Yacon root and leaf supplement extract use, toxicity tests, by Ray Sahelian, M.D.
March 17 2016

Yacon is a tasty, potato-like root vegetable found in Peru. Historically, yacon has been used in South America to lower blood sugar in those with diabetes and improve digestion. Yacon roots are a rich source of fructooligosaccharides (FOS) and have a long use tradition as food in the Andean region. Yacon has several flavonoids including protocatechuic, chlorogenic, caffeic and ferulic acids.

What does the research say?
It appears that substances in yacon have antioxidant, anti-microbial, blood sugar lowering, and liver protecting properties. However, this research, thus far, has only been in the laboratory and animals. Yacon syrup use may lead to weight loss. Other herbs that have a benefit for blood sugar control include Bitter-Melon, prickly pear cactus extract, Fenugreek, and cinnamon.

Human studies
As of 2016 few studies in humans are published with this plant.

Crit Rev Food Sci Nutr. 2015. Yacon (Smallanthus sonchifolius): a food with multiple functions. The present review aims to broaden the discussions of the functional properties attributed to yacon (Smallanthus sonchifolius), considered a food with multiple functions since it possesses bioactive compounds (antimicrobial, antioxidant, and probiotic substances) that exert beneficial effects on the body. Although some studies have already demonstrated several of these functions, clinical evidence is scarce, making it necessary that more studies are conducted in this area. Still, since the availability of this food in the market is relatively new, its popularity depends on publications aimed at consumer education and development of new products by the food industry.

Eur J Nutr. Jan 8 2014. Freeze-dried powdered yacon: effects of FOS on serum glucose, lipids and intestinal transit in the elderly. Freeze-dried powdered yacon (FDY) can be considered a prebiotic product due to its fructooligosaccharides (FOS) content. The effect of 9 weeks of daily intake of FDY containing 7.4 g of FOS on glucose, lipid metabolism and intestinal transit in a group of elderly people was investigated. Seventy-two elderly (mean age 67 ± 6.11) men and women were studied for 9 weeks in a double-blind, placebo-controlled experiment. They were randomly assigned to the supplement group (which received 7.4 g of FOS as FDY) or the control group. At the beginning and end of the study, anthropometric measurements, blood sampling, clinical analyses and dietary intake were assessed. A daily intake of FDY containing 7.4 g of FOS for 9 weeks was associated with a mean decrease in serum glucose (p = 0.013), but supplementation did not reduce serum lipids in the study group. The administered dose did not adversely affect intestinal transit. It did not cause bloating, flatulence or intestinal discomfort. Freeze-dried powdered yacon is a good source of FOS, and daily consumption can have a favourable effect on serum glucose in the elderly. It is also practical, easy and safe to use and store.

Yacon syrup: Beneficial effects on obesity and insulin resistance in humans.
Clin Nutr. 2009. Genta S, Cabrera W, Habib N, Pons J, Carillo IM, Grau A. Instituto Superior de Investigaciones Biológicas (INSIBIO), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Tucumán (UNT), Chacabuco, San Miguel de Tucumán, Tucumán, Argentina.
Syrup obtained from yacon roots could be well positioned as a nutraceutical product due to its high fructooligosaccharides content. We examined the beneficial effects and tolerance of yacon syrup on human health. Obese and slightly dyslipidemic pre-menopausal women were studied over a 120-day period in a double-blind placebo-controlled experiment. We used two doses of yacon syrup, 0.29g and 0.14g fructooligosaccharides/kg/day. At the start and end of the study, anthropometric measurements, blood glucose, calcium, lipid and insulin concentrations were determined. The recommended daily consumption of yacon syrup with no undesirable gastrointestinal effects is 0.14g fructooligosaccharides/kg. Daily intake of yacon syrup produced a significant decrease in body weight, waist circumference and body mass index. Additionally, decrease in fasting serum insulin was observed. The consumption of yacon syrup increased defecation frequency and satiety sensation. Fasting glucose and serum lipids were not affected by syrup treatment and the only positive effect was found in serum LDL-cholesterol levels. Yacon syrup is a good source of fructooligosaccharides and its long-term consumption produced beneficial health effects on obese pre-menopausal women with insulin resistance.

