VITAMINS

Animals fed chemically purified diets containing only proteins, carbohydrates, and fats develop malnutrition and die. Very small amounts of additional factor, vitamins and minerals, are necessary for survival.

维生素

用化学方法纯化的只含有含蛋白质、碳水化合物和脂肪食物喂养的动物会出现营养不良，并死亡。除非常少量的额外因素，维生素和矿物质是生存所必要的。

Vitamins are classified into two groups on the basis of their ability to dissolve in fat or water. The fat-soluble vitamins include vitamins A, D, E, and K. The water-soluble ones include vitamin C and the B vitamin complex. The term “B complex” refers to a group of water-soluble vitamins, which, although associated historically, in fact deserve specific individual attention as separate vitamins. The principal B vitamins are vitamin B6, vitamin B12, folacin (folic acid), niacin, riboflavin (vitamin B2), and thiamine (vitamin B1). See also VITAMIN.

根据它们溶于脂肪或溶于水的能力，维生素被分为两类。脂溶性维生素包括维生素A，D，E和K。水溶性维生素包括维生素C和复合维生素B。“复合维生素B”这个术语是指一组水溶性维生素，尽管它们在历史上有关联，但实际上作为单独的维生素族值得单独的特别关注。主要的B族维生是维生素B6、维生素B12、叶酸、烟酸、核黄素（维生素B2）以及硫胺素（维生素B1）。也可参阅维生素词条）。

Vitamin A.  Vitamin A is essential for the maintenance of the health of all epithelial tissues, such as the epidermis of the skin and the lining of the mouth, digestive tract, respiratory tract, and genitourinary tract. It may also help maintain the stability of cell membranes.

维生素A。维生素A对维护所有上皮组织的健康至关重要，比如皮肤表皮和口腔黏膜，消化道，呼吸道和泌尿生殖道。它还可以帮助维护细胞膜的稳定性。

The RDA for vitamin A for adults is 5,000 international units (IU). More is required by women who are pregnant or nursing babies.

对于推荐的每日摄入量来说，成人是5000国际单位。怀孕或哺乳的妇女需要更多。

Vitamin A is most abundant in animal liver. Other animal foods that are good sources of vitamin A include kidney, whole milk, and egg yolks. Plant foods that are high in vitamin A value include yellow-orange vegetables, such as carrots and yams, and dark leafy greens, such as spinach and kale. The vitamin A value of these goods comes from carotenes, yellow pigments that can be readily converted into vitamin A by the body.

维生素A在动物肝脏中最为丰富。其它动物性维生素A的优质资源包括肾脏、全脂牛奶和鸡蛋黄。富含维生素A的植物性食物包括橙黄色的蔬菜，诸如胡萝卜和蕃薯，以及深绿叶蔬菜，比如菠菜和甘蓝。这些物品的维生素A的价值来自胡萝卜素，一种可被身体容易地转换成维生素A的黄色色素。

An early sign of vitamin A deficiency is night blindness. More severe deficiency causes dryness of the eyes and scarring of the eye’s epithelial tissues, from which infection and blindness may result. Severe vitamin A deficiency also causes retarded or otherwise abnormal growth.

缺乏维生素A的早期症状是夜盲症。更严重的缺乏会导致眼睛干涩眼睛皮上组织结疤，由此可导致感染和失明。严重的维生素缺乏症还会导致智力迟钝或其它异常生长。

Too much vitamin A is dangerous. In adults the symptoms of vitamin A overdose include pain in the joints, bones, and abdomen; fatigue; and loss of hair. Vitamin A poisoning sometimes occurs as a result of taking too many vitamin A pills, and Arctic explorers have been poisoned by eating polar bear liver, which is extremely high in vitamin A. most cases of adult poisoning occurred only after Long ingestion of more than 50,000 IU a day. Poisoning in THREE-to-six-month-old infants sometimes occurs after a few months of 18,500 IU daily supplements. The Food and Nutrition Council of the National Academy of Sciences recommends that regular supplements of 6,700 IU of vitamin A or more should be taken only under the supervision of physician.

