monk-fruit

What is monk fruit

Monk fruit also known as Luo Han Guo or Siraitia Grosvenorii, is a herbaceous perennial vine of the Cucurbitaceae (gourd) family, native to southern China and northern Thailand. Monk fruit contains a sweet, fleshy, edible pulp that is widely used in traditional Chinese medicine. The major bioactive constituents in the Monk fruit extract are the cucurbitane-type triterpene saponins known as mogrosides. Among them, Mogroside V being the main mogroside in the Monk fruit extract is nearly 300 times sweeter than than sugar and has been used in China as a low-calorie sweetener for cooling drinks and in traditional Chinese medicine. Mogrosides are present in the fresh fruit (0.55–0.65%). The monk fruit extract may have different concentrations of mogroside V content (25%, 45% and 55%), varying according to the manufacturing process 1). Monk fruit is also known as natural non-nutritive sweetener (calorie free sweetener). Sweeteners are substances used to improve the palatability and shelf life of food products. Sweetness also balances bitterness, sourness, and saltiness. The consumption of sweeteners, natural as well as synthetic sugars, is implicated in an array of modern-day health problems. Therefore, natural nonsugar sweeteners are of increasing interest. Monk fruit and monk fruit extract contain 16kJ per gram calories (see Table 1 and 2). The powdered extract of monk fruit (Nectresse and Luo Han Guo), a round green melon that grows in central Asia is heat stable and can be used in baking and cooking and is more concentrated than sugar (¼ teaspoon or 0.5 grams equals the sweetness of 1 teaspoon or 2.5 grams sugar). The US FDA approved monk fruit extract as generally recognized as safe (GRAS) as a food additive and table top sweetener 2). In contrast, the European Food Safety Authority on Food Additives and Flavourings Panel concluded that “on the available toxicity database on Monk fruit extract is insufficient to conclude on the safety of the use of Monk fruit extract as a food additive” 3).

Sweetness is one of the fundamental human hedonic pleasures 4), even more reinforcing and attractive than drugs such as heroin and cocaine 5). However, in satisfying this desire, sugar consumption has risen exponentially from nearly 250 years ago and meta-analyses implicate sugar consumption in the development of obesity, diabetes, metabolic syndrome, and cardiovascular diseases 6). Noncaloric artificial sweeteners offer hope for calorie reduction and, although there has been a general acceptance of many of them as safe for consumption 7), recent research has pointed to effects of synthetic sweeteners on the intestinal microbiome, ironically leading to metabolic syndrome and glucose intolerance 8), 9). In light of the problems associated with both natural sugar and synthetic noncaloric sweeteners, there is great interest in developing alternative natural nonsugar sweeteners to satisfy the human “need” for sweet.

The active components responsible for the monk fruit sweetness are mogrosides, which are members of the family of triterpene glycosides. In studies the relationships of the structure and the taste, the number of glucose units at the 3 and 24-position of the aglycone moiety are thought responsible for the perception of taste 10). Among them, mogroside IV, V and mogroside VI which have more glucose units and are extremely sweet, but the fruit also contains some tasteless glycosides, as well as bitter-tasting glycosides such as mogroside III and mogroside II E which possess less glucose units 11). Previous research has indicated that the bitter mogroside II E and tasteless mogroside III are the main products in the fruit at the early growing stage, but these decrease as the fruit matures 12). The content of mogroside V increases rapidly from 50 to 70 days after flowering and levels off after 85 days after flowering 13).

What are Natural Sweeteners ?

First of all, we need to define what sweeteners are. Sweeteners are substances used to improve the palatability and shelf life of food products. Sweetness also balances bitterness, sourness, and saltiness. A preference for sweet taste is innate and sweeteners can increase the pleasure of eating.

