Yacon - Smallanthus sonchifolius

Detailed Description

A remarkable herb from South America now cultivated worldwide, including Central Europe.

Botanical Information

Yacon is an annual in Europe but a perennial in its native habitat, reaching up to 2.5 meters in height. The plant features densely branched, square, hairy, hollow stems that are deep green to dark purple. Leaves are arranged oppositely and shaped like arrows. The main stem produces yellow-orange, bisexual flowers approximately 3 cm wide. Fruits are tiny, about 2 mm long, black achenes (fruiting rarely occurs under European conditions). The most distinctive part of the plant is its knobby root tuber, which develops in irregular clusters of up to 20 and can weigh as much as 0.5 kg each. There are two types of tubers: short tubers used for vegetative propagation and thick, fleshy root tubers cultivated for their culinary and medicinal value. Fresh tubers are grayish-brown to reddish and darken upon exposure to air.

Origin and Distribution

Yacon originates from the moist Peruvian and Bolivian Andes, growing between 1,000 and 3,770 meters above sea level. Thanks to its newly discovered attributes and tolerance for various conditions, yacon has spread from its South American origins to gardens and farms across the globe. It can be grown in areas with light frosts and a mild climate—such as Nepal (Kathmandu), southern Australia, and New Zealand. Yacon became particularly popular in Germany and Italy after it was introduced into Europe. The plant was brought to Japan in the 1980s, from where it spread to South Korea and China. Yacon was first imported into Central Europe in 1993 from New Zealand.

Usage / Dosage

Yacon Tuber

Yacon is best known for its edible tubers, which resemble potatoes. These can be consumed raw or cooked by boiling or baking, delivering a sweet, slightly resinous flavor thanks to their unique compounds. In Incan culture, yacon roots had ritual significance, used in funerary rites as offerings for the afterlife according to early Catholic chroniclers. Until the early 2000s, yacon remained relatively unknown outside its native region. Its popularity surged after Japanese publications revealed potential antihyperglycemic effects.

From Lima to other cities in Peru, yacon cultivation expanded rapidly. Pharmaceutical companies followed by launching yacon syrups and teas as low-calorie sweeteners favored by diabetics and dietitians. Yacon is also hypothesized to be a potential hypolipidemic agent and anti-obesity tool. Yacon's active components support lipid balance, promote satiety, and aid intestinal motility, while reducing blood pressure by 5–10% and thinning the blood. Enzymes in the tuber increase calcium and vitamin absorption, and help relieve discomfort from gastrointestinal ulcers. Oligosaccharides in Yacon provide fiber that aids constipation and restore gut microbiota.

Yacon tubers are rich in inulin-like substances that promote optimal colon health and contain insulin, making them especially suitable for people with diabetes. Fructooligosaccharides remain undigested, do not raise plasma glucose, and deliver a sweet taste with minimal calories. They pass intact to the colon, where they undergo fermentation, exerting a prebiotic effect: feeding beneficial bacteria, aiding digestion, and exerting a bifidogenic effect (selectively stimulating growth of Bifidobacteria). Fermentation products—short-chain fatty acids—may enhance growth of beneficial bacteria and lower populations of pathogens such as Clostridium spp. and Escherichia coli. The prebiotic definition, established by Gibson and Roberfroid in 1995, involves indigestible substances beneficially modulating gut flora.

Fructooligosaccharides found in yacon also display antioxidant potential. Inulin and similar compounds can lower glycemic index, body weight, and possibly reduce risk of colon cancer. Colon cancer development is influenced by hereditary factors (about 15%) and modifiable ones such as lifestyle and diet (about 80%) (Siegel R.L., Cancer Statistics 2016; Jasperson K.W., Hereditary and familial colon cancer 2010). In-vivo studies show that yacon root water extract alone or with Lactobacillus acidophilus can reduce DNA damage in leukocytes. Balanced gut microflora is widely recommended to promote both digestive and immune system health.

Short-chain fatty acid production from yacon is associated with the suppression of inflammatory signals, cancer inhibition, and increased local immune response through pH reduction in the colon. Oligosaccharides in yacon modulate IgA production, cytokine levels, toll-like receptor expression, interleukin activity, and natural killer cell activity with increased macrophage responses. Consumption of yacon may directly support the immune system via gut-associated lymphoid tissue (GALT) or immunomodulation. The synergistic effect of yacon's components appears to reduce inflammation.

