Dit gewas uit de Andes is tegenwoordig enorm populair als calorie arme zoetstof onder liefhebbers van gezond eten. Tijdens het Inca tijdperk waren de knapperige, zoete knollen van groot belang voor reizigers, dit door de dorstlessende eigenschappen.
In het Quechua, de taal van de Inca’s, betekende yacon ‘waterknol’. Hoewel het een wortelgewas is wordt yacon meestal rauw gegeten, als een stuk fruit.
Polymnia sonchifolia Yacon is een gemakkelijk te kweken doorlevende plant. Hij gedijt in zowat alle grondsoorten, heeft een grote waterbehoefte en houdt van een warme beschutte plek. Yacon is niet wintervast maar heeft wel een lang groeiseizoen nodig. Yacon is een grote plant, tot 2 m hoog en ook in de breedte heeft hij zijn plaats nodig.
De eetbare delen van yacon zijn de reserveknollen. Net onder de grond maakt yacon ook broedbollen aan. Deze bollen kunnen, als ze vorstvrij overwinterd worden, het jaar erop terug opgekweekt worden. Met een laagje grond afdekken zorgt ervoor dat de broedbollen niet uitdrogen.
De reserveknollen worden hoofdzakelijk rauw gegeten. Maar kunnen ook gestoofd, gebakken, gedroogd of geperst worden. Dikwijls word er van de knollen ook siroop gemaakt. Deze siroop is een ideale suikervervanger in allerlei desserten. Yaconknollen kunnen zeer lang bewaard worden. Leg ze hiervoor vorstvrij weg en dek af met een laagje grond tegen het uitdrogen. Door yacon minstens enkele weken te bewaren/rijpen wordt de smaak ervan veel zoeter. Het blad kan gebruikt worden om thee van te zetten.
Polymnia sonchifolia Yacon bevat een zeer hoge concentratie aan inuline, deze wordt langzaam afgebroken tot fructo-oligosaccarides. Deze kunnen niet worden opgenomen door ons lichaam, maar geven wel een zoete smaakgewaarwording.
Clin Nutr. 2009 Apr;28(2):182-7. doi: 10.1016/j.clnu.2009.01.013. Epub 2009 Feb 28. Yacon syrup: beneficial effects on obesity and insulin resistance in humans. Genta S1, Cabrera W, Habib N, Pons J, Carillo IM, Grau A, Sánchez S.
BACKGROUND & AIMS:
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.
METHODS:
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, 0.29 g and 0.14 g fructooligosaccharides/kg/day. At the start and end of the study, anthropometric measurements, blood glucose, calcium, lipid and insulin concentrations and Homeostasis Model Assessment index were determined.
RESULTS:
The recommended daily consumption of yacon syrup with no undesirable gastrointestinal effects is 0.14 g 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 and Homeostasis Model Assessment index 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.
CONCLUSIONS:
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.
Digestion. 2008;78(1):30-3. doi: 10.1159/000155214. Epub 2008 Sep 10. Effect of yacon (Smallanthus sonchifolius) on colonic transit time in healthy volunteers. Geyer M1, Manrique I, Degen L, Beglinger C
BACKGROUND:
Yacon is a root crop which contains high amounts of fructooligosaccharides (FOS). The aim of this study was to investigate the effects of yacon syrup on colon transit time in healthy volunteers.
METHODS:
In a placebo-controlled, double-blind study yacon was administered to 16 healthy individuals (8 males, 8 females) in a dose of 20 g daily (equal to 6.4 g FOS) in a 2-week crossover design. Each period was interrupted by a 2-week wash-out phase. Transit time was assessed by a radio-opaque marker technique.
