"Well, how d'you do, my dear fellow?" said Dolgorukov, who was sitting at tea with Bilibin.
What d'you think of the treat?
How d'you do, friend?
The same article notes that it's very hard to get all the vitamin D you need from food.
However, many foods are fortified with vitamin D, so while fortified foods can't provide all the vitamin D you need, it's still helpful.
While there are many different schools of thought on how much D you need to maintain optimal health, doctors recommend that you get anywhere from 1,000 to 2,000 international units (IU) of vitamin D a day.
If you have concerns about how much D you should get in your daily diet, you should talk to your doctor about your specific circumstances.
The amount of vitamin D you need varies with your age.
Other factors can affect the amount of vitamin D you receive when outdoors.
In addition, if you are on medications such as birth control or diuretics, your doctor may advise against prolonged sun exposure, which can also affect how much vitamin D you receive.
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