According to the Pan-American Health Organization (PAHO), there is a growing increase of degenerative diseases in countries of the Americas, bringing on disability and death of the population. As eating properly is the most effective way to reduce the risk of diseases, food scientists are seeking alternatives for more nutritional foods, mainly through the investigation of functional compounds in natural foods. Among the functional compounds, fructans stand out for their beneficial effects on the animal body, favoring the growth of bifidobacteria in the colon that improve gastrointestinal metabolism, as well as regulating the levels of serum cholesterol and the absorption of minerals. Besides, fructans seem to be involved in the positive modulation of the immune system, mainly in an increased resistance to infections and microbicidal activity as well as by the reduction of allergic reactions and cancer in experimental models. This paper aims to analyze literature data concerning the benefits of consuming the fructans contained in natural food, especially their immunomodulatory actions in both animals and humans. © 2010 Elsevier Ltd.