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Yacon Syrup

Smallanthus sonchifolius
Evidence Level
Limited
3 Clinical Trials
5 Documented Benefits
2/5 Evidence Score

Yacon syrup is a natural sweetener made from the yacon root, rich in fructooligosaccharides (FOS), a type of prebiotic fiber. Because much of it is fiber rather than digestible sugar, it is lower in usable calories and acts as a prebiotic, feeding beneficial gut bacteria, which is why it is marketed as a lower-glycemic sweetener and for digestive and weight support. It is used as a syrup to sweeten foods, and it still contains real sugars, so it counts toward carbohydrate intake. Because of its high FOS content, larger amounts can cause gas, bloating, or a laxative effect, especially at first, so it is best started in small amounts, and those with sensitive guts or FODMAP sensitivity should use it cautiously.

Studied Dose 0.14 g FOS/kg/day (roughly 10 g FOS, or 20 to 25 g of syrup for a 70-kg adult). This is the lower of the two doses used in the single 120-day trial; the higher dose (0.29 g FOS/kg/day) caused digestive side effects. Commercial syrup FOS content varies from about 40 to 65 percent.
Active Compound Fructooligosaccharides (FOS) — primarily inulin-type fructans (40-70% of dry weight).

Benefits

Body Weight, Waist, and BMI Reduction

In one 120-day placebo-controlled trial in obese, slightly dyslipidemic pre-menopausal women, yacon syrup at 0.14 g FOS/kg/day was followed by decreases in body weight, waist circumference, and BMI. This is a single trial in one specific group of women, so it does not show what yacon syrup would do for someone who is not obese or not insulin resistant.

Supported by Trial 1

Insulin Resistance Improvement

In the same 120-day trial, women who started with raised insulin resistance had lower fasting insulin and a lower HOMA-IR score (a calculation used to estimate insulin resistance). Fasting blood sugar did not change. Neither study cited on this page measured GLP-1 or any other gut hormone, so the reason for the insulin change was never established.

Supported by Trial 1, Trial 2

LDL Cholesterol Reduction

In the 120-day trial in obese pre-menopausal women, LDL cholesterol fell, while total cholesterol and triglycerides did not change significantly. A 2025 systematic review of seven small trials with 161 participants in total also reviewed blood fats, but its authors flagged small sample sizes and differing doses and called for larger studies.

Supported by Trial 2, Trial 1

Increased Defecation Frequency and Satiety

Trial data documented increased defecation frequency and satiety sensation with yacon syrup. FOS is a fermentable fiber, and fuller feelings and more regular bowel movements are common with fibers of this kind. GLP-1, PYY and other appetite hormones were not measured in either study cited here, so no hormone explanation has actually been tested for yacon syrup.

Supported by Trial 1, Trial 2

Prebiotic / Gut Microbiome Support

FOS is fermented by gut bacteria such as Bifidobacterium and Lactobacillus, the same general behavior seen with inulin and other fructan fibers. That comes from fiber research in general rather than from bacterial measurements in the two studies cited on this page. A systematic review noted improvements in intestinal transit and gut microbiota across yacon trials.

Supported by Trial 2, Trial 3

Mechanism of action

1

Fructooligosaccharide (FOS) Prebiotic Effect

Yacon syrup is high in inulin-type FOS (40 to 70 percent of dry weight), which makes it one of the richer plant sources. FOS is not broken down by human digestive enzymes and is instead fermented by gut bacteria, producing short-chain fatty acids (acetate, propionate, butyrate). The metabolic and anti-inflammatory effects attributed to those fatty acids come from wider fiber research and were not measured in either yacon study cited on this page.

2

A Gut Hormone Idea That Has Not Been Tested for Yacon

One proposed explanation is that short-chain fatty acids from fiber fermentation prompt gut cells to release appetite and blood sugar hormones such as GLP-1 and PYY. This idea is borrowed from wider fiber research. Neither of the two studies cited on this page measured GLP-1, PYY or any other gut hormone, so it stays an untested hypothesis for yacon syrup.