过多的维生素A是危险的。在成人中，维生素A过量的症状包括关节、骨头和腹部的疼痛；以及脱发。维生素A中毒有时是由于服用过多的维生素A药片，而北极探险者是由于食用了维生素A含量极高的北极熊肝脏而中毒。在大多数成人中毒的病例中，只在长期摄取每天多于50000国际单位之后才发生。在3至6个月大的婴儿中毒中，有时会在每天补充18500国际单位的几个月之后发生。美国国家科学院食品与营养委员会推荐定期补充6700国际单位的维生素A，或者只有在医生的监督下才能服用更的维生素A。

Vitamin B6.  Vitamin B6 activity is shown by pyridoxine and two related compounds. It is intimately associated with the metabolism of the central nervous system and with amino-acid metabolism. Good sources of the vitamin include whole grain, meat, poultry, fish, potatoes, and sweet potatoes, and part of the amount one needs is synthesized by bacteria in the intestine. Deficiency of vitamin B6 can result in seizures, damage to peripheral nerves, or anemia. Doses of pyridoxine many times the RDA have been used to treat rare cases of pyridoxine-dependent seizures and anemias.

维生素B6。维生素B6的活性由吡哆醇和两个相关的化合物来表示。它与中枢神经和氨基酸的代谢密切相关。优质的维生素来源包括全谷物、肉类、家禽类、鱼类、土豆和红薯，以及由肠道细菌合成的人体需要的部分。缺乏维生素B6会导致癫痫，损害外围的神经，或导致贫血。吡哆醇的剂量多倍于推荐的日摄入量已用于治疗依赖性吡哆醇癫痫和贫血症的罕见病倒。

Vitamin B12.  This vitamin is necessary for the function of many cell processes catalyzed by enzymes. Vitamin B12 is found only in animal sources. The richest are liver and kidney, with other animal sources contributing substantial amounts. Since several years’ supply of vitamin B12 is normally stored in the liver, disease from simple dietary deficiency is rare. Strict vegetarians, however, run a risk of deficiency unless they take supplementary doses. Vitamin B12deficiency results in anemia and severe neurological disease. Some persons who lack a factor found in the stomach necessary for the absorption of B12 develop pernicious anemia.

维生素B12。 这种维生素对许多由酶催化细胞过程的功能是必不可少的。只有在动物来源中能发现维生素B12。最丰富的是肝脏和肾脏，虽然其它动物来源也贡献了丰富的数量。由于几年提供的维生素B12通常是储存在肝脏中，因此纯粹由饮食缺乏造成的疾病是很罕见的。然而，严格的素食者除非他们服用补充剂量，否则会冒缺乏症的风险。缺乏维生素B12会导致贫血和严重的神经系统疾病。有些人的胃中缺乏一种吸收B12的必要因子就会患上恶性贫血。

Vitamin C.  Vitamin C, or ascorbic acid, is a powerful antioxidant and may function in the regulation of respiratory reactions within the body’s cells. It functions in the synthesis of connective tissue and in the manufacture of hormones by the adrenal gland. The vitamin is found in large amounts in fresh, canned, and frozen citrus fruits and in smaller but still important amounts in other fruits, tomatoes, potatoes, and leafy vegetables. It is easily destroyed by prolonged cooking.

维生素C。维生素C，或叫抗坏血酸，是一种强大的搞氧化剂，并且可在调节身体细胞的呼吸反应中发挥作用。它在结缔组织的综合，以及在肾上腺分泌激素中发挥着作用。这种维生素大量存在于新鲜、罐装和冷冻的柑橘类水果和较小的水果中，但在其它水果、蕃茄、土豆和叶菜类中依然含量丰富。但它经过长时间烹饪会很容易被破坏掉。

The vitamin C deficiency disease, scurvy, was known in ancient Egypt as early as the 16^th century B. C. Oranges or limes were used to prevent scurvy in the British Navy in the 18^th century, but as late as 1912 a party headed by the Antarctic explorer Robert Scott was so weakened by scurvy that its members died of starvation, exposure, and exhaustion on their return from the South Pole.

早在公元前16世纪的古埃及，人们就知道维生素C缺乏症，坏血病。在18世纪，英国海军曾用橙子或酸橙来预防坏血病，但直到1912年，由南极探险家罗伯特·斯科特率领的一群人被坏血病弄得虚若不堪，以至于其成员从南极返回途中因饥饿、爆晒和筋疲力尽而死亡。

Scurvy in adults can be detected after two or THREE months of vitamin C deficiency. It first shows itself as tiny hemorrhages in the skin. As the disease worsens, the gums become swollen and bleed, and eventually profound weakness and neurological disorders occur. Scurvy can be prevented by a daily intake of 10 mg of vitamin C. The RDA for health adults has been set as 45 mg a day.