Sweeteners can generally be divided into three types of sweeteners depending how there are made:

  1. Natural Sweeteners come from plant origin e.g. sugar (sucrose), honey, molasses, maple syrup, coconut palm sugar, stevia, agave, brown sugar, fruit concentrates, Luo Han Guo (monk fruit) fruit extracts.
  2. Artificial (synthetic) Sweeteners are man made high-intensity sweeteners e.g. Aspartame (NutraSweet® and Equal®); Acesulfame-K (Sweet One®); Neotame; Saccharin (Sweet’N Low®); Sucralose (Splenda®) and Advantame. Artificial sweeteners also known as sugar substitutes are called ‘high-intensity’ sweeteners, because small amounts pack a large punch when it comes to sweetness. Artificial sweeteners are regulated by the U.S. Food and Drug Administration (FDA) 14). And because high-intensity sweeteners are many times sweeter than table sugar (sucrose), smaller amounts of high-intensity sweeteners are needed to achieve the same level of sweetness as sugar in food. People may choose to use high-intensity sweeteners in place of sugar for a number of reasons, including that they do not contribute calories or only contribute a few calories to the diet. High-intensity sweeteners also generally will not raise blood sugar levels 15).
  3. Sugar Alcohols (Polyols). Despite their name, sugar alcohols aren’t sugar, and they aren’t alcohol. They are carbohydrates that occur naturally in certain fruits and can also be manufactured. They get their name because they have a chemical structure similar to sugar and to alcohol. Examples of sugar alcohols, isomalt, maltitol, lactitol, trehalose, mannitol, erythritol, xylitol and D-tagatose.

To make it even more complicated, sweeteners can be further divided into two categories based on their calorie content:

  • Nutritive sweeteners – those that contain more than 2 percent of the calories in an equivalent amount of sugar, therefore nutritive sweeteners add caloric value to the foods that contain them 16). For example, sugar (sucrose), honey, molasses, maple syrup, coconut palm sugar, agave, brown sugar, fruit concentrates, Xylitol, Sorbitol, isomalt, maltitol, lactitol, trehalose, mannitol, erythritol and D-tagatose.
  • Non-nutritive sweeteners – since they offer no nutritional benefits such as vitamins and minerals and they are low or have no calories. Non-nutritive sweeteners are those that contain less than 2 percent of the calories in an equivalent amount of sugar or have no calories at all. Also known as artificial sweeteners, sugar substitutes, low-calorie sweeteners, noncaloric sweeteners, or high-intensity sweeteners 17). For example, Stevia, Luo Han Guo fruit extracts (Siraitia grosvenorii Swingle fruit extract), Aspartame (NutraSweet® and Equal®); Acesulfame-K (Sweet One®); Neotame; Saccharin (Sweet’N Low®); Sucralose (Splenda®) and Advantame. Food products are considered “no-calorie” if they have 5 calories or less per serving. Notice that even though the nutrition labels on sweetener packets claim to have zero calories and carbohydrate, there are a small amount calories and carbs from those added ingredients 18).

Figure 1. Monk fruit

monk fruit extract
health-benefits-of-monk-fruit

Figure 2. Mogroside V chemical structure

Mogroside V chemical structure
[Source 19) ]

Monk fruit nutrition facts

Table 1. Monk fruit nutrition facts

NutrientUnittsp 0.5 gValue per 100 g
Approximates
Energykcal00
Proteing00
Total lipid (fat)g00
Carbohydrate, by differenceg0.5100
Sugars, totalg0.5100
Minerals
Sodium, Namg00
Lipids
Fatty acids, total saturatedg00
Fatty acids, total transg00
[Source: United States Department of Agriculture, Agriculture Research Service. USDA Food Composition Databases. 20)]

Table 2. Monk fruit extract nutrition facts

NutrientUnitML 0.6 gValue per 100 g
Approximates
Energykcal00
Proteing00
Total lipid (fat)g00
Carbohydrate, by differenceg00
Sugars, totalg00
Minerals
Sodium, Namg00
[Source: United States Department of Agriculture, Agriculture Research Service. USDA Food Composition Databases. 21)]

Monk fruit vs Stevia

Stevia

Stevia (Truvia, Pure Via, Sun Crystals, Rebaudioside A, Reb A, rebiana) is a non-caloric plant-based sweetener; made from the plant Stevia rebaudiana, which is grown for its sweet leaves; common names include sweetleaf, sweet leaf, sugarleaf, or simply stevia 22). In addition to stevioside several other sweet principles such as steviosides A and B, Steviobioside, Rebaudioside A, B, C, D, E
and Dulcoside A were isolated from Stevia rebaudiana leaf 23). FDA approved as generally recognized as safe (GRAS) as a food additive and table top sweetener only certain high purity steviol glycosides purified from the leaves of Stevia rebaudiana (Bertoni). Stevia is 150 to 200 times sweeter than sucrose (table sugar) 24).

