章节大纲

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  • 营养、能源和建筑材料

    Are these really good for you?
    ::这些真的对你有好处吗?

    Fresh fruits and vegetables. Every child's favorite. Especially those vegetables. When your mother tells you to "eat your vegetables," there is a reason for that. Yes, they are actually good for you.
    ::新鲜水果和蔬菜,每个孩子都喜欢,尤其是那些蔬菜。 当你母亲叫你吃蔬菜的时候, 是有原因的。是的,它们实际上对你有好处。

    Nutrients, Energy, and Building Materials
    ::营养、能源和建筑材料

    Did you ever hear the saying, “You are what you eat?” It’s not just a saying. It’s actually true. What you eat plays an important role in your health. Eating a variety of healthy foods promotes good physical health and provides energy for growth and activity. Many common diseases and their symptoms can be prevented or helped with healthful eating. Knowing what your body needs can help you choose foods to meet those needs.
    ::你是否听过一句俗话说 : “ 你吃什么? ” 这不仅仅是一句俗话。 这是事实。 吃什么在健康中起着重要作用。 吃各种各样的健康食品可以促进良好的身体健康,为成长和活动提供能量。 许多常见疾病及其症状都可以预防或者通过健康饮食来帮助预防。 了解身体需要什么可以帮助你选择食物来满足这些需求。

    Nutrients are chemical elements or compounds that the body needs for normal functioning and good health. There are six main classes of nutrients: , , , , vitamins , and minerals . The body needs these nutrients for three basic purposes: energy, building materials, and control of body processes.
    ::养分是身体正常功能和健康所需的化学元素或化合物,有六类主要营养物质: 、 、 、 、 、 、 、 、 、 维他命 、 和 矿物质。 身体需要这些营养物质有三个基本目的: 能源、 建筑材料 、 和控制身体过程 。

    A steady supply of energy is needed by for all body functions. Carbohydrates, proteins, and lipids provide this energy. Chemical bonds in molecules of these nutrients contain energy. When the bonds are broken during digestion to form simpler molecules, the energy is released. Energy is measured in units called kilocalories (kcal), commonly referred to as Calories .
    ::所有身体功能都需要稳定的能源供应。 碳水化合物、 蛋白质和脂质提供了这种能量。 这些营养元素分子中的化学键含有能量。 当消化过程中的键断以形成更简单的分子时, 能量就会释放。 能源用称为千卡(kcal)的单位来测量, 通常被称为卡罗里。

    Molecules that make up the body are continuously broken down or used up, so they must be replaced. Some nutrients, particularly proteins, provide the building materials for this purpose. Other nutrients—including proteins, vitamins, and minerals—are needed to regulate body processes. One way is by helping to form . Enzymes are compounds that control the rates of chemical reactions in the body.
    ::构成身体的分子不断被分解或用掉,因此必须替换它们。一些营养物质,特别是蛋白质,为此目的提供了建筑材料。其他营养物质,包括蛋白质、维生素和矿物,是调节身体过程所必需的。一种方法是帮助形成。酶是控制身体化学反应率的化合物。

    Nutrients can be classified into two groups based on how much of them the body needs:
    ::养分可以分为两类,根据其中多少身体需要:

    • Macronutrients are nutrients that the body needs in relatively large amounts. They include carbohydrates, proteins, lipids, and water.
      ::宏营养素是身体需要大量营养素,包括碳水化合物、蛋白质、脂质和水。
    • Micronutrients are nutrients that the body needs in relatively small amounts. They include .
      ::微营养素是身体需要的营养素,其数量相对较少。它们包括:

    The exact amount of a macronutrient that an individual needs depends on many factors including gender and age. Recommended daily intakes of three macronutrients for young people of both genders are shown in  Table .
    ::个人需要的宏观营养物质的确切数量取决于许多因素,包括性别和年龄。

    Recommended Daily Intakes of Carbohydrates, Proteins, and Water
    Gender and Age Carbohydrates(grams/day) Proteins(grams/day) Water*(liters/day)
    Males 9–13 years 130 34 2.4
    14–18 years 130 52 3.3
    Females 9–13 years 130 34 2.1
    14–18 years 130 46 2.3
    • Includes water in foods as well as beverages.
      ::包括食品和饮料中的水。