成年人可在缺乏维生素两到三个月后会发现坏血病。它首先会表现为皮肤上的微小出血。随着病情的恶化，牙龈变得肿胀并出血，最终会出现极度虚弱和神经系统紊乱。每日服用10毫克维生素C可预防坏血病。健康成人推荐的日摄取日被设定为每日45毫克。

Vitamin D.  Vitamin D is actually a group of related compounds with similar activity in the body. The main actions of vitamin D are to increase the absorption of calcium and phosphorus from the intestine and to aid the process of bone mineralization.

维生素D。维生素D实际上是一组身体中具有类似活性的相关化合物。维生素D的主要作用是增加肠道对钙和磷的吸收和促进骨矿化的过程。

Vitamin D is made within the human body with the aid of the ultraviolet component of sunlight, and with adequate exposure to sunlight there may be little need for vitamin D in the diet. However, people often receive too little sunlight to form adequate vitamin D, especially in the temperate and Arctic zones. The vitamin is not well distributed in nature. The only major food sources are fatty fish, eggs, liver, and butter. Milk is not a good natural source of vitamin D, but in the United States most milk is now fortified with 400 IU of the vitamin per quart.

维生素D在身体内通过阳光中紫外线的组成部分合成，有充足的阳光照射也许很少需要饮食中的维生素D。然而，人们通常日照都很少，无法形成适当的维生素D，尤其是在温带和北极地区。该维生素在自然界中的分布并不理想。唯一的主要食物来源是含脂肪的鱼类、鸡蛋、肝脏和奶油。牛奶并不是优良维生素D的天然来源，但在美国，目前大多数的牛奶每夸脱都强化了400 IU的这种维生素。

Vitamin D deficiency causes abnormalities of bone and connective-tissue formation called rickets in children and osteomalacia in adults. One of the triumphs of modern nutrition has been the greatly decreased incidence of rickets among children in sun-poor countries where milk and other foods have been supplemented with vitamin D.

维生素缺乏症会导致骨骼和结缔组织异常，形成称为儿童的佝偻病和成人的软骨病。现代营养学的成就之一是在日照不足的国家中极大地降低了佝偻病的发生率，那里的牛奶和其它食物中都补充了维生素D。

The Food and Nutrition Bureau has not recommended a formal daily allowance for vitamin D, but it suggests that 400 IU is a reasonable amount, probably well in excess of the requirement for many purposes. An excess intake—in amounts of about 2,000 IU for long periods—is dangerous and may produce elevated levels of calcium in the blood and damage to the kidney.

食品与营养管理局并不推荐正式的维生素D每日摄取量，但它建议400 IU是合理的数量，可能已远远超过了许多目标的要示。过量摄入---长期摄入大约2000 IU---是危险的，而且可能造成血液中钙的升高，并损害肾脏。

Vitamin E.  Vitamin E activity is attributable to compounds called tocopherols that originate in plants. Foods richest in the vitamin include the unsaturated vegetable oils, such as corn, cotton, soy, and safflower oils, as well as eggs, meat, liver, fish, chicken, and oatmeal. An increased intake of polyunsaturated fatty acids in the diet increases the requirement for the vitamin, but since the foods highest in polyunsaturated fatty acids tend also to be highest in vitamin E, compensation tends to be automatic.

维生素E。维生素E的活性归因于源自植物中被称为生育酚的化合物。富含维生素的食物包括不饱和植物油，诸如玉米、棉花、大豆和红花油，以及鸡蛋、肉类、肝脏、鱼、鸡和燕麦片。增加饮食中多不饱和脂肪酸的摄入量会增加对维生素的需要，但由于多不饱和脂肪酸含量最高的食物往往也是含维生素E最高的，因此补偿往往是自动的。

Self-administration of massive doses (10—40 times the RDA) has been advocated by some as treatment for a variety of illnesses. However, most physicians and nutritionists have not been persuaded that massive doses of vitamin E are of value in most of the conditions for which it is popularly used.

