Feingold Kenneth R,
Emeritus Professor of Medicine, University of California San Francisco, San Francisco, CA.
The role of lipids and lipoproteins as causal factors for cardiovascular disease (CVD) is well established. Dietary saturated fatty acids (SFA), which are in milk, butter, cheese, beef, lamb, pork, poultry, palm oil, and coconut oil increase LDL-C and HDL-C. The increase in LDL-C is due to a decrease in hepatic LDL clearance and an increase in LDL production secondary to a decrease in hepatic LDL receptors. Monounsaturated fatty acids (MUFA) are in olive, canola, peanut, safflower, and sesame oil, and avocados, peanut butter, and many nuts and seeds and polyunsaturated fatty acids (PUFA) are in soybean, corn, and sunflower oil, and some nuts and seeds, tofu, and soybeans. Both MUFA and PUFA lower LDL-C by increasing hepatic LDL receptor activity. Dietary cholesterol is found in egg yolks, shrimp, beef, pork, poultry, cheese, and butter and increase LDL-C but the effect is modest and varies with approximately 15-25% of individuals being hyper-responders with more robust increases. Dietary cholesterol reduces hepatic LDL receptor activity, decreasing the clearance and increasing the production of LDL. Trans fatty acids (TFA) occur naturally in meat and dairy products and are formed during the partial hydrogenation of vegetable fat. TFA increase LDL-C and decrease HDL-C. Carbohydrates (CHO) can be divided into high-quality, for example fruits, legumes, vegetables, and whole grains, or low-quality, which include refined grains, starches, and added sugars. CHO increase TG with low quality CHO, particularly added sugars, having a more robust effect. Dietary CHO, particularly fructose, promotes hepatic de novo fatty acid synthesis leading to increased VLDL secretion. Fiber is found mostly in fruits, vegetables, whole and unrefined grains, nuts, seeds, beans, and legumes and phytosterols are naturally occurring constituents of plants and are found in vegetable oils, cereals, nuts, fruit and vegetables. Both dietary fiber and phytosterols decrease LDL-C by decreasing intestinal cholesterol absorption. With regards to CVD there are very few well conducted randomized controlled trials and most of the information is derived from observational studies that demonstrate associations. These observational studies have found that fruits, vegetables, beans/legumes, nuts/seeds, whole grains, fish, yogurt, fiber, seafood omega-3 fatty acids, and polyunsaturated fats were associated with a decreased risk of CVD while unprocessed red meats, processed meats, sugar-sweetened beverages, high glycemic load CHO, and trans-fats were associated with an increased risk of CVD. Randomized trials have shown that a Mediterranean diet reduces CVD. Based on this information current guidelines for the general population recommend 1. A diet emphasizing intake of vegetables, fruits, legumes, nuts, whole grains, and fish 2. Replacement of SFA with MUFA and PUFA 3. A reduced amount of dietary cholesterol 4. Minimizing intake of processed meats, refined CHO, and sweetened beverages and 5. Avoidance of TFA. For individuals with a high LDL-C limiting dietary SFA, TFA, and cholesterol and increasing fiber and phytosterols will help lower LDL-C while in individuals with high TG limiting low quality CHO, particularly simple sugars, and ethanol with weight loss, if indicated, will help lower TG. For complete coverage of all related areas of Endocrinology, please visit our on-line FREE web-text, WWW.ENDOTEXT.ORG.
脂质和脂蛋白作为心血管疾病（CVD）的致病因素，其作用已得到充分证实。存在于牛奶、黄油、奶酪、牛肉、羊肉、猪肉、家禽、棕榈油和椰子油中的膳食饱和脂肪酸（SFA）会升高低密度脂蛋白胆固醇（LDL-C）和高密度脂蛋白胆固醇（HDL-C）。LDL-C升高是由于肝脏LDL清除率降低以及肝脏LDL受体减少继发LDL生成增加所致。单不饱和脂肪酸（MUFA）存在于橄榄油、菜籽油、花生油、红花油、芝麻油、鳄梨、花生酱以及许多坚果和种子中；多不饱和脂肪酸（PUFA）存在于大豆油、玉米油、葵花籽油、一些坚果和种子、豆腐及大豆中。MUFA和PUFA均通过增加肝脏LDL受体活性来降低LDL-C。膳食胆固醇存在于蛋黄、虾、牛肉、猪肉、家禽、奶酪和黄油中，会升高LDL-C，但影响较小，约15 - 25%的个体为高反应者，LDL-C升高更为明显。膳食胆固醇会降低肝脏LDL受体活性，减少清除并增加LDL生成。反式脂肪酸（TFA）天然存在于肉类和奶制品中，也在植物油部分氢化过程中形成。TFA会升高LDL-C并降低HDL-C。碳水化合物（CHO）可分为优质碳水化合物，如水果、豆类、蔬菜和全谷物，以及劣质碳水化合物，包括精制谷物、淀粉和添加糖。劣质CHO，尤其是添加糖，会更显著地升高甘油三酯（TG）。膳食CHO，尤其是果糖，会促进肝脏从头合成脂肪酸，导致极低密度脂蛋白（VLDL）分泌增加。纤维主要存在于水果、蔬菜、全谷物和未精制谷物、坚果、种子、豆类和豆制品中；植物甾醇是植物的天然成分，存在于植物油、谷物、坚果、水果和蔬菜中。膳食纤维和植物甾醇均通过减少肠道胆固醇吸收来降低LDL-C。关于CVD，很少有精心设计的随机对照试验，大多数信息来自观察性研究，这些研究表明了相关性。这些观察性研究发现，水果、蔬菜、豆类/豆制品、坚果/种子、全谷物、鱼类、酸奶、纤维、海鲜ω-3脂肪酸和多不饱和脂肪与CVD风险降低相关，而未加工红肉、加工肉类、含糖饮料、高血糖负荷CHO和反式脂肪与CVD风险增加相关。随机试验表明，地中海饮食可降低CVD风险。基于这些信息，当前针对普通人群的指南建议：1. 强调摄入蔬菜、水果、豆类、坚果、全谷物和鱼类的饮食；2. 用MUFA和PUFA替代SFA；3. 减少膳食胆固醇摄入量；4. 尽量减少加工肉类、精制CHO和含糖饮料的摄入；5. 避免摄入TFA。对于LDL-C水平高的个体，限制膳食SFA、TFA和胆固醇，增加纤维和植物甾醇的摄入，将有助于降低LDL-C；对于TG水平高的个体，限制劣质CHO，尤其是单糖，并在必要时通过减重减少乙醇摄入，将有助于降低TG。欲全面了解内分泌学的所有相关领域，请访问我们的在线免费网络文本，网址为WWW.ENDOTEXT.ORG。
