IngredientsSalacia is a genus of flowering plants belonging to the family Celastraceae. Salacia is a genus of plants in the family Celastraceae, and they are woody climbers naturally found in tropical regions. The genus is a source of many important pharmaceutical chemicals used in the Ayurvedic system of medicine in India. Owing to morphological similarities between species, the taxonomy of Salacia is complex and not fully settled.
The three species most extensively studied for medicinal and nutritional applications are:
Because S. reticulata has been the most widely studied of the Salacia species, most clinical research focuses primarily on studies conducted with this species. Information is also available with respect to effects of aqueous extracts of S. oblonga and S. chinensis.
Salacia reticulata is known in Ayurvedic medicine as "kothala himbutu" in Sinhala. It is a herb widely used in Ayurvedic medicine to treat diabetes and obesity. In India, S. reticulata is also referred to by the Sanskrit name saptachakra. Salacia oblonga goes by the common name ponkoranti in parts of South Asia.
Extracts of Salacia reticulata Wight (Celastraceae) roots, stems, and leaves have been used in Asia for hundreds of years for the folkloric treatment of diabetes and other health problems. In research and traditional preparation, the roots and stems are the primary plant parts utilized. Many triterpenes, hydrocarbons and sitosterol have been isolated from roots and stem barks.
Salacia is available in several preparations:
Salacia roots have been used in Ayurvedic medicine for diabetes and obesity since antiquity, and have been extensively consumed in Japan, the United States, and other countries as a food supplement for the prevention of obesity and diabetes.
Several species in this genus have been used in traditional medicine, such as the Ayurvedic system from India. Salacia oblonga has been used for thousands of years in Ayurvedic medicine and is closely associated with prevention, treatment, and cure of various human ailments such as obesity and diabetes.
Beyond diabetes and obesity, the traditional pharmacopoeia employs Salacia across a broader range of conditions. In addition to treating diabetes, decoctions (aqueous extracts) of S. reticulata and extracts of other Salacia species have been used for hundreds of years for the treatment of asthma, rheumatism, hemorrhoids, itching and swelling, gonorrhea, skin diseases, and amenorrhea. The Ayurvedic tradition specifically utilizes this plant at early stages of the disease rather than in advanced diabetes.
S. reticulata has been used also as a supplementary food in Japan to prevent diabetes and obesity. The adoption of Salacia as a functional food ingredient in Japan is well-documented, and the country's rigorous regulatory framework β FOSHU β has formally recognized Salacia-derived preparations for blood glucose-related health claims.
The traditional preparation of Salacia as an aqueous infusion β either by boiling the dried root or stem bark in water or by soaking pieces of wood in water β is consistent with modern scientific findings showing that the key active compounds are water-soluble. The wooden-cup tradition in Sri Lanka, wherein the wood itself leaches compounds into the drinking water, represents one of the more distinctive delivery methods associated with this plant. The aqueous extract of the roots and stems of this plant is extensively used in Ayurvedic medicine in India and Sri Lanka in treatment in the initial stages of diabetes.
The constituents of Salacia are numerous and vary according to the species and place of origin. Multiple compounds with hypoglycaemic effects have been isolated from Salacia species. A vast and wide range of chemical compounds such as polyphenols, friedelane-type triterpenes, norfriedelane-type triterpenes, eudesmane-type sesquiterpenes including various glycosides have been isolated from this plant.
The most pharmacologically significant class of compounds found in Salacia species is a group of unusual sulfur-containing cyclitol derivatives β thiosugar sulfonium salts β that function as potent inhibitors of intestinal carbohydrate-hydrolyzing enzymes.
Unlike many botanical supplements with a single purported mechanism, Salacia extracts have been shown to act simultaneously on several biochemical targets involved in carbohydrate and lipid metabolism.
Alpha-glucosidase inhibitors are well suited to treat postprandial hyperglycemia, a common and serious problem faced by many people with type 2 diabetes metabolism. Alpha-glucosidase inhibitors cause competitive, reversible inhibition of the alpha-glucosidase enzyme. This enzyme is present in the brush border of the small intestine and hydrolyzes complex sugars into monosaccharides. Through bioassay-guided separation using alpha-glucosidase inhibitory activities, a potent glycosidase inhibitor named salacinol was isolated from the water-soluble fractions obtained from the dried roots of S. reticulata. The water-soluble fraction inhibited the increase in serum glucose levels after the administration of sucrose or maltose in rats. The consequence of this enzyme inhibition at the intestinal brush border is a blunting of the rise in postprandial blood glucose following carbohydrate-containing meals, particularly those containing sucrose, maltose, and starch-derived oligosaccharides.
