Zhou Yuan E, Kubow Stan, Dewailly Eric, Julien Pierre, Egeland Grace M
School of Dietetics and Human Nutrition, McGill University, CINE Building, 21,111 Lakeshore Road, Ste Anne de Bellevue, H9X 3V9 Montreal, Canada.
Br J Nutr. 2009 Sep;102(6):888-94. doi: 10.1017/S0007114509301609. Epub 2009 Apr 2.
Emerging evidence shows that desaturase 5 (Delta5), the key regulator in the synthesis of highly unsaturated long-chain fatty acids (HUFA), is modulated by factors including adiposity, diet and insulin resistance. We explored the association of these factors in a cross-sectional study within a high-risk Cree population. Anthropometric measures and fasting blood glucose and insulin were analysed. Delta5 was estimated as the 20 : 4n-6:20 : 3n-6 ratio in erythrocyte membranes. The setting of the present study was the Mistissini community in the Cree Territory of Québec, Canada with ninety-eight female and sixty-eight male subjects aged 20-88 years. Obesity (BMI > or = 30 kg/m2) was prevalent across age groups. Delta5 was inversely associated with BMI (Spearman's correlation coefficient (rs) - 0.175; P = 0.03) and positively associated with age (rs 0.593; P < 0.0001), which was driven by age-related increases in dietary intake of n-3 fatty acids and decreases in 20 : 3n-6. Homeostasis model assessment of insulin resistance (HOMA-IR) was significantly inversely associated with Delta5 in age-adjusted linear regression analyses in normoglycaemic individuals (beta - 2.110 (SE 0.566); P < 0.001), whereas no association was observed among glucose-intolerant individuals (interaction term P = 0.03). In contrast, there were no significant interactions indicating differences in the slope for each of the adiposity measures in their associations with Delta5. The present study indicates that the dietary transition of reduced consumption of fish among younger Cree may compound the effects of obesity and emerging insulin resistance which, in turn, could reduce bioavailability of HUFA n-3 (through reduced Delta5 activity). Also, the study suggests that disease progression is an important consideration when evaluating correlates of Delta5 activity in observational studies.
新出现的证据表明，去饱和酶5（Delta5）是高度不饱和长链脂肪酸（HUFA）合成中的关键调节因子，受肥胖、饮食和胰岛素抵抗等因素的调节。我们在一个高危克里人群中进行了一项横断面研究，探讨了这些因素之间的关联。分析了人体测量指标、空腹血糖和胰岛素。Delta5被估计为红细胞膜中20:4n-6与20:3n-6的比值。本研究的地点是加拿大魁北克克里地区的米斯蒂西尼社区，有98名女性和68名男性受试者，年龄在20至88岁之间。肥胖（BMI≥30kg/m2）在各年龄组中都很普遍。Delta5与BMI呈负相关（斯皮尔曼相关系数（rs）-0.175；P = 0.03），与年龄呈正相关（rs 0.593；P < 0.0001），这是由与年龄相关的n-3脂肪酸饮食摄入量增加和20:3n-6减少所驱动的。在血糖正常个体的年龄调整线性回归分析中，胰岛素抵抗的稳态模型评估（HOMA-IR）与Delta5显著负相关（β-2.110（标准误0.566）；P < 0.001），而在糖耐量异常个体中未观察到关联（交互项P = 0.03）。相比之下，没有显著的交互作用表明各肥胖指标与Delta5关联的斜率存在差异。本研究表明，年轻克里人鱼类消费量减少的饮食转变可能会加重肥胖和新出现的胰岛素抵抗的影响，而这反过来又可能降低HUFA n-3的生物利用度（通过降低Delta5活性）。此外，该研究表明，在观察性研究中评估Delta5活性的相关因素时，疾病进展是一个重要的考虑因素。
