© Magnific
August 14, 2026
Marianne Waldenfels
Smoothies are generally considered healthier than juices, largely because they retain more fiber. But new research suggests their effects on blood sugar may be more complex than previously thought.
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Whether it's a green smoothie or a freshly pressed juice for breakfast: both are seen as an easy way to get more fruit and vegetables into your daily routine. But when it comes to health, it does make a difference whether apples, berries, carrots, or spinach end up in a juicer or a blender.
For a long time, the answer seemed straightforward: smoothies are the better choice because, unlike juice, they retain the fiber from the ingredients and are therefore thought to cause a smaller rise in blood sugar. Yet on precisely this point, the scientific picture turns out to be surprisingly complicated.
During juicing, the solid components of fruit and vegetables are largely separated out. Depending on the method, the skin and pulp end up mostly in the pomace, while water, sugar, vitamins, minerals, and many secondary plant compounds pass into the juice.
With a smoothie, by contrast, the whole fruit or vegetable is blended, so the fiber is largely preserved. This is where an important nutritional difference lies: fiber supports digestion, helps you feel fuller for longer, and plays an important role in a healthy gut microbiome.
That does not, however, automatically make smoothies a health drink. What matters is what goes into the blender — and how much of it you consume.
Freshly pressed juice can provide vitamins, minerals, and secondary plant compounds. Vegetable juices in particular can be a useful dietary supplement. At the same time, however, juicing strips out one essential component of fruit and vegetables: a large portion of the fiber.
There is also a practical problem. Liquid calories are generally less satisfying than solid foods and can be consumed very quickly. A glass of orange juice, for example, requires several oranges — an amount you would probably never sit down to eat as whole fruit in one go.
With fruit juices in particular, this can mean taking in a relatively large amount of sugar in a fairly small volume. Juice should therefore not be seen as a straightforward substitute for whole fruits and vegetables.
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Here, smoothies have a clear advantage. Because the pulp is not removed, the fiber is retained. You can also add ingredients such as plain yogurt, oats, nuts, or nut butter, which provide protein, complex carbohydrates, or unsaturated fatty acids, among other things, and can help increase satiety.
However, a seemingly light smoothie can quickly become a small meal. Large amounts of banana, mango, or other sweet fruits, along with fruit juice or honey, can significantly increase the sugar and calorie content.
A smoothie made mostly from vegetables, a little fruit, and no added sugar is therefore nutritionally a very different thing from a large fruit smoothie made with juice, honey, and other high-calorie ingredients.
When it comes to blood sugar, there is an interesting twist. It is often assumed that blending fruit causes its sugars to be absorbed more quickly, leading to a sharper spike in blood sugar. However, early studies are beginning to challenge this simple explanation.
In a small study, nutrition scientists Lisa T. Crummett and Riley J. Grosso examined the effects of apples and blackberries on blood sugar in 20 healthy young adults — once as whole fruits and once blended into a smoothie. Surprisingly, both the peak blood sugar rise and the total glucose response were lower after the smoothie than after eating the whole fruits.
This does not mean, however, that smoothies are fundamentally better for blood sugar than whole fruit. The study was small, included only healthy young adults, and tested a specific combination of fruits. Its results therefore cannot be used to make broad recommendations about all smoothies.
A European Journal of Clinical Nutrition review article published in 2025 by researchers at the University of Plymouth also tackles the question of what blending does to the blood sugar response.
Among other things, the authors take issue with the fact that smoothies are sometimes treated similarly to fruit juices in dietary guidelines. The existing research, however, does not paint a clear picture suggesting that blended fruit is fundamentally worse for blood sugar than whole fruit. Some of the studies reviewed even found lower blood sugar responses after consuming blended fruit.
Why this might be the case has not yet been fully established. Mechanical blending alters the structure of plant tissue and could influence how sugar, fiber, and other components are released and absorbed during digestion.
These findings are interesting, but they are not yet reason enough to overturn existing dietary recommendations. Too many of the available studies are too small and too varied for that. Above all, they point to one thing: the blood sugar response to fruit is more complex than the simple equation suggests.
Here too, the response depends on several factors: the type of fruit used, the amount, how it has been processed, and what is eaten alongside it. Some individual studies have even found more favorable blood sugar responses with certain juices than expected.
This does not mean, however, that fruit juice is metabolically more favorable than whole fruit. Juice contains significantly less fiber, can be consumed quickly in large quantities, and is far less filling. These differences remain relevant regardless of how high any single blood sugar spike after drinking turns out to be.
That is precisely why blood sugar response alone should not be the benchmark for whether a food is healthy.
On this point, smoothies have the stronger case. The fiber they contain means they typically keep you fuller for longer than juice. If a smoothie also includes protein or fat — for example from plain yogurt, nuts or nut butter — the satiating effect can increase further.
But here too, portion size matters. A large smoothie can contain several servings of fruit and, with additional ingredients, deliver a substantial amount of energy. Anyone who drinks such a smoothie on top of a regular meal can easily consume significantly more calories than they realize.
Juice, on the other hand, is barely filling, yet it can still deliver considerable amounts of sugar and energy if large portions are consumed regularly rather than a small glass.
When weighing juice against smoothie, the initial case is stronger for the smoothie: blending preserves the fiber. What goes into the glass is crucial, however. A blend of plenty of vegetables and a little fruit is nutritionally a very different thing from a large fruit smoothie made with juice, honey, or other sweet additions.
Juice is not inherently unhealthy, either. In small amounts, it can certainly be part of a balanced diet. Fruit juice in particular, however, packs a relatively large amount of sugar into a small volume, is not very filling, and should not be treated as a substitute for whole fruit.
On balance, smoothies do have some advantages over juice. The healthiest option, however, is even simpler: whole fruit and vegetables should remain the first choice in everyday life.
