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.

Availability of Yacon
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.

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 has only been in the laboratory and animals. Other herbs that have a benefit for blood sugar control include Bitter-Melon, prickly pear cactus extract, Fenugreek, and cinnamon.

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

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Twice a month we Email you a brief abstract of several new studies on various supplements and natural medicine topics and their practical interpretation by Ray Sahelian, M.D. We will mention research updates on Yacon when available.  
 

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

Yacon Plant Research Update
The constituents relate to anti-oxidative and alpha-glucosidase inhibitory activities in Yacon aerial part extract
Yakugaku Zasshi. 2006 Aug;126(8):665-9. 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 focused on the 50% MeOH-eluted fraction on DIAION HP-20 column chromatography. The structure of the major component in the fraction 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 Jul 13;53(14):5577-82.
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 10.7-24.6%. 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 Nov;43(11):1657-65.
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 mgFOS/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 ( yacon ) leaf extracts on rat hepatic metabolism.
Cell Biol Toxicol. 2004 Mar;20(2):109-20.
Smallanthus sonchifolius ( yacon ), 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 S. sonchifolius on rat hepatocyte viability, on oxidative damage induced by tert-butyl hydroperoxide (t-BH) and allyl alcohol (AA), 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 in concentrations ranging from 1 to 1000 microg/ml, reduced hepatic glucose production via gluconeogenesis and glycogenolysis at 1000 microg/ml. Moreover, the effects of the organic fractions (200 and 250 microg/ml) and to a lesser extent, the tea infusion (500 microg/ml) 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 Apr;124(4):217-23.
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 using portal cannulae. 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 ( yacon ) and Lepidium meyenii (maca) - prospective Andean crops for the prevention of chronic diseases.
Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub. 2003 Dec;147(2):119-30.
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 Oct 17;1016(1):89-98.
Thin-layer chromatographic (TLC) screening of crude extracts of dried leaves and tubers of yacon (Smallanthus sonchifolius, Asteraceae) and products of acid hydrolysis of tubers on the silica gel HPTLC plates using the developing solvents ethyl acetate-formic acid-water (85:10:15, v/v/v) and n-hexane-ethyl acetate-formic acid (20:19:1, v/v/v) proved the presence of chlorogenic, caffeic and ferulic acid. These phenolic acids were isolated from the crude extract of yacon leaves by preparative TLC, and identified after elution by HPLC/MS, as well as by direct injection of the crude extract into the HPLC/MS system. Acid hydrolysis of tubers released the increased amount of phenolic acids (e.g. caffeic acid and ferulic acid), flavonoid quercetin and an unidentified flavonoid, which was detected by TLC analysis. Ferulic acid, isomers of dicaffeoylquinic acid and still an unidentified derivative of chlorogenic acid (Mr = 562) as constituents of yacon leaves and ferulic acid as constituent of yacon tubers are reported here for the first time. These acids gave significant contribution to the radical scavenging activity detected directly on the TLC plate sprayed with 1,1-diphenyl-2-picrylhydrazyl (DPPH).

Purification and identification of antimicrobial sesquiterpene lactones from yacon (Smallanthus sonchifolius) leaves.
Biosci Biotechnol Biochem. 2003 Oct;67(10):2154-9.
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 Aug 27;51(18):5278-84.
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. FOS consumption apparently depended on the degree of polymerization and the initial FOS composition. L. plantarum NRRL B-4496 and L. acidophilus NRRL B-1910 completely utilized 1-kestose molecules, while B. bifidum was able to utilize 1-kestose molecules as well as molecules with a higher degree of polymerization.

Antioxidant activity of extracts from the leaves of Smallanthus sonchifolius.
Eur J Nutr. 2003 Jan;42(1):61-6.
Yacon ( Smallanthus sonchifolius, Asteraceae) is a native Andean plant, cultivated for its tubers throughout South America. The leaves are used in folk medicine as a medicinal tea for hypoglycemia. This paper describes the antioxidant activity of various extracts from S. sonchifolius leaves for their content of phenolic components. The dried leaves were extracted in several ways. Two fractions were selected for their high content of phenolic compounds and analyzed by RP-HPLC. The antioxidant activity of these fractions was tested in 1,1-diphenyl-2-picrylhydrazyl (DPPH) and xanthine/XOD superoxide radical scavenging assays, as inhibition of lipoperoxidation of subcellular membranes and as protective activity against oxidative injury of rat hepatocytes in primary cultures. CONCLUSIONS: 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 Jan 29;51(3):793-6.
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. The structures of these compounds were determined by analysis of spectroscopic data. 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 structure of the aldaric moiety was determined by hydrolysis and comparison of NMR spectra with those of standard aldaric acids. 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 (yacon) leaves in normal and diabetic rats.
J Ethnopharmacol. 2001 Feb;74(2):125-32.
The hypoglycemic effect of the water extract of the leaves of Smallantus sonchifolius (yacon) 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 Nov;47(11):4711-3.
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 by 1, 1-diphenyl-2-picrylhydrazyl (DPPH) assay. Antioxidants were extracted by methanol and isolated and purified by gel permeation chromatography and preparative reverse-phase HPLC. Two of the major antioxidants were identified as chlorogenic acid and tryptophan by NMR and mass spectrometry.

Yacon questions
Q. Can yacon be taken the same day as serrapeptase or the herb 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.
 

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