一些人主张自我服用大剂量（推荐的日摄食量10—40倍）作为各种疾病的治疗方法。然而，大多数医生和营养专家并没有被说服，即大剂量的维生素在大多数情况下，广泛地使用它是有价值的。

Vitamin K. This vitamin is necessary for the synthesis in the liver of prothrombin and other factors needed for blood clotting. In fact, poor blood clotting is the only well-established sign of vitamin K deficiency in animals.

维生素K。这种维生素对肝脏中凝血酶原和血液凝固所需的其它因素的合成是必不可少的。事实上，血液凝固不良是动物缺乏维生素K唯一得到确认的迹象。

Intestinal bacteria manufacture vitamin K in quantities sufficient to provide most of our daily needs, except among infants in the first week of life before the intestine has been colonized with bacteria. Vitamin K deficiency sometimes occurs among persons on antibiotic therapy, because the antibiotics inhibit intestinal bacteria. Vitamin K is also provided by dark green vegetables such as spinach and kale, and in cabbage, cauliflower, peas, and cereals.

肠道细菌制造的维生素K在数量上足以提供我们每日的大部分需要，除了在出生第一周婴儿的肠道中尚未被细菌繁殖外，维生素缺乏症有时会出现在抗生素治疗的人员中，因为抗生素抑制了肠道细菌。深绿色蔬菜也会提供维生素K，诸如菠菜和甘蓝，以及卷心菜、菜花、豌豆和谷类也有。

Folacin.  Folacin, like vitamin B12, is necessary for many enzyme-catalyzed cell processes. It is plentiful in leafy greens, yeast, liver, and kidney. It is easily destroyed by heat in cooking.

叶酸。叶酸，像维生素B12一样，是许多酶催化细胞过程必须的。它在绿叶蔬菜、酵母、肝脏和肾脏中很丰富。经过加热烹饪很容易被破坏掉。

Folacin deficiency, which is common among alcoholics and other malnourished individuals, results in severe anemia. Administration of folic acid to persons with untreated pernicious anemia is dangerous because it may result in a worsening of the neurological symptoms of B12 deficiency.

缺乏叶酸，在酗酒者和其他营养不良的个体中很常见，会导致严重贫血症。给未经治疗的恶性贫血的人服用叶酸是危险的，因为这可能导致B12缺乏症的神经症状恶化。

Niacin.  Niacin functions as part of the vital oxidation coenzymes NAD and NADH. It is plentiful in meat, poultry, liver, fish, and yeast. A deficiency of niacin results in pellagra.

烟酸。烟酸起到了重要的氧化酶NAD（烟酰胺腺嘌呤二核心苷酸）和NADH（烟酰胺腺嘌呤二核心苷酸还原态）的部分作用。它在肉类、家禽、肝脏、鱼和酵母中很丰富。烟酸缺乏症会导致糙皮病。

Riboflavin.  This vitamin is a coenzyme for several important enzymes. It is plentiful in milk, liver and many vegetables. Riboflavin deficiency is fairly common in poor countries, but its symptoms are often overshadowed by the more striking symptoms of other associated vitamin deficiencies.

核黄素。这种维生素是几种重要酶的辅酶。它在牛奶、肝脏和许多蔬菜中很丰富。核黄素缺乏症在贫穷国家相当普遍，但它的状态常常被其它相关维生素缺乏症更引人注目的症状所遮盖。

Thiamine.  Thiamine is essential in cells for the working of the citric-acid cycle, a key step in the extraction of energy from food molecules. Thiamine is found in large amounts in unrefined grain, liver, and kidney, and in small amounts in most other animal and plant foods. Excess heat in cooking may destroy thiamine, and excess cooking water may leach it out. Deficiency of thiamine is responsible for several deficiency diseases, including beriberi.

硫胺素。硫胺素对细胞中柠檬酸循环的运作至关重要，是从食物分子中提取能量的关键一步。硫胺素大量存在于未精制的谷物、肝脏和肾脏中，以及在大多数其它动物和植物食物中也有少量存在。烹饪时过热会破坏硫胺素，而烹饪时过多的水会将硫胺素滤出。硫胺素缺乏症会导致各种缺乏症疾病，包括脚气病。

MINERAL

In nutrition the term mineral is applied to the mineral elements—the chemical elements other than carbon, hydrogen, oxygen, and nitrogen—and to compounds consisting chiefly of such elements. The mineral elements can be considered in two groups: (1) those needed in the diets in amounts of 100 mg or more a day, such as calcium, phosphorus, and magnesium; and (2) trace elements needed in amounts of not more than a few milligrams a day, such as iodine, iron, and zinc.

