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Old 10-13-2009, 09:24 PM   #2
Brian Lau
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Some data from Kraft et al. 2008 attached below. They examined the lipid content from four beef breeds (2 grass-fed, and 2 grain-fed). The relevant data is in the bottom left of the table, where the arachidonic acid content (20-4 n-6) is shown to be practically similar between the breeds.

It's probably not as simple as labeling a food "pro-inflammatory" based on the AA content. A recent commentary on this paper raises some interesting points:
Quote:
In contrast to what might be predicted, studies assessing a range of immune functions and inflammatory markers in healthy adults in response to increased intake of arachidonic acid (up to 15 g/d) have not identified any major effects. Taken together with the studies on blood lipids, platelet reactivity and bleeding time, including this latest study, it seems appropriate to conclude that a significant increase in arachidonic acid intake by healthy adults, up to an intake of, say, 15 g/d appears unlikely to have any adverse effect. However, the earlier study by Seyberth et al. suggests that higher intakes of arachidonic acid should be approached with caution. Furthermore, there is no information on the impact of increased arachidonic acid supply in disease. It is possible that inflammatory processes that already exist within an individual could be exacerbated by providing exogenous arachidonic acid. However, the discovery of novel anti-inflammatory mediators produced from arachidonic acid and the identification of hitherto unknown anti-inflammatory actions of mediators previously considered to be pro-inflammatory in nature indicate first, the complexity of this system and, second, that predicting the effect that increased arachidonic acid supply might have is difficult. Nevertheless, it is important to keep in mind that, just because there is little biological impact of an increase in arachidonic acid intake or status, there may still be significant benefit from a decrease in its intake or status.

It is important to note that a role for arachidonic acid in neurological development has been identified, that arachidonic acid-derived eicosanoids are not confined to pathology but have many physiological roles, that human breast milk contains arachidonic acid, that infant formulas, which include arachidonic acid (and DHA), are associated with improved growth and development and that formula containing arachidonic acid (and DHA) has been shown to enable preterm infants to achieve immune development similar to that seen with breast-milk feeding and to lower the risk of necrotising enterocolitis in preterm boys. These observations suggest an important role for arachidonic acid in the normal growth and development of infants and demonstrate that harmful actions are not seen as a consequence to its provision, at least when given in combination with DHA.

In conclusion, this new study by Katsumoto et al. adds valuable new information to our knowledge about the impact of increased dietary intake of arachidonic acid. Taken together with earlier studies, this study suggests that, rather than being harmful, moderately increased arachidonic acid intake is probably harmless in healthy adults, although the effect of intakes above 15 g/d are not known and the effect of increased intake in diseased individuals is not known. Furthermore, arachidonic acid appears to be an important constituent of infant formulas and in this setting may be helpful in growth, development and health.

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