Can oils derived from genetically-modified plants replace fish oil as a source of long chain n-3 polyunsaturated fatty acids in the human diet?

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Omega-3 fats called EPA and DHA are known to be beneficial to human health. They lower the chance of getting heart disease and can control the symptoms of conditions that involve inflammation such as arthritis. The main food source of EPA and DHA is fatty fish like salmon and sardines. EPA and DHA are also found in fish oil supplements. The UK government recommends that people consume EPA and DHA regularly in order to stay healthy, particularly during ageing. However, many people do not follow these recommendations, partly because they do not like to eat fatty fish or find it too expensive. Also, there are not enough fish in in the sea to provide everyone in the world with enough EPA and DHA to stay healthy, and fish stocks are declining. Therefore, there is a need to find a sustainable source of EPA and DHA that can be increased in order to meet the need for these healthy fats. Research sponsored by the BBSRC has led to the development of plants that can make EPA and DHA. This has been achieved by inserting the genes needed for making EPA and DHA into plants that do not normally have those genes. The oil produced in the seeds of these so-called transgenic plants contains similar amounts of EPA and DHA to fish oils. Therefore, it is possible that this seed oil could be used to replace fatty fish and fish oil supplements as a sustainable and inexpensive source of EPA and DHA. However, the structure of the oil produced by the plants is different from that of fish oils, and it is not known whether this difference would result in the plant oil being a better or worse source of EPA and DHA for people. It is important to know this, because if the plant oil was less effective than fish oil in increasing the amount of EPA and DHA in people's blood and tissues, and in benefiting health, then it may be less attractive as a source of EPA and DHA in the diet. This project will determine whether the plant oil is as effective as fish oil in changing the amounts of EPA and DHA in the blood and in modifying some processes that are related to health. In the latter regard, we plan to study the concentrations of fats like cholesterol in the blood and the ability of immune cells taken from the blood to respond when stimulated in the laboratory. We will address our aims in two ways. First, we will recruit healthy men and women in two age groups (18 to 30 years or 50 to 65 years) to take part in a study that involves consuming a single meal containing either fish oil or new plant oil. We will then take a series of blood samples over the following 8 hours. This will allow us to assess whether EPA and DHA derived from the plant oil are absorbed as efficiently by the gut as when they are provided as fish oil. We will also compare the effect of the two oils on the levels of fat and on substances involved in immune function in blood. Second, we will recruit another group of healthy volunteers as above, and provide them with fish oil or plant oil as a dietary supplement to take over 8 weeks. We will take blood samples after 4 and 8 weeks and compare the effect of the different oils on the levels of EPA and DHA in blood and in blood cells. We will also compare the effect of these oils on immune function, the levels of fat in blood, and on the activity of genes in white blood cells. The findings will show whether the plant oil is as effective as fish oil in raising the levels of EPA and DHA in blood and in changing immune function. We expect that the findings of this project will provide strong evidence for or against using the plant oil as a replacement for fish oil. Furthermore, these results will contribute to the continuing debate about the introduction of transgenic crops into agricultural practice. Ultimately, we hope that a positive outcome will lead to the use of the plant oil as a major source of EPA and DHA in the UK diet as this would have important positive implications for marine ecology and for health of the UK population.