#均衡饮食
#系列课程
所有脂肪都一样吗？
与碳水化合物和蛋白质一样，脂肪是健康均衡饮食的重要组成部分，在维持健康和预防疾病方面发挥着重要作用。然而，为了获得健康和长寿的益处，选择最佳的膳食脂肪至关重要。
脂肪的组成部分称为脂肪酸。脂肪酸根据其独特的分子结构分为两大类：硬脂肪（通常称为饱和脂肪酸和反式脂肪酸）和软液体脂肪（不饱和脂肪酸）。不饱和脂肪酸进一步分为多不饱和脂肪酸和单不饱和脂肪酸。
医学研究表明，适量食用不饱和脂肪往往对健康有益，而饱和脂肪和反式脂肪则会增加健康状况不佳和癌症、心脏病等慢性疾病的风险。除了脂肪种类外，每日摄入的脂肪总量也会对健康产生积极或消极的影响。高脂饮食会增加您健康状况不佳和患病的风险，而含有适量脂肪（单不饱和脂肪和多不饱和脂肪）的中低脂饮食则对健康有益。因此，了解哪些食物富含不饱和脂肪，哪些食物富含不太理想的饱和脂肪和反式脂肪至关重要。
为什么我们的饮食中需要脂肪？
了解脂肪在体内的具体功能非常有用，因为这将有助于您明智地选择饮食中的脂肪。此外，有些类型的脂肪是人体无法自行合成的，只能从食物中获取。Omega-6 和 Omega-3 就是其中两种脂肪酸，它们被认为对健康至关重要。它们都参与调节血压、心率、血液凝固、免疫力、新陈代谢，并有助于维持大脑和神经系统的功能。
脂肪的其他重要功能如下：
不饱和脂肪有助于减少体内的炎症过程。
不饱和脂肪还能通过减少甘油三酯（血液中与冠心病风险增加相关的脂肪类型）的产生，起到预防冠心病的作用。
所有不饱和脂肪在脂肪运输和代谢以及维持体内细胞膜的功能和完整性方面都发挥着重要作用。
脂肪有助于脂溶性维生素（例如维生素A、D、E、K）的运输和吸收。
脂肪可以增强许多食物的风味和口感，还能通过增加饱腹感来增强饱腹感。尽管如此，在使用脂肪时，仍然应该做出最健康的选择，以实现风味、享受和整体健康的益处。
哪些类型的脂肪最健康？
富含不饱和脂肪的食物是理想的选择，而单不饱和脂肪比多不饱和脂肪略胜一筹。研究发现，当单不饱和脂肪取代饮食中的饱和脂肪时，低密度脂蛋白胆固醇 (LDL-C) 水平会降低，这反过来对心脏健康有积极的影响。单不饱和脂肪对于维持细胞膜的健康功能也至关重要。因此，虽然所有不饱和脂肪都比饱和脂肪更可取，但建议优先选择单不饱和脂肪。
哪些食物提供不同类型的脂肪？
单不饱和脂肪的最佳食物来源：牛油果、橄榄、橄榄油、菜籽油、花生油、花生酱以及多种坚果，例如杏仁、腰果、榛子、澳洲坚果、花生、碧根果和开心果。
多不饱和脂肪的最佳来源：核桃、松子、巴西坚果、芝麻、葵花籽和亚麻籽。葵花籽油、大豆油、棉籽油、葡萄籽油、芝麻油、玉米油、核桃油和红花籽油也是多不饱和脂肪的来源。由多不饱和脂肪制成的食品，例如人造黄油、沙拉酱、沙拉酱和蛋黄酱，也含有相当数量的多不饱和脂肪。
饱和脂肪含量较低的食物包括：大多数动物脂肪、黄油、猪油、奶油以及某些植物脂肪，例如：椰子油、棕榈仁油、可可脂和椰子油。鸡肉也含有大量的饱和脂肪。
饱和脂肪也存在于动物性食品中，例如全脂乳制品、肥牛肉、鸡肉（尤其是鸡皮）和猪肉。因此，去除鸡皮上所有可见的脂肪非常重要。
含有反式脂肪的食物包括：硬砖人造黄油、起酥油、快餐店使用的商用煎炸油、高脂肪烘焙食品和咸味零食。反式脂肪酸也天然存在于一些动物食品中。
含有反式脂肪的食品包括：硬砖人造黄油、起酥油、快餐店使用的商业煎炸油、高脂烘焙食品和咸味小吃。反式脂肪酸也天然存在于一些动物产品中，例如乳制品、牛肉和羊肉。为了帮助您识别所购买食品中的反式脂肪和饱和脂肪，请查看产品上的营养成分表。您食用的所有食物都应尽可能减少反式脂肪和饱和脂肪的含量。如果产品符合下表中的标准，则可以进行以下声明：
营养成分声明标准
不含饱和脂肪酸：每参考量和每份规定大小的食品中饱和脂肪酸含量低于0.2克，反式脂肪酸含量低于0.2克
低饱和脂肪酸：每参考量和每份规定大小的食品，或每100克食品中饱和脂肪酸和反式脂肪酸的含量合计不超过2克；且食物中饱和脂肪酸和反式脂肪酸总和所提供的能量不超过15%。
您吃哪些类型的脂肪？
请使用以下表格作为指南，追踪您本周的饮食习惯：
| 脂肪类型 | 食物 |
|---|
| 饱和脂肪 | 存在于肥肉、带皮鸡肉、全脂乳制品（包括全脂牛奶、奶酪、酸奶油、冰淇淋和黄油）、椰子油/牛奶、棕榈仁油、棕榈油和可可脂中。 |
| 单不饱和脂肪和多不饱和脂肪 | 存在于坚果、种子、沙拉酱和蛋黄酱、橄榄、橄榄油、菜籽油、牛油果、葵花籽油、葡萄籽油和软桶装人造黄油中。 |
| 反式脂肪 | 蛋糕、曲奇、薄脆饼干、甜甜圈、糕点、加工肉类、硬质或砖状人造黄油、炸土豆、薯片、曲奇棒、微波炉爆米花、商业油炸食品（例如裹面包屑的炸鸡）中都含有反式脂肪。 |
本周重点信息
健康均衡饮食中最理想的脂肪是不饱和脂肪，它存在于橄榄油、菜籽油、鳄梨油、花生油、花生酱、鳄梨以及各种坚果和种子中。
日常饮食中应包含一些含脂肪的食物，但应始终少量食用，因为高脂肪饮食也会增加健康风险。
Are all fats created equally?