Apart from the well-known action of decreasing postprandial blood glucose by inhibiting alpha-glucosidase and alpha-pancreatic amylase, Salacia also inhibits aldose reductase, which otherwise results in microvascular complications. Aldose reductase, the first enzyme in the polyol pathway, drives the conversion of excess glucose to sorbitol in tissues such as nerve, lens, retina, and kidney; its inhibition is regarded as a mechanism for reducing diabetic microvascular complications.
The hot water extract of S. oblonga suppressed pancreatic lipase activity. Therefore, the inhibition of pancreatic lipase activity in the small intestine was suggested as one of the main mechanisms of improvement of postprandial hyperlipidemia in type 2 diabetes and obesity by Salacia root.
PPAR-Ξ± is a nuclear receptor that regulates genes governing fatty acid oxidation in the liver and heart. Improvement by Salacia oblonga extract of excess cardiac lipid accumulation and increased cardiac fatty acid oxidation in diabetes and obesity occurs by reduction of cardiac fatty acid uptake, thereby modulating cardiac PPAR-alpha-mediated fatty acid metabolic gene transcription.
Studies indicate that Salacia extracts modulate multiple targets that influence carbohydrate and lipid metabolism including alpha-glucosidase, aldose reductase, pancreatic lipase, peroxisomal proliferator-activated receptor-alpha, glucose transporter-4 mediated glucose uptake, and angiotensin II type 1 receptor.
In mouse mesenteric fat it enhances the mRNA expression for hormone-sensitive lipase (HSL) and adiponectin, thus increasing lipolysis and reducing insulin resistance respectively. In 3T3-L1 adipocytes, lipogenesis factors are down-regulated and lipolysis factors are up-regulated with Salacia reticulata treatment.
Furthermore, Salacia extracts exhibit free radical scavenging, antioxidant, and hepatoprotectant activities.
Strength of evidence: Moderate (multiple randomized controlled trials in humans, consistent direction of effect, but individual trials generally small)
This is the most rigorously investigated area of Salacia research and the basis for its approved health claims in Japan.
A number of human clinical studies have assessed the ability of aqueous S. reticulata extracts to modulate carbohydrate metabolism. Shimoda et al. (1998) conducted one of the earliest clinical studies on the hypoglycemic effects of an aqueous extract of S. reticulata, demonstrating that the extract was beneficial in controlling postprandial hyperglycemia. Kajimoto et al. (2000) conducted a double-blind placebo-controlled study with borderline type II diabetics and observed that S. reticulata extract significantly decreased blood glucose levels relative to the control group.
Jayawardena et al. (2005) administered a S. reticulata tea to 51 type II diabetic subjects in a double-blind, randomized placebo-controlled cross-over study. These studies have indicated that aqueous extracts when administered to type II diabetic subjects effectively control blood glucose levels and do so without adverse effects. Furthermore, blood lipids are also modulated. In addition, tissue-damaging glycosylation reactions involving elevated glucose levels are also decreased as indicated by lowered levels of HbA1c.
A randomized double-blind, placebo-controlled, crossover trial using Salacia chinensis extract (SCE) demonstrated dose-dependent effects: In a placebo-controlled, randomized, double-blind cross-over trial, dose-dependent suppression of postprandial hyperglycemia and improvement of blood glucose parameters were confirmed following a single dose of SCE (150, 300, or 600 mg). Additionally, in a placebo-controlled, randomized double-blind trial, 12-week ingestion of SCE (600 mg before each of three meals daily) improved parameters related to blood glucose, such as HbA1c, glycoalbumin, and 1,5-anhydro-d-glucitol levels, and glucose tolerance after a glucose challenge.
A 2023 randomized triple-blind placebo-controlled crossover clinical trial examined a food-matrix delivery approach: This trial showed that biscuits containing aqueous Salacia reticulata extract taken as a snack reduced HbA1c by 0.25% (2.7 mmol/mol) compared to placebo biscuits without serious renal or liver adverse effects. The study was a pragmatic triple-blind randomized clinical trial.
