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Vitamin D is a truly miraculous natural substance — clinically proven to heal pain, prevent disease and improve your mood. Vitamin D deficiency, however, is linked to a wide variety of health problems. Increasing the amount of vitamin D in your body can help heal a remarkable number of diseases and ailments, including arthritis, high blood pressure, back and muscle pain, obesity, cancer and diabetes. A dose of daily sunshine doesn't give you enough to get better, either.

An unbalanced diet, a vitamin D deficiency, and the medical problems they cause affect more than two-thirds of the U.S. population (about 200 million people). The chances are good that you or someone in your family figures into those scary statistics.

To figure out where you stand, start with an assessment of your need for vitamin D:

Vitamin D Risk Analysis Quiz

Question 1: If your ethnic background is half or more than half African, Indian, Southeast Asian, Latin American or Arabic (or you have skin type 4, 5, or 6 from the chart below), add 3 points.

Skin Types:1 - Always burn, never tan2 - Burn easily, rarely tan3 - Occasionally burn, slowly tan4 - Rarely burn, rapidly tan5/6 - Never burn, always dark

Question 2: If your body mass index (BMI) is 30 or greater, add 3 points.

BMI reflects body weight adjusted for a person's height. Multiply your weight (in pounds) by 703 and divide by your height (in inches) squared to find your BMI. If your BMI is higher than 25, you're overweight, according to CDC standards.

Question 3: If you were a breast-fed infant who is not on vitamin or formula supplements, add 3 points.

Question 4: If you have fatigue or recurring muscle, bone or joint pain, add 2 points.

Question 5: If you are fifty years or older, add 2 points.

Question 6: If you wear sunscreen of SPF 8 or greater before you go outdoors, add 2 points.

Question 7: If you rarely (less than three times a week) spend time outdoors between 11:00 a.m. and 4:00 p.m., add 2 points.

Question 8: If you are a woman, add 1 point.

______ Total score

Risk Analysis0-2 points     Low risk, No supplements; only sun3-5 points     High risk, 20 IU/lb. body weight> 5 points     Very high risk, 25 IU/lb. body weight

If your score shows that you're high risk or very high risk, you need to increase your vitamin D production with sun or supplements. If you're in the low-risk group, you may want to consider having your vitamin D level measured.

Some people, however, prefer to skip blood tests and proceed straight to vitamin D supplementation. This is perfectly acceptable, but it leaves you guessing why you may or may not have responded the way you expected.

Here are some handy guidelines on buying supplements:

  • Buy vitamin D3, not D2. D3 is the vitamin D your body makes from sunlight. It hangs around longer in your blood, which allows for once-a-week dosing, unlike vitamin D2, which must be dosed daily to be close in efficacy. Most over-the-counter vitamin D sold in the United States is vitamin D3. This is not the case in Europe. 
  • Stick to major distributors of vitamin D. You can choose from a number of reliable brands. Generally speaking, the larger the company distributing the product, the higher the quality and the lower the price. A few companies that make high-quality, low-cost vitamin D are Carlson Labs, Now Foods, Swanson Health Products, Jarrow Formulas, Nature Made and Solgar. You can also buy national store-brand vitamin D of reliable quality at Wal-Mart, Costco, CVS and Walgreens. 
  • In liquid vitamin D, buy Ddrops of Canada (www.ddrops.ca). This is the only liquid vitamin D with a patented, precise, gravity­-fed dropper top. You invert the bottle, and it delivers exactly the same size drop of liquid every time. Manual droppers and squeeze bottles, in contrast, deliver drops of different sizes, which make accurate dosing difficult. This can be problematic when you are supplementing the vitamin D of infants and children. 
  • Don't pay more than $20 for a year's supply of vitamin D. This figure will vary according to the size of the dose you take, of course. Keep in mind that the price of vitamin D supplements has dropped by more than half since 2008. Paying more doesn't give you higher-quality supplements. 
  • Most people have better tolerance for vitamin D gel caps and drops than for tablets combined with calcium. The majority of vitamin D tablets are combined with calcium, even though the label may not indicate that this is the case. The problem is that calcium tends to cause constipation and stomach upset in some people. Tablets with calcium would be especially troublesome if you're dosing with vitamin D weekly.