Health benefits of omega-3 fatty acids
Ruxton C (2004) Health benefits of omega-3 fatty acids. Nursing Standard. 18. 48, 38-42. Date of acceptance: July 7 2004.
Evidence suggests that omega-3 polyunsaturated fatty acids play an integral role in cell membrane function and development of the brain and eyes. Optimising intake appears to confer many benefits, including reduced risk of heart disease and possibly a reduced likelihood of behavioural problems, depression and inflammatory conditions such as rheumatoid arthritis. Although there is some disagreement on what level of intake is optimal, British diets are low in omega-3 fatty acids. Good sources include oily fish and novel sources include fortified eggs and oils derived from microalgae.
* Children: development
* Heart disease
* Mental health
These key words are based on the subject headings from the British Nursing Index. This article has been subject to double-blind review.
THE DIET of our ancestors, as is often the case, can teach us a lesson about modern nutrition. Palaeontologists suspect that early man consumed a diet rich in marine foods, with women gathering shellfish and sharing their catch with the children of the community (Crawford 1992). It is thus a coincidence that most abundant fatty acids in marine foods, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), are key components of our eyes and brain, and are particularly important during infant development (Ruxton et al 2004).
EPA and DHA are parts of a family of polyunsaturated fatty acids called omega-3 (or sometimes n-3). Table 1 summarises the key types of dietary fatty acids. The array of fatty acids and the terminology that applies to them can be daunting. A simple approach is to look at their chemical structure. All fats, and their constituent fatty acids, are made up of an even-numbered chain of carbon atoms with hydrogen and oxygen molecules tacked on to the sides. Those fatty acids with only single bonds between the carbon atoms are called saturated fatty acids. They tend to be solid at room temperature, for example, butter or meat fat. Fatty acids with one double bond in the carbon chain (C=C) are called unsaturated, while those with two or more double bonds are called polyunsaturated. Unsaturated and polyunsaturated fatty acids tend to be liquid at room temperature, for example, olive oil or sunflower oil. Their fluidity makes them useful in human cells where flexible membranes are vital for the transport of oxygen, glucose and other molecules around the body (Yehuda et al 1999). Foods normally contain a mixture of different types of fatty acids with one type dominating the mix.
The polyunsaturates alpha-linolenic acid (ALA), arachidonic acid (AA) and linoleic acid are essential fatty acids because they cannot be made in the body and must be obtained in the diet. ALA can be used as a precursor in the body to create EPA and DHA, but the latter process is ineffective in preterm babies. Although DHA is not an essential fatty acid, the inefficiency of its synthesis from ALA combined with its role in fetal and infant...
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