Biofortified and functional food: a healthy future?
30 Jan 2012
The challenges associated with providing sufficient food in the near future are now high profile, but the nutritional quality of food is also an issue for huge numbers of people today. The first conference organised by Technical Interest Groups linked into the Agri-Food Hub took place in May 2011 and brought together participants involved in all aspects of the food chain to discuss agronomic and genetic approaches to biofortifying crops and developing functional foods.
Prof Hilary Powers (University of Sheffield) opened the programme with an eye-opening overview of the role of micronutrients in human health. There are four key globally important micronutrients: vitamin A, in which 140 million pre-school children and seven million pregnant women are deficient and at risk of blindness; iodine, in which two billion people are deficient, leading to physical and cognitive disabilities; zinc, without enough of which two billion people suffer growth defects and are susceptible to infection; and iron, in which, incredibly, four to five billion people are deficient. Even in the UK, more than 50% of adolescent girls have iron deficiency.
Selenium deficiency
Another micronutrient causing concern is selenium. Deficiency results in an impaired immune system, low fertility, cognitive problems and an increased risk of cancer. Selenium intake has been below recommended levels for 20 years in the UK principally because of the use of more home grown wheat produced on soils low in selenium, and reduced use of fossil fuels which release particulate selenium. Martin Broadley (University of Nottingham) pointed out that UK wheat typically contains around 40% less selenium than Canadian wheat. Finland has required fertilisers to be amended with selenium (currently at 10 mg/kg) since 1984 and now leads the country table of selenium intake. Kevin Moran (Yara) described the International Fertiliser Industry Association's initiative on 'Fertiliser use and Human Health'. The effects of micronutrient fertilisers in deficient situations can be dramatic. For example, experiments in which 1% zinc was added to urea increased yields of rice and wheat by 17% and 14%, respectively, and grain zinc contents by 30% and 23%.
Prof Richard Mithen summarised the general topic of plant natural products and health with particular reference to research carried out by a collaborating cluster of institutes in Norwich including the Institute of Food Research, the John Innes Centre, the BBSRC Genome Analysis Centre and the Norfolk and Norwich University Hospitals. A specific example of how their research has been put into commercial use is the breeding of a broccoli variety containing 2-3 times more of the beneficial phytonutrient glucoraphanin than conventional varieties. In the body glucoraphanin is converted to the antioxidant sulphoraphane.
Five a day
Other breeding research was reported by Dr Broadley and Reading University's Carol Wagstaff. Dr Broadley's work has involved enhancing levels of calcium and magnesium in brassica crops. Deficiency is widespread in the West (10 – 15% of individuals), despite encouragement to eat 'five-a-day'. Over-expression of a gene involved in calcium transport in cells (CAX) has been demonstrated to increase its bioavailability 100% in carrots and potatoes. Dr Wagstaff is working with lettuce to increase the concentration of sequiterpenoid lactones. In plants these are involved in defence against may forms of pests and have been shown to have benefits against diverse aliments in humans including cancer, heart disease and influenza.
Lisa Ryan (Oxford Brooks University) described how fruit and vegetables are naturally 'colour-coded' to indicate their specific health benefits. Blue/purple colours are from anthocyanins (betalains have an equivalent role in some species); yellow-orange colours indicate antioxidants such as vitamin C, carotenoids and bioflavanoids; reds include lycopene. Other pigments which are possibly beneficial to health are curcumin, present in turmeric, a curry flavouring, and saffron is another tradition spice also used as a food dye which contains both water and lipid soluble carotenoids. One particular issue is the bioavailability of these phytochemicals in practice.
Alexander Sher (Nestlé) introduced some of the more practical considerations involved with the development of novel food products using iron fortification as an example. Increased rancidity due to lipid oxidation, metallic taste and colour changes resulting from reactions with polyphenols can all be problematic. Ferrous ammonium phosphate is a new alternative to the standard ferric pyrophosphate and has been shown to be absorbed more than twice as well by the body in addition to having superior sensory properties.
Meat
Enhancing the quality of meat was addressed by Michael Lee (Institute of Biological, Environmental and Rural Sciences). Ruminant products are high in saturated fat, but the content of various polyunsaturated fatty acids believed to be beneficial to health can be influenced by forage diets. Pasture or silage, and their red and white clover content, can all have effects. These diets differ in fatty acid composition and different fibre content affects the rate at which they pass through the rumen and, therefore, the time they are exposed to rumen bacteria resulting in metabolism to saturated fatty acids. Volatiles, known as the 'green odour', released when grass is chewed have an inhibitory effect on some rumen microflora also influencing final meat quality. Animal diets also affect shelf-life with meat from forage-fed animals retaining its colour for longer than that from animals reared on grain-based concentrate.
Mary Brennan (Newcastle University) discussed consumer acceptance of novel food technologies, but pointed out that consumers do not buy technologies, but food and then make meals and eat them. Whether any new technology is accepted depends on a complex mix of psychological, sociological, sensory and environmental factors. The ultimate assessment of perceived risks and benefits has personal and societal elements. Consumers may be categorised as those concerned primarily with price, taste, safety, or simply how a foodstuff, its production or processing, etc, fit with their values.
Food safety
Finally, Nigel Baldwin (Cantox) reported on the state of EU health claims legislation. The European Food Safety Authority (EFSA) has reviewed food product health claims recently and has been generally ruthless in rejecting the vast majority. Those that have been accepted relate to minerals and vitamins, PUFAs, tomato concentrate and chewing gum. Well-known product categories which have been unsuccessful include probiotics. However, the relevant expertise of the review panel of academics was questioned because this is a sector which has been developed by industry. Others rejected include products claiming weight loss and immunity.
Speakers' presentations from the conference are available to view via the link below.
Alan Baylis,
Chair, BioResources Group
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