Stevia (Stevia rebaudiana) is a bushy shrub that is native to northeast Paraguay, Brazil and Argentina 25). It is now grown in other parts of the world, including Canada and part of Asia and Europe. It is probably best known as a source of natural sweeteners.

Extracts from the stevia leaves are available as sweeteners in Japan, South Korea, Malaysia, Taiwan, Russia, Israel, Mexico, Paraguay, Uruguay, Venezuela, Colombia, Brazil, and Argentina 26).

Some people take stevia by mouth for medical purposes such as lowering blood pressure, treating diabetes, heartburn, high uric acid levels in the blood, for weight loss, to stimulate the heart rate, and for water retention.

Studies on the glycemic effect of rebaudioside A is still not clear, but it seems that consumption of rebaudioside A did not worsen glycemic control in individuals with and without diabetes 27).

The appropriate dose of stevia depends on several factors such as the user’s age, health, and several other conditions. At this time there is not enough scientific information to determine an appropriate range of doses for stevia. Keep in mind that natural products are not always necessarily safe and dosages can be important. Be sure to follow relevant directions on product labels and consult your pharmacist or physician or other healthcare professional before using.

Stevia and chemicals contained in stevia, including stevioside and rebaudioside A, are LIKELY SAFE when taken by mouth as a sweetener in foods 28). The U.S. Food and Drug Administration (FDA) has given the generally recognized as safe (GRAS) status for Rebaudioside A in the U.S. for use as a sweetener for foods 29). Stevioside has been safely used in research in doses of up to 1500 mg daily for 2 years.

In March 2010, the European Food Safety Authority (EFSA) concluded that the stevia sweeteners are not carcinogenic, genotoxic or associated with any reproductive/developmental toxicity and established an Acceptable Daily Intake (ADI) of 4 mg/kg body weight/day. Conservative estimates of steviol glycosides exposure, both in adults and in children, suggest that it is likely that the ADI would be exceeded at the maximum proposed use levels. The use of Stevia is now authorised in the European Union at appropriate levels for 31 different food categories including soft drinks, desserts, confectionary and table top sweeteners 30).

Some people who take stevia or stevioside can experience bloating or nausea. Other people have reported feelings of dizziness, muscle pain, and numbness.

Special precautions & warnings:

