Promise in prebiotics
The yacon plant grows in the Andes mountains of South America and has a long history of medicinal use-for diabetes and digestive disorders-among indigenous people living in these areas. Yacon syrup is rich in prebiotics, a type of fiber that fuels the growth of healthy bacteria in the human gastrointestinal tract. Yacon is a good source of polyphenols as well, which are nutrients found in a variety of plant foods and beverages, such as red wine, green tea, and berries. Polyphenol-rich diets are associated with reduced risk of chronic diseases such as heart disease and cancer.
The major type of prebiotics found in yacon are FOS (fructooligosaccharides) also found in many common plant foods, such as leeks, onions, and asparagus. FOS are not readily digested and so reach the colon largely intact. Once in the colon, FOS are fermented to short-chain fatty acids, which support healthful gut bacteria growth and inhibit the growth of harmful, disease-causing bacteria.
FOS provide just 2 calories per gram, instead of the usual 4 for most carbohydrates. This means that as a sweetener, yacon syrup provides about 20 calories per tablespoon, compared with 48 calories for a tablespoon of sugar, and 64 for honey. FOS are soluble fiber, and can increase stool bulk and potentially minimize constipation.
Will the syrup slim you?
Studies in mice and rats support the notion that FOS from yacon root may improve insulin sensitivity and levels of cholesterol and other blood fats in animals with diabetes, but much more research is needed to better understand if these results are applicable to humans.
Of the three human studies available at the time of writing, two examined safety and short-term effects on how quickly food moves through the gastrointestinal tract (colon transit time). One small, double-blind, placebo-controlled trial in 55 obese women does suggest that FOS from yacon syrup may improve the odds of losing pounds. According to this study, 140 mg of FOS from yacon syrup per kg of body weight per day (that's 60 mg per pound) improved fasting insulin levels, body weight, and waist circumference. On average, the yacon syrup group lost 33 pounds in three months, while the control group gained about three and a half pounds in the same period.
For reference, 60 mg of FOS per pound translates to around 11 grams of FOS for a person weighing 180 pounds, or a little more than one-third of an ounce of FOS from yacon syrup per day.
Should you say yes to yacon?
The early word on yacon syrup is certainly interesting, though much more research is needed to better understand how this sweetener works and who might best benefit from using it. Keep the following in mind before deciding if yacon syrup is right for you:
- Work with your doctor. If you take medications to manage diabetes or insulin resistance, talk to your doctor before using yacon products. If you add in FOS without accounting for their insulin-sensitizing effects, you may end up with low blood sugar levels.
- Go slow. FOS may cause uncomfortable gastrointestinal effects, such as gas, in many people. Use sparingly and work up to higher amounts to minimize these issues.
- Seek food. Yacon isn't the only way to get FOS. Other FOS-rich foods include bananas, onions, chicory root, garlic, barley, oats, asparagus, leeks, and dandelion greens. Aim for a varied diet with plenty of plant foods and you'll naturally increase your FOS intake.
- Seek balance. While yacon syrup may help some people lose a few pounds, even the best diet aid is useless unless combined with balanced nutrition and regular physical activity.
(Dig Liver Dis 2002;34:S111-20; Clin Nutr 2009;28:182-7; J Diabetes Metab Disord 2013;12:28)