3

Reduced Caloric Density (Low-Glycemic Sweetener)

FOS provides ~1.5-2 kcal/g vs. ~4 kcal/g for sucrose — and most of those calories come from colonic SCFAs that are partially used by gut bacteria. Swapping it in for sugar therefore adds fewer usable calories, though yacon syrup still contains real sugars and counts toward carbohydrate intake, and fasting blood sugar did not change in the trial cited here.

4

Bulk Stool Formation and Transit

Like other soluble fibers, FOS adds water-binding bulk to stool and may accelerate colonic transit. This may explain the more frequent bowel movements reported in the trial cited here.

5

Modest Mineral Absorption Enhancement

FOS may modestly enhance calcium and magnesium absorption via colonic SCFA-induced mineral solubilization. Any such effect is likely small, and it has not been shown for yacon syrup in either study cited on this page. Nothing about bone health has been tested here.

Clinical trials

1
Yacon Syrup in Obese Pre-Menopausal Women (single 120-day trial)

Double-blind, placebo-controlled trial. Two doses of yacon syrup (0.29 g and 0.14 g FOS/kg/day) vs. placebo for 120 days in obese pre-menopausal women. Anthropometric measurements, blood glucose, calcium, lipid and insulin concentrations, HOMA-IR. (Genta, Cabrera, Habib, Pons, Carillo, Grau, Sánchez 2009, Clin Nutr)

Obese, slightly dyslipidemic pre-menopausal women with baseline insulin resistance (HOMA-IR > 2.70).

Recommended dose without GI side effects: 0.14 g FOS/kg/day. Significant decreases in body weight, waist circumference, and BMI. Significant decreases in fasting serum insulin and HOMA-IR. Significant LDL cholesterol reduction. Increased defecation frequency and satiety sensation. Fasting glucose unchanged. Higher dose (0.29 g/kg) caused GI side effects. This is a single trial in one narrow group of women, with no participant count reported here. Gut hormones such as GLP-1 were not measured. The results have not been repeated in a large independent trial.

2
Yacon Syrup Human Health Evidence Review

PRISMA-compliant evidence review of yacon syrup clinical trials over the last decade. Searched Medline (PubMed), Science Direct, Embase, Scopus, SciELO through. Inclusion: clinical trials of yacon syrup on glycemic control, lipid profile, insulin sensitivity, appetite regulation, gut microbiota in healthy/overweight/obese individuals. (Nutrients)

7 clinical trials included, totaling 161 participants from diverse populations.

The review reported that across the included trials yacon syrup was associated with lower fasting insulin, lower HOMA-IR and lower LDL cholesterol, along with better reported fullness and bowel transit. The seven trials together included only 161 people, and the authors flagged small sample sizes and differing doses and called for larger trials. The review covered blood sugar control, blood fats, insulin sensitivity, appetite and gut bacteria; it did not assess GLP-1 or any other gut hormone.

3
Yacon Flour, a Different Product Form (not one of this page's cited references)

Randomized, double-blind, placebo-controlled clinical trial of yacon flour vs. placebo in overweight adults. Outcomes: body composition, intestinal function. (Machado, da Silva, Chaves, Clin Nutr ESPEN)

Overweight adults.

This study is reported as finding better body composition and bowel function with yacon flour than with placebo. It tested yacon flour rather than yacon syrup, no participant count or dose is given, and it is not one of the two references listed at the bottom of this page, so it has not been checked against the published record.

Side effects and drug interactions

Common Potential side effects

Digestive symptoms (gas, bloating, cramping, loose stools) are common with FOS-rich foods, and at the higher dose tested (0.29 g FOS/kg/day) they were frequent enough that the researchers recommended the lower dose instead. Start with a small amount and increase slowly.
Possible osmotic diarrhea at high doses.
Allergic reactions are uncommon but documented (one case report of anaphylaxis after yacon ingestion: PMID 20358031).
FOS may aggravate symptoms in IBS or SIBO (small intestinal bacterial overgrowth) due to fermentation.
Not appropriate for those on low-FODMAP diets.
Pregnancy and lactation: yacon is consumed as food in Andean regions; supplemental yacon syrup at moderate doses is likely safe but rigorous data is absent.
Children: introduce gradually; high doses may cause GI symptoms more readily.