    Carbohydrates
    ::碳水合物

    Carbohydrates are organic (or carbon-containing) compounds consisting of the elements carbon, hydrogen, and oxygen. The elements are arranged in small molecules called saccharides. Carbohydrates are classified as either simple or complex, based on the number of saccharides they contain.
    ::碳水化合物是指由碳、氢和氧等元素组成的有机(或含碳)化合物,这些元素以小分子(称为沙焦化物)排列,碳水化合物根据其所含的沙焦化物数量分为简单或复杂类别。

    Simple carbohydrates contain just one or two saccharides. They are all sugars. Examples of sugars in the diet include fructose, which is found in fruit, and lactose, which is found in milk. The main function of simple carbohydrates is to provide the body with energy. One gram of carbohydrate provides four kilocalories of energy. Glucose is the sugar that is used most easily by cells for energy production. It circulates in the , providing energy to cells throughout the body. Glucose is the only source of energy used by the brain .
    ::简单的碳水化合物只含有一到两个碳水化合物。它们都是糖。饮食中的糖包括水果中的甘蔗和牛奶中的乳糖。简单的碳水化合物的主要功能是给身体提供能量。一克碳水化合物提供了四千卡热量的能量。甘蔗是细胞最容易用于能源生产的糖。它在体内循环,为整个身体的细胞提供能量。甘蔗是大脑使用的唯一能量来源。

    Complex carbohydrates, called polysaccharides , generally contain many saccharides. They include starches and fiber. Starches are found in plant foods such as vegetables and grains. They are broken down during digestion to form sugars that provide energy. Fiber consists of indigestible starches and other materials such as cellulose . It is present in all plant foods.
    ::复合碳水化合物,称为聚碳酸盐,通常含有许多盐酸盐,包括淀粉和纤维;在蔬菜和谷物等植物食品中发现了恒星;在消化过程中将其细分成能提供能量的糖;纤维由不可稀释的恒星和其他材料组成,如纤维素;在所有植物食品中都有。

    Fiber may be soluble or insoluble:
    ::纤维可以溶解或溶解:

    • Soluble fiber dissolves in water as it passes through the . It helps form substances that keep blood levels of glucose stable and blood levels of harmful lipids low.
      ::溶解纤维在水中溶解,因为溶解纤维穿透水面。它有助于形成能保持葡萄糖血清稳定、有害脂质血液含量低的物质。
    • Insoluble fiber does not dissolve, but it attracts water as it passes through the large intestine. This helps keep waste moist and moving easily through the intestine.
      ::不可溶解的纤维不会溶解,但它在通过大肠道时会吸引水。 这有助于让废物潮湿,并容易通过肠道移动。

    Proteins
    ::蛋白质

    Proteins are relatively large containing carbon, hydrogen, oxygen, and nitrogen. The elements are arranged in small molecules called amino acids . Amino acids are the building blocks of proteins. They bond together to form long chains called polypeptides . Proteins consist of one or more polypeptides.
    ::蛋白质中含有碳、氢、氧和氮的含量相对较大,这些元素由小分子组成,称为氨基酸。氨基酸是蛋白质的构件。它们结合成长链,称为聚苯醚。蛋白质由一种或多种聚苯醚组成。

    Proteins play many vital roles in the body including the following:
    ::蛋白质在人体中发挥着许多关键作用,其中包括:

    • Making up the majority of muscle tissue .
      ::构成肌肉组织的大多数。
    • Regulating many body processes.
      ::规范许多身体过程。
    • Forming antibodies that destroy and other “foreign invaders.”
      ::形成毁灭体和其他“外来侵略者”的抗体。
    • Regulating the salt-water and acid-base balances in body fluids.
      ::调节体液中的盐水和酸基平衡。
    • Transporting nutrients and other vital substances in the blood.
      ::在血液中输送营养素和其他关键物质

