How are ye doing, guys!
Today we're going to be talking about fruit sugar.
Recently I've witnessed people passing on fruit on a number of occasions over fear about
it's sugar content.
Even though dietary guidelines suggest not counting sugar from fruit towards your RDA,
this message seems to not be getting through.
It is understandable, public awareness of the negative effects of sugar is at an all-time
high and people are becoming increasingly aware of how damaging diet in general can
be to our health.
Because of the problems with dissemination of dietary advice, even people who are motivated
to eat healthier can become confused and run into trouble like this.
Then there are those who would argue that sugar is bad for us regardless of the form
it comes in.
These are the reasons I felt compelled to make this video.
Let's take a look at the science and see if and why sugar from fruit should be restricted.
First of all, why do we actually want to limit sugar intake?
Why is there a sugar RDA?
To understand the damaging effects of sugar on the body, it is useful to look at the oral
glucose tolerance test, a test commonly used to diagnose diabetes.
In this test, a patient is given a drink containing 75 g of glucose and their blood sugar response
over the next few hours is measured.
Predictably, after taking in this much sugar, our blood glucose begins to rise.
But if it gets too high it results in oxidative stress, inflammation and endothelial dysfunction,
which over time contribute to cardiovascular disease, dementia and other chronic diseases.
This is why our body has evolved elaborate mechanisms to keep blood glucose within a
very narrow range.
The body's primary mechanism for getting blood glucose back down to normal is the release
of insulin from the pancreas, which shuttles the glucose into our muscles and other tissues.
However, the spike in sugar can be so great that sometimes the pancreas releases too much
insulin and our blood sugar actually ends up lower than where it started - the so-called
"sugar crash."
Low blood sugar is one of the body's primary hunger signals, so when this happens we become
paradoxically more hungry a few hours after consuming sugar.
This chronic inappropriate hunger is one of the mechanisms by which excess sugar consumption
eventually leads to weight gain and obesity.
This rebound hypoglycaemia has an even more detrimental effect than paradoxical hunger,
though.
When we are fasting and blood glucose is low, our body releases fat into the blood as a
backup fuel source.
These patients were fasting overnight before the test, so their starting fat level was
quite high.
This fuel source comes at a cost, however.
Like with sugar, if fat levels are too high in our blood it also over time results in
oxidative stress, inflammation and endothelial dysfunction, increasing our risk of chronic
disease.
When we consume sugar, our blood glucose rises so the body stops releasing these free fatty acids and
they begin to fall.
But when our blood sugar crashes our body interprets the situation as starvation, and
once again begins to release these fatty acids into the blood stream far sooner than it would
after a meal that did not cause a sugar crash.
The overall result is that we spend a lot of time with high blood sugar and high serum
free fatty acids, both of which are detrimental to our health.
Additionally, added sugar is approximately 50% fructose, depending on the source of the
sugar.
Fructose is broken down predominantly in the liver and if we consume too much fructose
too quickly fat begins to accumulate in the liver as a result of this rushed breakdown
process.
This accumulation of fat in the liver contributes to what is becoming our latest chronic disease
epidemic - non-alcoholic fatty liver disease.
Another by-product of this rushed fructose breakdown process is uric acid, which in addition
to causing gout causes further endothelial dysfunction and increases our blood pressure
and cardiovascular disease risk by it's inhibition of nitric oxide synthase and through other
mechanisms.
These pathological reactions all combine to increase our risk of insulin resistance and
type 2 diabetes, and this increased risk has been shown to be independent of weight gain.
So that's a lot of bad stuff sugar can do to our body!
No wonder the WHO recommends consuming less than 5% of calories from sugar, or around
25 g or 6 teaspoons per day.
So what then about fruit?
A single apple could take you over that limit for the entire day!
Remember, fruits contain thousands of other nutrients besides just sugar.
Could these other nutrients be having an effect?
Does fruit cause all this bad stuff to happen to our body?
In this landmark study, researchers looked at the physiological responses to free sugar
consumption versus that same amount of free sugar with berries added.
As expected, 35 g of sugar caused a big blood glucose spike, followed by a sugar crash and
release of fat into the blood.
But the addition of berries, even with the extra 10 g of sugar contained therein on top
of the 35 g, resulted in less of a sugar spike, no sugar crash and no premature release of
fat into the blood.
Amazing!
You see, when you seperate the sugar from the fruit, you remove all the fibre and phytonutrients
that came pre-packaged with the fruit by nature.
The fibre has a gelling effect in the stomach that delays gastric emptying, preventing the
sharp rise in blood sugar, but there are also specific phytonutrients in fruit that can
actually inhibit absorption of sugar from the intestine and may play more of a role
in blunting the spike, which then prevents the sugar crash.
This slowed absorption, in addition to some insulin-modulating effects of the fibre, gives
the liver time to deal with the influx of fructose, and allows it to process it without
depositing that disease-causing fat.
Additionally, if we eat fruit, blood sugar spikes are not as damaging anyway because fruit also
comes pre-packaged with antioxidants that counteract the deleterious effects of the
spike.
But this is all experimental data.
What we are really interested in, the bottom line is disease risk - does fruit raise our
risk of disease like free sugar?
Fructose from fruit does not appear to have the blood pressure-raising effect and is associated
with a LOWER risk of type 2 diabetes.
Including fruit in our diet actually helps us lose more weight compared with restricting
all fructose, and weight loss helps prevent and treat non-alcoholic fatty liver disease.
In addition to this weight loss effect, risk of fatty liver disease may also be directly
reduced with increasing fruit consumption, and it appears that the more fruit you eat,
the better, with no adverse effects reported even with "very high" amounts.
Remember as well that fruit juices, while not as purified as refined sugar, have removed
most of the fibre and a large portion of these wonderful phytonutrients from the whole fruit.
As a result, juices can have the same deleterious effect on our physiology to varying degrees,
and this is why guidelines include fruit juice in the RDA for sugar.
In summary, we have a sugar RDA because it raises our risk of chronic disease.
As a result, the notion has propogated that fruit is an unhealthy food due to it's sugar
content, even though the science shows that fruit does not increase our risk of disease.
Indeed, according to the Global Burden of Disease Study, the number two dietary risk
factor for death Worldwide is not consuming enough fruit, right behind not eating our
whole grains.
Fruit sugar is exempt from your sugar RDA because of all the other good stuff it contains
- you can, and should, eat as much as you want!
Thanks for watching, if you have any questions or comments leave them in the comment section
below and I'll get back to you.
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Sláinte!