Vitamin（维生素）D is called “sunshine vitamin，”and it is very important to health，yet more Americans are not getting enough，U．S．researchers said on Monday．Researchers found that 75 percent of Americans can’t reach the levels of vitamin D，up from about 50 percent of them 20 years ago．Getting enough vitamin D can be easy：spend 10 minutes in the sun with legs and arms exposed （暴露），or take vitamin pills．

    “But people’s habits have changed…they are less active and outdoors less，and also protecting their skin from the sun because of skin cancer risk（皮癌风险），”said Dr．Adit Ginde，who did the study．Traditionally, vitamin D has been seen important to bone（骨）health and to prevent rickets（软骨病），but recent discoveries show many kinds of cells（细胞）use vitamin D in some way, Ginde said．

    Food can boost（提升）vitamin D levels，but only a few foods．Those include some kinds of fish（salmon，sardines，tuna and mackerel）and milk．But the amounts in milk are not enough to keep people healthy．In the last few years，vitamin D has gained more attention．People are paying a lot more attention to it．A second study in the journal supposed the idea of providing more vitamin D for bone health．Researchers did a research on some people aged 65 or older．They found that spinal bone fractures（脊椎断裂）decreased（卜降）20 percent when the patients took vitamin D every day．

    Researcher Heike Bischoff-Ferrari wrote in the report．”it is possible for people to increase the amount of vitamin D earlier to keep healthy．”

1．Why Vitamin D is called“sunshine vitamin”?

A．Because it is like sunshine

B．Because people can get vitamin D in the sun．

C．Because it is very important

D．Because there isn’t enough vitamin D in the food．

2．If people have enough vitamin D．they can avoid __________．

A．cold                       B．cancer                   C．rickets                   D．fever

3．We can get vitamin D by __________．

A．eating some food                                        B．spending time in the sunshine

C．taking vitamin D Pills                                  D．all of the above

4．Americans get __________ vitamin D than before．

A．more                   B．less                       C．better                     D．worse