本研究的局限性

Dietary sources of omega-3 fatty acids can broadly be divided into alpha linolenic acid (ALA) or long chain omega-3 fatty acids, also referred to marine omega-3 fatty acids as they are typically derived from fish and seafood, and can include eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA). These fatty acids vary in their chain lengths, with ALA, EPA, DPA, and DHA being comprised of 18, 20, 22, and 22 carbon atoms, respectively. The four fatty acids we studied are essential, i.e., they are obtained almost entirely from the diet, with minimal endogenous synthesis, though small amounts of ALA can be converted to EPA, as well as EPA and DHA may be metabolized to form DPA. Food sources for ALA include walnuts, flaxseeds, soy products, and vegetable oils (particularly soybean oil or canola oil). On the other hand, long-chain omega-3 fatty acids are obtained primarily from fish/seafood (particularly oily fish such as salmon, mackerel, or sardines) as well as in certain fortified foods such as milk and eggs. Long-chain omega-3 fatty acids, particularly EPA and DHA are also often taken in the form of fish oil or cod liver oil supplements.

請(qǐng)問(wèn)現(xiàn)階段美國(guó)膳食指南對(duì)n-3多不飽和脂肪酸的攝入量有何相關(guān)建議？

The 2015-2020 Dietary Guidelines for Americans (DGA) recommends for the general population to consume about 8 ounces (~227 grams) per week of various seafood products, which will provide approximately 250 mg per day of long-chain omega-3 fatty acids. This level of intake has been shown in many prior studies to be related to a lower incidence of cardiovascular disease, and in particular, sudden cardiac death. A similar amount of intake has also been suggested for pregnant and breastfeeding women to help promote optimal brain development among infants. However, this recommendation should be balanced with the known risks of methylmercury exposure from seafood products, particularly large species of fish such as tuna or king mackerel. The DGA has also recommended intakes of ALA, ranging from 1-1.6 g per day, to promote optimal cardiovascular health.

該研究對(duì)糖尿病的預(yù)防具有怎樣的現(xiàn)實(shí)指導(dǎo)意義？

Previous individual studies and even meta-analyses have shown conflicting findings on whether fish/seafood intake is beneficial or detrimental for the prevention of type 2 diabetes. The vast majority of prior studies have used dietary questionnaires, which have the limitations of measurement error and recall bias. Our study employed a global consortium of studies using objective biomarkers of omega-3 fatty acids, which functioned as a robust proxy of dietary intakes, and confirmed prior findings (predominantly from cohort studies conducted in Asia) that fish/seafood intake may be beneficial for the prevention of type 2 diabetes. Our work has important implications for future dietary guidelines and perhaps highlights new therapeutic targets for the prevention and treatment of diabetes.

該研究對(duì)后續(xù)的研究有怎樣的啟發(fā)？

While our study demonstrated an inverse association between marine omega-3 fatty acids and incident type 2 diabetes, the specific mechanisms underlying our findings remain incompletely understood. Additional research is needed to understand how these fatty acids may influence pathways of glucose-insulin homeostasis, inflammation, adipocyte function, and cell membrane functions that collectively reduce metabolic risk. Analyzing the downstream metabolites of these fatty acids may be a useful approach to gaining additional insights into how these fatty acids exert their beneficial effects, and human clinical trials should continue to assess whether supplementation with these fatty acids or their respective metabolites may reduce the risk of incident diabetes.