"Green Smoothies: What Does the Science Say?"
As I’ve explored previously, drinking sugar water
is bad for you.
If you have people drink a glass of water with
3 tablespoons of table sugar in it, which is like a can of soda,
this is the big spike in blood sugar you get within the first hour.
Our body freaks out and releases so much insulin
we actually overshoot, and by the second hour
we’re relatively hypoglycemic, dropping our blood sugar
below where it was when we started our fasting.
In response, our body dumps fat
into our blood stream as if we’re starving,
because our blood sugars just dropped so low.
And the same thing happens after drinking apple juice.
Here’s what happens to your blood sugar in the 3 hours
after eating 4 1/2 cups of apple slices:
It goes up and comes down.
But if you eat the same amount of sugar in apple juice form,
about 2 cups, your body overreacts, releasing too much insulin
and you end up dipping below where you started.
The removal of fiber in the production of fruit juice
can enhance the insulin response
and result in this “rebound hypoglycemia.”
What would happen though if you stuck those 4 1/2 cups of sliced apples
in a blender with some water and pureed them into an apple smoothie?
It would still have all it’s fiber,
yet it still caused that hypoglycemic dip.
The rebound fall in blood sugars
which occurred during the second and third hours
after juice and puree was in striking contrast
to the practically steady level after apples.
This finding not only indicates how important the presence of fiber is,
but also perhaps whether or not
the fiber is physically disrupted, like in the blender.
Let’s play devil’s advocate, though.
Eating 4 1/2 cups of apples took 17 minutes,
but to drink 4 1/2 cups of apples in smoothie form
only took about 6 minutes
and you can down 2 cups of juice in like 90 seconds.
So maybe these dramatic differences have more to do with how fast
the fruit entered into our system rather than its physical form.
If it’s just the speed we can instead sip a smoothie
over 17 minutes and it would be the same. Right?
So they put it to the test.
Fast juice was drinking it in 90 seconds,
but what if you instead sipped the juice over 17 minutes?
Same problem—so it wasn’t the speed,
it was the lack of fiber.
What if you disrupt that fiber with blending,
but sip it as slowly as the whole apple eating?
A little better, but not as good as just eating the apple.
So eating apples is better than drinking apple smoothies,
but who drinks apple smoothies?
What about bananas, mangoes, or berries?
There was a study that compared whole bananas
to blended bananas and didn't see any difference,
but they only looked for an hour
and it was while they were exercising.
Bananas in general, though, may actually improve
blood sugars over time.
The same thing with mangoes— and this was with powdered mango—
can’t get any more fiber disrupted than that.
It may be due to a phytonutrient called mangiferin,
which may slow sugar absorption through the intestinal wall.
Berries help control blood sugar so well
they can counter the effects of the sugar water
even when they’re pureed in a blender.
Adding blended berries in addition to the sugar water,
and you don’t get the hypoglycemic dip;
you don’t get that burst of fat in the blood.
Drinking blended berries isn’t just neutral,
but improves blood sugar control.
Again thought to be due to special phytonutrients
that may slow sugar uptake into the bloodstream.
Indeed six weeks of blueberry smoothie consumption
may actually improve whole body insulin sensitivity.
So while apple smoothies may be questionable,
a recipe like Mayo’s basic green smoothie recipe
packed with berries and greens would be expected to deliver
the best of both worlds, maximum nutrient absorption
without risking overly rapid sugar absorption.