  • Pregnancy and breast-feeding: There is not enough reliable information about the safety of taking stevia if you are pregnant or breast feeding. Stay on the safe side and avoid use.
  • Allergy to ragweed and related plants: Stevia is in the Asteraceae/Compositae plant family. This family includes ragweed, chrysanthemums, marigolds, daisies, and many other plants. In theory, people who are sensitive to ragweed and related plants may also be sensitive to stevia.
  • Diabetes: Some developing research suggests that some of the chemicals contained in stevia might lower blood sugar levels and could interfere with blood sugar control. However, other research disagrees. If you have diabetes and take stevia or any of the sweeteners it contains, monitor your blood sugar closely and report your findings to your healthcare provider.
  • Low blood pressure: There is some evidence, though not conclusive, that some of the chemicals in stevia can lower blood pressure. There is a concern that these chemicals might cause blood pressure to drop too low in people who have low blood pressure. Get your healthcare provider’s advice before taking stevia or the sweeteners it contains, if you have low blood pressure.
  • Lithium: Stevia might have an effect like a water pill or “diuretic.” Taking stevia might decrease how well the body gets rid of lithium. In theory, this could increase how much lithium is in the body and result in serious side effects. Talk with your healthcare provider before using this product if you are taking lithium. Your lithium dose might need to be changed 31).
  • Medications for diabetes (Antidiabetes drugs): Some research shows that stevia might decrease blood sugar in people with type 2 diabetes. In theory, stevia might cause an interaction with diabetes medications resulting in blood sugar levels going too low; however, not all research has found that stevia lowers blood sugar. Therefore, it is not clear if this potential interaction is a big concern. Until more is known, monitor your blood sugar closely if you take stevia. Some medications used for diabetes include glimepiride (Amaryl), glyburide (DiaBeta, Glynase PresTab, Micronase), insulin, pioglitazone (Actos), rosiglitazone (Avandia), chlorpropamide (Diabinese), glipizide (Glucotrol), tolbutamide (Orinase), and others. The dose of your diabetes medication might need to be changed 32).
  • Medications for high blood pressure (Antihypertensive drugs): Some research shows that stevia might decrease blood pressure. In theory, taking stevia along with medications used for lowering high blood pressure might cause your blood pressure to go too low. However, some research shows that stevia does not affect blood pressure. Therefore, it’s not known if this potential interaction is a big concern. Some medications for high blood pressure include captopril (Capoten), enalapril (Vasotec), losartan (Cozaar), valsartan (Diovan), diltiazem (Cardizem), Amlodipine (Norvasc), hydrochlorothiazide (HydroDiuril), furosemide (Lasix), and many others 33).
  • Herbs and supplements that might lower blood pressure: Stevia might lower blood pressure. Using it along with other herbs and supplements that have this same effect might increase the risk of blood pressure dropping too low in some people. Some of these products include andrographis, casein peptides, cat’s claw, coenzyme Q-10, fish oil, L-arginine, lycium, stinging nettle, theanine, and others 34).
  • Herbs and supplements that might lower blood sugar: Stevia might lower blood sugar. Using it along with other herbs and supplements that have the same effect might cause blood sugar to drop too low in some people. Some of these products include alpha-lipoic acid, bitter melon, chromium, devil’s claw, fenugreek, garlic, guar gum, horse chestnut seed, Panax ginseng, psyllium, Siberian ginseng, and others 35).
stevia

Monk fruit benefits

Monk Fruit (Nectresse and Luo Han Guo) also known as Siraitia grosvenori Swingle, has been used in China for centuries as a natural sweetening agent and has been reported to be beneficial for diabetic population 36), 37). Monk fruit is also widely used for respiratory conditions in traditional Chinese Medicine, for bronchitis, tonsillitis, cough, and sore throat. The leaf (luo han ye) is also used to make a tea for these conditions. In the summer, monk fruit is used in beverages to quench thirst and reduce body heat 38).

However, limited research has been conducted to elucidate the relationship between the sweetening action and biological parameters that may be related to potential health benefits of Luo Han Kuo fruit. The present study 39) examined the effect of Monk Fruit and its chemical components on insulin secretion using an in vitro cell model system. Mogroside V is the most abundant and the sweetest chemical component among the mogrosides in Luo Han Kuo fruit. The experimental data demonstrated that the crude Luo Han Kuo fruit extract stimulated the secretion of insulin in pancreatic beta cells; furthermore, pure mogroside V isolated from Luo Han Kuo fruit also exhibited a significant activity in stimulating insulin secretion by the beta cells, which could partially be responsible for the insulin secretion activity of Luo Han Kuo fruit and fruit extract. The current study supports that Luo Han Kuo fruit/extract has the potential to be natural sweetener with a low glycemic index and that mogroside V, possible other related mogrosides, can provide a positive health impact on stimulating insulin secretion 40).

Monk fruit is collected as a round green fruit that turns brown upon drying. The sweet taste of the fruit comes mainly from mogrosides, a group of triterpene glycosides that make up about 1% of the flesh of the fresh fruit 41). The mogrosides have been numbered 1-5 42) and the main component is called mogroside-5, previously known as esgoside. Other, similar compounds from luohanguo have been labeled siamenoside and neomogroside 43). The mixed mogrosides are estimated to be about 300 times as sweet as sugar by weight, so that the 80% extracts are nearly 250 times sweeter than sugar; pure mogrosides 4 and 5 may be 400 times as sweet as sugar by weight 44). Through solvent extraction, a powder containing 80% mogrosides can be obtained, the main one being mogroside-5 (esgoside). Other similar agents in the fruit are siamenoside and neomogroside 45). The powdered extract of monk (Luo Han Kuo fruit) fruit, a round green melon that grows in central Asia; 150 to 200 times sweeter than sucrose (table sugar); heat stable and can be used in baking and cooking and is more concentrated than sugar (¼ teaspoon or 0.5 grams equals the sweetness of 1 teaspoon or 2.5 grams sugar). FDA approved as generally recognized as safe (GRAS) as a food additive and table top sweetener.