Just like carbohydrate and protein, fat is an important part of a healthy balanced diet and plays an important role in maintaining health and preventing disease. However, it is important to be able to make the best choices with regards to dietary fat in order to reap the benefits of good health and longevity.
The building blocks of fat are called fatty acids. Fatty acids are classified according to their unique molecular structures into two main groups: hard fats (typically identified as saturated fatty acids and trans fatty acids) and soft liquid fats (unsaturated fatty acids). Unsaturated fatty acids are further classified into polyunsaturated and monounsaturated fatty acids.
Medical research has shown that unsaturated fats tend to offer many health benefits, when eaten in controlled amounts, while saturated and trans fats tend to increase the risk for poor health and chronic diseases such as cancer and heart disease. Apart from the type of fat, the total amount of fat eaten daily also tends to affect health either positively or negatively. High-fat diets increase your risk for poor health and illness and moderate- to low-fat diets, which contain the right types of fat (monounsaturated and polyunsaturated fat), have a positive effect on health. For these reasons it is important to know which foods provide you with unsaturated fat and which foods are significant sources of the less desirable saturated fat and trans fats.
Why do we need fat in our diet?
It is useful to know the specific functions of fat in the body, as this will help you to make informed choices about the fats that you choose to include in your diet. In addition, there are some types of fat that the body is unable to manufacture itself and are obtained from the food we eat. Two such fatty acids are Omega-6 and Omega-3, considered essential to health. Both are involved with the regulation of blood pressure, heart rate, blood clotting, immunity, metabolism and help to maintain brain and nervous system function.
Other important functions of fats are listed below:
Unsaturated fats play a role in reducing inflammatory processes in the body.
Unsaturated fats also have a protective effect against the development of coronary heart disease, by decreasing the production of triglycerides (types of fats found in the blood that are associated with an increased risk for developing coronary heart disease).
