question about smoothies

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question about smoothies

This topic contains 3 replies, has 2 voices, and was last updated by  annette52 7 years, 11 months ago.

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  • I realise not all smoothies are the same – but I see lots about the perils of vast quantities of sugar in smoothies and fruit juice

    whilst I see that eating fruit is way better than drinking just the juice – I don’t really understand why smoothies are so bad

    for example if I made a banana/strawberry and kiwi smoothie – I would use exactly the same amount of fruit that I would eat – and it would include the fibre/vitamins/minerals etc

    so why are smoothies considered bad – but then at other times good?

    am I missing something here?

    Dr Robert Lustig (Fat chance, the hidden truth about sugar, obesity and disease) he explains that dietary fibre which is found in fruits, vegetables, whole grains and legumes is undigestible by the human gut. There are 2 types of fibre, soluble and insoluble. Soluble(lentils, apples, oranges, nuts, flaxseeds, dried peas, blueberries, carrots, oatmeal)slow the digestion and absorption. Insoluble(wholewheat, wholegrains,nuts, couscous,seeds,brown rice, fruit, dark leafy vegetables etc). Together they work as a team, the insoluble fibre forms a lattice and soluble sits in the gaps to slow the rate of flux from the intestine to the blood stream, which allows the liver to meabolize what is coming in, so there is no overflow.
    He suggests that although fruit contains fructose, eating it whole, the fibre matches the fructose content. However by using a blender on fruit, the action of the blades destroys the insoluble fibre of the fruit. So without the lattice to slow down the absorption of the sugar, it is absorbed quickly. Fibre is responsible for maintaining both the dose and flux of carbohydrates.

    thank you Annette
    I didn’t realise that blending would change the fibre as you said – but that does explain why I have heard some – including Lustig – say about smoothies being less good

    I knew about the high sugar in the fruit juices which are often used as a base for smoothies, but I was surprised at the function of the fibre in the fruit too. I also thought about those people who think that lots of fruit is good and so put loads of fruit in a blender and consume the contents which would be far more than they would eat at one sitting.

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