Monk fruit side effects

No incidents of negative side effects of monk fruit have been reported. Many animal studies have shown a lack of toxicity of monk fruit extracts 46) and in recent human studies, Tey, Salleh, and Henry 47) found that a beverage containing monk fruit had no effect on total daily energy intake, blood glucose, and insulin responses in healthy human males.

In Europe, monk fruit is classified as an unapproved “Novel Food” which means that it may be marketed as a food or food ingredient only after a safety assessment and approval by the European Commission; as of 2017, monk fruit was not listed among approved Novel Foods in the EU 48). In 2019, the European Food Safety Authority on Food Additives and Flavourings Panel concluded that based “on the available toxicity database on Monk fruit extract is insufficient to conclude on the safety of the use of Monk fruit extract as a food additive” 49).

The toxicity of monk fruit extract has been explored in numerous in vivo (animal) and in vitro (test tube) studies, including acute toxicity, short-term toxicity, long-term toxicity, genotoxicity and mutagenicity studies. In all cases there were no observed adverse effects, establishing an no-observed-adverse-effect-level (NOAEL) for each category of toxicity for both the extract itself and for mogroside V. The lowest (i.e. most restrictive) no-observed-adverse-effect-level (NOAEL) of any category is 600 mg/kg body weight for genotoxicity of mogroside V. All other NOAELs for mogroside V are above 1 g/kg body weight (or 70 grams for a 70kg person). The NOAEL for acute toxicity of monk fruit extract is 10 g/kg body weight. Even at 600 mg/kg body weight, a 150-fold safety factor exists over the highest estimated daily intake (EDI) for 90th percentile consumers given in any of the GRAS determinations submitted to the US FDA. 86 mg/kg body weight per day for a healthy child. Conservatively assuming this highest EDI applies to a 75 kg individual, this would still only represent around the same intake of mogroside V as is contained in a single monk fruit, which is consistent with the consumption of monk fruit for traditional purposes in China.

Human studies

In a cross‐over design, the comparative effect of consumption of Monk fruit extract and sucrose on blood glucose level was investigated 50). After fasting overnight, five healthy men and five healthy women aged 19–25 years consumed 200 mg/kg body weight of Monk fruit extract dissolved in water. Their blood glucose levels were tested at 0, 15, 30, 60, 120 and 180 min after dosing. Three days later, the same 10 participants consumed 3,000 mg/kg body weight of sucrose dissolved in water, again after an overnight fast, and blood samples were taken at the same time intervals. While ingestion of sucrose resulted in a 70% increase in blood glucose, level during the first 15 min, gradually decreasing to the starting level over 3 hour, ingestion of Monk fruit concentrate had no effect on blood glucose 51).

In another cross‐over design, Monk fruit extract was tested to investigate the effects on blood levels of liver enzymes 52). Six healthy males aged 19–25 years fasted overnight and then consumed 200 mg/kg body weight of Monk fruit extract dissolved in water; 3 days later they consumed only water. On both days, blood samples were taken at 0, 1, 2, 3, and 6 h after administration. Five liver enzymes were analysed: alkaline phosphatase (ALP), y‐glutamyl‐transpeptidase (GGT), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH). There was no statistically significant change in the blood level of any of these enzymes over time, nor any difference between enzyme levels after dosing with Monk fruit extract or with water.

Overall, studies in humans demonstrated that Monk fruit extract, following ingestion of a single 200 mg/kg body weight per day dose, had no effect on blood glucose nor did it produce changes in liver enzymes (ALP, GGT, ALT, AST or LDH). No adverse effects were reported in these clinical studies. However, it should be noted that the duration of the studies is very short (single administration), the number of subjects tested was too low to draw conclusions on the safety of monk fruit extract in humans. In addition, the composition of the Monk fruit extract was not reported.

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