矿物质

在营养学中，矿物质这个术语是指矿物元素---除了碳、氢、氧和氮以外的化学元素---以及主要由这种元素组成的化合物。矿物元素可分为两类：（1）饮食中每天需要数量为100毫克或更多的那些元素，比如钙、磷和镁；以及（2）每天需要量不超过几毫克的微量元素，诸如碘、铁和锌。

Calcium.  The standard 154-pound (70-kg) adult male typically contains about 2.5 pounds (1.2kg) of calcium, of which 99% is present in bone. In addition, calcium is present in blood, cells, and body fluids. It is important in controlling the excitability of muscles and nerves and in the clotting of blood.

钙。标准的154镑（70公斤）成年男性一般含有大约2.5镑（1.2公斤）的钙，其中99%存在于骨骼中。另外，钙存在于血液、细胞和体液中。它在控制肌肉和神经的兴奋性，以及在血液凝固中都很重要。

Milk, cheese, and some other dairy products are the major calcium-providing foods in the United States. Other sources include beans, nuts, egg yolk, cabbage, cauliflower, figs, and asparagus. One pint of fresh whole milk provides in excess of 500 mg of calcium—more than half of the daily requirement of most adults.

在美国，牛奶，奶酪和一些其它的乳制品是提供钙的主要食物。其它的来源包括豆类、坚果类、鸡蛋黄、卷心菜、花菜、无花果和芦笋。一品脱的新鲜全脂牛奶提供超过500毫克的钙---超过了大多数成人每天需要量的一半。

Calcium absorption is enhanced by vitamin D and retarded by phytic acid, which occurs in whole wheat and other cereal grains, and oxalic acid, which occurs in certain other foods. In the presence of excess calcium, less is absorbed from the intestine. In persons on low-calcium diets the calcium balance is generally maintained by the reduced calcium loss in the feces.

维生素D可提高钙的吸收，全麦和其它谷物中的植酸会阻碍钙的吸收，而草酸存在于某些其它的食物中。当摄入钙过量时，肠道会减少吸收。在低钙饮食的人群中，钙的平衡一般通过减少排泄物中的钙流失来进行维持。

Calcium needs of apparently healthy persons differ widely, so it is hard to make a firm recommendation for daily intake. The Food and Nutrition Board recommends 800 mg daily for adults and 1,200 mg daily during the teenage years of rapid growth. In contrast, the World Health Organization accepts a figure of 400—500mg a day as adequate for adults.

看上去健康的人群对钙的需求差别很大，因此很难给出每日摄入量的建议。食品与营养管理局推荐成人每天为800 毫克，在成长快速的青少年期间每天为1200毫克。相比之下，世界卫生组织认可成人适用于400—500毫克。

There is no strong evidence to suggest any benefit from exceeding recommended intakes, so long as vitamin D levels are adequate. Dangerously high levels of calcium in the blood have resulted from excessive calcium intake, especially in combination with excessive vitamin D. Rarely, high calcium levels are caused by the milk and antacid therapy of ulcer patients, because the antacid promotes the absorption of calcium from the milk. The symptoms of high levels of calcium include mental sluggishness, constipation, urinary frequency, and kidney stones.

只要维生素D的水平足够，尚无强有力的证据表明超过摄入量会有任何益处。血液中钙的高危水平是因摄入了过多的钙，尤其是与过多维生素D的结合。高钙的情况很少是由牛奶和溃疡患者的抗酸剂治疗引起的，因为抗酸剂会促进牛奶中钙的吸收。高钙含量的症状包括大脑反应迟钝、便秘、尿频和肾结石。

Magnesium.  Magnesium is important in maintaining the electrical potential across nerve-and-muscle-cell membranes. Magnesium deficiency occurs in severely malnourished persons, especially among alcoholics. Magnesium deficiency can lead to tremors, convulsions, and behavior disorders. However, magnesium occurs widely in foods, and deficiency symptoms caused by too little magnesium in the diet are very rare.

