Powder-based food replacements became a bit of a fad two years ago, when the much-hyped Soylent hit the US market. Promoted as a cheap, healthy and convenient way of getting all your nutritional requirements in one powdery hit, Soylent’s developer went as far as heralding his creation as “the end of food”.

Fast-forward two years later and Soylent has just started selling Soylent 2.0, the company’s first pre-mixed ready-to-drink product, which is available in bottled form. But in light of Soylent’s ongoing growth – in addition to Soylent 2.0, the company began shipping its products to Canada this year and intends to move into Europe next – is it safe and healthy to replace your entire diet with food in powder or liquid form?

One study from last year suggests not. Researchers at Tohoku University in Japan wanted to investigate the health effects of feeding of animals with soft food in place of a hard food diet over a long period of time. Using mice as their subjects, the researchers replaced the animals’ regular pellet-based diet with powdered food for 17 weeks.

In the short term – after three days – the mice showed signs of greater glycemic response than when they consumed pellet food, consistent with the fact that powdered food is more easily digested.

But it was the long-term result that gave cause for alarm. Long-term feeding on powdered food induced hyperglycemia and related systemic signs of illness in the mice, showing elevations in blood glucose, hypertension, and abnormal social behaviours between the animals. But why?

The researchers concluded that the mastication (chewing) of food of adequate hardness might be very important for the maintenance of physical and mental health in animals, possibly through the reduction of blood glucose levels or adrenal stress hormones.

In other words, chewing might be more than just something we do to break our food down into swallow-able pieces; it could be a fundamental part of a healthy eating process.

None of which is to say that Soylent is bad for you. We don’t know that it is – and Soylent isn’t what the researchers were feeding the mice in the study.

But while a lot of Soylent’s marketing literature seems focused on pointing out how its product ticks lots of recommended nutritional checkpoints, it’s also worth questioning whether it ticks the recommended checkpoints for food. Because a lot of food requires some amount of chewing. And chewing just could be important for health.

As observed by Francie Diep at Popular Science, there’s not an awful lot of published research in this area, which ultimately means: “When it comes to non-chewing, you’re in uncharted territory.”