Presentation on theme: "TILAPIAS FROM DIFFERENT AQUACULTURE SYSTEMS CONTAIN VARIABLE AMOUNTS OF -3 AND -6 POLYUNSATURATED FATTY ACIDS: IMPLICATIONS FOR HUMAN NUTRITION Ioannis."— Presentation transcript:
TILAPIAS FROM DIFFERENT AQUACULTURE SYSTEMS CONTAIN VARIABLE AMOUNTS OF -3 AND -6 POLYUNSATURATED FATTY ACIDS: IMPLICATIONS FOR HUMAN NUTRITION Ioannis T. Karapanagiotidis 1 *, Michael V. Bell 1, David C. Little 1,2, Amararatne Yakupitiyage 2 1 Institute of Aquaculture, University of Stirling, UK 2 AARM, SERD, Asian Institute of Technology (AIT), Thailand Support from the Aquaculture and Fish Genetics Programme, DFID, UK
Basic Concepts Fatty acids are the basic units of fats and oils (lipids) The polyunsaturated fatty acids (PUFA) are a group of fatty acids with great significance in animal nutrition (including fish and humans) PUFA are categorised according to their chemical structures, from which the most important are those of the -3 and -6 fatty acids.
The Importance of PUFA -3 and -6 PUFA are essential (Essential Fatty Acids or EFA) for normal growth, development and reproduction of all vertebrate organisms, including fish & humans Because of the fact that animals cannot synthesise -3 and -6 PUFA inside their body (de novo), these should be provided from the diet
The Vital Importance of -3 PUFA Particularly the -3 PUFA (i.e.DHA & EPA) have beneficial effects on general health and prevent many health disorders such as: Diseases of the heart & of blood vessels Diseases of the immune system Cancer & respiratory diseases Allergic reactions
The Human Diet – A growing concern In recent decades, it is fact that the profiles of fats in Western diets have become increasingly unbalanced The intake of saturated fat and -6 PUFA has increased, whereas -3 PUFA intake has decreased Formerly the ratio -3/ -6 was 1:5 but it has now declined to ratios below 1:20
The Human Diet – A growing concern These changes in the fat patterns have been linked with many common health disorders in the western world (i.e. Coronary Heart Disease, cancer etc.) However, these changes appear to be spreading and influencing diets around the World The incidence of many health disorders is now increasing in several countries in Asia
The Availability of Fats by economic group (1961-1990, 165 countries) Source: FAO Food balance sheets, Agrostat PC, 1993
Fish is not only a high-quality protein food, for which there are many competing alternatives in nature But also contains high concentrations of -3 PUFA (i.e. DHA & EPA) for which there are currently no real competing alternatives Fish is by far the richest source of -3 in nature Fish in the Human Diet: A Unique Nutritional Role
Linkages between lipids and rural aquaculture The inland Asian communities are traditionally dependent on freshwater aquatic foods, and especially fish There is an increasing reliance on farmed fish as diets and livelihoods change Is this more better? What are the qualitative impacts of increasing fish consumption through intensification of aquaculture?
Impacts of intensification Most aquaculture production in Asia is semi-intensive relying on use of both fertilisation and supplementary feeding The traditional supplementary feeds are high energy brans and oilcakes, which are high in -6 PUFA The increasing trend towards intensive systems is making use of formulated feeds to satisfy the nutrient requirements of fish The fish feeds are using an increasing proportion of global marine fishmeal (rich in -3 PUFA), but the least cost formulations, commonly practised, result in more -6 PUFA.
The current study to determine the fat content and fatty acid composition of tilapia (Oreochromis niloticus) produced in systems across a range of intensification
Conclusions of the study The fat content of tilapia is moderate but increases as we shift from extensive production totally dependent on natural food to more intensive culture systems. Tilapia contain considerable amounts of the valuable DHA in the edible muscle tissue
Conclusions of the study -3/ -6 ratios in tilapia cultured at different intensities ranged from 1:1 to 1:2, indicating their high lipid nutritional value However, higher levels of -6 and lower ratios of -3/ -6 were found in the more intensively farmed fish compared to the wild fish and those cultured mainly on natural food.
General Conclusions The aquaculture sector has a very important role to play both in the developing and developed world by providing food security and ensuring future fish supplies. Fish is the richest source of the -3 PUFA in nature and consumption of fish improves human nutrition and health. However, since the input of -6 PUFA from other dietary components is often excessive in humans it is desirable, or even essential, that fish continue to supply long-chain -3 PUFA in the human diet.
Recommendations Participation of the feed industry assessing the potential for developing feed formulations that enhance -3: -6 ratios to optimal a better understanding of the underlying mechanisms that result in more desirable ratios observed in less intensively farmed and natural stocks
Recommendations An assessment of the fat quality of other common aquatic animals, cultured and natural stocks, consumed by rural communities Awareness raised among change agents and policy makers that production methods can affect fish quality and that these in turn may have impacts on human health