Monk fruit (Siraitia grosvenorii), or Luo han guo, is a fruit native to southeast Asia and a member of the gourd (Cucurbitaceae) family. It is a natural sweetener with many health benefits, including anti-inflammatory, antioxidant, and anti-cancer effects, promoting heart and liver health and reducing fatigue. Read more to learn about the benefits and side effects of this fruit.
What is Monk Fruit?
Monk fruit is a fruit native to southeast Asia and a member of the gourd (Cucurbitaceae) family. It is named after the Buddhist monks who first cultivated the fruit nearly 800 years ago.
It contains powerful antioxidants called mogrosides that are 250 times sweeter than table sugar (sucrose) .
For this reason, its extract has been traditionally used as a natural, non-caloric sweetener to replace sugar .
Monk fruit has:
- Zero calories [2, 3]
- Vitamin C, which decreases blood histamine levels and maintains collagen [4, 5]
- Kaempferol, a flavonoid with potent antimicrobial and antioxidant effects [6, 7]
- Triterpene glycosides, compounds that suppress reduce the growth of tumor cells [8, 9]
- Mogrosides I-V :
- Cucurbitacins, compounds that have anti-inflammatory effects by inhibiting TNF-alpha and COX-2 [13, 14]
- Polysaccharide fibers, which lower cholesterol levels [15, 16]
Mechanism of Action
Monk fruit contains mogrosides, antioxidants that decrease blood vessel leakiness (permeability), inhibit histamine release from mast cells, and prevent inflammatory damage.
Mogrosides are saponins, chemicals that prevent the excess leakiness of cell membranes (membrane hyperpermeability), which protects mitochondria and DNA from oxidative damage [17, 18, 19, 20, 17, 2, 21].
Mogrosides also protect DNA by increasing the production of PARP1, p53, and MAPK9 .
Mogrosides have anti-cancer effects by:
- Promoting programmed cell death (apoptosis) and arresting the cell cycle of cancer cells [11, 22]
- Suppressing cancer proliferation by increasing p53, a protein that suppresses tumors, and decreasing MMP-9 
- Reducing VEGF, which helps reduce blood vessel growth 
Mogrosides also decrease inflammation by:
- Reducing NF-kB and suppressing the PI3K/Akt pathway 
- Decreasing the production of inflammatory molecules such as iNOS, COX-2, and IL-6 
- Reducing CREB and activating AMPK, which helps reduce blood sugar and suppress fat production
Monk fruit contains compounds that have antibacterial activity. In the lab, beta-amyrin, aloe-emodin, sitosterol, and daucosterol inhibited the growth of Streptococcus mutans, Actinobacillus, Fusobacterium nucleatum, and Candida albicans .
Health Benefits of Monk Fruit
1) Monk Fruit Has Anti-cancer Effects
Cancer may occur due to a variety of environmental factors. Chronic oxidative damage, carcinogens, nutrient deficiency, and an inadequate supply of oxygen to tissue (respiratory perfusion) all contribute to the initiation and progression of cancer by causing genetic stress [27, 28, 29].
Monk fruit contains a variety of compounds that have anti-cancer effects:
- Mogroside IV suppressed throat and colorectal cancers in mice (dose-dependent) .
- Mogroside V inhibited tumor growth in mice with pancreatic cancer. It also inhibited the growth of new blood vessels (angiogenesis) in mice with cancer, which helps reduce tumor growth [R, R].
- Mogrosides inhibited the proliferation of cancer cells in mice .
- Cucurbitacin E inhibited the growth of human breast cancer cells in the lab .
- Triterpene glycosides significantly inhibited the effects of carcinogens (cancer-causing substances) on mouse skin tumors .
Selective mutations allow limitless replication and evasion of programmed cell death (apoptosis) by cancerous cells.
DNA repair is crucial in warding off these mutations. Mogrosides increase protective genes involved in DNA repair, genomic stability, and apoptosis (PARP, p53, and MAPK9) .
Furthermore, a key signature of cancer cells that differentiates them from healthy cells is how they burn fuel to create energy (ATP).
Healthy cells use oxygen in their mitochondria to produce more energy than burning glucose alone (fermentation).
If used as a replacement for sugar, monk fruit may have synergistic anti-tumor effects. It limits the fuel (blood glucose) cancer needs to thrive and protects the genes that initiate cancer cell death (p53) [35, 36, 37].
2) Monk Fruit Is Anti-Inflammatory
A diet high in simple sugars and deficient of essential nutrients can lead to cancer, cardiovascular disease, diabetes, gastrointestinal irritability, and allergies. Chronic inflammation is at the root of the most prevalent diseases [37, 38, 39].
Administering monk fruit extract before exposing mice to a carcinogen blocked the induction of inflammation .
Histamine increases blood vessel leakiness, which enhances inflammation, to allow immune cells to engage pathogens in infected tissue.
3) Monk Fruit Is a Potent Antioxidant
Free radical damage alters the cellular environment. Excessive damage leads to tissue destruction (necrosis) and eventually organ dysfunction.
Mogroside treatment of a mouse pancreatic tumor decreased the intracellular concentration of reactive oxygen species .
