Eczema is a chronic and often distressing skin condition thought to affect around 1.7 million children in the UK. These figures equate to 1 in 8 school children, and it is believed that these figures are steadily rising. Atopic eczema is the most common form of eczema, beginning in the first year of life in about 60% of children and within the first five years in 85%. Whilst the exact cause of eczema is unclear, it is known that over activity of the immune system plays a significant role. Furthermore, eczema often occurs together with allergies such as hay fever or asthma, and is frequent within families, suggesting a genetic element to the condition.
Atopic eczema varies in severity, with some people only mildly affected with a small, contained area of dry and occasionally itchy skin patches. In its most extreme case, eczema can manifest severe symptoms such as cracked, sore and bleeding skin. The role of diet and nutrition in the management of eczema is gaining increasing attention and is often used alongside pharmaceutical treatment, and in some cases as a complete alternative. One particular area of interest is the role that polyunsaturated fatty acids play in modulating inflammation and immune reactions in eczema. The level and composition of these polyunsaturated fats in the human body is highly dependent on their intake in the diet and on the intake of specific precursors. The essential fatty acid alpha-linolenic acid is generally found in botanical oils, seeds and nuts, and must be converted to the longer chain fatty acid eicosapentaenoic acid (EPA) which plays a specific and important regulatory role in the cardiovascular, reproductive, inflammatory, immune, and nervous systems. The delta-5 and delta-6 desaturases (FADS1 and FADS2) have long been known to be important enzymes in the endogenous formation of long-chain polyunsaturated fatty acids such as EPA from this dietary precursor. Small genetic changes called polymorphisms within these genes are highly associated with the actual concentrations of omega-6 and omega-3 fatty acids within the body. Furthermore, specific variations in FADS1 and FADS2 are associated with the prevalence of atopic eczema (Glaser et al, 2010). However, consuming preformed long chain omega-3 EPA in the form of fish and fish oils bypasses FADS1 and FADS2 and is a direct way of increasing blood and tissue levels of this important fatty acid, and thereby the production of products involved in modulation eczema symptoms. Most importantly, is seems, is that introducing fish into the diet of children at an early age can influence the development of eczema. The Prevention of Allergy among Children in Trondheim study, a prospective birth cohort study in primary healthcare in Trondheim, Norway, followed 3086 children prospectively from 1 year to approximately 2 years of age. The primary outcome variable was parental reported asthma and eczema at 2 years, and the findings suggested a reduced risk of developing eczema if the child was eating fish once or more a weekor within the first year of life (Oien et al, 2010).
Nevertheless, benefits of consuming fish, especially that which is farmed, may be offset by the presence of contaminants, such as methyl mercury, dioxins, polychlorinated biphenyls (PCBs) and several other organic pollutants. The benefits of fish consumption as a direct source of omega-3 are well known, and based on clear epidemiological evidence. However, whilst consumption of two portions of fish weekly appears to offer a relatively safe level of consumption, the use of purified fish oils as an addition or alternative to fish consumption certainly has numerous benefits. Highly purified oils offer a safe and convenient method of increasing omega-3 intake without the risk of contamination associated with farmed and wild fish.
Glaser C, Heinrich J, Koletzko B. (2010) Role of FADS1 and FADS2 polymorphisms in polyunsaturated fatty acid metabolism. Metabolism. 59:993-9.
Oien T, Storrø O, Johnsen R. (2010) Do early intake of fish and fish oil protect against eczema and doctor-diagnosed asthma at 2 years of age? A cohort study. J Epidemiol Community Health. 64:124-9.