VOA慢速英语2009年-Health Report - Vitamins: D and the Diet

This is the VOA Special English Health Report.

Vitamin D helps bones and muscles grow strong and healthy. Low levels of vitamin D can lead to problems like rickets¹ and osteoporosis. Rickets is a deformity mainly found in children. Osteoporosis is the thinning of bone, a common problem as people, especially women, get older.

Studies in recent years have suggested that vitamin D may also have other uses. Studies have shown that low levels of D may increase the risk of heart attacks in men and deaths from some cancers. Other studies have shown that people with rheumatic diseases often have low levels of D.

The easiest way to get vitamin D is from sunlight. The ultraviolet rays react with skin cells to produce the vitamin. But many people worry about skin cancer and skin damage from the sun.

Also, darker skinned people produce less vitamin D than lighter² skinned people. Production also decreases in older people and those living in northern areas that get less sunlight.

Not many foods naturally contain vitamin D. Foods with high levels include oily fish such as salmon³, tuna and mackerel, and fish liver oils. Boston University researchers reported in two thousand seven that farmed salmon had a lot less vitamin D than wild salmon.

Small amounts of D are found in beef liver, cheese and egg yolks. And some people take dietary supplements containing the vitamin. But most of the D in the American diet comes from foods like milk with the vitamin added.

These days, more doctors are testing for vitamin D levels in their patients. But as research continues, some experts worry that if people take too much D, it might act as a poison. Also, skin doctors warn people to be careful with sun exposure.

How much vitamin D does a healthy person need? Nutrition experts who advise the American government set the current recommendations in nineteen ninety-seven. The daily amount is two hundred international units from birth through age fifty. Then it rises to four hundred I.U.s through age seventy, and six hundred for those seventy-one and older. But some groups say these amounts are not high enough.

The nutrition experts are taking another look at how much vitamin D and calcium⁴ people should get. The Institute of Medicine of the National Academies expects to release a report by this coming May.

And that's the VOA Special English Health Report, written by Caty Weaver⁵. I'm Bob Doughty⁶.

1 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。

2 lighter   

n.打火机，点火器；驳船；v.用驳船运送；light的比较级

参考例句：

• The portrait was touched up so as to make it lighter.这张画经过润色，色调明朗了一些。
• The lighter works off the car battery.引燃器利用汽车蓄电池打火。

3 salmon   

n.鲑，大马哈鱼，橙红色的

参考例句：

• We saw a salmon jumping in the waterfall there.我们看见一条大马哈鱼在那边瀑布中跳跃。
• Do you have any fresh salmon in at the moment?现在有新鲜大马哈鱼卖吗？

4 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。

5 weaver   

n.织布工；编织者

参考例句：

• She was a fast weaver and the cloth was very good.她织布织得很快，而且布的质量很好。
• The eager weaver did not notice my confusion.热心的纺织工人没有注意到我的狼狈相。

6 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。