Consumers have increasing choice in food products and within the social environment of today's consumer, the factors of demand are increasingly complex. Food is no longer simply a primary necessity for survival, it is a leisure and family activity, the participation in which, takes up a considerable amount of time. Today, food is a social and a political issue - something about which people have opinions, be it food quality, healthiness, or the food supply itself. It is also central to consumer's self-image. There is a large sector of the economy which supplies food demand, and this sector is itself now under considerable scrutiny from the consumer. This thesis examines consumer behaviour and attitudes towards food, with particular reference to the health aspects of food issues. It describes a programme of qualitative and quantitative research - group discussions, personal interviews and postal questionnaires. The programme examines milk (particularly low fat milk) as a diet and health case study; knowledge about food; attitudes towards food; the food industry and related issues; shopping behaviour and eating habits. It is important to both the consumer and the supplier of food, that consumer behaviour and attitudes are understood as fully as possible. This research highlights the misunderstandings between consumer and producer, emphasises the mistrust of the consumer for the producer and concludes with the need for communication between them. The thesis discusses the background to diet and health as an issue, describes the development of the current consumer environment and gives a profile of today's consumer. It then goes on to detail the research - two quantitative surveys, each undertaken over two years and a series of group discussions. The final section summarises the findings of each individual piece of the programme as a whole for various groups: food Oroducers; food manufacturers; food retailers; advertisers; the media; health professionals; the consumer; consumer organisations and government.

Variation in quality and quantity of food resources can affect consumer productivity responses throughout the food chain, particularly the efficiency at which basal resources are converted to consumer biomass. I performed a manipulative feeding experiment to investigate the somatic growth and fatty acid incorporation in the benthic generalist isopod Asellus aquaticus, in response to differing ratios of autochthonous (high quality algae) to allochthonous (low quality leaf litter) foods. I used stable isotopes to quantify the assimilated diet proportions across a range of diet treatments to determine the relative resources that contributed to growth. There were significant differences in growth between treatments, being lowest in treatments A (100% leaf litter) and G (100% algae), with highest growth experienced in treatment B (90% leaf litter/ 10% algae). Stable isotope data revealed that there was very little variation in algal assimilation among combined diet treatments. Fatty acids (FA) indicators eicosapentaenoic acid (EPA):total FA and EPA:omega 3 (ω3) FA and arachidonic acid (ARA):total FA declined with increasing growth and docosahexaenoic acid (DHA):ω3 showed a positive relationship with growth. These findings provide support for previous feeding trials conducted with Asellus, though there are some contrasts with zooplankton. The results suggest a balance between allochthonous and autochthonous dietary sources combine to enhance primary consumer fitness, and the relative availability of each may interact to determine growth and accumulation of important FA compounds. In terms of FA and trophic transfer, temporal and spatial variation in consumer physiological demands might determine the retention and use of FA.