VOA慢速英语2013 SCIENCE IN THE NEWS - Vitamins are Important to Good Health

 

SCIENCE IN THE NEWS - Vitamins are Important to Good Health

This is SCIENCE IN THE NEWS, in VOA Special English. I’m Bob Doughty¹.

And I’m Faith Lapidus. This week, we tell about vitamins.

Many jobs must be done with two people. One person takes the lead. The other helps. It is this cooperation that brings success.

So it is with the human body. Much of our good health depends on the cooperation between substances. When they work together, chemical reactions take place smoothly². Body systems are kept in balance.

Some of the most important helpers in the job of good health are the substances we call vitamins.

The word “vitamin” dates back to Polish scientist Casimir Funk in 1912. He was studying a substance in the hull³ that covers rice. This substance was believed to cure a disorder⁴ called beriberi.

Funk believed the substance belonged to a group of chemicals known as amines. He added the Latin word "vita," meaning life. So he called the substance a “vitamine” -- an amine necessary for life.

Funk was not able to separate the anti-berberi substance from the rice hulls⁵. It was later shown to be thiamine. Other studies found that not all vitamines were amines. So the name was shortened to vitamin. But Funk was correct in recognizing their importance.

Scientists have discovered thirteen kinds of vitamins. They are known as vitamins A, the B group, C, D, E and K. Scientists say vitamins help to carry out chemical changes within cells. If we do not get enough of the vitamins we need in our food, we are at risk of developing a number of diseases.

This brings us back to Casimir Funk. His studies of rice were part of a long search for foods that could cure disease.

One of the first people involved in that search was James Lind of Scotland. In the 1740s, Lind was a doctor for the British Navy. He was investigating a problem that had existed in the Navy for many years.

The problem was the disease scurvy⁶. So many sailors had scurvy that the Navy’s fighting strength was very low. The sailors were weak from bleeding inside their bodies. Even the smallest wound would not heal. Doctor Lind thought the sailors were getting sick because they failed to eat some kinds of foods when they were at sea for many months.

Doctor Lind separated 12 sailors who had scurvy into two groups. He gave each group different foods to eat. One group got oranges and lemons. The other did not. The men who ate the fruit began to improve within seven days. The other men got weaker. Doctor Lind was correct. Eating citrus fruits prevents scurvy.

Other doctors looked for foods to cure the diseases rickets⁷ and pellagra. They did not yet understand that they were seeing the problem from the opposite direction. That is, it is better to eat vitamin-rich foods to prevent disease instead of eating them to cure a disease after it has developed.

Which foods should be eaten to keep us healthy? Let us look at some important vitamins for these answers.

Vitamin A helps prevent skin and other tissues from becoming dry. It is also needed to make a light-sensitive substance in the eyes. People who do not get enough vitamin A cannot see well in darkness. They may develop a condition that dries the eyes. This can result in infections and lead to blindness.

Vitamin A is found in fish liver oil. It also is in the yellow part of eggs. Sweet potatoes, carrots and other darkly colored fruits and vegetables contain substances that the body can change into vitamin A.

Vitamin B-one is also called thiamine. Thiamine changes starchy foods into energy. It also helps the heart and nervous system work smoothly. Without it, we would be weak and would not grow. We also might develop beriberi.

Thiamine is found not just in whole grains like brown rice, but also in other foods. These include beans and peas, nuts, and meat and fish.

Another B-vitamin is niacin. It helps cells use food energy. It also prevents pellagra -- a disease that causes weakness, reddish skin and stomach problems. Niacin is found in meat, fish and green vegetables.

Vitamin B-12 is needed so folic acid can do its work. Together, they help produce red blood cells. Vitamin B-12 is found naturally in foods like eggs, meat, fish and milk products. Folic acid has been shown to prevent physical problems in babies when taken by their mothers during pregnancy⁸.

Vitamin B-12 is found in green leafy vegetables and other foods, like legumes and citrus fruits. In some countries, it is added to products like bread.

In 2003, Japanese researchers identified a substance they think is a member of the B-vitamin group. It is called pyrroloquinoline quinone, or PQQ.

The researchers found that PQQ is important in the reproductive and defense⁹ systems of mice. They said the substance is similarly important for people. PQQ is found in fermented¹⁰ soybeans and also in parsley, green tea, green peppers and kiwi fruit. Other researchers have disputed the Japanese findings. They say more information is needed to confirm them.

Vitamin C is needed for strong bones and teeth, and for healthy blood passages. It also helps wounds heal quickly. The body stores little vitamin C. So we must get it every day in foods such as citrus fruits, tomatoes and uncooked cabbage.

Vitamin D increases levels of the element calcium¹¹ in the blood. Calcium is needed for nerve and muscle cells to work normally. It also is needed to build strong bones.

Vitamin D prevents the children’s bone disease rickets. Ultraviolet light from the sun changes a substance in the skin into vitamin D. Fish liver oil also contains vitamin D. In some countries, milk producers add vitamin D to milk so children will get enough.

Vitamin K is needed for healthy blood. It thickens the blood around a cut to stop bleeding. Bacteria in the intestines¹² normally produce vitamin K. It can also be found in pork products, liver and in vegetables like cabbage, kale and spinach¹³.

Experts agree that everyone needs vitamins so that their bodies can operate normally. In general, a complete diet should provide all the vitamins a body needs in their natural form. In addition, many foods and food products now have extra vitamins and minerals added.