4) Monk Fruit May Combat Obesity and Diabetes
During type II diabetes, inflammation damages the cells of the pancreas, impairing insulin secretion. As blood sugar rises, the kidneys get damaged, releasing greater amounts of albumin out through urine. This is known as diabetic nephropathy.
The therapeutic effects of monk fruit on diabetic rabbits was studied by administering an extract for 4 weeks.
It significantly decreased sugar, total cholesterol, and triglyceride levels in the blood, while increasing HDL cholesterol (“good” cholesterol, which is inversely correlated with hardening of the arteries) .
Monk fruit extract prevented the rise of blood sugar in mice when given 3 minutes before administering maltose .
It also reduced blood sugar and urinary albumin levels in diabetic rats, indicating that it can improve kidney damage caused by diabetes .
Mogroside antioxidants protected the kidney and pancreas from free radical damage (lipid peroxidation) .
Components of monk fruit prevent fat cells from maturing. Mogrol suppresses fat production (adipogenesis) by inhibiting the enzymes that convert stem cells to fat cells (adipocytes) .
5) Monk Fruit May Be Anti-Aging
Chronic inflammation and oxidative stress contribute to many diseases of aging (cancer, atherosclerosis, Alzheimer’s). The most widely studied aspect of senescence is an increase in systemic inflammatory cytokines .
Mogrosides decreased blood markers associated with lower grip strength and gait speed in older adults .
6) Monk Fruit Is Anti-Fibrotic
Mogroside IIIE possesses anti-fibrotic faculty, which decreases cell surface tension and prevents pulmonary fibrosis by inhibiting inflammation and extracellular matrix deposition (by lowering myeloperoxidase, TGF-beta, and MMP9) in mice .
7) Monk Fruit May Promote Heart Health
Accumulating LDL cholesterol in macrophages contributes to hardening of the arteries (atherosclerosis). Lowering LDL cholesterol reduces the risk of heart disease, while HDL cholesterol levels are inversely correlated with hardening of the arteries and heart disease .
Administering mogroside extract to diabetic mice for over 4 weeks significantly decreased total cholesterol and increased HDL cholesterol (“good” cholesterol) .
8) Monk Fruit May Reduce Fatigue
Monk fruit extract decreased physical fatigue in mice in a dose-dependent manner. The treated mice had extended swimming times compared to the control group .
Monk fruit extract also stimulated the production of new mitochondria (by increasing PGC-1ɑ activity) .
9) Monk Fruit Protects the Liver
Liver inflammation slows down bile flow, which is detrimental to fat metabolism and the excretion of cholesterol, drugs, and toxic metabolites. Disrupting bile acid metabolism clogs the gallbladder (cholestasis) and causes fatty liver disease, cardiovascular diseases, and diabetes .
Mogroside helps break down cholesterol and protect the liver from oxidative damage. In diabetic mice, mogroside treatment reactivated liver antioxidant enzymes (superoxide dismutase, and glutathione peroxidase), which play a critical role in detoxification [15, 57, 54].
10) Monk Fruit Protects Against Infections
The fruit has been used for centuries in traditional Chinese medicine to treat a sore throat and cough.
In the lab, components of monk fruit prevented the growth of oral bacteria and fungal species .
11) Monk Fruit Is a Natural Antihistamine
After repeated administration, monk fruit extract prevented allergic symptoms (nasal rubbing or scratching) in mice. The mogrosides and extract inhibited the release of histamine from mast cells .
12) Monk Fruit Improves Immunity
A meta-analysis on monk fruit found that extracts and individual compounds in monk fruit are non-toxic according to existing research .
Monk fruit juice concentrate is generally recognized as safe (GRAS) by the U.S. Food and Drug Association as an ingredient in conventional food and infant and toddler foods, as stated on the FDA website .
Limitations and Caveats
- Most studies have been performed on animals
- Limited human studies
- No long-term studies on monk fruit effects
- Overall, the number of studies on monk fruit is limited
Natural Sources/Forms of Supplementation
- Whole fruit extract
- Mogroside extract
- Pure Monk
- Lakanto (powder and liquid)
- Monk Fruit in the Raw
- Health Garden
- Smart 138
- Dried fruit (tea)
Monk Fruit vs. Stevia
Both are zero-calorie, high-intensity sweeteners .
Although monk fruit and stevia are increasingly used as sweeteners, the number of studies on their health effects are limited .
Monk Fruit Pros:
- The carbon and water footprint of cultivating stevia is significantly lower than beet or cane sugar 
- Stevia is proven safe in more than 200 studies 
Monk fruit can be taken in tea by simmering 1 to 2 whole fruits for 60 minutes.
The serving size of commercial monk fruit ranges from 0.8 to 4 grams.
One user reports that the whole fruit concentrate tastes like molasses and goes very well with coffee and chocolate.
An experienced non-nutritive sweetener user reports that the whole fruit concentrate does not sweeten coffee and has a bitter aftertaste.
Another user reports a maple syrup smell and flavor, with no aftertaste.
A review on Luo Han Guo whole fruit concentrate prefers the taste compared to Stevia but also reports a faint alcohol aftertaste when used in drinks.
Overall, it comes down to preference with taste. Some users are disappointed with the flavor/aftertaste, while others report no aftertaste and prefer the flavor.