Ask a Nutritionist: Smoothies!

Gut Stuff reader:

When you make smoothies do the greens and other healthy foods lose any of the benefits? Do the microbes still get the same amount and type of fiber?

Miguel answers:

When you make smoothies with fibrous foods like leafy greens or fruit in a high speed blender you’re not damaging the fibre at all or getting any less of it. If anything, if your blender is powerful enough, you might be breaking some of the fibre molecules so that they’re more accessible for your gut bacteria to start chomping on it straight away, thereby enhancing nutrient absorption. This is just theoretical as there aren’t any good quality studies to support it, but it’s plausible. I’m unsure what you mean by “other healthy foods”, but when it comes to foods containing fibre that you can blend into a smoothie, my answer applies to all of them. Be careful to use a high speed blender (where you put whole pieces of fruit and veg in and add water) rather than a “juicer”. The former keeps all the fibre in the drink, the latter extracts just the juice, and most of the fibre, which is the tasty food for your gut bacteria often ends up in the bin. 

Dietary fibre feeds the your gut bacteria. This helps support digestion, nutrient absorption, as well as to support a strong immune system. There is plenty of evidence to support that adequate fibre intake helps balance blood sugar levels and that it protects against colon cancer. Additionally, these fibrous foods you’re blending – especially if they’re brightly coloured like kale, ginger and turmeric root, blueberries, apples – will contain a myriad of different natural compounds such as polyphenols, flavonoids, etc. that work in two ways. Firstly, they’re prebiotic. Your gut bacteria will play around with them and as a result produce some very interesting compounds called short chain fatty acids which are needed for gut health but also for brain and heart health. And secondly, they’re good all round antioxidants, so they not only protect your gut from the oxidative stress (a bit like “rusting”) that happens as a normal fact of life, they add to your body’s own antioxidant reserve. Some of these “healthy foods” get named “superfoods”. In reality, even humble foods like apples can be superfoods, so don’t be fooled by the more exotic (and normally more expensive) names. You don’t need to pay through the nose to supercharge your smoothies! Just keep them colourful and tasty. Hope you find this useful. 

No advice in this column is designed to override any by your medical doctor and should not be relied on as a substitute for specialist dietary advice. If you have any concerns about your health, visit your general practitioner, or medical consultant. 

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