats in our food. So if we aren’t chewing our food, we’re missing this crucial early step in our digestive process.

Long before we had meta-analyses and glucose curves American “great masticator” Horace Fletcher famously advocated in the late 19th century chewing every mouthful 50-100 times. That may sound like Victorian-era eccentricity but modern research suggests Fletcher was on to something. For instance, a 2015 meta-analysis of multiple clinical trials confirmed that increasing the number of chews per bite consistently reduced self-reported hunger and lowered subsequent food intake. While a 2018 study had participants chew 50 times per bite rather than 15 times per mouthful, it found those who chewed more consumed less food overall.

Several studies show longer chewing and slower eating increase “oral exposure”, that is the time food spends in the mouth, allowing greater saliva uptake and enzyme mixing, which helps initiate starch digestion and influences glucose and “feeling full” after a meal. Consistent with this, clinical trials using foods such as chicken and rice have found that more thorough chewing breaks food into smaller particles, improves mixing with salivary enzymes, and supports more effective protein and starch digestion further along the gut.

Also, there are hints from emerging animal studies that a lifetime of soft-diet eating might influence jaw development and orthodontic health. Though, as Robin Whyman, director of dental policy at the New Zealand Dental Association, notes, “There isn’t strong evidence in humans that soft or ultra-processed diets directly cause crowded teeth or jaw problems – genetics and growth play a much bigger role.”

He adds the greater dental concern is free sugars in ultra-processed foods that raise the risk of tooth decay; in young children, early loss of baby teeth due to decay can later contribute to crowding when adult teeth emerge. So while chewing texture itself may not be a primary driver of orthodontic problems, diets high in soft, sugary foods can still have important downstream consequences for oral health.

In short, eating might just be too easy nowadays. Choosing foods that give your mouth a workout helps us slow down, chew properly and create more satisfying meals that are kinder to our digestion and the body overall.

As well as Jennifer Bowden’s columns in the NZ Listener, listener.co.nz subscribers can access her fortnightly Myth busters column which explore food and nutrition myths.

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