Sperm health
Toxicol Mech Methods. September 2013. A mixture of extracts from Peruvian plants (black maca and yacon) improves sperm count and reduced glycemia in mice with streptozotocin-induced diabetes.

Yocon is found in a variety of ways, including dry root slices, powdered root, cut leaves for tea, yacon syrup, and in the form of various concentrations of extracts. Yacon capsules are available for sale.

Yacon syrup for diabetes, glycemic index
Q. We are a magazine working on a story about alternative sweeteners and I was hoping Dr. Sahelian could tell me whether or not yacon syrup is a safe alternative sweetener for people with diabetes.
   A. Although some websites selling yacon syrup claim it has a low glycemic index and does not raise blood sugar, as of February 2009 I have not seen studies regarding the influence of yacon syrup on blood sugar levels. I suspect yacon syrup, when used in low amounts, should be okay to use those who are diabetic, but until formal studies are done with yacon syrup in terms of determining its glycemic index effects, I would suggest keeping intake to a minimum. Diabetics can safely use stevia, the no calorie natural sweetener.

Yacon benefit review
At this point it is difficult to make any firm recommendations regarding yacon herb since human studies are lacking, but there is a possibility yacon supplements could be helpful in blood sugar control. Yacon capsules are sold as supplements.

Yacon root composition
Many substances are found in the root including tryptophan, caffeic acid, chlorogenic acid, protocatechuic and ferulic acids. Roots contain beta-1,2-oligofructans as the main saccharides.

Essential oils in yacon herb
Three compounds--beta-pinene, caryophylene and y-cadinene have been found as the predominant essential oils.

Yacon leaves composition
Many chemicals are found in this
herb including melampolide-type sesquiterpene lactones including sonchifolin, uvedalin, enhydrin and fluctuanin. Yacon leaves are used traditionally for blood sugar control.

Side effects, safety, toxicity
Kidney yacon side effects have been reported thus far.

J Ethnopharmacol. 2011. Renal toxicity caused by oral use of medicinal plants: the yacon example. Yacon [Smallanthus sonchifolius (Poepp. & Endl.) H. Robinson, Asteraceae] is an Andean species that has traditionally been used as an anti-diabetic herb in several countries around the world, including Brazil. Its hypoglycaemic action has recently been demonstrated in normal and diabetic rats. However, studies about the safety of prolonged oral consumption of yacon leaf extracts are lacking. Thus, this work was undertaken to evaluate the repeated-dose toxicity of three extracts from yacon leaves: the aqueous extract (AE) prepared as a tea infusion; the leaf-rinse extract (LRE), which is rich in sesquiterpene lactones (STLs); and a polar extract from leaves without trichomes, or polar extract (PE), which lacks STLs but is rich in chlorogenic acids (CGAs).MATERIALS AND METHODS:The major classes of the compounds were confirmed in each extract by IR spectra and HPLC-UV-DAD profiling as well as comparison to standard compounds. The toxicity of each extract was evaluated in a repeated-dose toxicity study in Wistar rats for 90 days. The PE was rich in CGAs, but we did not detect any STLs. The AE and LRE showed the presence of STLs. The polar extract caused alterations in some biochemical parameters, but the animals did not show signs of behavioural toxicity or serious lesions in organs. Alterations of specific biochemical parameters in the blood (creatinine 7.0 mg/dL, glucose 212.0 mg/dL, albumin 2.8 g/dL) of rats treated with AE (10, 50 and 100 mg/kg) and LRE (10 and 100 mg/kg) pointed to renal damage, which was confirmed by histological analysis of the kidneys. The renal damage was associated with increased blood glucose levels after prolonged oral administration of the AE. This observation suggested that the hypoglycaemic effect observed after treatment for 30 days in an earlier study is reversible and was likely the result of renal injury caused by the toxicity of yacon. Because STLs were detected in both AE and LRE, there is strong evidence that these terpenoids are the main toxic compounds in the leaves of the yacon. Based on our results, we do not recommend the oral use of yacon leaves to treat diabetes.

