There is a secret vitamin in the neighborhood, wandering around your body under cover. This "vitamin" has just one single purpose, although some researchers believe he has ulterior motives. He goes by the inconspicuous codename of "D" Vitamin D.

Don't be fooled by his clever disguise. D is no vitamin. He's a steroid hormone, slipping through your body under guise of a vitamin. And he doesn't have dozens of functions, like vitamin C or vitamin E, just one vital mission to mineralize your bones!

Mineralization is a key objective of every body. Imagine if we all had flabby bones. The world would look like a Salvador Dali nightmare. Vitamin D saves us from having flabby bones.

More importantly, vitamin D saves us from having brittle bones. He prevents us from rickets and osteomalacia by balancing the calcium and phosphorous in our blood. Ooh, that D is a clever one. Not only is he a master of disguises, but he is a master chemist, constantly monitoring, measuring and balancing the mix so it just right to ensure everybody has strong and healthy bones.

Word on the grapevine is that 30% to 40% of hip fractures in elderly people are the result of insufficient vitamin D. So we caught up with D, and managed to slip away with a rare interview transcript:

"D, some of your fans can't get enough of you. What should they do?"

"Get plenty of sun. That is the key. Where the sun touches your skin, that's where I will be."

"But, D, what about people who can't? What about people in the far north, or those who wear head-to-toe clothing or who are stuck indoors?"

"If you find yourself overdressed in a dungeon in Mongolia, get a good multi-vitamin supplement."

"D, that's a wonderful idea."

"Or drink lots of milk, fortified with me, of course. Some breakfast cereals are fortified with me, too. I also hang out in a lot of saltwater fish, like tuna and sardines and herring and salmon. And I love to slip around in the ol' cod liver oil."

"So if we can't get enough sun, milk and fish will do the trick."

"That's right, but be careful about milk products. Not all of them are made with fortified milk. I make no commitment to be there if they are not."

"What about the supplements, D?"

"A good multivitamin supplement should do it for most people. Get a liquid supplement, cause those pills just don't digest. You just end up flushing me down the toilet...ooh, I hate that feeling."

"Yuck."

"And you shouldn't need a specific vitamin D supplement, because it is possible to overdose. And you wouldn't want too much of a guy like me around."

That was all we could slip through the lines. But I think we learned a lot about what it is like to live the life of a secret vitamin. To our hero, vitamin D, we offer our best wishes. May everybody get plenty of vitamin D to keep their bones strong and healthy for many years to come.