A study using S. oblonga extract in patients with type 2 diabetes was published in the American Journal of Clinical Nutrition (Williams et al., 2007) and is frequently cited as a key trial. A separate crossover study by Jeykodi et al. (2016), published in the Journal of Diabetes Research, examined Salacia extract in healthy volunteers: This result was shown through repeated measurements of the effect of different doses of SOE on postprandial glycemic, insulinemic, and breath hydrogen responses in healthy adults through a double-masked, randomized, crossover design in 39 healthy, nondiabetic adults.
Lack of adequate detail with respect to plant part used and methods of extract preparation constitutes the major problems associated with a number of the clinical studies. This limitation, combined with generally small sample sizes, means that while the direction of evidence is consistent, a larger and more rigorously standardized evidence base is still needed.
Strength of evidence: Preliminary to moderate (several trials show significant reductions; effect sizes modest)
Clinically significant reductions of HbA1c and plasma insulin are reported with treatment of 6 weeks to 3 months. In human studies, Salacia extracts have been shown to decrease plasma glucose and insulin levels, decrease HbA1c, and modulate serum lipid levels with no adverse effects being reported.
The 2023 crossover trial with S. reticulata extract biscuits confirmed a 0.25% reduction in HbA1c, though researchers noted this is a modest effect: The KH biscuit as a treatment for type 2 diabetes needs further research. However, only a modest effect on HbA1c can be expected because the unadjusted decrease depends on baseline values.
Strength of evidence: Preliminary in humans; stronger in animal models
A polyherbal product containing S. oblonga was used to treat hyperlipidemic conditions in patients with type II diabetes. The product was given at a dose of 1000 mg per day for 8 weeks. What plant parts, how the combination was prepared, and the relative proportions of each constituent were not disclosed. Significant decreases were observed with respect to triglycerides, total cholesterol, and low-density lipoprotein cholesterol with an increase in HDL cholesterol.
Much of the lipid evidence comes from animal models. Salacia oblonga extract reduced plasma triglyceride levels after loading with olive oil in Zucker diabetic fatty (ZDF) rats, whereas it had no effect on plasma triglyceride in the fasted state. These results suggested that S. oblonga inhibited olive oil-induced hypertriglyceridemia by targeting the gastrointestinal system. These multi-target actions may mainly contribute to Salacia root-induced improvement of type 2 diabetes and obesity-associated hyperglycemia, dyslipidemia, and related cardiovascular complications seen in humans and rodents. Well-powered, prospective, randomized trials specifically targeting lipid outcomes as a primary endpoint in humans are still lacking.
Strength of evidence: Preliminary (primarily animal studies; limited human data)
Animal studies indicate Salacia reduces body weight, possibly due to its alpha-glucosidase inhibitor properties, but this has not been examined rigorously in humans. One clinical trial reported significant reduction of weight and BMI when Salacia is used in combination with vitamin D. No clinical studies have examined the effects of Salacia extracts on human weight loss, although weight loss and decreases in weight gain have been demonstrated in animal models.
A randomized controlled trial using Salacia chinensis at doses of 300 mg and 500 mg in overweight and obese adults (n = 48) examined appetite and gut hormones as outcomes: In this study, a randomized, placebo-controlled, three-way cross-over design was used to evaluate whether Salacia chinensis reduces appetite in healthy overweight/obese individuals (BMI 28.8 Β±3.6 kg/mΒ²; 32 Β± 12 years). Forty-eight participants were fasted overnight and consumed a dose of Salacia chinensis (300 or 500 mg) or placebo with a fixed breakfast meal at each visit. Appetite sensations, glycemic indices, and gastrointestinal peptides were measured. Results indicated that Salacia chinensis had no effect on postprandial appetite.
A 12-week trial examining a dietary supplement containing Salacia extract showed favorable changes in adiponectin: Results from the present study indicate that Salacia extract and chromium (SEC) supplementation over 12 weeks and when compared to placebo led to favorable increases in adiponectin levels.
In a preclinical murine study: Salacia supplementation led to significant reductions in body weight gain, adipose tissue weight, adipose tissue mass, and adipocyte size in high-fat diet-fed mice. Human evidence for meaningful weight loss effects remains insufficient at this time.
Strength of evidence: Preclinical only
Apart from the well-known action of decreasing postprandial blood glucose, Salacia also inhibits aldose reductase which otherwise results in microvascular complications. Salacia oblonga has been described as an active ingredient hitting multiple targets, preferably in the case of all diabetic complications such as impaired glucose uptake, insulin resistance, dyslipidemia, cardiac complications, and kidney disorder by acting through the inhibition of alpha-glucosidase, aldose reductase, pancreatic lipase, or by the activation of GLUT-4-mediated glucose uptake, and various PPAR subtypes. Evidence for these effects in humans with established diabetic complications has not yet been produced in dedicated clinical trials.
