The vitamin that can keep you on your toes

When you're young and healthy, everything seems to come easy. But when you reach a certain age, just tying your shoes can turn into a body-bending exercise that'll leave you out of breath and gasping for air.

No one ever said aging would be easy.

But there's a single nutrient that can make it a little easier -- a critical vitamin that can help make sure the simple things in life stay simple as you get older.

It's vitamin D, and new research of vitamin D shows that older people with lower levels have a much higher risk of functional problems.

If you're in your 50s or early 60s, low levels of vitamin D can double your risk of problems with basic activity over the next six years. And by basic, I mean the stuff that's supposed to come easy -- like sitting down, standing up and just getting around.

And if you're over 65, low levels of that same nutrient can cause your risk of functional problems to jump by 70 percent over the next three years, according to the new study in the Journal of Clinical Endocrinology & Metabolism.

Vitamin D is essential to muscle growth, balance and coordination -- so much so that even the very mainstream (and it would appear anti-supplement) U.S. Preventive Services Task Force says D supplements can slash the risk of falls, a leading source of functional problems and disability in seniors.

D is of course also one of the most important ingredients in bone health -- and another new study shows why: It's critical to keeping your bones "young" even as you get old.

When your vitamin D levels sink, you start to lose bone density and the quality of your bone begins to suffer -- putting you at risk for breaks and fractures even if you don't have osteoporosis.

And in the new study, bone scans revealed that low vitamin D levels also appear to accelerate aging by short-circuiting the mineralization process.

That in turn leads to more brittle bone.

Not something you want, believe me -- because as you get older, any break or fracture can knock you out of commission for a very long time. In some cases, breaks and fractures can lead to permanent disability, a loss of independence and even an early death.

Unfortunately, up to 90 percent of all seniors are quietly suffering from insufficiencies and outright deficiencies when it comes to the sunshine vitamin -- and along with functional and mobility problems, low vitamin D levels can damage the immune system, heart, brain and more.

There's an easy way to prevent all that -- and all you have to do is get more D.

The most natural way to get it of course is from sunlight. But that's not exactly the safest way to get it given the very real risk of sunburn, skin damage and even skin cancer.

Try a natural D3 supplement if you're not taking one already. They're safe, inexpensive and you'll find them in any store that sells vitamins.

I recommend between 2,000 and 5,000 IUs a day for most people, but some will need more -- your own doctor can help figure out the amount that's best for you.