Some people fear they do not get enough vitamins from the foods they eat. So they take products with large amounts of vitamins. They think these products, called vitamin supplements, will improve their health and protect against disease. Many adults now take vitamin supplements every day.

In 2006, medical experts gathered near Washington, D.C. to discuss studies about vitamin supplements. The experts reported finding little evidence that most supplements do anything to improve health. But they noted¹⁴ that some do help to prevent disease.

The experts said women who wish to become mothers should take folic acid to prevent problems in their babies. And, they said vitamin D supplements and calcium can protect the bones of older women.

The medical experts agreed with doctors who say that people who know they lack a vitamin should take vitamin supplements. Some older adults, for example, may not have enough vitamin B-twelve. That is because, as people get older, the body loses its ability to take it from foods.

The experts also noted that taking too much of some vitamins can be harmful. They said people should be sure to discuss what vitamins they take with their doctors.

Several studies have not been able to show that taking vitamin supplements in addition to a balanced diet helps to prevent disease. One study found that older Americans do not get enough Vitamin C and required minerals. The study involved more than six thousand individuals. More than half of them took vitamin supplements.

Vitamins are important to our health. A lack of required vitamins can lead to health problems.

Different vitamins are found in different foods -- grains, vegetables and fruits, fish and meat, eggs and milk products. And even foods that contain the same vitamins may have them in different amounts. Experts say this is why it is important to eat a mixture of foods every day, to get enough of the vitamins our bodies need.

This SCIENCE IN THE NEWS program was written by Brianna Blake. I’m Faith Lapidus.

And I’m Bob Doughty. Join us again next week for more news about science in Special English on the Voice of America.

1 doughty   

adj.勇猛的，坚强的

参考例句：

• Most of successful men have the characteristics of contumacy and doughty.绝大多数成功人士都有共同的特质：脾气倔强，性格刚强。
• The doughty old man battled his illness with fierce determination.坚强的老人用巨大毅力与疾病作斗争。

2 smoothly   

adv.平滑地，顺利地，流利地，流畅地

参考例句：

• The workmen are very cooperative,so the work goes on smoothly.工人们十分合作，所以工作进展顺利。
• Just change one or two words and the sentence will read smoothly.这句话只要动一两个字就顺了。

3 hull   

n.船身；(果、实等的)外壳；vt.去(谷物等)壳

参考例句：

• The outer surface of ship's hull is very hard.船体的外表面非常坚硬。
• The boat's hull has been staved in by the tremendous seas.小船壳让巨浪打穿了。

4 disorder   

n.紊乱，混乱；骚动，骚乱；疾病，失调

参考例句：

• When returning back,he discovered the room to be in disorder.回家后，他发现屋子里乱七八糟。
• It contained a vast number of letters in great disorder.里面七零八落地装着许多信件。

5 hulls   

船体( hull的名词复数 )； 船身； 外壳； 豆荚

参考例句：

• Hulls may be removed by aspiration on screens. 脱下的种皮，可由筛子上的气吸装置吸除。
• When their object is attained they fall off like empty hulls from the kernel. 当他们的目的达到以后，他们便凋谢零落，就象脱却果实的空壳一样。

6 scurvy   

adj.下流的，卑鄙的，无礼的；n.坏血病

参考例句：

• Vitamin C deficiency can ultimately lead to scurvy.缺乏维生素C最终能道致坏血病。
• That was a scurvy trick to play on an old lady.用那样的花招欺负一个老太太可真卑鄙。

7 rickets   

n.软骨病，佝偻病，驼背

参考例句：

• A diet deficient in vitamin D may cause the disease rickets.缺少维生素D的饮食可能导致软骨病。
• It also appears to do more than just protect against rickets.除了防止软骨病，它还有更多的功能。

8 pregnancy   

n.怀孕，怀孕期

参考例句：

• Early pregnancy is often accompanied by nausea.怀孕早期常有恶心的现象。
• Smoking during pregnancy increases the risk of miscarriage.怀孕期吸烟会增加流产的危险。

9 defense   

n.防御，保卫；[pl.]防务工事；辩护，答辩

参考例句：

• The accused has the right to defense.被告人有权获得辩护。
• The war has impacted the area with military and defense workers.战争使那个地区挤满了军队和防御工程人员。

10 fermented   

v.（使）发酵( ferment的过去式和过去分词 )；（使）激动；骚动；骚扰

参考例句：

• When wine is fermented, it gives off gas. 酒发酵时发出气泡。 来自《简明英汉词典》
• His speeches fermented trouble among the workers. 他的演讲在工人中引起骚动。 来自辞典例句

11 calcium   

n.钙(化学符号Ca)

参考例句：

• We need calcium to make bones.我们需要钙来壮骨。
• Calcium is found most abundantly in milk.奶含钙最丰富。

12 intestines   

n.肠( intestine的名词复数 )

参考例句：

• Perhaps the most serious problems occur in the stomach and intestines. 最严重的问题或许出现在胃和肠里。 来自辞典例句
• The traps of carnivorous plants function a little like the stomachs and small intestines of animals. 食肉植物的捕蝇器起着动物的胃和小肠的作用。 来自辞典例句

13 spinach   

n.菠菜

参考例句：

• Eating spinach is supposed to make you strong.据说吃菠菜能使人强壮。
• You should eat such vegetables as carrot,celery and spinach.你应该吃胡萝卜、芹菜和菠菜这类的蔬菜。

14 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。