Strength of evidence: Preclinical (animal and in vitro); limited clinical data
Several animal studies have found that Salacia extract improves non-alcoholic fatty liver disease without hepatotoxicity. Phenolic constituents have been shown to exert hepatoprotective effects in mice challenged with carbon tetrachloride. Clinical trials measuring liver parameters as secondary endpoints have generally found no hepatotoxic signal, and renal and liver parameters measured throughout relevant trials showed no adverse effects.
Strength of evidence: Preliminary; single-dose crossover design; no effect on appetite demonstrated in available RCT
The mechanism of alpha-glucosidase inhibition implies a potential to alter postprandial gut hormone responses, including glucagon-like peptide-1 (GLP-1) and other incretins, by shifting the site of carbohydrate digestion distally in the gastrointestinal tract. However, the human RCT by Hao et al. using S. chinensis (300 mg and 500 mg) found: Salacia had no significant effect on peak serum insulin or amylin concentrations, but both doses of Salacia chinensis lowered insulin and amylin at 60 min compared to placebo (p < 0.05). Postprandial integrated AUC did not differ between groups for any appetite measures. The breath hydrogen responses observed in S. oblonga studies β reflecting carbohydrate fermentation in the colon β confirm genuine alpha-glucosidase inhibitory activity in humans.
Based on published peer-reviewed evidence, Salacia has been associated with the following body systems and health domains:
The following dosages are those reported in published studies and should not be interpreted as prescriptive recommendations:
Dosing is complicated by the lack of standardization across species, plant parts, and extraction methods. The biologically active thiosugar sulfonium content varies by species and geographic origin.
In none of the human studies reviewed were any serious adverse effects described or reported, with studies varying from a single dose to daily dosing for up to 3 months with aqueous extracts of S. reticulata and S. oblonga. Safety of S. reticulata and other Salacia species as S. oblonga and S. chinensis in rats and mice indicates that extracts are exceedingly safe.
The most commonly described adverse effects are gastrointestinal in nature, consistent with the known class effects of alpha-glucosidase inhibitors (such as acarbose). Salacinol is generally well tolerated but is associated with some gastrointestinal side effects. These include bloating, flatulence, abdominal pain, belching, nausea, and diarrhea. Also, drinking Salacia tea has been associated with loose stools and dyspepsia. These adverse reactions seem to be dose dependent. Mild to moderate increases in intensity of flatulence and distension in individuals treated with 1000 mg Salacia extract were observed.
Theoretically, based on the pharmacology of Salacia, concomitant use with prescription antidiabetic drugs could cause additive glucose-lowering effects, increasing the risk for hypoglycemia. As in Europe, many patients use herbal preparations concurrently with prescribed medication but do not tell their doctor about it. There is anecdotal evidence of such patients showing improved control and even an increased incidence of hypoglycemia.
A safety signal has been noted in animal research. Ratnasooriya et al. (2003) reported adverse pregnancy outcomes in rats following exposure to a Salacia reticulata root extract (published in Brazilian Journal of Medical and Biological Research). Human data are absent. Although toxicological studies have suggested minimal adverse effects of the herbal medicine in rodents, a clinical trial is crucial to further confirm the safety of Salacia roots.
Given the glucose-lowering pharmacology, Salacia has the potential to interfere with blood glucose management during surgical procedures, as is consistent with the behavior of any antihyperglycemic agent.
Renal and liver parameters were measured throughout relevant clinical trials and no adverse effects were noted. Several animal studies have found that Salacia extract improves non-alcoholic fatty liver disease without hepatotoxicity.
A larger evidence base is required from well-planned studies to confirm its efficacy and safety. Further mechanistic studies are necessary in order to allow a better understanding of how use of Salacia root may interact with other therapeutic interventions. Additionally, the taxonomic complexity of the genus and inter-species variation in phytochemical profiles means that products labeled generically as "Salacia" may differ substantially in their active compound content. Owing to morphological similarities between species, the taxonomy of Salacia is complex and not fully settled, which presents a challenge for quality control and standardization of commercial preparations.
Health conditions that Salacia may help support.
Body systems that Salacia may help support.
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