A collaborative effort to apply the evidence-based review process to the field of nutrition: Challenges, benefits, and lessons learned

Tufts-New England Medical Center Evidence-based Practice Center, Institute for Clinical Research and Health Policy Studies, Tufts-New England Medical Center, Boston, MA 02111, USA.
American Journal of Clinical Nutrition (Impact Factor: 6.77). 07/2007; 85(6):1448-56.
Source: PubMed


Evidence-based systematic reviews evaluating dietary intake and nutritional interventions are becoming common but are relatively few compared with other applications. Concerns remain that systematic reviews of nutrition topics pose several unique challenges. We present a successful collaboration to systematically review the health effects of a common nutrient, n-3 (or omega-3) fatty acids, across a wide range of clinical conditions. More generally, we discuss the challenges faced and the lessons learned during the review, the benefits of systematic review of nutritional topics, and recommendations for conducting and reviewing nutrition-related studies. Through a structured but flexible process, 3 Evidence-based Practice Centers in the Agency for Healthcare Research and Quality program produced 11 reports on a wide range of n-3 fatty acid-related topics. An important resource has been created, through which nutrition and dietetics researchers, clinical dietitians and nutritionists, clinicians, and the general public can understand the state of the science. The process identified challenges and problems in evaluating the health effects of n-3 fatty acid consumption, highlighted challenges to reviewing the human nutrition literature, and yielded recommendations for future research. The goals of these systematic reviews, the processes that were used, the benefits and limitations of the collaboration, and the conclusions of the reviews, including recommendations for future research, are summarized here.

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    • "The persuasive link between dietary n-3 PUFAs and lower cognitive decline in epidemiological studies has led to further experiments aimed at finding the molecular basis (or bases) for benefits. Apart from the known effects of DHA on neuronal conduction (Hashimoto et al., 2006), in reducing amyloid-b accumulation (Calon and Cole, 2007), for benefiting cardiovascular function (Balk et al., 2007), and reducing inflammation and oxidative stress (Cunnane et al., 2009), DHA gives rise to lipid signalling molecules apart from the well-known eicosanoids formed from other PUFAs (e.g. ARA, EPA). "
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    ABSTRACT: An appropriate animal model that can eliminate confounding factors of diet would be very helpful for evaluation of the health effects of nutrients such as n-3 fatty acids. We recently generated a fat-1 transgenic mouse expressing the Caenorhabditis elegans fat-1 gene encoding an n-3 fatty acid desaturase that converts n-6 to n-3 fatty acids (which is absent in mammals). The fat-1 transgenic mice are capable of producing n-3 fatty acids from the n-6 type, leading to abundant n-3 fatty acids with reduced levels of n-6 fatty acids in their organs and tissues, without the need of a dietary n-3 supply. Feeding an identical diet (high in n-6) to the transgenic and wild-type littermates can produce different fatty acid profiles in these animals. Thus, this model allows well-controlled studies to be performed, without the interference of the potential confounding factors of diet. The transgenic mice are now being used widely and are emerging as a new tool for studying the benefits of n-3 fatty acids and the molecular mechanisms of their action.
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