    Dietary proteins are broken down during digestion to provide the amino acids to cells that need to make proteins for the body. Twenty different amino acids are needed for this purpose. Ten of these amino acids can be synthesized by cells from simple components. The other ten cannot be synthesized and must be obtained from foods. They are called essential amino acids because they are essential in the diet.
    ::消化过程中对饮食蛋白进行分解,以便向需要为身体制造蛋白质的细胞提供氨基酸,为此需要20种不同的氨基酸。这些氨基酸中有10种可以用简单成分的细胞合成。其他10种不能合成,必须从食物中获取。它们被称为基本氨基酸,因为它们在饮食中必不可少。

    Proteins that contain all ten essential amino acids are referred to as complete proteins. They are found in foods such as milk and meat. Proteins that are missing one or more essential amino acids are referred to as incomplete proteins. They are found in plant foods such as legumes and rice. By eating a variety of different plant foods containing incomplete proteins, you can include all ten essential amino acids in your diet.
    ::含有十种基本氨基酸的蛋白质被称为完整的蛋白质,存在于牛奶和肉类等食品中;缺少一种或多种基本氨基酸的蛋白质被称为不完整蛋白质;存在于豆类和稻米等植物食品中;通过食用含有不完全蛋白的各种植物食品,你可以将所有十种基本氨基酸纳入饮食。

    If you eat more protein than is needed for the synthesis of new proteins by cells, the excess is used for energy or stored as fat. One gram of protein provides four kilocalories of energy. This is the same amount of energy that one gram of carbohydrate provides.
    ::如果您食用蛋白质的量超过细胞合成新蛋白质所需的量,超量将用作能量或储存为脂肪。一克蛋白质提供四千卡热量。这与一克碳水化合物的能量相同。

    Lipids
    ::唇唇

    Lipids, or fatty acids , are organic compounds that consist of repeating units of carbon, hydrogen, and oxygen. They provide the body with energy. The heart and rely mainly on lipids for fuel. One gram of lipid provides nine kilocalories of energy, more than twice the amount provided by carbohydrates or proteins. Lipids have several other functions as well. Lipids form an insulating sheath around nerve cells that helps nerve messages travel more quickly. Lipids also help form substances that regulate , blood clotting, and blood lipid levels. In addition, lipids make up the membranes that surround cells.
    ::脂酸或脂肪酸是有机化合物,由碳、氢和氧的重复单位组成。它们为身体提供能量。心脏和主要依靠脂质作为燃料。一克脂质提供九千卡的能量,超过碳水化合物或蛋白质的两倍以上。脂质还有其他几种功能。脂质在神经细胞周围形成一种绝缘层,有助于神经信息更快地传递。脂质还有助于形成调节物质、血液凝胶和血脂水平。此外,脂质构成细胞周围的膜。

    The term fat is often used interchangeably with the term lipid, but fats are actually a particular type of lipid, called triglycerides, that have three fatty acids bound to a compound called glycerol. Fats are important in the body. They are the main form in which the body stores energy. Stored body fat is called adipose tissue . Stored fat not only provides an energy reserve, but also cushions and protects internal organs . In addition, stored fat insulates the body and helps prevent heat loss in cold weather .
    ::脂肪一词通常与脂类一词交替使用,但脂肪实际上是一种特定类型的脂类,称为三甘甘甘酸酯,有三种脂肪酸被捆绑在一种叫做甘油醇的化合物上。脂肪在身体中很重要。脂肪是人体储存能量的主要形式。腐烂的脂肪被称为脂肪组织。腐烂的脂肪不仅提供能量储备,而且还提供衬垫和保护内脏器官。此外,储存脂肪将身体隔绝,有助于防止寒冷天气的热量流失。

    Although lipids and fats are necessary for life, they may be harmful if they are present in the blood at high levels. Both triglycerides and the lipid called cholesterol are known to damage if their concentrations in the blood are too high. By damaging blood vessels, triglycerides and cholesterol also increase the risk of heart disease.
    ::尽管脂类和脂肪是生命所必需的,但如果在高水平的血液中出现脂类和脂肪,则可能有害,如果血中浓度过高,已知三甘酸盐和被称为胆固醇的脂类都会受损。 通过破坏血管,三甘酸盐和胆固醇也会增加心脏病的风险。

