雷春译文:美国心脏和营养医生对食用油的权威建议
作者:Tori Rodriguez, MA, LPC
原文发表于2017年8月31日《Cardiology Advisor》
翻译:雷春 于2017年11月30日
虽然美国心脏协会在1961年建议用不饱和脂肪取代饱和脂肪来预防心血管类疾病,但在1980和1990年代,这一信息被曲解为减少总脂肪摄取,并取之于碳水化合物。这导致精加工的面粉和糖的摄取大增。肥胖病比列从1980年代初期的10%飞跃到2014年的近40%,同时,二型糖尿病的比例加倍。
Frank Hu,MD/PhD(医学和研究双博士)说:“流行病学研究和临床实验显示减少总脂肪的摄取,不利于预防心血管病。因为当人们少吃脂肪的同时,取代之于碳水化合物。”Hu医生是麻省的波士顿市的哈佛TH Chan公共医疗学院营养系主任和教授,他最近和同事共同发表了一篇相关综述。由于这项研究,2015-2020年的美国饮食指南,建议用植物油、坚果和果仁、以及含油丰富的鱼取代饱和脂肪以及反式脂肪。
2017年6月,美国心脏协会主席公布的多项研究结果指出,用多元不饱和脂肪取代饱和脂肪,心血管病危险系数会降低近30%。作者们一致认为:“减少饱和脂肪,代之于不饱和脂肪,特别是多元不饱和脂肪,会降低心血管疾病。”
为了得到最前沿的信息《Cardiology Advisor》访谈了几位专家,他们是:哈佛大学的Hu医生;约翰霍普金斯大学心血管防治副主任和流行病副教授Michos医生;科罗拉多州丹佛市国家犹太健康中心心血管健康和防治主任和副教授Freeman医生。
《Cardiology Advisor》:降低饱和脂肪增加不饱和脂肪会减少心血管发病率的机理是什么?
Hu医生:与非饱和脂肪相比,饱和脂肪会增加总胆固醇和低密度脂蛋白胆固醇(LDL)的水平,这是心血管病的主要致病因素。饱和脂肪还会提高胰岛素耐受、慢性炎症、以及血栓危险,这些都是和心血管病息息相关的。
Michos医生:饱和脂肪提高低密度脂蛋白胆固醇(LDL)的水平,这是动脉粥样硬化的主要因素。用多元不饱和脂肪和单元不饱和脂肪取代饱和脂肪,会降低LDL的血液浓度。另外,多元不饱和脂肪可能有其它潜在的心血管保护作用,比如,减少血小板的应激反应和血栓的形成。
《Cardiology Advisor》:医生如何鼓励和支持病人选择这类食物?
Freeman医生: 许多医生缺乏营养学方面的训练。他们应该,通过网络或者面对面课程以及阅读相关文献,进一步学习营养学知识,并在日常工作中使用。每次见到病人都应该简短地询问运动习惯,及头天晚上的晚餐食谱。建议把饮食服务作为延伸的治疗手段之一 。医生也要“说到做到”,以低脂的植物为主食,为病人做好榜样。最后,要积极推动医学院把营养饮食和生活习惯纳入教学,并作为考核内容。
Hu医生:关注健康食品的选择和健康饮食习惯非常重要。使用植物性脂肪,如橄榄油、菜籽油和豆油做菜,而不用奶油、猪油和棕榈油。以植物性食物为主,多吃水果、蔬菜、全谷物、坚果和果仁、以及豆类, 同时减少红肉和加工过的肉类,以及加糖的甜点和饮料。
医生Michos:简而言之,少吃动物性食物,多吃植物性食物!蔬菜应该是主餐,肉类蛋白是副餐。我也建议病人多吃真正的新鲜食物,尽量少吃加工过的包装食品。我认为,病人被各种混淆视听的信息所迷惑,搞不清什么是健康饮食。我想饮食习惯比某类食物更重要。我鼓励病人吃DASH类(降血压类饮食)和地中海饮食,它们都是以植物为主。饮食结构要根据每个病人的具体情况来定,要以他们现有的饮食习惯为基本点,并以心血管疾病危险指数和改变饮食的愿望程度为参考。
我强烈建议病人读食物标签,知道一次应该吃多少,监控自己食物摄取量,增强对自己所吃的饱和脂肪及卡路里量的意识;这方面,有很多便于使用的手机软件。我会根据他们的食物单,建议做一些改变,并倾听他们的反馈,看是否这些改变是可行的。我也会让病人自己决定哪些是他们可以改变的:医务人员应该引导病人寻找适合自己的饮食方案,而不是说教。
《Cardiology Advisor》:实施更健康的饮食方案,对病人最大的挑战是什么?