Important Drug interactions

Diabetes medications (insulin, sulfonylureas): fasting blood sugar did not change in the trial cited here, but if you take these medicines it is still sensible to monitor your levels and speak with your prescriber.
Other prebiotics or probiotics: generally synergistic; no specific concerns.
Iron supplements: theoretical interaction via mineral absorption changes — clinical relevance unclear.
Antibiotics: short-term yacon use during antibiotic courses may help maintain microbiome balance, though this is not specifically RCT-demonstrated.
No major drug interactions documented.

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Frequently asked questions about Yacon Syrup

What is yacon syrup?

Yacon syrup is a natural sweetener from the yacon root, rich in fructooligosaccharides (FOS), a type of prebiotic fiber. Because much of it is fiber rather than digestible sugar, it is lower in usable calories and acts as a prebiotic.

What is yacon syrup used for?

It is used as a lower-glycemic sweetener and as a prebiotic to feed gut bacteria, and it is sometimes marketed for digestive regularity and weight support. Its FOS content is the active component. It is also marketed as a GLP-1 booster, but neither study cited on this page measured GLP-1 or any other gut hormone.

Does yacon syrup cause digestive issues?

Because it is high in FOS prebiotic fiber, larger amounts can cause gas, bloating, or a laxative effect, especially at first. Start with small amounts (such as a teaspoon) to assess tolerance.

Is yacon syrup safe?

It is generally safe as a food sweetener. The main consideration is digestive tolerance due to its fiber content. People with sensitive guts or FODMAP sensitivity should use it cautiously.

What is the recommended dosage of Yacon Syrup?

The clinically studied dose is 0.14 g FOS/kg/day (roughly 10 g FOS, or 20 to 25 g of syrup for a 70-kg adult). This is the lower of the two doses used in the single 120-day trial; the higher dose (0.29 g FOS/kg/day) caused digestive side effects. Always follow the product label and check with a healthcare provider for personal advice.

Is Yacon Syrup safe, and does it have side effects?

For most healthy adults, Yacon Syrup is well tolerated at studied doses. Reported effects can include: Digestive symptoms (gas, bloating, cramping, loose stools) are common with FOS-rich foods, and at the higher dose tested (0.29 g FOS/kg/day) they were frequent enough that the researchers recommended the lower dose instead. Start with a small amount and increase slowly. It may also interact with some medications. Yacon Syrup is not right for everyone, so check with a healthcare provider first if you are pregnant or breastfeeding, have a medical condition, or take prescription medication.

Does Yacon Syrup interact with any medications?

Possible interactions include: Diabetes medications (insulin, sulfonylureas): fasting blood sugar did not change in the trial cited here, but if you take these medicines it is still sensible to monitor your levels and speak with your prescriber. If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for Yacon Syrup?

NutraSmarts rates the evidence for Yacon Syrup as Limited (2 out of 5). It is backed by 3 clinical trials and 2 cited references summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(2 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. Genta S, Cabrera W, Habib N, Pons J, Carillo IM, Grau A, Sánchez S Yacon syrup: beneficial effects on obesity and insulin resistance in humans Clinical Nutrition. 2009;28(2):182-7. doi:10.1016/j.clnu.2009.01.013.PubMedUsed to support: The single placebo-controlled trial of yacon syrup, run over 120 days in obese, slightly dyslipidemic pre-menopausal women, reporting lower body weight, waist circumference, BMI, fasting insulin, HOMA-IR and LDL cholesterol, plus more frequent bowel movements and greater reported fullness. Of the blood sugar related measures it recorded only glucose, insulin and HOMA-IR; no gut hormone such as GLP-1 was measured.
  2. Pereira MF, Soares IC, Cabral MM, and colleagues Impacts of Yacon Syrup (Smallanthus sonchifolius) on Human Health: A Systematic Review of Scientific Evidence from the Last Decade Nutrients. 2025;17(5):888. doi:10.3390/nu17050888.PubMedUsed to support: Systematic review of seven clinical trials with 161 participants in total, covering blood sugar control, blood fats, insulin sensitivity, appetite and gut bacteria. The authors noted small sample sizes and varying doses and called for larger trials. GLP-1 and other gut hormones were not assessed.