    Lipids are classified as either saturated fatty acids or unsaturated fatty acids . This is based on the number of chemical bonds between carbon atoms in lipid molecules.
    ::利皮被归类为饱和脂肪酸或不饱和脂肪酸,其依据是脂分子中碳原子之间的化学联结数量。

    • Saturated fatty acids have only single bonds between carbon atoms. This gives them properties that make them unhealthy. Their amount in the diet should be kept as low as possible. If consumed in excess, they contribute to high blood levels of cholesterol and triglycerides. Saturated fatty acids are found in animal foods such as meat, whole milk, and eggs .
      ::饱和脂肪酸在碳原子之间只有单一的关联。 这使得碳原子具有不健康的特点。 他们的饮食量应该尽可能低。 如果摄入量超量,它们会增加胆固醇和三甘酸酯的高血水平。 饱和脂肪酸存在于肉类、全奶类和蛋类等动物食品中。
    • Unsaturated fatty acids have at least one double bond between carbon atoms. This gives them properties that make them more healthy. Eaten in appropriate amounts, they may help lower blood levels of cholesterol and triglycerides, decreasing the risk of . They are found mainly in plant foods.
      ::不饱和脂肪酸在碳原子之间至少有一种双倍联系。 这使得碳原子的特性更健康。 以适当数量进食,它们可以帮助降低胆固醇和三甘酸酯的血液水平,降低其风险。 它们主要存在于植物食品中。

    The can synthesize all but two of the fatty acids it needs: omega-3 fatty acids and omega-6 fatty acids. Both are unsaturated fatty acids. They are called essential fatty acids because they must be present in the diet. They are found in salmon, vegetable oil, flaxseed, eggs, and whole grains. Small amounts of these two fatty acids may help lower blood pressure as well as blood levels of harmful lipids.
    ::除了两种脂肪酸外,所有所需的脂肪酸都是可合成的:奥米加-3脂肪酸和奥米加-6脂肪酸。这两种酸都是不饱和脂肪酸。它们被称为基本脂肪酸,因为它们必须存在于饮食中。它们存在于鲑鱼、植物油、麻籽、蛋和整粒中。 这两种脂肪酸中的少量可以帮助降低血压和有害脂肪的血液水平。

    Unsaturated fatty acids known as trans fatty acids (or trans fats) are manufactured from plant oils and do not occur naturally. Trans fat is made by adding hydrogen to vegetable oil through a process called hydrogenation, which makes the oil less likely to spoil. They are added to foods to extend their shelf lives. Trans fats have properties like saturated fats and may increase one's risk of developing cardiovascular disease. They should be avoided in . Many manufacturers no longer add trans fats to food products, and their use in restaurants has been banned in some cities. 
    ::所谓的不饱和脂肪酸,即反脂肪酸(或反脂肪酸),是用植物油制造的,不会自然发生。反脂肪是通过一种叫作氢化的过程将氢添加到植物油中,这样油更不会腐蚀,而是被添加到食物中以延长其储量寿命。反脂肪具有饱和脂肪等特性,并可能增加个人患心血管疾病的风险。应该避免这种情况。许多制造商不再将反脂肪添加到食品中,而且有些城市禁止在餐馆使用反脂肪。

    Water
    ::水 水

    You may not think of water as a food, but it is a nutrient. Water is essential to life because it is the substance within which all of the chemical reactions of life take place. An adult can survive only a few days without water. Table shows water requirements for young people.
    ::水对生命至关重要,因为水是生命中所有化学反应发生的物质。 成年人没有水只能活几天。 表格显示了年轻人的用水需求。

    Water is lost from the body in exhaled air, sweat, and urine . Dehydration occurs when a person does not take in enough water to replace the water that is lost. Symptoms of dehydration include headaches, low blood pressure, and dizziness. If dehydration continues, it can quickly lead to unconsciousness and even death. When you are very active, particularly in the heat, you can lose a great deal of water in sweat. To avoid dehydration, you should drink extra fluids before, during, and after .
    ::体液在呼吸空气、汗水和尿液中流失。当一个人没有足够的水来代替失去的水时,就会缺水。脱水的症状包括头痛、低血压和眩晕。如果脱水继续下去,它会很快导致失去知觉甚至死亡。当你非常活跃的时候,特别是在热中,你可能会在汗水中流失大量水。为了避免脱水,你应该在之前、期间和之后多喝水。

