The strong scientific evidence for the health effects of antioxidants has been established through biological and medical research exclusively focused on low molecular weight antioxidants (mA)—such as vitamins A, C and E, carotenoids and polyphenols. However, recent findings have shown plant foods contain—in addition to mA—abundant amounts of other type of high molecular weight antioxidant: non-extractable polyphenols or macromolecular antioxidants (MA). These are high molecular weight proanthocyanidins and tannins, and are polymeric structures of low molecular weight polyphenols and carotenoids bound to polysaccharides and proteins.
MA have so far been ignored because they are not extracted from plant material using aqueous-organic solvents nor are they detected by the usual methods of analysis for antioxidants. However, the human diet includes significant amounts of both mA and MA daily. It should be noted MA are major antioxidants in the diet and therefore it is quite possible MA make a major contribution to all the health effects currently attributed exclusively to mA.
Macromolecular antioxidants have high biological and antioxidant activity and exhibit promising health related properties. Their high molecular size confers them some specific physiological characteristics and mechanisms of action, which differentiates them from mA. Most mA are absorbed in the small intestine and pass into the blood stream between 0.5 and 2 hours after intake, producing an increase in antioxidant status (blood antioxidant concentration) and being distributed to target cells and organs. Contrary, MA pass through the stomach and small intestine intact and reach the colon where they interact with the colonic microbiota in a fermentative process—resulting in a high intestinal antioxidant status and the production of antioxidant metabolites. These metabolites are absorbed through the colonic mucosa and reach the bloodstream about 8 hours after ingestion. This indicates MA may increase and prolong antioxidant status and the health effects associated to dietary antioxidant intake.
Several biological assays, animal experiments and clinical studies have been carried out, obtaining positive results indicating macromolecular antioxidants may play an important role in healthy ageing through an improvement of antioxidant status in both the gastrointestinal tract and plasma and may also offer protection against various risk factors for chronic diseases.
An updated review of MA properties supports the development of macromolecular antioxidant ingredients and their applications in healthy ageing, prevention of risk factors associated with oxidative stress, and gastrointestinal health.
Current technology for obtaining antioxidant ingredients is based primarily on extracting them from various plant materials but this is not applicable to MA as non-extractable substances. The two first patents for obtaining MA ingredients have been recently licensed to food companies.
Macromolecular antioxidants are an emerging topic for scientific and technological research with promising applications in nutrition and health*
*Non-extractable polyphenols and carotenoids: importance in human nutrition and health”.
Edited by F. Saura-Calixto and J. Pérez-Jimenez. Royal Society of Chemistry, UK (in press)
Dr Saura-Calixto will be speaking on the Vitafoods Europe 2018 Education Programme on this topic. To register to attend, click here, where you can also view the entire Programme. To learn more about macromolecular antioxidants ahead of the session in the Education Programme, listen to this podcast with Dr Perez-Jiminez.