Yacon Plant Research studies
The constituents relate to anti-oxidative and alpha-glucosidase inhibitory activities in Yacon aerial part extract
Yakugaku Zasshi. 2006. Research Laboratory, Zenyaku Kogyo Co. Ltd., Tokyo, Japan.
Hot water extract of the aerial part of Yacon (Smallanthus sonchifolia, Compositae) showed potent free radical-scavenging activity and inhibitory effects on lipid peroxidation in rat brain homogenate. The most potent antioxidative activity was identified as 2,3,5-tricaffeoylaltraric acid (TCAA). The antioxidative activity of TCAA is superior to that of natural antioxidants such as catechin, alpha-tocopherol, and ellagic acid,. As the hypoglycemic activity of yacon extract was described in a previous report, the present results showing that the aerial part of yacon has strong antioxidative activity may encourage its potential use as a food supplement to prevent type II diabetes.

Radical scavenging and anti-lipoperoxidative activities of Smallanthus sonchifolius - yacon - leaf extracts.
J Agric Food Chem. 2005.
Radical scavenging and anti-lipoperoxidative effects of two organic fractions and two aqueous extracts from the leaves of a neglected Andean crop- yacon (Smallanthus sonchifolius Poepp. & Endl., Asteraceae) were determined using various in vitro models. The extracts' total phenolic content was 10-24%. These results make yacon leaves a good candidate for use as a food supplement in the prevention of chronic diseases involving oxidative stress.

Subchronic 4-month oral toxicity study of dried Smallanthus sonchifolius (yacon) roots as a diet supplement in rats.
Food Chem Toxicol. 2005.
The aim of this study was to analyze the effects of subchronic (4-months) oral consumption of dried yacon root flour as a diet supplement using normal Wistar rats. Two daily yacon intake levels were used, equivalent to 340 mg and 6800 mg FOS/body weight, respectively. Yacon administered as a diet supplement was well tolerated and did not produce any negative response, toxicity or adverse nutritional effect at both intake levels used. Yacon root consumption showed no hypoglycemic activity in normal rats and resulted in significantly reduced post-prandial serum triacylglycerol levels in both doses assayed. Conversely, serum cholesterol reduction was not statistically significant. Cecal hypertrophy was observed in rats fed only the high dose. Our results indicating lack of yacon toxicity and a certain beneficial metabolic activity in normal rats warrant further experiments with normal subjects and patients suffering metabolic disorders.

The effect of Smallanthus sonchifolius leaf extracts on rat hepatic metabolism.
Cell Biol Toxicol. 2004.
Smallanthus sonchifolius, originating from South America, has become popular in Japan and in New Zealand for its tubers which contain beta-1,2-oligofructans as the main saccharides. The yacon plant is also successfully cultivated in Central Europe in the Czech Republic in particular. Its aerial part is used in Japan and in Brazil as a component in medicinal teas; while aqueous leaf extracts have been studied for their hypoglycemic activity in normal and diabetic rats. We have already demonstrated the high content of phenolic compounds in yacon leaf extracts and their in vitro antioxidant activity. In this paper, we present the effects of two organic fractions and two aqueous extracts from the leaves of yacon on rat hepatocyte viability, on oxidative damage and on glucose metabolism and their insulin-like effect on the expression of cytochrome P450 (CYP) mRNA. All the extracts tested exhibited strong protective effect against oxidative damage to rat hepatocyte primary cultures , reduced hepatic glucose production via gluconeogenesis and glycogenolysis. Moreover, the effects of the organic fractions and to a lesser extent, the tea infusion on rat CYP2B and CYP2E mRNA expression, were comparable to those observed with insulin. The combination of radical scavenging, cytoprotective and anti-hyperglycemic activity predetermine yacon leaves for use in prevention and treatment of chronic diseases involving oxidative stress, particularly diabetes.

