#均衡饮食
#系列课程
蛋白质的来源有哪些？它的作用是什么？
蛋白质通常主要存在于动物源性食物（例如肉类、鱼类、禽类、蛋类和乳制品）中，而植物性食物和豆类的含量则较少。
含蛋白质的食物在消化系统中会被分解成更小的成分，称为氨基酸。人体利用氨基酸进行自我修复和再生。
哪些类型的蛋白质最值得食用？
健康均衡饮食的最佳蛋白质来源是那些能够提供蛋白质以及其他必需营养素（例如铁、锌、硒和B族维生素）的食物，同时还能减少您摄入不良营养素（例如饱和脂肪）的摄入。
富含蛋白质的最佳食物还含有必需的Omega-3脂肪酸，它们属于不饱和脂肪酸家族。这些脂肪对心脏和身体有益。由于人体无法自行合成这些脂肪酸，因此必须从饮食中获取。鸡蛋和富含油脂的鱼类（例如鲑鱼、鲭鱼、沙丁鱼和鳟鱼）中富含 Omega-3 脂肪酸。
理想的高蛋白食物选择及其营养特性：
| 理想的高蛋白食物 | 营养特性 |
|---|
| 富含油脂的鱼类 | Omega-3 脂肪酸、锌、少量铁、B 族维生素、不饱和脂肪 |
| 所有其他鱼类 | 锌、少量铁、B 族维生素、少量不饱和脂肪，总脂肪含量低 |
| 豆类 | 高纤维、低盐，含有少量不饱和脂肪，但总脂肪含量低。富含铜、铁、镁、磷、钾、锌以及维生素，例如硫胺素（维生素B1）、核黄素（维生素B2）、烟酸（维生素B3）和叶酸。 |
| 去皮鸡肉 | 富含蛋白质、锌、铁和B族维生素，去皮后总脂肪含量低。 |
| 瘦肉（去脂） | 富含锌、铁和B族维生素，去脂后脂肪含量中等至低。 |
| 鸡蛋（煎蛋除外） | 富含维生素B12和胆碱。如果添加营养强化剂，鸡蛋还可以补充必需的Omega-3脂肪酸（商店的食品标签上会注明）。鸡蛋也是胆固醇的来源之一，因此，适量且少量食用至关重要。 |
| 脱脂和低脂牛奶及酸奶： | 富含B族维生素和钙，总脂肪含量低（建议每日2至3份，以帮助您满足每日钙需求）。 |
为了实现并保持健康均衡的饮食，请尝试每天从上表中选择食物。
有哪些富含蛋白质的食物不太理想？
一些富含蛋白质的食物具有不良的营养特性，例如总脂肪、饱和脂肪、胆固醇和盐含量高。这些特性如下表所示。
不太理想的高蛋白食物及其营养特性：
| 不太理想的高蛋白食物 | 营养特性 |
|---|
| 油炸鱼 | 可能含有反式脂肪，卡路里和总脂肪含量高 |
| 肥肉 | 例如排骨 总脂肪、饱和脂肪和胆固醇含量高 |
| 加工肉类 | 例如萨拉米香肠、香肠、热狗和其他高脂肪熟食肉类 总脂肪、饱和脂肪、胆固醇和盐含量高 |
| 奶酪 | 总脂肪、饱和脂肪、胆固醇和盐含量高 |
方便食品通常具有许多不良的营养特性，包括高脂肪含量和大量的饱和脂肪和/或反式脂肪。这些食物包括快餐、商业加工食品（例如炸鱼和炸鸡）以及加工肉类（例如高脂肪熟食肉类）。食用高脂肪食物很容易超过每日推荐能量摄入量。过量的卡路里、脂肪和饱和脂肪会增加患慢性生活方式疾病的风险。为了避免摄入不良营养成分，请优先选择新鲜和家常烹饪的食物。例如，从熟食柜台购买的加工鸡肉午餐肉，其盐分和脂肪含量可能高于第二天烹饪切片后用于三明治的自制鸡肉。
最理想和最不理想的高蛋白食物示例。
本周重点信息
最佳的高蛋白食物选择不仅能为您的饮食提供蛋白质，还能提供重要的维生素、矿物质和脂肪酸，同时将不良营养成分含量降至最低。
一些高蛋白食物的主要不良营养特征是总脂肪、饱和脂肪、胆固醇和盐含量高。应尽量减少或避免食用具有这些特征的食物。
最理想的高蛋白食物包括鱼类、豆类、脱脂和低脂乳制品、去皮禽肉和瘦肉。
What are sources of protein and what is its function?
Protein is generally found in greater quantities in food from animal origin (such as meat, fish, poultry, eggs and dairy products), and in smaller quantities in food from vegetable origin and legumes.
Foods containing protein are broken down within your digestive system into smaller components called amino acids. The body uses amino acids to repair and regenerate itself.
What are the best types of protein to eat?
The best sources of protein for a healthy balanced diet are foods that provide protein along with other desirable nutrients, such as iron, zinc, selenium and B-vitamins, while reducing your exposure to undesirable nutrients such as saturated fat.
The best protein-rich foods also have essential Omega-3 fatty acids, which are within a family of unsaturated fatty acids. These are the fats that are good for your heart and body. Since the body cannot manufacture them, they must be obtained from the diet. Omega-3 fatty acids are found in eggs and oil-rich fish such as salmon, mackerel, sardines, and trout.
Desirable protein-rich food choices and their nutritional characteristics:
To achieve and maintain a healthy balanced diet, try to select foods from the above table each day.
Are there protein-rich foods that are less desirable?
Some protein-rich foods have undesirable nutritional characteristics, such as high levels of total fat, saturated fat, cholesterol and salt. These characteristics are illustrated in the table below.
Less desirable protein-rich foods and their nutritional characteristics:
Convenience foods typically have many undesirable nutritional characteristics including a high fat content and significant amounts of saturated and/or trans fat. These foods include fast foods, commercially prepared items such as fried fish and chicken, and processed meats such as high-fat deli meats. Eating foods that are high in fat make it easy to exceed your recommended daily energy intake. Excess Calories, excess fat, and saturated fat can increase your risk of developing chronic lifestyle diseases. To avoid undesirable nutritional components, give preference to fresh and home-cooked foods. For example, processed chicken lunchmeat bought from a deli counter is likely to have a high salt and fat content compared to home-cooked chicken that has been cooked and sliced for use on sandwiches the next day.
An illustration of the most desirable and undesirable protein-rich foods.
Key messages for this week
The best protein-rich food choices contribute protein as well as important vitamins, minerals and fatty acids to your diet, with the least amount of undesirable nutritional components.
The primary undesirable nutritional characteristics of some protein-rich foods are high levels of total fat, saturated fat, cholesterol and salt. The consumption of foods with these characteristics should be minimized or avoided.
The most desirable protein-rich foods include fish, legumes, fat-free and low-fat dairy, skinless poultry and lean meat.
