Niki Bezzant: The good oil on those smoothies

Relying on a smoothie to give you all your daily veges could have a downside.

Chew your food properly. It's an old-school piece of motherly wisdom that we rarely think about.

But it might be worth thinking about a bit more, given we're eating more food that requires less chewing.

Juices and smoothies are standard fare on cafe menus these days and they're a huge category in supermarkets, too.

There's a wide variety of exotic flavours popping up; the last cafe I visited offered, for example, a carrot, ginger and turmeric juice and a green smoothie with broccoli and kale.

We like the idea of squeezing all those veges and fruit into an easy-to-consume small bottle.

We wouldn't eat three platefuls of kale, we reason, but we can have it in a smoothie.

There's some sense behind that, at least when it comes to vegetables. Boosting your daily vege intake with a few extra servings in a smoothie (particularly a home-made one) may give you a boost of vitamins and fibre.

But relying on that smoothie to give you all your daily veges could have a downside.

Chewing is the first stage of digestion. It releases saliva to mix with our food and sends signals to the brain to prepare our stomachs for food.

Texture is also a very important part of our enjoyment of food; having everything "pre-chewed" is, in a way, a type of sensory deprivation.

When we chew, we also necessarily take more time over our meals, which is a good thing. Eating mindfully has been shown to help us eat less.

Knocking back a smoothie is convenient, yes, but it may not leave us feeling particularly satisfied.

There's speculation, too, in the nutrition community that consuming even fibre-rich fruits and veges all smooshed up, as in a smoothie, may not offer us the same gut health benefits we get from consuming the same fruit and veges in their whole form.

Juices have their own issues. Fruit juice is now included in the "free sugars" category by the World Health Organisation. That means it's the same as cane sugar, syrup and honey. It's not really any different, in that sense, from other types of sugary drinks. Fruit juice is no longer counted as a serving of fruit in our New Zealand healthy eating guidelines.

Given that, it pays to check when you're choosing what looks like a vegetable juice. Many are just fruit juices with a few veges tossed in; you'll still be getting a big whack of sugar.

The other thing juices don't have (which smoothies do) is fibre. Juicing leaves all that behind, so while you may be getting the vitamins of the fruit, you're not getting the fibre.

If you're a juice or smoothie fan, don't despair. There are some easy tweaks to make that liquid meal a useful addition to your day.

Choose (or ideally make) truly vegetable-based juices and smoothies; don't overload them with fruit or fruit juice and try to keep added sweeteners to a minimum. And make sure you eat lots of whole veges.

• Niki Bezzant is editor-at-large for Healthy Food Guide www.healthyfood.co.nz