Yacon is a root vegetable native to the Andean highlands of South America, prized for its sweet, crisp flesh and unusually low calorie content. Unlike most root vegetables that store energy as starch, yacon stores it primarily as fructooligosaccharides (FOS), a type of fiber your body can’t digest. This makes it taste sweet without delivering the blood sugar spike of a potato or carrot. It’s eaten raw, cooked into dishes, or processed into syrup and powder.
How Yacon Looks and Tastes
The yacon plant produces large, tuberous roots that look similar to sweet potatoes on the outside, with brown or reddish skin. Inside, the flesh is pale and juicy, more like a jicama or water chestnut than a typical tuber. The texture is crunchy and refreshing, and the flavor is mildly sweet, sometimes compared to a cross between an apple and a watermelon. Ancient Incan travelers reportedly crushed the roots to make a lightly sweet juice for hydration on long journeys.
The plant itself is a member of the daisy family and grows well at high altitudes. It’s cultivated primarily in Peru, Bolivia, Ecuador, and parts of Myanmar. In recent years, interest in yacon has expanded well beyond South America, with commercial products like syrup, herbal tea, and dried powder now widely available.
What Makes Yacon Nutritionally Unusual
The defining feature of yacon is its fructooligosaccharide content. These sugar-like molecules can make up 34 to 60% of the root’s dry weight, and in some varieties, up to 70%. Your digestive enzymes can’t break down the chemical bonds in FOS, so these compounds pass through your stomach and small intestine intact. They arrive in your colon undigested, which means they contribute far fewer calories than regular sugars or starches.
This is why yacon is sometimes marketed as a natural low-calorie sweetener. The roots also contain chlorogenic acid (the same antioxidant compound found in coffee), caffeic acid, ferulic acid, and tryptophan, which is a building block for serotonin and melatonin. The leaves of the plant carry even higher concentrations of these antioxidant compounds, which is why yacon leaf tea has its own following.
Prebiotic Effects on Gut Health
Because FOS reaches your colon intact, it becomes food for the bacteria living there. This is what makes yacon a prebiotic. Gut bacteria ferment FOS into short-chain fatty acids, which nourish the cells lining your colon and help maintain a healthy intestinal environment. At the same time, FOS specifically promotes the growth of beneficial bacteria, particularly Bifidobacteria and Lactobacillus species.
Research comparing yacon to commercial FOS supplements found that yacon tubers actually promoted greater growth of these beneficial bacteria and produced higher concentrations of short-chain fatty acids, even at the same FOS dose. This suggests that the other compounds naturally present in yacon may enhance its prebiotic effects beyond what isolated FOS supplements provide.
Weight and Blood Sugar Research
The most cited human study on yacon involved obese women with mildly elevated cholesterol who consumed yacon syrup daily for 120 days. The results were striking: participants lost an average of 15 kg (about 33 pounds), reduced their waist circumference by roughly 10 cm (4 inches), and saw their BMI drop from 34 to 28. They also experienced significant reductions in LDL cholesterol, fasting insulin levels, and a key measure of insulin resistance. Bowel frequency and feelings of fullness both increased.
On the blood sugar side, a separate trial found that a single dose of yacon syrup containing 14 grams of FOS reduced both blood glucose and insulin levels after a meal compared to a placebo. The glucose-lowering effect was measurable at 30 minutes, and insulin stayed lower at the 15, 30, and 45 minute marks.
Not all studies have been this dramatic, though. A shorter two-week trial using a similar daily dose of FOS found no significant changes in fasting glucose, cholesterol, insulin, or body measurements. Duration seems to matter. The positive results came from the four-month study, suggesting that yacon’s effects build gradually as gut bacteria populations shift and metabolic changes accumulate.
How to Eat Yacon
Raw is the most common and arguably the best way to enjoy yacon root. Just peel off the brown skin with a vegetable peeler and slice, shred, or chop the flesh. It works well in salads and slaws, on crudité platters alongside vegetables and dip, or simply eaten in slices as a snack. The crisp, juicy texture holds up well without cooking.
Yacon also appears in some curry and stew recipes, though cooking softens its texture and can break down some of the FOS content. For people who want the health benefits without sourcing fresh roots, yacon syrup is the most accessible option. It has a dark, molasses-like appearance and a mild caramel sweetness. It can be drizzled over oatmeal, stirred into smoothies, or used as a sweetener in baking. Yacon powder and herbal tea made from the leaves are also commercially available.
Side Effects and Tolerance
The same property that makes yacon healthy for your gut can also cause digestive discomfort if you eat too much. Because FOS ferments in the colon, large amounts can produce gas, bloating, and loose stools. This is the same mechanism that makes beans gassy, just with a different type of fermentable fiber.
Most people tolerate moderate amounts without issues, but starting with a small serving and increasing gradually gives your gut bacteria time to adjust. The clinical studies that showed benefits used a dose of roughly 0.14 grams of FOS per kilogram of body weight per day, which works out to about 10 to 14 grams of FOS for most adults. Jumping straight to high doses is where digestive problems tend to show up.
People with existing digestive sensitivities, particularly those who react poorly to foods high in fermentable carbohydrates, may want to be cautious. Yacon is high in the same category of compounds that a low-FODMAP diet restricts.