Thursday, January 17, 2013

Calcium and Vitamin D


You probably know that sufficient intake of calcium and adequate vitamin D from either diet or through exposure to the sun’s rays are necessary for bone health. Here are a few facts that may be new news:

Approximately 200 mg of calcium is lost from your skeleton each day and needs to be replaced.
Calcium is difficult to absorb. That’s where vitamin D comes in. When vitamin D receptors in the gut are adequately stimulated by the circulating vitamin D in your blood stream, then you are able to absorb more calcium. But even if your gut is healthy, fully capable of absorbing nutrients, and if you have at least 32 ng/ml vitamin D in your blood…even then, the bare minimum of calcium you will need to replace this loss is 600 mg/day. That is when everything is perfect.
And here is the definition of perfect in this case:
     -  You are a healthy individual with normal bone density
     -  Your 600 mg is quality, bioavailable calcium
     -  Your gut health is perfect
     -  You are less than 60 years of age
     -  You blood contains at least 32 ng/ml
         of vitamin D
     -  Your kidneys are healthy enough to resorb
         lost calcium
     -  Your kidneys are healthy enough to form
         active vitamin D
     -  You are not loosing extra calcium in your
         sweat (watch out athletes!)

Calcium (and vitamin D) affects both the formation of bone and its resorption.
Low calcium intake (or absorption) not only reduces your ability to form bone but – because low calcium stimulates your parathyroid glands to secrete more hormones – it also causes increased bone resorption (a break-down of bone) due to an increase in bone remodeling activity. When a person is osteoporotic, his/her bone remodeling activity is often increased; by taking in at least 1,000 mg calcium/day (and preferably 1,200), this remodeling activity (and therefore bone loss) can be reduced by 10 to 20%.

As you get older, your ability to absorb calcium decreases for several reasons.
First, some of the vitamin D receptors in your gut fade away and others become less responsive, thereby limiting your ability to absorb calcium. Second, with aging also comes a loss of hydrochloric acid in your stomach. With less acidity, you are less able to break down food and absorb nutrients such as calcium. Third, if you have any food sensitivities/allergies, nutrient absorption capacity is further reduced due to irritation of the gut lining.

Vitamin D helps you absorb calcium from the gut.
It’s best if you maintain vitamin D blood levels – year-round - of at least 32 ng/ml. Obtaining optimal vitamin D levels only through sun exposure is difficult; vitamin D production is compromised when people slather on the sunscreen. The solution is two fold: 1) take oral vitamin D3, and 2) make sure to have your vitamin D blood level tested annually – preferably in early spring when your D level will be at  its lowest. If it is lower than 32 ng/ml, you know you will have to increase your daily dosage of D for the next year.

In addition to its role in building bone, vitamin D is also important for immune health and muscle strength.
Vitamin D affects both the innate (promotes) and adaptive (represses) immune responses and is, therefore, important for overall normal immune function. Low vitamin D levels are seen in autoimmune disorders and are associated with chronic systemic inflammation - the powerfully destructive promoter of all chronic disease including osteoporosis. Vitamin D receptors are also present on muscle fibers and thought to play an important role in maintaining muscle performance. Trials that tested vitamin D supplementation in the elderly show over 20% reduction in risk for falls (the number one cause of fractures) with at least 800 IU/day of D.

Knowing these facts can be a life saver.
It has been determined that fewer than 1 in 10 women over the age of 70 and only 25% of all males obtain adequate calcium from their diet. If you are over 50, the U.S. Academy of Sciences recommends 1,200 mg/day of calcium.  As for vitamin D, blood levels vary dramatically depending upon sun exposure, diet, age, and latitude of where the individual lives. This is why it is extremely important to be tested for vitamin D.  Many doctors, myself included, recommend maintaining blood vitamin D [25(OH)D] at 40 to 60 ng/ml. Taking 2,000 IU/day of D3 should be adequate…but have your doctor test your blood level just to make sure.
Are calcium and vitamin D important only in adults? No! We must make sure that our children and young adults are getting enough calcium and vitamin D as well.

I hope you will make it a point to tell others about the importance of calcium and vitamin D. You may just help save someone else from future health problems.
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