“knowledge is power.”

Well, today we're going to give you more power

to control your diet and lifestyle

by giving you the facts.

Welcome to the Nutrition Facts Podcast.

I'm your host, Dr. Michael Greger.

Today we look at the safety

of fourth generation sweeteners

such as the rare sugar allulose.

First there was sugar and high fructose corn syrup,

the original industrial sweeteners.

They were cheap, but had lots of empty calories,

and contributed to diseases

such as obesity, type 2 diabetes, cavities, and metabolic syndrome.

So then came the second-generation sweeteners, the artificial sweeteners,

the colored pastel packets: Nutrasweet, Splenda,

Sweet & Low. Practically zero calories,

but adverse effects have been described, cautions have been raised.

For example, artificial sweeteners were found to induce glucose intolerance

by altering the gut microbiome, thereby producing

the counterintuitive effect of inducing metabolic derangements.

They also taste kind of funny.

Enter the third-generation Sweeteners, sugar alcohols,

such as sorbitol, xylitol, and erythritol, low-calorie sweeteners,

however, their laxative effects can create difficulties,

which brings us to rare sugars like allulose, which are

natural sweeteners with low or zero calories and a sugar-like taste.

For those of you who haven't heard of allulose,

it's been through a bit of rebranding.

Just like rapeseed oil morphed into canola, forcing municipalities

to update their town slogans,

allulose used to be called psicose, a sugar you may not want to eat

in the shower.

The name "psicose" is derived from the antibiotic from which

it was isolated --- a strange origin story for a sweetener.

In the Frontiers of Bioengineering and Biotechnology, emphasis

is placed on the fact that allulose is a real and natural sugar

rather than artificial, but ironically if you look at a reference they cite,

it talks about how allulose is made, via functionalized

polyhydroxyalkanoate nano-beads

decorated with D-tagatose 3-epimerase (DTE)

produced in recombinant endotoxin-free branded bacteria.

And now technically allulose is a natural sugar, a so-called rare sugar,

which have been defined by the International Society of Rare Sugars

as sugars that are present in limited quantities in nature.

But recent technological advances, such as enzymatic engineering

using genetically modified microorganisms, now allow

manufacturers to produce otherwise rare sugars

like allulose in substantial quantities.

But small amounts have pre-existed in the food supply,

so the FDA granted it generally recognized as safe status,

but it's been like really small amounts, like a few

dozen milligrams, or a quarter of a quarter of a quarter of a teaspoon.

See, allulose is generated when fructose is heated.

And allulose is created incidentally

in the process by which high fructose corn syrup is made.

So basing the safety of allulose on the fact that it's already been

present in the food supply isn't very convincing.

You don't know if it's safe until you put it to the test.

Unlike table sugar, allulose is safe for the teeth;

isn't apparently metabolized by cavity-causing bacteria

to make acid and build up plaque.

It doesn't raise blood sugars, even in diabetics.

It can be labeled as having zero calories, though technically

it may have like one and a half calories per teaspoon,

similar to what you see with erythritol.

Also like erythritol, it's only about 70% as sweet as table sugar

but has almost the same taste, performance,

and texture as regular sugar.

Are there any toxicities?

Allulose is considered a relatively nontoxic sugar.

What does that mean?

Well, in pets, we know a sweetener called xylitol can

be extremely dangerous to dogs.

As little as a half teaspoon in a 30-pound dog can be life-threatening,

whereas a similar dose of allulose apparently wouldn't be a problem,

though like over half cup at a time could make them sick.

This was a single dose study though.

The long-term safety of allulose was tested over a period

of a few months and didn't seem to cause any harmful effects at a dose

of about one and a half teaspoons a day for healthy 30-pound dogs.

In fact, their cholesterol actually went down,

leading the investigators to suggest clinical studies to see

if it's something vets should start prescribing for overweight pooches.

What about in people?

When the dose of allulose was gradually increased

to identify the maximum single dose for occasional ingestion,

no cases of severe gastrointestinal symptoms were noted

until a dose of 0.4 g/kg of bodyweight was reached,

which could be about 7 teaspoons, with severe symptoms

of diarrhea noted once you get up around 9 teaspoons.

And you say, "who could eat that much sugar at a time anyway?"

A single can of Coke has 10 teaspoons,

and a bottle of Mountain Dew has nearly twice that.

So allulose is clearly not suitable as a standalone sweetener

for sugary beverages.

In terms of the daily upper limit given in smaller doses

throughout the day, once you hit around 17 teaspoons a day,

depending on your weight, people start getting

severe nausea, abdominal pain, headache, diarrhea.

So people should probably stay under single doses

of about 7 teaspoons,

and not exceed around 15 for the whole day.

The average American may be getting 17 teaspoons

of added sugar a day, so it's certainly not something

the food industry can completely switch over to.

In this way, allulose is close to xylitol in terms of

maximal single dose,

whereas the average-weight man in the US could get away with

14 teaspoons of erythritol at a time,

and the average woman, 15 teaspoons.

Still not enough to sweeten a bottle of Coke, but offers

a little more leeway for sweetening tea

or sprinkling on a grapefruit or something.

Allulose is claimed to provide health benefits

though, compared to erythritol.

Forth generation sweeteners like allulose are said to have

as an advantage: additional functions.

We'll find out if that's true, next.

Allulose is a kind of low-calorie sugar naturally existing

in very small quantities,

but now industrially produced as a commercial sweetener,

said to have advantages

that make it comparable to erythritol as a sugar substitute.

It's said to have anti-diabetic effects,

but this was in obese mice.

Allulose decreases LDL cholesterol levels in high fat-fed hamsters and

is said to have a substantial impact on obesity in lard-munching mice,

but what about men and women?

In a petri dish, allulose inhibits fat cell precursors

from maturing into fat cells

and reduced the amount of fat accumulation within fat cells.

Therefore, the researchers conclude, allulose may be

a promising sugar substitute for an anti-obesity diet,

but you don't know until you put it to the test.

They gave people about a teaspoon of allulose a half hour

before eating a meal, and compared to the no-sugar control group,

the allulose group started burning more fat.

The researchers concluded that allulose enhances

after-a-meal fat burning, indicating that it could be

a novel sweetener to control and maintain

healthy body weight through enhanced energy metabolism.

Okay, but first of all, it was only 15 calories of fat

burned over that 4-hour period.

And they didn't burn more calories overall.

They just switched from burning carb calories to fat calories

and so may have just switched back later on and made up

for it later in the day. You can't just look at one meal.

You need to track people's actual weight over time, and here we go.

A weight reducing effect of a syrup that included about 5% allulose,

compared to high fructose corn syrup.

The results show significant decreases in body weight, body fat,

and waist circumference, but it was some proprietary syrup mixture,

and look, anything would look good against high fructose corn syrup.

This is the study I've been looking for.

Evaluating the effect of allulose for fat mass reduction in humans.

Over a hundred individuals

randomized to a placebo control -- sucralose --

or a teaspoon of allulose twice a day,

or one-and-three-quarter teaspoons twice a day,

and despite no change of physical activity

or calorie consumption between the two groups,

body fat was significantly decreased following allulose supplementation.

They even took CT scans, so they could tell where

the fat was disappearing from.

Now, the drop in body fat was only about 2 pounds over 12 weeks,

and the drop in abdominal fat in the higher dose group

was almost totally a drop in subcutaneous fat,