镁。镁在维护通过神经和肌肉细胞膜的电位是很重要的。镁缺乏症会出现在严重营养不良的人群中，尤其是在酗酒者中。镁缺乏症会导致震颤、抽搐和行为障碍。然而，镁广泛存在于食物中，而由饮食中镁过少而造成的缺乏症是非常罕见的。

Phosphorus.  Phosphorus is combined with calcium in bones and teeth. It is also an important factor in the energy metabolism of cells. Phosphorus is present in nearly all foods, and dietary deficiency does not occur except when large amounts of compounds such as antacids bind phosphorus into forms that are not absorbed from the intestine.

磷。磷是在骨骼和牙齿中与钙结合。它在细胞的能量代谢中也是很重要的因素。磷元素几乎存在于所有食物中，除了像抗酸剂结合的磷这样大量的化合物转变成肠道无法吸收的形式，否则不会出现饮食性营养不良。

Sodium, Potassium, and Chlorine.  These elements have many functions in the body, but deficiency symptoms are uncommon except among persons taking certain medicines. Potassium deficiency, for example, is most commonly found among persons taking diuretics. A sodium-restricted diet can help lower the blood pressure of persons with high blood pressure. No RDA’s have been set for these elements.

钠、钾和氯。这些元素在身体中有许多功能，但除了服用某些药物的人群外，缺乏症并不常见。例如，钠缺乏症最常于服用了利尿剂的人群。限制钠的饮食可以帮助患高血压的人群降低血压。推荐的日摄食量并没有对这些元素进行设定。

Trace Minerals.  Many other elements can be detected in living tissue in minute amounts. So far, only 17 of these trace minerals have been shown to function biologically in animals. Among the most important trace elements in human nutrition are chromium, copper, fluorine, iodine, iron, and zinc. Nutritional overdoses of race elements are unusual, although illness has been caused by industrial pollution of the atmosphere and of water supplies by trace elements. In Japan, for example, a painful bone and nerve disease called itai-itai has been attributed to cadmium-polluted water supplies.

微量矿物质。在活组织中可以检测到许多其它微小的元素。到目前为止，这些微量矿物质只有17种被证明在动物身上具有生物学功能。人类营养中最重要的微量元素是铬、铜、氟、碘、铁和锌。尽管疾病是由工业对大气的污染和供水被微量元素污染造成的，但族元素的营养过量却是不寻常的。例如在日本，一种被称为痛痛病的骨痛和神经疾病都归因于镉污染的供水。

Chromium may contribute to the prevention of diabetes in animals, but its elation to diabetes in humans is not yet known. No RDA has been established for it. Good sources include meat protein, whole grain, and brewer’ yeast.

铬元素可能有助于预防动物的糖尿病，但尚不了解它对人类糖尿病的影响。对其推荐的日摄食量还没有建立。优质的来源包括肉类蛋白质、全谷物和啤酒的酵母。

Copper is an essential nutrients, but severe deficiency is rare in man. A deficiency resulting in anemia or bone disease has been reported among malnourished Peruvian children. In the United States, similar symptoms have been reported among some premature infants fed exclusively on modified cow’s milk.

铜元素是必须的营养素，但严重的缺乏症在人类是罕见的。据报道，在营养不良的秘鲁儿童中缺乏症导致贫血或骨骼疾病。在美国，据报道在一些仅仅喂养改良牛奶的婴儿中有类似的症状。

Fluorine deprivation, in rats, causes stunted growth, which can be corrected by restoring fluorine to their diet. For humans the main role of fluorine has been in the prevention of tooth decay. Where natural fluoride levels in water are low, the rate of dental caries is usually high. Adding fluoride to the water at the rate of one part per million reduces the rate of dental caries, and fluoridated drinking water is now the main source of fluorine for most persons. At two to eight parts per million of fluoride, some mottling of teeth occurs.

老鼠缺少氟元素会导致发育迟缓，恢复它们进食中的氟元素可得到纠正。对人类来说，氟的主要功能是预防蛀牙。在水中天然氟化物低的地方，龋齿率通常很高。向以百万分之一比率的水中加入氟化物可降低龋齿率，而且向饮水中加入氟化物是目前大多数人氟的来源。当氟化物达到每百万分之二至八时，牙齿会出现一些斑点。

Iodine is essential for the normal functioning of the thyroid gland. Seafood is an excellent source of iodine, and regular use of iodized salt can provide sufficient iodine.