Suppression of glucose absorption by various health teas in rats
Yakugaku Zasshi. 2004.
The inhibitory effects on the intestinal digestion and absorption of sugar of health teas that claim beneficial dietary and diabetes-controlling effects were compared in rats. The measured durations were the times during which the elevation of portal glucose levels resulting from continuous intragastric infusion of sucrose or maltose was suppressed by concentrated teas. The teas investigated included salacia oblonga, mulberry, guava, gymunema, taheebo, yacon, and banaba. The duration of the inhibitory effect on the sucrose load of salacia oblonga, mulberry, and guava were 110 min, 20 min, and 10 min, respectively. In contrast, gymunema, taheebo, yacon, and banaba had no significant effect on the continuous infusion of sucrose. These results suggest that there is considerable difference in the efficacy of commercial health teas in influencing glucose absorption.

Smallanthus sonchifolius and Lepidium meyenii (maca) - prospective Andean crops for the prevention of chronic diseases.
Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub. 2003.
Smallanthus sonchifolius (yacon) and Lepidium meyenii (maca) were the traditional crops of the original population of Peru where they are also still used in folk medicine. These plants are little known in Europe and Northern America although at least yacon can be cultivated in the climatic conditions of these regions. This article deals with the botany and the composition, the structure of main constituents, biological activity of maca and the cultivation of yacon in the Czech Republic. The potential of yacon tubers to treat hyperglycemia, kidney problems and for skin rejuvenation and the antihyperglycemic and cytoprotective activity of its leaves seems to be related mostly to its oligofructan and phenolic content, respectively. Maca alkaloids, steroids, glucosinolates, isothicyanates and macamides are probably responsible for its aptitude to act as a fertility enhancer, aphrodisiac, adaptogen, and immunostimulant. Yacon and maca are already on the European market as prospective functional foods and dietary supplements, mainly for use in certain risk groups of the population, e.g. seniors, diabetics, postmenopausal women etc.

Investigation of phenolic acids in yacon (Smallanthus sonchifolius) leaves and tubers.
J Chromatogr A. 2003.
Thin-layer chromatographic screening of crude extracts of dried leaves and tubers of yacon (Smallanthus sonchifolius, Asteraceae) revealed the presence of chlorogenic, caffeic and ferulic acid.

Purification and identification of antimicrobial sesquiterpene lactones from yacon (Smallanthus sonchifolius) leaves.
Biosci Biotechnol Biochem. 2003.
The extraction of yacon [Smallanthus sonchifolius (Poepp. and Endl.) H. Robinson; Asteraceae] leaves and chromatographic separation yielded two new antibacterial melampolide-type sesquiterpene lactones, 8beta-tigloyloxymelampolid-14-oic acid methyl ester and 8beta-methacryloyloxymelampolid-14-oic acid methyl ester, as well as the four known melampolides, sonchifolin, uvedalin, enhydrin and fluctuanin. The newly identified compound, 8beta-methacryloyloxymelampolid-14-oic acid methyl ester, exhibited potent antimicrobial activity against Bacillus subtilis and Pyricularia oryzae, while 8beta-tigloyloxymelampolid-14-oic acid methyl ester showed lower activity. Fluctuanin exhibited the strongest antibacterial activity against B. subtilis among these six sesquiterpene lactones.

Andean yacon root (Smallanthus sonchifolius Poepp. Endl) fructooligosaccharides as a potential novel source of prebiotics.
J Agric Food Chem. 2003.
The ability of three known probiotic strains (two lactobacilli and one bifidobacterium) to ferment fructooligosaccharides (FOS) from yacon roots (Smallanthus sonchifolius Poepp. Endl) was compared to commercial FOS in this study. Results indicate that Lactobacillus acidophilus NRRL-1910, Lactobacillus plantarum NRRL B-4496, and Bifidobacterium bifidum ATCC 15696 were able to ferment yacon root FOS.

