Vitamin D is attracting a great deal of attention. Scientists are finding that when we avoid sunlight all the time by slathering ourselves with sunscreen or avoiding the outdoors altogether we lose our most effective source of vitamin D. When the body is exposed to the sun’s UV light, it produces its own vitamin D. No one is saying that you should lie out on the beach and tan all day the way we used to before we knew about the dangers of skin cancer. All that’s required is about 10 minutes a day in the summer, and about 15 in the winter.

Unfortunately, between our sedentary lifestyle and our conscientious use of sunscreens, most Americans don’t get enough vitamin D. Studies have shown that this vitamin’s beneficial effects extend to reducing the risk of colon, breast, and prostate cancers. And it’s long been know that vitamin D helps maintain strong bones. Older adults can also reduce their risk of falls by ore than 20% by ensuring that they get enough vitamin D. A study recently reported in the Journal of the American Medical Association noted that “vitamin D may also improve muscle strength, thereby reducing fracture risk through falls.”

Blood levels of vitamin D are low in at least one in five women who live in North America and northern Europe, and the most postmenopausal women also get too little dietary calcium. But the former deficiency may be more important than the latter, according to new research results. In fact, recent research suggests that higher-than-RDA intake of vitamin D is probably more important than RDA-level intake of calcium to bone health!
That’s because there is actually a tightly intertwined connection between vitamin D, calcium, and a lesser-known (to the lay public) substance called parathyroid hormone (PTH). PTH regulates the amount of calcium in the bloodstream. When blood levels of calcium are low, the thyroid gland secretes more PTH, which raises the level of calcium by taking it from the bone. If this pattern continues, bones will eventually become brittle and prone to breakage.

Enter vitamin D. High blood levels of vitamin D inhibit secretion of PTH, thereby preventing the loss of calcium from bones. Conversely, low vitamin D levels prompt loss of calcium from bones and raise the risks of osteoporosis and fractures. This is one reason why most experts say the RDA for vitamin D (400 international units per day) is too low and should be increased to 600 to 800 international units per day or even higher.

Is vitamin D part of your daily D’s?