Dietary management is central for type 2 diabetes. Yacon compounds lower high blood glucose but do not reduce it below optimal levels. Oligosaccharides in the tubers may also suppress appetite for sweets. In animal models, yacon increases insulin-positive cells and levels of glucagon-like peptide, reduces visceral fat, and raises fasting serum insulin in diabetic rats. Other studies confirm improved glucose tolerance and increased insulin sensitivity in the liver. Clinical studies have shown correlations between yacon oligosaccharides and lowered blood glucose in elderly individuals.

Some components in yacon lower triglyceride and cholesterol levels, inhibit glucose uptake, glycogen synthesis, and support metabolic activity, thereby potentially helping to reverse insulin resistance in obese patients. Other oligosaccharide-influenced peptides improve glucose control, increase insulin, and reduce pancreatic glucagon. Studies also report positive effects on HDL, VLDL, triglycerides, and postprandial insulin.

Potassium in yacon supports the nervous system, muscle function, and blood circulation. Calcium helps blood clotting, assists with muscle contraction, nerve transmission, and growth of bones and teeth. Iron reduces fatigue and supports red blood cell production, hemoglobin synthesis, and oxygen transport. After a month of yacon consumption, parameters of pancreatic activity and nutrient absorption improved. Additional proteins and enzymes may assist weight reduction and support individuals at risk of obesity.

Yacon Leaf

Leaf components exhibit diuretic and wound-healing effects when used topically. Interestingly, yacon leaves have demonstrated hypoglycemic effects in both healthy and diabetic animals. The first scientific publications in 2001 described a 10% aqueous yacon leaf extract as lowering plasma sugar, reducing weight, and stabilizing insulin levels in diabetic rats. Further studies found that after eight weeks of leaf decoction use, both sugar and insulin levels were better controlled in rats. Regular use of yacon leaf extract showed significant hypoglycemic effects after 30 days. The proposed mechanisms include modified insulin and antioxidant activity.

Traditionally, yacon leaves are consumed alone in decoctions or combined with other leafy vegetables, and in Japan, often enjoyed with tea leaves. In the USA and Japan, yacon leaves are used to make dietary products, bread, and more for reduced-calorie or diabetic diets. Yacon leaves also support liver diets due to their hepatoprotective properties.

Folk Medicine

Yacon has long been used in traditional medicine for supporting the treatment of diabetes, body detoxification, liver protection, high blood pressure, constipation, inflammatory diseases of the bladder, kidneys, joints, and insomnia. Both tubers and leaves are frequently consumed for atherosclerosis, digestive issues (constipation), high cholesterol, and blood sugar. In Andean folk therapy, yacon is used to delay aging and support youthful appearance.

Decoctions or dried yacon leaves are traditionally used against fungal infections, mycoses of the toes and nails, and for gargling with oral thrush. The antibacterial properties of yacon leaves make them useful for washing cuts, burns, scars, and abrasions. Internally, yacon leaf infusions help stabilize glycemia, lower blood pressure, and are consumed as antioxidants and hepatoprotectants.

Precautions

Overconsumption may lead to discomfort (abdominal pain, bloating, diarrhea) but is not life-threatening. To minimize breakdown of oligofructans into fructose—which could increase glycemia in large quantities—tubers should be kept cool and in the dark.

Active Compounds

Dried yacon tubers contain about 80% sweet fructooligosaccharides, 0.3–3.7% protein, and trace fiber. Per 100 grams, tubers provide about 81 g water, 14 g carbohydrates, 1 g protein, 0.9 g fiber, 200 mg potassium, 23 mg calcium, small amounts of magnesium, 0.2 mg iron, phosphorus, beta-carotene, vitamins A, B1, B2, C, about 20 amino acids, and various enzymes. Oligosaccharides (mainly inulin types) are not absorbed by the human body, serving as prebiotics instead. Energy value per 100 g is about 1,574 kJ or 373 kcal. Yacon leaves contain much higher levels—up to five times more—protein, fiber, calcium, phosphorus, iron, manganese, and zinc, plus catechol, terpenes, kaurenoic acid, diterpenes, gibberellins, melampolides, sonchifolin, polymatin, enhydrin, and flavonoids.

Traditional Dosage

Yacon root powder is taken 1–3 times daily on an empty stomach in doses of 2–5 g mixed with water. It is best blended with water in a 1:1 ratio to form a paste, which can then be further diluted to a smooth drink. Alternatively, 2–10 g of root can be steeped in 700–1,000 ml of cold water, brought to a boil for 5 minutes, allowed to stand, and sipped 1–3 times daily, 30 minutes before meals. For dried leaves, use 1–2 tablespoons per 750 ml water, bring to a boil and simmer for 5 minutes. Let stand, strain, and drink 2–3 times daily, about one cup per serving.