Consumption of fish can help to prevent cardiovascular disease. The precise way in which fish is beneficial is not fully understood. This is important to find out as fish consists of a complex mixture of fatty acids and micronutrients such as vitamin D and selenium that could individually, or collectively, be responsible for the beneficial effects.

Fish farming in Scotland is playing an increasingly important role in the provision of fish for human consumption. But issues with sustainability of raw materials are requiring fish farming to reformulate fish diets, which may affect the levels of beneficial omega-3 fatty acids and other components in fish.

In this study we will be comparing the long-term health effects of eating two portions a week of Scottish salmon raised on a traditional fish diet versus eating two portions a week of Scottish salmon raised on a more sustainable fish diet. In addition, we will be looking at differences in health outcomes when eating two portions a week of either Scottish salmon, compared with eating no fish at all.

Aquaculture has the potential to take the pressure off wild fish stocks whilst meeting the dietary needs of the population for omega 3 fatty acids and other key nutrients such as vitamin D. The industry is working hard to improve sustainability - between 1995 and 2006 it has been estimated that the input to output ratios for salmon improved from 7.5 to 4.9 and trout from 6.0 to 3.4- but there is a need to do more. Reductions in fish stocks and catch quotas, in addition to sustainability considerations, mean that farmed fish may have to be raised on vegetable oils for example but this may reduce the omega 3 content and may affect the content of other nutrients. Fish are an important component of the diet and there is a need to understand the effect of pressures from sustainability on methods of production and the health giving properties of fish. We have now been commissioned by the Scottish Government's Rural and Environment Science and Analytical Services Division (RESAS) to do research on the health effects of Scottish farmed fish fed different feeding regimes in the Scottish population, and assess how differential effects in measured health outcomes could be related to fish composition.

Consumption of fish or omega-3- fatty acids from fish reduces coronary heart disease mortality, the leading cause of death in developed nations. The precise way in which fish provides benefit is not fully understood. This is important as fish and fish oils consist of a complex mixture of fatty acids and micronutrients that could individually, or collectively, be responsible for the beneficial effects. Aquaculture in Scotland is playing an increasingly important role in the provision of fish for human consumption, but issues with sustainability are requiring aquaculture to replace traditional fish oil and meal in formulated fish diets by oil from more sustainable sources, which may affect the levels of beneficial omega-3 fatty acids (EPA and DHA) and other components in fish. We will investigate the health effects of consuming two portions oily fish (Scottish farmed salmon) per week (current UK recommendation) using fish raised on different feeding regimes.

HYPOTHESIS

The health effects of consuming two portions oily fish (Scottish farmed salmon) per week (current UK recommendation) will be different for fish raised on different feeding regimes, primarily in terms of improving the omega-3 index.

OBJECTIVE

The main objective of this proposed study is to determine 1) whether the health benefits of consuming two portions of Scottish farmed salmon per week that have been fed a diet high in fish oil and fish meal significantly outweigh the health benefits of consuming two portions of Scottish farmed salmon per week that have been fed a diet with more sustainable levels of fish meal and fish oil, and 2) whether the difference in health benefits could justify the use of less sustainable dietary regimes for farmed fish.

Inclusion criteria: Healthy men and women aged 35-75 years BMI ranging from 18-35 kg/m2 Blood pressure below 160/90 mmHg; Total cholesterol < 8.00 mmol/L Total/HDL cholesterol < 6 mmol/L Fasting plasma glucose , 7 mmol/L Having a 10-20% risk for developing cardiovascular disease within the next 10 years based on the ASSIGN calculation (http://cvrisk.mvm.ed.ac.uk/index.htm) including the following factors: age, gender, number of cigarettes smoked per day, Scottish Index of Multiple Deprivation (SIMD)/postcode, systolic blood pressure, levels of total and HDL cholesterol and family history of cardiovascular disease, or having at least one additional risk factor such as being over 50 years old, BMI above 25 kg/m2, elevated triglyceride levels (> 1.7 mmol/L) or elevated glucose levels (> 5.6 mmol/L); platelet count > 1709/L haematocrit above 40 % for males and above 35 % for females haemoglobin above 130 g/L for males and above 115 g/L for females

Exclusion criteria Regularly taking aspirin or aspirin-containing drugs, or other anti-inflammatory drugs; Taking drugs or herbal medicines known to alter the haemostatic system in general; Taking any medicine known to affect lipid metabolism; Taking certain dietary supplements/multivitamin tablets; Diagnosis of diabetes, hypertension, renal, hepatic, haematological disease or coronary heart disease; Unsuitable veins for blood sampling; Inability to understand the participant information sheet; inability to speak, read and understand the English language.