Is Monk Fruit Sweetener Safe?

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Natural Sweeteners

A number of artificial sweeteners have been FDA-approved in North America, including aspartame and sucralose (sold as Splenda). But, there are also natural high-intensity sweeteners found in plants. The global market for non-nutritive sweeteners in general—these non-caloric sweeteners—is in the billions, including all the artificial ones, “and two natural [ones] extracted from plants…stevia…and monk fruit.” I’ve done a video about stevia; what about monk fruit?

“The fruits of Luo Han Guo [monk fruit in Chinese] have [evidently] been used for hundreds of years as a natural sweetener and…folk medicine. “The non-caloric sweet taste [comes from] mogrosides, a group of cucurbitane-type triterpene glycosides that [make up] about 1% of the fruit,” and are like hundreds of times sweeter than sugar.

The Reported Benefits of Monk Fruit

“The mixed mogrosides have been estimated to be about 300 times as sweet as [table sugar], so that an 80% extract was nearly 250 times sweeter than sugar.” If you read reviews in Chinese natural medicine journals, you’ll see pronouncements like this: monk fruit “has been shown to have anti-coughing effects, anti-asthma.., anti-oxidation, liver-protection, [blood sugar]-lowering, immunoregulation, and anti-cancer.” But, what they don’t tell you up front is that they’re talking about reducing ammonia-induced mouse coughs.

“A natural food sweetener with anti-pancreatic cancer properties.” Monk fruit “may be used for daily consumption as an additive in foods and drinks to prevent or treat pancreatic cancer.” Yeah, maybe in your pet mouse. And, the “[a]nti-proliferative activity of…monk fruit in colorectal cancer and throat cancer” was on colorectal and throat cancer cells in a petri dish. Now, they did show mogrosides killing off colorectal cancer cells and throat cancer cells, and our digestive tract could be directly exposed to these compounds if we ate them, but what’s missing? Right, they didn’t test it against normal cells. You could pee in a petri dish and kill off cancer cells. The whole point is to find something that kills off cancer but leaves normal cells alone, something that they weren’t able to show here.

Surprising Results on Sugar Spikes

Are there any human studies on monk fruit? No, … until, now. “Owing to the rapidly growing popularity of natural plant-[based sweeteners],” they thought it would be “of interest to determine whether natural [sweeteners] would be a healthier alternative to sugar [or] artificial [sweeteners].” So, they randomized people to drink an aspartame-sweetened beverage versus monk fruit-sweetened, versus stevia, versus table sugar. Then, they measured blood sugars over 24 hours, and there was “no significant difference…found” between any of them.

But, wait a second. The sugar group was given 16 spoonfuls of sugar, the amount of added sugar in a 20-ounce bottle of Coke; so, the other three groups consumed 16 fewer spoonfuls of sugar, and still had the same average blood sugars? But, table sugar causes a big blood sugar spike. Here it is; I’ll show you. Drink that bottle of sugar water with its 20 sugar cubes’ worth of sugar, and your blood sugars jump 40 points over the next hour. Whereas, you give them an aspartame-sweetened beverage, or monk fruit, or stevia, and nothing happens—which is what you’d expect, right? These are non-caloric sweeteners; no calories. It’s just like you’re drinking water, right? So, how could your daily blood sugar values average out the same? The only way that could happen is if the non-calorie sweeteners maybe made your blood sugar spikes worse somehow later in the day?

Look what happens when you give people Splenda mixed with sugar water. You get a greater blood sugar spike, a greater insulin spike chugging the sugar with sucralose than without, even though Splenda alone causes no spike of its own. So, does aspartame do the same thing? At the one-hour mark, they fed people a regular lunch. And, so, the blood sugars went back up and down as they normally would after a meal. Not spiking as high as drinking straight sugar water, just a gentle up and down. Okay, but that was in the group that drank the sugar an hour before. In the group that drank the aspartame, even though their blood sugars didn’t rise at the time, an hour later at lunch, they shot up higher, as if the person had just drank a bottle of soda.

Okay, but what about the natural sweeteners, stevia and monk fruit? Same thing. Same exaggerated blood sugar spike to a regular meal taken an hour later. So, you can see how it all equals out in terms of average blood sugars, even though in these three non-caloric sweetener groups, they took in 16 spoonfuls less sugar, at least in part because they ate more. After drinking a Diet Coke, you’re more likely to eat more at your next meal than drinking a regular Coke. In fact, so much more that the energy ‘saved’ from replacing sugar with non-caloric sweeteners “was fully compensated for at subsequent meals; hence, no difference in total daily [calorie] intake was found.”

“The [sugar]-sweetened beverage led to large spikes in [both] blood [sugar] and insulin…, whereas these responses were higher for [the three other] beverages following the…lunch.” So, when it came to calorie intake, or blood sugars, or insulin spikes, they were all just as bad.

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• Liu C, Dai L, Liu Y, et al. Antiproliferative Activity of Triterpene Glycoside Nutrient from Monk Fruit in Colorectal Cancer and Throat Cancer. Nutrients. 2016;8(6)

Motion graphics by Avocado Video.

• animal studies
• artificial sweeteners
• aspartame
• asthma
• beverages
• blood sugar
• cancer
• colon cancer
• fruit
• insulin
• liver health
• monk fruit
• nutrition myths
• oxidative stress
• pancreatic cancer
• soda
• Splenda
• stevia
• sucralose
• sugar
• sweeteners