Carotenoids bioavailability from foods: From plant pigments to efficient biological activities

Carotenoid pigments are a group of bioactive compounds that are of interest to the food scientists, nutritionists and food industries due to their positive impact on human health and their economic benefits. Carotenoids are responsible for the attractive colour of many plant food (mainly fruit and vegetables), which is perhaps the first attribute that consumers assess when determining the quality and appearance of a product, and therefore conditions its acceptability. In addition, carotenoids have diverse biological functions and activities, such as the well known provitamin A activity, antioxidant capacity and enhancement of the immune system. There are an extensive number of factors affecting the efficient incorporation of these phytochemicals from the diet, although in many cases no biological activity will be put in action within the consumer body (animal or human) without a first visual attraction. The term bioaccessibility is used to evaluate the amount of a nutrient that is released from a food during the digestion process. The bioaccessibility of lipophilic compounds, such as carotenoids. in natural foods (mainly fruits and vegetables) is usually fairly low and is constrained by various factors, particularly the degree of food processing and matrix composition. There are evidences that homogenisation and thermal treatment have positive effects on the bioaccessibility of these compounds, whereas the presence of dietary fibre has a negative effect. The presence and co-ingestion of fat in the diet are a key factor, with a minimum quantity needed to facilitate carotenoid absorption, and this seems to be one of the advantages of the Mediterranean diet. Most of the relevant data on the bioaccessibility of carotenoids from natural or processed foods has been obtained in postprandial absorption studies and supplementation studies. This approach, although highly valuable, is insufficient for a detailed analysis of the food matrix composition effects, and also it does not take into consideration other factors that may be involved in carotenoid absorption in each stage of the bioaccessibility process (digestibility and absorption). In vitro experimental processes that reproduce the physiological conditions and events that take place in the human gastrointestinal tract during digestion have been developed and fine-tuned in recent years. These digestion models become an excellent analytical resource to establish both the significance and scope of diverse factors in the efficiency of digestibility of carotenoids allowing a detailed analysis of the influence of the food matrix composition on the digestive process. (c) 2011 Elsevier Ltd. All rights reserved.