RESULTS:
Transit time (mean +/- SEM) through the gastrointestinal tract was significantly decreased from 59.7 +/- 4.3 to 38.4 +/- 4.2 h (p < 0.001). Yacon was well tolerated with an excellent side effect profile. Bloating is not an uncommon side effect observed with FOS, but bloating-related disturbances were not significantly more often reported with yacon compared to placebo. Stool frequency increased from 1.1 +/- 0.1 to 1.3 +/- 0.2 times per day and the consistency showed a tendency for softer stools as assessed by a numerical depicted stool protocol. Neither parameter did, however, reach statistical significance.
CONCLUSION:
Yacon markedly accelerates colonic transit in healthy individuals. Further studies are needed in constipated patients to confirm these preliminary data. Due to the low caloric content of yacon, the root could be a useful treatment in constipated diabetics or obese patients
Biomol Ther (Seoul). 2013 Mar; 21(2): 153–160. doi: 10.4062/biomolther.2012.093. The Spermatogenic Effect of Yacon Extract and Its Constituents and Their Inhibition Effect of Testosterone Metabolism. Jeong Sook Park and Kun Han*
We screened the pharmacological effects of a 50% ethanol extract of Yacon tubers and leaves on spermatogenesis in rats. As a result, we found that Yacon tuber extracts increased sperm number and serum testosterone level in rats. It has been reported that the crude extract of Yacon tubers and leaves contain phenolic acids, such as, chlorogenic acid, ferulic acid and caffeic acid by HPLC/MS analysis. We were interested in the contributions made by phenolic acid, particularly chlorogenic acid of Yacon tuber extract to the spermatogenic activity. After administering Yacon tuber extract or chlorogenic acid to rats for 5 weeks, numbers of sperm in epididymis were increased by 34% and 20%, respectively. We also administered ferulic acid, which has been reported to be a metabolite of chlorogenic acid and a constituent of Yacon tuber extract to investigate its spermatogenic activity in rats. Yacon tuber extract and ferulic acid increased sperm numbers by 43% and 37%, respectively. And, Yacon tuber extract, and chlorogenic acid showed significantly inhibition effect of testoeterone degradation in rat liver homogenate. We considered that the spermatogenic effect of Yacon tuber extract might be related to phenolic compounds and their inhibitory effect of testosterone degradation. Yacon showed the possibility as ameliorable agents of infertility by sperm deficiency and late onset hypogonadism syndrome with low level of testosterone.
Keywords: Smallanthus sonchifolius, Sperm, Spermatogenesis, Chlorogenic acid, Testosterone
Smallanthus sonchifolius (Yacon, Asteraceae) was originally cultivated in the Andean highlands of South America, and has been used as a food and a medicine by the local population. Its tubers are used as a source of natural sweeteners and syrups, which are used to treat digestive problems, and contain fructose, glucose, saccharose and β-(2-1)-fructo oligosaccharide (inulin type oligofructans) (Ohyama et al., 1990; Goto et al., 1995). Aybar et al. (2001) reported that tuber extracts have hypoglycemic effects, and much information is available on the beneficial effects of Yacon roots, in diabetes or as a means of weight reduction. Recently, the antioxidant activity of Yacon tuber extract was studied, and tryptophan and chlorogenic acid were identified as major components (Yan et al., 1999). Both the leaves and tubers of Yacon are rich in phenolic acids (Valentova et al, 2003). Barcellona et al. (2012) reported that aqueous extracts of Yacon leaf did not show any acute and subchronic toxicity in rat.
This study aimed at investigating the usefulness of a treatment of hypogonadic men suffering from infertility and LOH. We reported that the extracts of Yacon tuber and leaf have spermatogenic activity in rat (Park et al., 2008) and spermatogenic activity and testosterone level increasing effect in men (Park et al., 2009). Herein, we firstly report on the spermatogenic effect of Yacon constituent, that is, chlorogenic acid and ferulic acid. Furthermore, we found that the spermatogenic effect of Yacon and its constituents attributed to the inhibition effect of testosterone degradation. Yacon showed the possibility as safe ameliorable agents of infertility by sperm deficiency and LOH syndrome with low level of testosterone.