[Hydrolyzable tannins; biochemistry, nutritional & analytical aspects and health effects]

Hydrolysable tannins (HT) have been of scientific interest because of their nutraceutical potential. Both gallotannins (GT) and ellagitannins (ET) show different biochemical properties that result in various health benefits (eg anti-diabetic, anti-mutagenic, anti-microbial) for consumers, all associated with their antioxidant capacity (AOXc).

To analyze the most relevant aspects (biochemical, nutritional/analytical and health effects) of HT reported in the scientific literature.

A systematic search was conducted in several databases (PubMed, Cochrane, ScienceDirect) and free-access repositories (Google Scholar) on HT, GT and ET. This information was further sub-classified into biochemical, nutritional and analytical aspects (narrative review) and health effects (systematic review).

The high molecular complexity and amount of hydroxyl groups (-OH) in both ET and GT, are responsible not only for a plethora of methods for extraction and purification but also for the several pro-and anti-physiological effects of them such as enzyme inhibitions, protein excretion stimulation, AOXc and anti-proliferative effects.

The association of ET/GT with several macromolecules present in foodstuffs and the digestive tract, counteract the AOXc of these compounds but conversely allow the differential distribution of GT and ET to different target organs in such way that their health effects seems to be different.