All unsaturated fats have important roles in fat transport and metabolism and maintaining the function and integrity of cell membranes in the body.
Fats aid in the transport and absorption of fat soluble vitamins (e.g., vitamins A, D, E, K).
Fats enhance the flavour and texture of many foods and also tend to make your feel more satisfied by increasing the feeling of fullness you experience after eating a meal. Nonetheless, the healthiest choices should still be made when using fats in order to realize the benefits of flavour, enjoyment and overall health.
What are the healthiest types of fats to eat?
Foods that provide unsaturated fats are desirable, and monounsaturated fats are slightly more desirable than polyunsaturated fats. Research has found that when monounsaturated fats replaces saturated fats in the diet, levels of LDL-cholesterol are lowered and this in turn has a positive effect on heart health. Monounsaturated fats are also important for maintaining the healthy functioning of cell membranes. So while all unsaturated fats are preferable to saturated fat, it is recommended that preference be given to monounsaturated fats.
Which foods provide the different types of fat?
The best food sources of monounsaturated fats: avocado, olives, olive oil, canola oil, peanut oil, peanut butter and a number of nuts such as almonds, cashews, hazel, macadamia, peanuts, pecans and pistachios.
The best sources of polyunsaturated fats: walnuts, pine nuts, Brazil nuts, sesame seeds, sunflower seeds and linseeds. Oils from sunflower seed, soy bean, cottonseed, grape seed, sesame seed, corn, walnut and safflower seed are also sources of polyunsaturated fats. Food products made from polyunsaturated fats such as margarines, salad dressings, salad creams, and mayonnaises will also contain a fair amount of polyunsaturated fats.
Foods that provide less desirable saturated fat: most animal fats, butter, lard, cream and certain plant fats such as: coconut oil, palm kernel oil, cocoa butter and coconut. Chicken also contains a significant amount of saturated fat.
Saturated fats are also found in animal food products such as full cream dairy products, fatty cuts of beef, chicken (especially the skin) and pork. It is therefore important to remove all visible fat and the fatty skin of chicken.
Foods that contain trans fat are: hard brick margarines, shortening, commercial frying fats such as those used in fast-food outlets, high-fat baked goods and salty snacks. Trans fatty acids are also found naturally in some animal product such as dairy products, beef and lamb. To help you identify trans fats and saturated fats in the food items you buy, look at the nutrition facts table on the product. All the food you consume should contain as little trans fat and saturated fat as possible. The following claims can be made if the product meets the criteria given in the table below:
| Nutrient content claim criteria | - |
|---|
| Free of saturated fatty acids | less than 0.2 g saturated fatty acids and less than 0.2 g trans fatty acids per reference amount and serving of stated size |
| Low in saturated fatty acids | 2 g or less of saturated fatty acids and trans fatty acids combined per reference amount and serving of stated size, or per 100 g of the food; and the food provides 15% or less energy from the sum of saturated fatty acids and trans fatty acids |
What types of fats do you eat?
Use the grid below as a guide to track your eating habits this week:
| Type of fat | Foods |
|---|
| Saturated fats | Found in fatty cuts of red meat, chicken with skin, full-cream dairy products (including full-cream milk, cheese, sour cream, ice cream and butter), coconut oil / milk, palm kernel oil, palm oil and cocoa butter. |
| Monounsaturated and Polyunsaturated fats | Found in nuts, seeds, salad dressings and mayonnaise, olives, olive oil, canola oil, avocado, sunflower oil, grape seed oil and soft tub margarines. |
| Trans fats | Found in cakes, cookies, crackers, doughnuts, pastries, processed meats, hard or brick margarines, fried potatoes, potato chips, cookie bars, microwave popcorn, commercially deep-fried foods (such as breaded and fried chicken). |
Key messages for this week
The most desirable fats to include as part of a healthy balanced diet are unsaturated fats, which are found in olive oil, canola oil, avocado oil, peanut oil, peanut butter, avocado and a wide variety of nuts and seeds.
Foods that contribute fat to the diet should be included daily, but should be used sparingly at all times, as high-fat diets are also associated with an increased risk of poor health.
