The sweet food that controls your weight, glucose, and even depression

 

Imagine a food that is sweet to the palate but, instead of spiking your glucose, it controls it. A tuber that satisfies sugar cravings without sabotaging your body weight. That improves your digestion, feeds the "good" bacteria in your gut, and, surprisingly, can even improve your mood.

Some studies have shown that yacon consumption has positive health effects, including anticancer activity [study], anti-inflammatory and antioxidant activity related to its phenolic compounds [study], improved immunity in preschool children [study], diabetes control in older people [study]; as well as weight control and obesity prevention in overweight adults [study,study ,study ,study]. All these effects of yacon are reportedly associated primarily with its high content of fructooligosaccharides (FOS) and inulins.

Today I will tell you about the nutritional and chemical composition of yacon, its beneficial health properties as a healthy food, and the bioactive components of yacon that make it a dietotherapeutic ingredient.

 

The key lies in the unique chemical composition of yacon

Yacon is a plant native to South America where it is consumed as food and used in folk medicine to treat diabetes, constipation, and other ailments.

The main substances present in fresh yacon roots are: water (>70%), carbohydrates (20%, of which 80% are FOS and inulin), proteins (2%), lipids (1%), and ash (2%).  

The carbohydrate content in the dry matter of yacon roots is approximately 94%. Apart from free sugars such as glucose, fructose, and sucrose, yacon roots store carbohydrates in the form of fructans, unlike most vegetable roots in the human diet, which store carbohydrates in the form of starch. This is the great difference and what makes yacon an outstanding food for maintaining your digestive health, a healthy body weight, controlling your appetite, and even promoting a good mood.A fructan is a polymer of fructose molecules. Short-chain fructans are known as FOS fructooligosaccharides, and linear long-chain fructans are inulins. Both FOS and inulin are β-D-fructafuranoses linked by a β-(2,1) bond, present in the composition of yacon.

 

Effects of fructooligosaccharides (FOS) on your health

Fructooligosaccharides are oligosaccharide fructans naturally found in the cell vacuoles of plant leaves, stems, and roots. FOS can be extracted from plants, fruits, vegetables, and some grains and cereals, such as wheat and barley. The content of FOS and inulin-type fructans reaches up to 70% of the dry matter of yacon roots. The highest concentration of FOS in cultivated plants has been found in yacon, on the order of 16% of fresh weight.

As soluble fibers, FOS are commonly used as low-calorie alternative sweeteners and are currently enjoying increasing popularity for their prebiotic effects [study]. This is because amylases cannot hydrolyze the β-(2,1) bonds, and FOS are resistant to enzymatic hydrolysis by salivary and intestinal digestive enzymes, so they pass through the upper gastrointestinal tract unmetabolized before being fermented by anaerobic bacteria in the colon to produce end products: short-chain fatty acids (SCFAs) [study]. The human intestinal microflora is composed of more than 400 species, and the colon is the region with the largest microbial population. FOS exert an indirect influence on immunity through the production of SCFAs.

Research in animal models has suggested that SCFA production through FOS fermentation in the colon can increase the local immune response, lower colon pH, and thus suppress inflammation and, in the long term, colorectal cancer development [study].

At the genus level, both FOS and SCFAs promote the growth of beneficial bacteria such as Bifidobacteria spp. and Lactobacillus spp. Bifidobacteria constitute between 25% and 30% of the total gut bacterial population, while Lactobacillus constitutes less than 1% of the gut bacterial population. Probiotic strains of Lactobacilli and Bifidobacteria can alter gut microbiology. Their optimization in the intestinal microflora can alleviate constipation, improve serum lipids in hyperlipidemia, and suppress the production of putrefactive intestinal substances in the digestive tract.

Due to their non-digestible nature, FOS have a low glycemic impact. A randomized, double-blind trial in obese adults (body mass index [BMI] of 25 to 30 kg m^-2) showed that daily intake of 20 g of FOS (n = 40) for three months led to a significant reduction in atherogenesis and body weight, compared to the placebo control group (n = 32) [article].

 

Effects of inulin on your health

Inulins, the other constituent of yacon, are fructan-type polysaccharides found in many roots, fruits, and vegetables, as well as some grains and cereals. [study]. It is very likely that the favorable characteristics attributed to FOS also apply to inulins.

Inulin is water-soluble and is therefore classified as a soluble fiber. Due to the β-(2, 1) linkages, inulin is not digested by enzymes in the upper gastrointestinal tract but is fermented in the colon, contributing to its reduced caloric value and prebiotic properties.

