Vitamin D: The Facts Everyone Should Know

by Linda S. Mills
Vitamin D is on everyone’s radar these days, and the newest research points to its critical influence on nearly every system in our bodies.  This fat-soluble nutrient helps us absorb calcium and phosphorus - essential minerals for maintaining strong bones and teeth.  It also appears to lower the risk of certain diseases including osteoporosis, autoimmune disorders, cardiovascular conditions and even cancer. 

While it was once assumed that the body naturally acquired and maintained adequate levels of vitamin D through sunlight (and to a lesser extent foods), the Archives of Internal Medicine reports that an alarming 77 percent of Americans are currently deficient, prompting the medical community to re-examine risk factors and current recommendations for daily intake. 

Where does vitamin D come from and what seems to be causing the decline?

With the exception of fatty fish, eggs and fortified dairy products, there are very few dietary sources of vitamin D, and most people simply don’t eat enough of these foods to maintain an adequate supply of this vital nutrient.   

Our main source of vitamin D comes when ultraviolet light signals a chemical reaction in the skin.  Dr. Michael Holick, a professor at Boston University’s School of Medicine, explains that humans have depended on the sun for vitamin D throughout their evolution.  Because of our increasing precautions against skin cancer, we have succeeded in limiting harmful exposure, but may be severely draining our vitamin D levels in the process.  There is also evidence that America’s obesity epidemic might play a vital role, since body fat absorbs vitamin D, making it less available to the intestines and other organs.

What is the connection between breast cancer and vitamin D?

Optimal levels of vitamin D help regulate the growth of healthy cells, and inhibit the formation of cancer cells throughout the body, especially in the breast.  Population-based studies point to a higher incidence of breast cancer in women living in northern latitudes where sun exposure is more limited, and scientists believe that vitamin D deficiency might play a critical role. 

In 2008, a research team from University of Toronto reported over 75 percent of breast cancer patients in their study had inadequate levels of vitamin D at the time of diagnosis.  Long-term survival rates also declined, considerably, in patients who remained deficient throughout a 10-year treatment period.

Why is vitamin D critical for healthy bones?

Most people know that calcium plays a critical role in preventing osteoporosis.  What they may not realize is that adequate amounts of vitamin D are essential for regulating how much calcium remains in the bloodstream, and how much is actually deposited into the bones.  According to the National Institute of Health, people with a vitamin D deficiency absorb less than 10 percent of the available calcium.  As men and women age, these low levels are associated with bone loss and increased risk of fracture.

Can vitamin D help prevent heart disease?

Low levels of vitamin D may contribute to inflamed arteries, a known risk factor for heart attacks.  There is also evidence that patients with a deficiency had a higher rate of cardiac distress over a 5-year period, and the risk appears to go up as D levels decline.  Recent studies also point to increased incidents of high blood pressure, stroke and even congestive heart failure.  While the role of supplementation needs further study, many cardiologists believe that adequate amounts of vitamin D play an important role in maintaining a healthy heart, and should be included in a preventative healthcare regimen.

How can I increase my vitamin D level and what is the optimum dose?

Many health professionals believe that previous recommended levels of vitamin D were too low for most people.  The average man or women, in reasonably good health, needs approximately 1,000-2,000 IUs per day.  This can be obtained from a combination of diet, sunlight and supplementation, and proportions depend upon lifestyle, dietary preferences and climate.  |

  • Natural sunlight (minus sunscreen) will provide the best form of vitamin D, but it is difficult to measure a dose of exposure that gives adequate D without increasing skin cancer risk.  Some experts suggest 10-15 minutes daily for Caucasians and longer for darker pigmented individuals.
  • Foods high in vitamin D include fatty fish like salmon and tuna, (300-700 IUs per serving), egg yolk (18 IUs) (milk (120 IUs per glass) or fortified cereals (100-200 IUs).
  • A vitamin D3 supplement is the most effective, long-lasting way to maintain optimum levels.  If you are taking a high-potency multiple and a calcium supplement with D included, you may not need an additional tablet.
  • Even if you exceed the upper limit of 2,000 daily IUs, research suggests that up to 10,000 IUs is safe for most people.  Symptoms of toxicity include constipation, fatigue, appetite loss, nausea and kidney stones (from too much calcium absorption).

If you live in the northern half of the U.S., suffer from a chronic illness or suspect a deficiency, you may want to ask your doctor for a blood test to determine the best dose for your body.  Otherwise, daily supplementation, combined with good nutrition and time outdoors should keep your levels adequate.

Sources:
Consumer Reports on Health
Natural News
WebMD

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