A team of researchers in the area of Technology, Post-harvest and Food Industry of the Institute for Agricultural and Fisheries Research and Training (IFAPA), at the Alameda del Obispo Centre in Cordoba, Spain, has studied the process of absorption and metabolism of two groups of micronutrients in raspberries: anthocyanins and ellagitannins, considered responsible for the fruit's health benefits. According to the experts, the digestive system transforms these initial compounds into smaller substances or metabolites with anti-inflammatory, anti-diabetic and anti-cancer effects. For the scientists, identifying these molecules is an essential step to learn about the contribution of raspberries in a healthy diet. Anthocyanins and ellagitannins are two groups of polyphenol or antioxidant compounds found naturally in some plants and fruits, such as raspberries and blueberries. The former are responsible for the red and blue tones of these fruits, while ellagitannins, also present in almonds or nuts, are micronutrients known for their complex chemical structure. According to the researchers, both nutrients have a number of anti-cancer, anti-inflammatory, anti-diabetic, and anti-microbial effects, as shown in several studies performed on humans, animals and with cell culture. However, the scientists have found that these beneficial effects are not produced by the compounds themselves, but by their metabolites. "The healthy function of anthocyanins and ellagitannins cannot be fully understood if it is not known how and where they are processed by the body. And so far, there been no comprehensive studies regarding the absorption, metabolism and excretion of the antioxidants present in raspberries," explained one of the researchers involved in this project, Gema Pereira-Caro, of IFAPA Cordoba, who has counted with the collaboration of experts from the universities of Glasgow (UK) and Parma (Italy). The expert states that these compounds are micronutrients that, when ingested, are metabolised by the body and become simpler molecules or metabolites. "These substances, derived from the transformation of the initial micronutrients, are the ones going into the bloodstream, reaching major organs and thus positively affecting our health," argues Pereira-Caro. The researcher also highlighted the importance of the colon in metabolising these micronutrients. "Both compounds are transformed by the action of intestinal microflora, either by breakage, processing or destruction of chemical bonds. Identifying and quantifying metabolites in the plasma and urine, from the moment of intake until their expulsion, indicates where the transformation of the antioxidants has taken place," she explains. In this sense, the experts have found that the highest concentration of these molecules in plasma is recorded between an hour and an hour and a half after the intake of raspberries. Meanwhile, in urine, a greater concentration of other metabolites is found between 6 and 24 hours after the fruit has been consumed. "This entails that most of the metabolites are the result of the degradation of antioxidants carried out by bacteria in the colon," continues the author of the study. Furthermore, both the metabolites and their concentration vary depending on the person, a result which confirms the role of the colon in the transformation process, as "each individual has a different microbiota that absorbs and metabolises micronutrients in a different way," she argues. To reach these conclusions, gathered in the article "New insights into the bioavailability of red raspberry anthocyanins and ellagitannins", published in the journal Free Radical Biology and Medicine, the researchers conducted an experiment with ten healthy volunteers, 5 men and 5 women, aged between 18 and 60 years, who ate 300 grams of mashed raspberries. The experts evaluated the bioavailability of the major antioxidants in raspberries, i.e., the processes of absorption, transformation and excretion of anthocyanins and ellagitannins in plasma and urine. To this end, samples of both fluids were taken and analysed during the 36 hours after the fruit's intake using advanced analytical techniques. The results showed the mismatch between the initial compounds present in raspberries and the metabolites found in plasma and urine. "This is a consequence of the transformation process undergone by anthocyanins and ellagitannins when they go through the digestive tract: they decompose into a wide variety of molecules different from the original," continues the researcher. For the researcher, the identification of these raspberry metabolites entails gaining access to a key testing tool to find out about the fruit's health properties. "To learn about the anti-cancer properties of these fruits, it makes no sense, for example, to conduct tests on extracts that are rich in raspberry antioxidants, as the metabolite is what will actually reach our organs," she assured. Source: Fundación Descubre. Source: http://www.freshplaza.com