Antioxidant activity of extracts from the leaves of Smallanthus sonchifolius.
Eur J Nutr. 2003.
The leaves are used in folk medicine as a medicinal tea for hypoglycemia. This paper describes the antioxidant activity of various extracts from yacon leaves for their content of phenolic components. The presence of protocatechuic, chlorogenic, caffeic and ferulic (traces) acids were determined in the two fractions. Both fractions showed potent antioxidant activity in DPPH and xanthine / XOD superoxide radical scavenging equivalents tests, they inhibited the lipoperoxidation of rat liver subcellular membranes and they protected rat hepatocytes against oxidative injury. Our results may predetermine the use of yacon leaves in human diet as a potential remedy in the prevention of chronic diseases caused by radicals, e. g., arteriosclerosis.

Caffeic acid derivatives in the roots of yacon (Smallanthus sonchifolius).
J Agric Food Chem. 2003.
Five caffeic acid derivatives were found in the roots of yacon, Smallanthus sonchifolius (Poepp. and Endl.) H. Robinson, Asteraceae, as the major water-soluble phenolic compounds. Two of these were chlorogenic acid (3-caffeoylquinic acid) and 3,5-dicaffeoylquinic acid, common phenolic compounds in plants of the family Asteraceae. Three were esters of caffeic acid with the hydroxy groups of aldaric acid, derived from hexose. The compounds were novel caffeic acid esters of altraric acid: 2,4- or 3,5-dicaffeoylaltraric acid, 2,5-dicaffeoylaltraric acid, and 2,3,5- or 2,4,5-tricaffeoylaltraric acid.

Hypoglycemic effect of the water extract of Smallantus sonchifolius leaves in normal and diabetic rats.
J Ethnopharmacol. 2001.
The hypoglycemic effect of the water extract of the leaves of Smallantus sonchifolius was examined in normal, transiently hyperglycemic and streptozotocin (STZ)-induced diabetic rats. Ten-percent yacon decoction produced a significant decrease in plasma glucose levels in normal rats when administered by intraperitoneal injection or gastric tube. In a glucose tolerance test, a single administration of 10% yacon decoction lowered the plasma glucose levels in normal rats. In contrast, a single oral or intraperitoneal administration of yacon decoction produced no effect on the plasma glucose levels of STZ-induced diabetic rats. However, the administration of 2% yacon tea ad libitum instead of water for 30 days produced a significant hypoglycemic effect on STZ-induced diabetic rats. After 30 days of tea administration, diabetic rats showed improved body (plasma glucose, plasma insulin levels, body weight) and renal parameters (kidney weight, kidney to body weight ratio, creatinine clearance, urinary albumin excretion) in comparison with the diabetic controls. Our results suggest that yacon water extract produces an increase in plasma insulin concentration.

Extraction and identification of antioxidants in the roots of yacon (Smallanthus sonchifolius).
J Agric Food Chem. 1999.
Yacon, Smallanthus sonchifolius (Poepp. & Endl.) H. Robinson, Asteraceae, an important economic species grown for its juicy tuberous root, is potentially beneficial in the diet to diabetics. The antioxidative activity of yacon root was studied. Two of the major antioxidants were identified as chlorogenic acid and tryptophan.

Traditional use
Traditionally, Yacon has been used in South America both as food and to help control blood sugar and improve digestion. The fructooligosaccharide (FOS) in Yacon is an indigestible sugar that is low in calories and does not appear to have a significant effect on increasing blood sugar levels. Not only that, this product is a prebiotic, feeding friendly bacteria and boosting the immune system.

About the plant
Yacon (Smallanthus sonchifolia) is a showy, perennial plant that can reach several feet high. It is commonly grown from Venezuela to Argentina, and is believed to have originated in the mountains of Peru. It grows best in climates that have little or no frosts, and has been found to grow well in the Philippines, New Zealand, and Australia.

Q. Can yacon herb be taken the same day as serrapeptase or the herbal extract curcumin?
   A. Probably. Curcumin should be fine, serrapeptase is an enzyme which still needs to have more studies to determine its interactions with other herbs and supplements.