碘元素对于甲状腺的正常功能是必不可少的。海产品是一种极好的碘源，而经常使用碘盐可提供充足的碘。

Iron is a major component of hemoglobin, the substance in red blood cells responsible for transporting oxygen. It is also a part of various enzymes. Major dietary sources of iron include liver, heart, and kidney. Other good sources include egg yolk, whole wheat, fish, shellfish, nuts, dates, figs, beans, asparagus, and spinach. Milk is a poor source.

铁元素是一种血红蛋白的主要成分，红血细胞中的物质负责运送氧气。它也是各种酶的一部分。铁元素的主要饮食来源包括肝脏、心脏和肾脏。其它的优质来源包括蛋黄、全麦、鱼、贝类、坚果类、枣类、无花果、豆类和菠菜。牛奶缺乏铁元素。

Iron is not well absorbed by the digestive system, and the degree of absorption depends to a considerable extent on what other foods are eaten at the same time. For example, meat protein and ascorbic acid increase absorption, while phosphates and phytic acid (found in cereals) retard absorption.

铁元素无法被消化系统很好地吸收，很大程度上取决于同时食用什么其它食物。例如，肉类的蛋白质和抗坏血酸可增加吸收，而磷酸盐和值酸（谷物含有的）会阻碍吸收。

Women of menstrual age need nearly twice as much iron as do men because of the loss of iron in menstrual blood. Depleted iron reserves and mild iron-deficiency anemia are fairly common among women of menstrual age, and would be even more common among pregnant women if iron supplements were not prescribed routinely during pregnancy. Iron deficiency may also occur in children fed little but milk after the first six months of infancy.

经期妇女需要铁元素几乎是男人的两倍，因为经血中流失了铁元素。铁储备不足和轻度缺铁性贫血在经期妇女中很常见，并且如果在孕期没有进行常规补铁元素的话，该情况在孕妇中甚至更为普遍。

Excessive iron intake occur among the Bantu-speaking peoples of South Africa, probably because of iron absorbed from their iron cooking pots in combination with their low phosphorus diet. The resulting disease may damage the liver and pancreas. Hemochromatosis is a rare disease in which iron absorption is increased for unknown reasons. In this disease the iron accumulates in and damages the heart, liver, pancreas, and other organs.

铁元素过量摄入发生在南非说班图语的人群中，可能是由于从他们烹饪用的铁锅中吸收了铁元素，再加上他们低磷的饮食造成的。导致的疾病可能会损害肝脏和胰腺。血色沉着病是一种不明原因的铁元素吸收增加的罕见疾病。在这种疾病中，铁元素积累在心脏、肝脏、胰腺和其它器官中，并对它们造成损害。

Zinc forms part of several important enzymes and is essential for man. Dwarfism due to severe dietary zinc deficiency has been found in the Middle East. Mild zinc deficiency resulting in decreased taste sensation and impaired growth in otherwise apparently healthy children, has been reported in the United States. Zinc has been used medically to promote wound healing. Good sources of zinc include meat, liver, eggs, seafood, milk, and whole grain.

锌元素形成了几种重要酶的组成部分，而且对人是必不可少的。在中东发现因饮食中严重缺锌元素而造成的侏儒症。据美国的报道，轻度锌元素缺乏症会导致味觉下降和在其它方面看起来健康孩子的发育受阻。锌在医学上被用来促进伤口愈合。锌的优良来源包括肉类、肝脏、鸡蛋、海产品、牛奶和全谷物。

RICHARD N. PODELL, M. D., M. P. H.

                                                  Overlook Hospital, Summit, N. J.

                                                      理查德·N. 波德尔，医学博士，

  公共卫生学硕士

                                                             眺望医院，新泽西州SUMMIT

 

                                                                                       2023年7月28日译

（译者注：词条部分位列《大美百科全书》1985年版，第20卷，第568页至573页）

待续部分：MALNUTRITION营养不良；DISEASES OF OVERNUTRITION营养过剩的疾病；VEGETARIANISM素食主义； CONTROVERSIES IN NUTRITION对营养的争议。