能量平衡状态下膳食脂肪摄入与肥胖等慢性病关系研究

Accumulated studies proposed the increase in percentage of energy from fat is closely correlated with the incidence of chronic diseases such as obesity ,diabetes,etc. But these investigators did not take into consider of the concept of energy balance. The Expert Consultation of FAO proposed the upper value of acceptable macronutrient distribution range (ADMR) of total fat could reach to 35% of energy. But many scholars hold the oppsite attitude. So far there are few studies on suitable ratio of diet fat intake in energy balance status. There are two parts i.e. animal and population studies included in this project. For the animal study, which was divided into food restriction and non-restiction experiments, we aim to observe the effects of different fat intake on the body fat volume, blood glucose, blood pressure, blood lipid, adipokines, gut flora distribution, brain-gut peptide and the expressions of adipokines in fat tissues and brain-gut peptide in stomach tissues in energy balance and energy positive balance status in rats. The population study is intended to use the the data performed in Zhejiang Province in 2009-2012 of "China National Nutrition and Health Survey". Four hundred and eighty subjects will be selected whose dietary pattern and habits are stable and fats intake ranged between 25% and 40% of energy.The subjects will be assigned to three groups, whose fat intake from diets are between 25-30%, 30-35% and 35-40% of energy,repectively. According to the body weight changes from the original survey of 2009-2012,each group will be divided into two subgroups: energy balance subgroup (body weight has no change) and energy positive subgroup (body weight gained).The follow-up study for 3 years will be conducted to investigate the effects of different percentage of energy from dietary fats in energy balance and energy positive balance status on the risk factors of chronic diseases such as obesity and other metablic disorders. We hope to obtain the important mechanism and data of dietaru fat intake on the incidence and developpment of chronic disease and to provide the basis and foundation for guiding the suitable diets and prevention and control of non-communicable chronic diseases.

许多研究提示膳食脂肪供能比的提高与肥胖等相关慢病发病风险升高密切相关，但这些研究多没有考虑能量平衡这一关键因素。FAO建议能量平衡条件下脂肪供能比的上限可以提高到35%，但许多学者对此执异议。目前缺少在能量平衡条件下膳食脂肪适宜比例的研究。本项目拟开展动物实验和人群研究两部分。动物实验通过限食和不限食，观察大鼠在能量平衡及能量正平衡状态下不同脂肪摄入量对大鼠体脂含量、血糖、血压、血脂、肠道菌群分布、脂肪因子和脑肠肽及其表达等因素的影响。人群研究拟利用2009-2012年中国居民营养与健康状况监测浙江地区的人群，选取脂肪供能比在25-40%间处于能量平衡及正平衡状态的成年受试对象480人，进行为期3年的跟踪研究，观察不同脂肪供能水平对肥胖、糖脂代谢紊乱等慢性病相关危险因素的影响。通过以上研究，获得不同膳食脂肪含量与慢性病发生的相关机理及数据，为科学指导合理膳食、慢病防控提供重要科学依据。

本项目开展动物实验和人群研究两部分。动物实验，分为3个实验，限食实验，分低脂组、普通组、中脂组和高脂组四组，四组的饲料中脂肪供能比分别为5%、10%、25%及40%，其他营养素在相同能量中的含量都相同。各组动物喂食等能量的饲料，将动物的体重限定在300-350g范围内；半限食实验，饲料及分组与限食实验相同，低脂组动物不限食，其他组动物给予等能量的对应饲料；不限食实验，动物分为低脂高碳水、低脂高蛋白、普通组、中脂低碳水、中脂低蛋白、高脂低碳水和高脂低蛋白7组。动物实验观察不同脂肪摄入量对大鼠体重、体脂含量、血糖、血压、血脂、肠道菌群分布、脂肪因子和脑肠肽及其表达等因素的影响。人群研究选取浙江地区脂肪供能比在25-40%间的成年受试对象498人，进行为期3年的跟踪研究，观察不同脂肪供能水平对肥胖、糖脂代谢紊乱等慢性病相关危险因素的影响。结果，动物实验，限食实验中，中脂及高脂供能比组血中甘油三酯（TG)较低脂组显著降低；而饥饿素基因表达水平与低脂组相比显著升高；半限食实验，中脂组、高脂组血中胆固醇(CHO）、TG和高密度脂蛋白(HDL-C)与低脂组比显著降低，而血糖却显著升高；不限食实验中，中脂低蛋白、2个高脂组与普通组比HDL-C显著降低，2个高脂组胰岛素及胰岛素抵抗指数与低脂高碳水比显著升高；低脂高碳水及低脂高蛋白组的脂联素表达水平与普通组比显著降低；动物实验中不同脂肪供能比对体重、血压、体脂、游离脂肪酸、脂肪因子、脑肠肽等指标均无显著影响；不同脂肪摄入量及膳食结构对肠道菌群的丰富度和多样性没有影响；人群研究，不同脂肪供能比仅对男性血糖、女性舒张压有一定影响，但对肥胖相关的其他指标如总能量摄入、BMI、腰围、血脂、胰岛素、游离脂肪酸、脂肪因子及脑肠肽均没有显著差异。动物实验结果显示高脂肪供能比对糖脂代谢有一定影响，降低血脂，升高血糖。人群研究未得到相似的结果，不同脂肪供能比的摄入与肥胖及相关慢性病指标无相关性。该结果还需进一步分析验证。