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Delivering the benefits of functional foods
Date: 03/02/2012
Food with a health benefit claim is only useful if it can reach its target in the body – this can be estimated before expensive human dietary intervention studies, says Dr Amanda Forde of Food for Health IrelandDairy products are an ideal source of nutrition and an untapped resource for ingredients with functional benefits, according to Dr Amanda Forde and colleagues at Food for Health Ireland. Milk, for example, contains a myriad of proteins, carbohydrates and lipids that can yield bioactive components with positive health effects when systematically deconstructed.
Both academic and industrial research programs focus significant effort on the discovery of novel food ingredients, including dairy ingredients, which exert functional effects. This involves the application of a number of analytical techniques and cell culture bioassays, as well as research in animal models and human dietary intervention studies. Due to the complexity and financial risk required to progress to and perform human intervention studies, it is important to identify ingredients at an early stage that hold the most promise for human health. Of particular importance is the ability of the ingredient to reach its target organ and safely exert its beneficial effect.
Better living through pharmaceuticals
By applying some of the tools developed for pharmaceutical discovery, such as high content analysis (a form of automated fluorescence microscopy), it is now possible to predict the effects of bioactive ingredients on cell health and a wide range of biological processes. Crucially, this facilitates selection of the most promising ingredients for development before progressing to human dietary intervention studies.
Bioavailability is the fraction of the ingredient that reaches the systemic circulation, and determining this is paramount to the development of functional foods. For example, some active ingredients need to be absorbed from the gastrointestinal tract into the blood stream, such as those that could help to maintain cardiovascular health. Others may have an intestinal target, for example those which could alleviate the symptoms of intestinal bowel diseases, and in that case it is important to prove that they are not absorbed. Bioavailability can be predicted using an intestinal cell-culture model, which reduces the risk of an ingredient failing animal or human studies due to low bioavailability. For this purpose, the US FDA approves the use of Caco-2 cells (See below: electron micrograph of the intestinal epithelial barrier), which when grown under certain conditions, can be used to measure the rate of transport of a substances across the intestinal wall. Thereafter, a permeability coefficient is calculated which determines if a substance is likely to be absorbed.
In the case of pharmaceutical drug discovery, two key factors – solubility and permeability – determine whether a substance is absorbed across the gut wall. These are also applicable to certain ingredients in the food industry. Poor bioavailability as a result of low solubility can be addressed by using carrier ingredients (for example, triglycerides) that can help solubilisation. However, overcoming poor bioavailability due to low permeability is more challenging. For dairy ingredients, lipids tend to have good bioavailability while intact proteins and carbohydrates are often less bioavailable. To this end, micro- or nano-encapsulation technologies can be employed to help improve bioavailability.
While it is clear that a number of hurdles must be overcome to successfully deliver the benefits of functional foods, combining nutritional and technological solutions with knowledge gained from the pharmaceutical industry could pave the way for a more efficient and cost-effective process.
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