Like FOS, the functional effects of inulins include promoting digestive health as prebiotics and contributing to butyrate production in the colon, which is associated with a lower risk of colon and breast cancer [study].

 

Benefits of consuming Yacon (tuber and leaves)

Anticancer, antioxidant, antimicrobial, antidiabetic, anti-obesity, and weight control properties have been detected. These properties can almost certainly be attributed to fructose oligosaccharides (FOS), inulin, and phenolic compounds, which are the main components of yacon.

The antidiabetic effects of yacon roots have been demonstrated in animal models and human studies, although here I focus mainly on studies done in humans, if available.

In a controlled trial with elderly individuals (over 60 years old), daily consumption of 18 g of freeze-dried yacon powder, containing 7.4 g of FOS, for nine weeks led to a decrease in serum glucose, but no reduction in serum lipids was observed [study].

The effects of yacon on weight control and obesity prevention are mainly due to its high content of non-digestible fructose oligosaccharides (FOS) and phenolic compounds.

Regarding the promotion of gastrointestinal health, Utami et al. [study] demonstrated that, compared to commercial FOS, consumption of yacon tuber (containing the same amount of FOS) promoted the growth of Bifidobacteria and Lactobacillus in the cecum of rats, leading to a higher concentration of SCFAs.

The researchers concluded that yacon tuber has more beneficial effects on maintaining colonic health than other sources of FOS. It has been proposed that yacon tuber also contains resistant starch and polyphenols, which contribute to the difference in the intestinal environment.

Let's remember that resistant starch is a type of carbohydrate that "resists" digestion in the small intestine, does not increase glucose, acting more like fiber. It reaches the colon, where it is fermented to feed beneficial gut bacteria and produce beneficial fatty acids, thus improving digestive health, insulin sensitivity, and feelings of fullness.

No adverse effects of yacon have been detected in human studies.  No adverse effects were observed after 120 days of supplementation with yacon syrup, providing 0.14 g of FOS per kilogram of body weight [study]. However, in another study, anaphylactic reactions were reported in a 55-year-old woman after ingesting yacon root [study]. This appears to be an isolated response, but further studies would be needed to investigate the safety of yacon and consolidate its use as a dietary supplement.

In any case, side effects of FOS consumption, including digestive disorders and abdominal discomfort, should be considered when used as dietary supplements or food ingredients, particularly in infant formula.

How should yacon be consumed?

Yacon is a herbaceous perennial plant with sweet-tasting tuberous roots. These roots, often referred to as tubers, have thin, tan skin and crisp flesh.

Both the leaves and tubers of yacon contain significant amounts of bioactive compounds.

For antioxidant and antidiabetic effects: 

Yacon leaves contain protocatechuic, chlorogenic, caffeic, and ferulic acids which confer antidiabetic and antioxidant properties to infusions (herbal teas) made from the leaves [study].

For blood glucose control, lyophilized yacon powder would have beneficial effects (study)

Gut health:

Yacon roots contain antioxidants, fructose, glucose, sucrose, and β-(2,1) fructooligosaccharides (inulin-type oligofructans) [study]. Inulin-type oligofructans are fermented by beneficial species of gut bacteria and, therefore, can be potential prebiotics [study].

Body weight control:

In human studies, daily consumption for six weeks of a breakfast drink containing 25 g of yacon flour by overweight adults (BMI 30 ± 2.4 kg m⁻², body fat 40 ± 6.7%) resulted in a reduction in body weight, body fat, waist circumference, and sagittal abdominal diameter [article].

Mental health:

In animal models of behavioral despair (mice), antidepressant-like effects have been observed after the administration of inulin-type oligosaccharides extracted from yacon roots; the results suggested that yacon consumption has the potential to treat patients with depression [study].

Yacon represents much more than a nutritious food; it is a testament to how traditional medicine and modern science converge in natural solutions. Its proven safety profile, combined with growing evidence of its multisystemic benefits, positions it as a dietotherapeutic ingredient of considerable interest.

While further studies are needed to fully consolidate its use as a supplement, consuming yacon in its natural form—whether as fresh tuber, lyophilized powder, or leaf infusion—offers an evidence-backed option for optimizing gastrointestinal, metabolic, and mental health. The question is no longer whether yacon works, but when we will begin to integrate it as part of our daily preventive medicine.