    Taking in too much water—especially without consuming extra salts—can lead to a condition called hyponatremia. In this condition, the brain swells with water, causing symptoms such as nausea, vomiting, headache, and coma. Hyponatremia can be fatal, so it requires emergency medical care.
    ::吸水量过大 — — 特别是不食用额外的盐类 — — 会导致一种称为低温的症状。 在这种情况下,大脑会随水膨胀,导致恶心、呕吐、头痛和昏迷等症状。 发性硬化症可能是致命的,因此需要紧急医疗护理。

      

     

    Summary
    ::摘要

    • Nutrients are chemical elements or compounds that the body needs for normal functioning and good health.
      ::养分是指身体正常运转和健康所需的化学元素或化合物。
    • There are six main classes of nutrients: carbohydrates, proteins, lipids, water, vitamins, and minerals.
      ::营养物质有六大类:碳水化合物、蛋白质、脂类、水、维生素和矿物。
    • Energy is measured in units called kilocalories (kcal), commonly referred to as Calories.
      ::能源用称为千卡热量(kcal)的单位测量,通常称为卡路里。
    • Some nutrients, particularly proteins, provide the building materials to replace things that are broken down.
      ::一些养分,特别是蛋白质,提供建筑材料,以取代被细分的物品。
    • Simple carbohydrates contain just one or two saccharides and are all sugars.
      ::简单的碳水化合物只含有一两个盐酸盐,都是糖。
    • Complex carbohydrates, called polysaccharides, generally contain many saccharides. They include starches and fiber.
      ::复杂的碳水化合物,称为聚沙酸盐,通常含有许多碳酸盐,包括淀粉和纤维。
    • Roles of proteins include making up muscle, regulating body processes, forming antibodies, regulating salt-water and acid-base balances, and transporting nutrients and other vital substances.
      ::蛋白质的作用包括组成肌肉、调节身体过程、形成抗体、调节盐水和酸基平衡、运输养分和其他关键物质。
    • Proteins that contain all ten essential amino acids (which cannot be synthesized by cells) are referred to as complete proteins.
      ::含有十种基本氨基酸(不能由细胞合成)的蛋白质被称为完整的蛋白质。
    • Roles of lipids include forming insulating sheets around nerves, forming substances that regulate blood pressure, blood clotting, and lipid levels, and making up membranes that surround cells.
      ::脂肪的作用包括围绕神经形成隔热板,形成调节血压、血凝结和脂质的物质,组成细胞周围的膜。
    • Unsaturated fatty acids known as trans fatty acids (or trans fats) are manufactured from plant oils and do not occur naturally. Trans fat is made by adding hydrogen to vegetable oil through a process called hydrogenation, which makes the oil less likely to spoil.
      ::不饱和脂肪酸,即反脂肪酸(或反脂肪酸)是用植物油制造的,不会自然发生。 反脂肪酸是通过一种称为氢化的过程在植物油中添加氢来制造的,这使得油更不可能腐坏。
    • Water is essential to life because it is the substance within which all of the chemical reactions of life take place.
      ::水对生命至关重要,因为生命的所有化学反应都是在这种物质中发生的。

    Review
    ::回顾

    1. What are the three main purposes of nutrients?
      ::养分的三个主要目的是什么?
    2. Which nutrients provide energy for the body?
      ::哪些养分能为身体提供能量?
    3. Which nutrients help regulate body processes? What is one way that they regulate the body?
      ::哪些营养物质有助于调节身体过程?它们监管身体的方式是什么?
    4. What sugar is most easily used by cells?
      ::牢房最容易使用什么糖?
    5. How do soluble fiber and insoluble fiber differ in their purposes?
      ::可溶性纤维和不可溶性纤维在目的上有何不同?
    6. How many amino acids are needed for the proteins that make up the body? How many amino acids can be synthesized by cells using simple components?
      ::构成身体的蛋白质需要多少氨基酸?用简单的成分细胞可以合成多少氨基酸?
    7. What are the essential fatty acids?
      ::什么是基本脂肪酸?