Hu医生:很多人对饱和脂肪很困惑,一些研究说它不像以前认为的那样有害。但是,这些研究,把饱和脂肪与精制碳水化物做比较,其实,两者对心血管都是有害的。然而,如果与不饱和脂肪或全谷物相比,大量摄取饱和脂肪会极大提高心血管疾病的风险。因此,饮食建议应该强调用不饱和脂肪和健康碳水化物如全谷物等取代饱和脂肪。
Freeman医生:网络上到处都是误导信息, 认为高脂肪饮食有益健康。其中一些高脂肪饮食,确实会减肥减血脂,但通常是暂时的,而且高脂肪饮食对身体的危害,远大于减肥功效。
Michos医生:改变一个人一生形成的饮食习惯非常困难,特别是如果这种饮食习惯与其社会传统和文化习俗紧密相连。有的时候,只能一点一点地改变:每一次见病人时,只设定一个目标,缓慢但持续的改变就是进步。一次只取代一种食物,循序渐进。
原文链接:http://www.thecardiologyadvisor.com/prevention/dietary-fats-and-cardiovascular-disease-risk/article/685537/
我去年的译文,与这篇文章互补:https://www.sayweee.com/article/view/0i1h5?t=1512088681164
Although the American Heart Association (AHA) recommended replacing saturated fat with unsaturated fat for cardiovascular disease (CVD) prevention in 1961, the message shifted to reducing total fat and replacing it with carbohydrates in the 1980s and 1990s.1,2 This led to an increased intake of refined starches and sugars. Obesity rates jumped from 10% in the early 1980s to nearly 40% in 2014, and rates of type 2 diabetes doubled.1-3
“Epidemiological studies and clinical trials have shown that reducing total fat is not effective in preventing [CVD] because when people cut back on total fat, they replace it with carbohydrates,” according to Frank B. Hu, MD, PhD, professor and chair in the Department of Nutrition at the Harvard T.H. Chan School of Public Health in Boston, Massachusetts, and coauthor of a recent review on the topic.1 As a result, the 2015-2020 Dietary Guidelines for Americans recommend replacing saturated and trans fats with unsaturated fats from vegetable oils, nuts and seeds, and oily fish.4
In June 2017, the AHA released a presidential advisory highlighting results of randomized controlled trials showing that replacement of saturated fats with polyunsaturated fats reduced CVD risk by almost 30%, as well as similar findings from additional studies.5,6 The authors concluded that “lowering intake of saturated fat and replacing it with unsaturated fats, especially polyunsaturated fats, will lower the incidence of CVD.”
To learn more about these updates and glean suggestions for helping patients make the recommended dietary changes, Cardiology Advisor asked several experts to weigh in: Dr Hu; Erin D. Michos, MD, MHS, FACC, FAHA, associate professor of medicine and epidemiology and associate director of preventive cardiology at Johns Hopkins School of Medicine in Baltimore, Maryland; and Andrew M. Freeman, MD, FACC, FACP, associate professor and director of cardiovascular prevention and wellness at National Jewish Health in Denver, Colorado.
Cardiology Advisor: What are the proposed mechanisms by which lower intake of saturated fats and higher intake of unsaturated fats may lower CVD risk?
Dr Hu: Compared with unsaturated fats, saturated fat intake increases total and LDL [low-density lipoprotein] cholesterol levels, a major risk factor for CVD. Saturated fat has also been shown to increase insulin resistance, chronic inflammation, and clotting factors, which have all been associated with elevated CVD risk.21
Dr Michos: Saturated fats raise LDL cholesterol, a major fuel of atherosclerosis. Replacing saturated fats with polyunsaturated and monounsaturated fats appears to reduce LDL concentrations. In addition, polyunsaturated fats may have other potentially beneficial mechanisms for reducing CVD risk, such as reducing platelet reactivity and thrombosis risk.
Cardiology Advisor: What are some ways physicians can encourage and support patients in shifting toward these kinds of dietary choices?
