When it comes to quick, easy and healthy breakfasts, smoothies often come out on top. Bung a scoop of protein in for a recovery shake, add a spoon of flax or husk for added fibre or top with yoghurt and cacao nibs for a probiotic hit. For years, smoothies were often favoured over juices, because a smoothie often involves the blitzing of whole fruit and veg – keeping in all that gut-loving fibre – while juices tend to strip away most of the bulk, leaving behind a sugary (but delicious) liquid.

But, perhaps predictably in an age of blood sugar panic, smoothies are now in the firing line. Dr Idress Mughal (AKA Dr Idz) recently shared a video by a wellness podcaster who claimed that blending fruits “quadruples the glycemic profile”. This influencer went on to explain when you blitz a fruit, you disperse the fibre, which he argued leads to a four-time elevation in blood sugar compared with eating a whole fruit. That’s a worry, he said, because “blood sugar is the root of all evil”. 

Now, leaving aside the hyperbole of that last statement, this all sounds quite worrying. Even if you aren’t fully subscribed to the glucose fear doing the rounds at the moment, no one wants to see a huge surge at breakfast – especially if you can’t afford to take an 11am crash break. 

So, what’s the truth? Are smoothies still a good way to start the day or are we better off eating whole fruits and nuts?

Dr Idz cleared up the claims by pointing to a controlled trial which compared the blood sugar effect of eating whole and blended apples and blackberries. It found that blended fruits actually resulted in a 15% lower blood sugar spike, with the research suggesting that the reduction was down to that fibre being dispersed around the drink.  

That’s seconded by Sophie Medlin, director and specialist dietitian at CityDietitians. “Firstly, there is evidence that smoothies cause less of an increase in blood sugars than whole fruit does,” she says. “This is thought to be because the fibre is dispersed amongst the fructose from the fruit, allowing us to process it more slowly. Adding protein will further dampen any increase in blood sugars. 

“Secondly, we don’t need to worry about normal fluctuations in blood glucose from things like fruits or smoothies because people who are free from diabetes are perfectly capable of managing this without any harm being caused.”

In other words, for the majority of us, this whole hoo-hah over glucose spikes is just noise. “[Spikes] are a completely normal function of the human body and not a concern for most people,” says Rohini Bajekal, nutritionist and co-author or Living PCOS Free. 

“After we consume carbohydrates (like fruits and veg), they are broken down into sugars that enter the bloodstream to deliver energy to the muscles.” She says that a smoothie containing only fruit will have more of an impact on blood sugar than a smoothie with additional fats and protein, but a “’spike’ in itself is not something to worry about and there is no solid evidence that these normal fluctuations are harmful in people without diabetes.

As such, she says that smoothies are “absolutely” a healthy meal or snack. But she also says that smoothies should be more than just blended fruit, veg and water. “They an be a great vehicle for nutrients such as healthy fats – including plant milks, avocado, soya yogurt, ground flaxseed, chia seeds, nuts, nut butter or tahini – which make smoothies more satiating. These ingredients also boost the protein content – you could even use silken tofu or a vegan protein powder.

“Drizzle nut butter on top and add some granola for crunch or fresh fruit and seeds. You can also add in fresh herbs such as mint for a refreshing taste, or cinnamon.”

Bajekal also says they’re great for anyone struggling to eat enough – those who are nauseous post-workout of during pregnancy, for example. “When you blend ingredients, you break down plant cell walls, which makes many nutrients even more digestible. They are also an excellent way to add some greens into the diet. You can hardly taste the kale in a banana, soya milk, kale, cacao and peanut butter smoothie.” 

Are there any benefits to eating fruits whole rather than blitzing them? “Eating or blending fruits makes very little difference to me as a dietitian,” says Medlin. “As long as people are eating plenty of plants, they’ll be fine. That said, blending fruits and vegetables will mean you get less insoluble fibre – the type of fibre that comes from skins, peels and pips – from them, so this may reduce the bulk of your stools, making it harder for your bowel to move them along the gut.” But she also says that smoothies contain plenty of soluable fibre, so your gut bacteria will still have plenty to feed on.

The only people who might be better off plumping for whole foods over smoothies most of the time are people who struggle with blood sugar control, like women with PCOS or pre-diabetes.

For the most part, “issues with high blood sugar are only a concern for diabetics who maintain high blood sugar levels over a period of years – after which it starts to damage their bodies,” says PT and dietitian Adam Enaz. “With the new hype of everyone glucose monitoring, a fear has built around having raised glucose levels after eating.”

In a rare form of humility, the influencer called out by Dr Idz actually took his feedback on board and wrote in the video comments that he’d been wrong in his conclusions. 

Enaz offers three tips for making the most nutritious smoothie:

Keep it to two fruits

Along with milk, he recommends using two fruits and more veg. If you are concerned about sugar, then make one of those fruits a berry, as these tend to be slightly less sweet and are packed with antioxidants and other micronutrients. Just be aware that blending bananas and berries can corrupt the nutrients of berries, so you might be better off keeping the two apart.

Add fibre

By adding extra fibre, you’re going to slow down the energy production, meaning the smoothie will leave you fuller for longer.

Load up on protein

“Add in a source of protein like Greek yoghurt or plant-based protein powder to balance the macronutrients,” says Enaz. 

Bajekal offers the following tip for her go-to breakfast smoothie: “Freeze a medium sized ripe banana in advance and chop it into thirds to make it easier for your blender. I usually dice several bananas at once, separate them on a plate and pop the plate in my freezer for an hour or so. Then I remove the plate and add all the diced bananas to a ziplock silicone bag and freeze. This prevents the banana pieces sticking together, which is what usually happens if you dice and freeze them immediately in the bag.”

Ingredients

½ cup unsweetened soya, pea or oat milk

1 medium-sized frozen banana

1 cup frozen mango

80g cucumber (1 small or ½ medium)

20g (around a thumb-sized/2-inch piece) of fresh ginger

1 sprig of fresh mint, including the leaves

1 tbsp hemp seeds

Method 

Blend for a minute until smooth and enjoy immediately. Top with a sprig of mint and hemp seeds.  

“If you don’t have frozen mango, you can use 1 cup frozen pineapple or ½ a medium fresh mango. A cup of frozen blueberries works, although the colour won’t be pretty! If you dislike the taste of banana in smoothies, try 1 frozen courgette instead, and add a date for sweetness. Add a soft date (e.g. Medjool date) or two to the smoothie for a sweeter flavour.”

Images: Getty