The Nutritional Value of the Major Food Groups

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蛋白质是通常一餐的核心。鱼的鱼片，鸡胸或一个鸡蛋可以是重头戏，而蔬菜和谷物作为伴奏。有一个很好的理由：蛋白质及其组成的氨基酸是建筑模块of the body, forming the tissue that makes up bones, muscles, skin, organs and hair. Protein is also crucial for healthy immune function.

蛋白质的食物 - 其中包括豆类，坚果和种子，除了鱼，肉和鸡蛋 - 含有丰富的某些维生素和矿物质，其中包括：

• B族维生素: Aid metabolism and energy production.
• Vitamin E: A powerful antioxidant that fights free radicals that contribute to disease formation.
• 铁: Helps provide your muscles with oxygen and supports metabolism.
• 镁: Plays a role in protein synthesis, muscle and nerve control, and blood sugar regulation.
• Zinc：支持健康的免疫功能和伤口愈合。

Each meal should include some foods from the grains group, such as rice, bread or cereal. Grains provide carbohydrates — the energy your body relies on to get through the day. Grains are alsoB族维生素的良好来源和硒，播放再生产的重要作用，并防止氧化损伤和感染矿物。

Grains are a good source ofdietary fiberas well. This type of carbohydrate isn't digested and contributes few calories. Instead, it travels through the digestive system and adds bulk to stool, making it easier to pass. Fiber also helps lower cholesterol because it prevents some cholesterol from being absorbed into the bloodstream.

了解颗粒组最重要的是，并非所有的谷物都是一样的。当谷物加工，其胚芽和麸皮被去掉，只留下淀粉质胚乳后面。然而，麸皮和胚芽含有大部分的营养和纤维。全谷物，而另一方面，没有被剥夺的营养素。它们的维他命和矿物质更丰富的来源，其纤维含量较高显著。美国农业部建议至少一半of your daily grains come from whole grains — but more is better.

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水果和蔬菜是营养强国 - 富含维他命，矿物质，纤维和抵抗疾病的抗氧化剂。灌装多数水果和蔬菜在每餐你的盘子将大大改善你的健康，因为他们很富有的几个关键营养素来源：

• Vitamin C: A potent antioxidant that fights free radicals and is essential for the synthesis of collagen, which makes up connective tissue and aids wound healing.
• Vitamin A：视觉维生素，同时也支持免疫功能，复制和细胞间通讯。
• Potassium：甲矿物质，结余钠在神经和肌肉功能的血液和助剂。
• 叶酸: An important vitamin forgrowth and development和prevention of birth defects.
  

Some of the best superfoods belong to the fruit and vegetable group. Superfoods are especially rich sources of nutrients and include foods such as blueberries, kale and acai berries. Try to include some of these foods in your daily meal plan.

美国农业部建议，成年人拿到1 1/2至2杯fruits的每一天，2至3杯蔬菜每天。吃的所有不同颜色的水果和蔬菜，这一点很重要，因为它们的颜色都表示它们含有的植物化学物质的类型。每个植物化学物质发挥了重要的作用fighting disease.

Not all fats are bad, and some are essential to the optimal functioning of your heart and brain. As opposed to saturated and trans fats, found in fatty meats and junk food, the单不饱和脂肪酸和多不饱和脂肪在油，如橄榄油和菜籽油，有助于降低坏的低密度脂蛋白胆固醇，提高健康的高密度脂蛋白胆固醇。健康脂肪在坚果，种子和多脂鱼也有发现。

Dairy foods are richsources of calcium, which you need for strong bones, and a source of vitamin D that works with calcium to build bone health. Fermented dairy products, such as yogurt and kefir, are good sources of益生菌that improve gut health. Dairy is also high in fat and saturated fat, so it's recommended that you choose low-fat and nonfat versions of milk and yogurt and limit your intake of cheese, sour cream and other high-fat dairy foods.

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