Fruits and vegetables are both great sources of fibre.

Fruits and vegetables are both great sources of fibre.Credit:iStock

But are nutrients lost when fruits and vegetables are chopped into bits by a blender blade? We asked experts to help us break it down so you can get the most out of your smoothie.

How blending affects nutrients

Unlike juicing,blending can incorporate all of the edible parts of fruits and vegetables – including the skin,seeds and pulp – so a smoothie can be nutritionally very similar to eating the produce whole,says Mary Ann Lila,a professor of food,bioprocessing and nutrition sciences at North Carolina State University.

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And blending shouldn’t degrade the vitamins or minerals found in fruits and vegetables,Lila says. Nor will it immediately harm certain antioxidant and anti-inflammatory compounds,like anthocyanins and flavonols,she says.

Fruits and vegetables are also good sources of fibre,which most of us could benefit from eating more of. And whether you eat an apple whole or as part of a smoothie,“you’ve consumed exactly the same amount of fibre,” says Balazs Bajka,a gut physiologist at King’s College London.

Blending does,however,break the fibres into smaller pieces,which will affect how they move through your digestive system,he says. Some types of fibres,when chopped into bits,may disperse more quickly within your gut and slow digestion and absorption – usually a good thing – while others might lose some of the “roughage” effect that keeps things moving in your digestive tract and prevents constipation.

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But there’s not much research on this topic,Bajka says,and specific effects may depend on the person and the fruit or vegetable. Regardless,“eating any kind of fibre is good,” he says.

How blended fruit affects blood sugar

Processing food often disrupts its natural structure,which can lead to faster digestion and absorption. So it’s reasonable to wonder if puréeing fruit could cause a bigger spike of blood sugar,says Anthony Fardet,a nutrition scientist at the National Research Institute for Agriculture,Food and the Environment in France.

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But in a few small studies that measured adults’ blood sugars after they consumed fruit blended or whole,researchers have found reassuring results. The preparation style of mango,for instance,seemed to make no difference in blood sugar response. And when researchers tested smoothies containing seeded fruits like passion fruit,raspberries or kiwi fruit,participants had more gradual rises in blood sugars than when they ate the same fruits whole.

That result surprised Gail Rees,a senior lecturer in human nutrition at the University of Plymouth in Britain who led two of the studies. She hypothesised that mashing up the fruits’ seeds in the blender might release some fibre,protein and fat,which could slow nutrient absorption and cause a more gradual rise in blood sugars.

That said,liquid meals are generally less satiating than those composed of solid foods,Fardet says;it’s not clear why this is,but it may result in a desire to consume more,or it may leave you hungry for a snack sooner.

Tips for the most nutritious smoothies

Beyond the fruits and vegetables you use in your smoothies,other ingredients also affect their nutritional value,Petersen says. Water is a good liquid base if you’re aiming for a light snack. For a more balanced and filling smoothie,low-fat or fat-free dairy milk or unsweetened yoghurt,kefir or fortified plant-based milks can provide protein,calcium and vitamin D,she adds.

“Throw some nuts in there,” or avocado,Lila suggests. Both provide healthy fats and fibre,as do chia or flaxseeds;whole grains like millet or rolled oats are good fibre sources,too.

Smoothies also provide a great opportunity to use frozen produce,which is generally just as nutritious as when it is fresh,Lila says. She recommended storing frozen fruits and vegetables at the back of your freezer to minimise the slight thawing and refreezing that can cause nutrient losses when you open your freezer door.

Finally,keep in mind that once fruit is blended,its healthful compounds gradually become less stable,Lila says. Yesterday’s smoothie that has separated and turned a bit gray has probably lost some of its antioxidant and anti-inflammatory value,she says. For the same reason,prepackaged smoothies may not be as beneficial,she adds,and they also often contain added sugars.

In other words,Lila says,enjoy your smoothie – but make it fresh and drink it right away.

The New York Times

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