Dr Freeman: Many physicians have limited, if any, nutritional training. They should further their nutrition knowledge through online or live coursework and reading about nutrition, and be able to apply this in day-to-day practice. Quick questions about exercise habits and what the patient ate last night for dinner should be asked at every visit. Engaging the extended care team, including dietary and nutrition services, is suggested. “Walking the walk” in terms of eating a predominantly low-fat, plant-based diet can set the example for many patients. Finally, advocating for additional nutrition and lifestyle education during medical school training and beyond is strongly suggested.
Dr Hu: It is important to focus on healthy food choices and healthy dietary patterns. Use liquid vegetable oils such as olive oil, canola oil, and soybean oil for cooking instead of butter, lard, and palm oil. Consume a diet rich in plant-based foods such as fruits, vegetables, whole grains, nuts and seeds, and legumes, and limit consumption of red and processed meats and sugar-sweetened foods and beverages.
Dr Michos: My simple message is to eat [fewer] animals and eat more plants! Vegetables should be the main course and animal protein the side dish. I also advise patients to eat more real foods and minimize processed, packaged foods. I think patients are simply overwhelmed with mixed and confusing messages about what constitutes a healthy diet. I like to think of dietary patterns rather than specific foods. I encourage patients to shift toward DASH-type [Dietary Approaches to Stop Hypertension] and Mediterranean-style diets, which are more plant-based. Approaches should be individualized to each patient based on their current eating habits, [CVD] risk factors, and willingness to make change.
I strongly recommend that patients read food labels and understand serving sizes, and track their food intake to increase awareness of how much saturated fat and total calories they consume; there are many easy-to-use [mobile phone] apps [for this purpose]. I may gently point out specific examples based on their food log and suggest replacement choices, and I get their feedback on whether they think those changes are feasible. I also let patients make their own suggestions of what they can change: the clinician should facilitate, not dictate, the discussion.
Cardiology Advisor: What are potential challenges for patients in adopting a healthier dietary pattern?
Dr Hu: There is a lot of confusion about saturated fat,with some studies suggesting it is not harmful, as previously believed. However, in these studies, saturated fat was compared with refined carbs, and both are unhealthy in terms of CVD risk. However, when compared [with] unsaturated fats or whole grains, higher consumption of saturated fat is a significant risk factor for CVD. Therefore, dietary recommendations should emphasize that saturated fat should be replaced by unsaturated fats and healthy carbohydrates such as whole grains.
Dr Freeman: There is widespread misinformation available [to patients] on the Internet about the potential benefits of a high-fat diet. In some of the high-fat diets, it is true that weight loss and lipids may improve, but often this is transient, and the deleterious effects of a high-fat diet often outweigh the weight loss benefit.
Dr Michos: It can be difficult to overhaul a whole lifetime of food patterns, especially when dietary food patterns are embedded in social traditions and cultural norms. Sometimes it just takes baby steps: address 1 goal at each visit, for gradual but relentless forward progress. Replace 1 food now, and next visit, make the next change, and so forth.
References
1. Wang DD, Hu FB. Dietary fat and risk of cardiovascular disease: recent controversies and advances. Ann Rev Nutr. 2017;37:423-446.
2. Flegal KM, Carroll MD, Kuczmarski RJ, Johnson CL. Overweight and obesity in the United States: prevalence and trends, 1960-1994. Int J Obes RelatMetab Disord. 1998;22(1):39-47.
3. Flegal KM, Kruszon-Moran D, Carroll MD, Fryar CD, Ogden CL. Trends in obesity among adults in the United States, 2005 to 2014. JAMA. 2016;315(21):2284-2291.
4. US Department of Health and Human Services, US Department of Agriculture. Dietary guidelines for Americans: 2015-2020. 8th ed. Washington, DC: 2015. http://health.gov/dietaryguidelines/2015/guidelines. Accessed August 29, 2017.
5. Sacks FM, Lichtenstein AH, Wu JHY, et al. Dietary fats and cardiovascular disease: a presidential advisory from the American Heart Association [published online June 15, 2017]. Circulation. doi: 10.1161/CIR.0000000000000510
6. Hooper L, Martin N, Abdelhamid A, Davey Smith G. Reduction in saturated fat intake for cardiovascular disease. Cochrane Database SystRev. 2015;(6)CD011737.