On April 1, 2003, the Revised Code of Federal Regulations was released.1 The law states that only the following foods may be fortified with vitamin D:
The restrictions on vitamin D fortification to food are troubling, due to the fact that there is less vitamin D in foods than any other vitamin. The best sources are fatty fish. Vitamin D is also found in egg yolks, butter, cream and liver. Of the food groups in which fortification is allowed, only milk (100 IU/8 oz - 25 percent U.S. RDA) is a significant source.
In many Western countries, including the United States, populations are aging. In the U.S., consumption of milk, butter and eggs is decreasing. People are also using more sunscreen and trying to stay out of the sun. All of this contributes to vitamin D deficiency, a growing problem and an important factor in the increasing rates of osteoporosis.
Causes and Effects of Inadequate Vitamin D | |
Cause | Effect |
| inadequate vitamin D | Serum calcium is reduced. |
| reduced serum calcium | Parathyroid hormone (PTH) is increased. |
| increased PTH | Calcium is reabsorbed from the bones. |
| bone calcium resorption | Serum calcium is elevated; bone density is decreased. |
Risk Factors for Vitamin D Deficiency
- individuals concerned about skin wrinkles and skin cancer who avoid sun exposure;
- living in temperate or higher latitudes;
- individuals with dark skin;
- indoor occupations and living;
- pregnancy;
- the elderly (two-thirds less 7-DHC is produced in the skin);
- sunscreen use; and
- the fall and winter seasons.
Vitamin D and Calcium
- Vitamin D stimulates calcium absorption from the gut.
- Vitamin D stimulates calcium reabsorption from the kidney.
- Vitamin D stimulates calcium resorption from bone (when dietary calcium is deficient).
Many scientists do not consider vitamin D a true vitamin, since humans can synthesize it internally.
How We Make Vitamin D
Sebaceous oil glands in the skin secrete 7-dehydrocholesterol (7-DHC) to the skin surface:
- | Ultraviolet light converts 7-DHC to cholecalciferol (D3); |
- | In the liver, enzymes convert D3 to 25-hydroxycholecalciferol (25-D3); |
| - | In the kidneys, 25-D3 is converted to 1,25-dihydroxycholecalciferol (1,25-D3); and |
| - | 1,25-D3 is the active form of vitamin D. |
Most of the companies that sell supplements to chiropractors are concerned about hypervitaminosis D and use low levels of vitamin D, even in their bone-building formulas. In my personal experience, I have seen scores of patients with vitamin D deficiency.
Vitamin D Deficiency Statistics2,3
- 25-D3 is the most accurate lab measurement.
- In a South Wales study, 50 percent of non-Caucasian women were deficient in vitamin D.
- In a Finnish study, 75 percent of adolescent girls needed 800 IU/day in the winter just to maintain normal levels.
- Fifty percent or more of nursing home patients are deficient.
- Thirty-five percent of adults over age 50 admitted to Massachusetts General Hospital for any reason were vitamin D deficient.
- The farther north you live from the equator, the less vitamin D you produce. If you live in cities such as Boston, Mass., Milwaukee, Wisc., or Boise, Id., you will not produce vitamin D from November to February, even if you are in the sun all day. Go farther north to Edmonton, Alberta, Canada, and you will not make vitamin D from mid-October to mid-April.
Conversely, I have never had a case of hypervitaminosis D in my practice. I have found one brand of multivitamin that contains 2,000 IU of vitamin D per three-tablet serving. I have used this successfully with the abovementioned low-vitamin-D bone-building formulas in many patients who want to increase bone density.
Hypervitaminosis Overkill?
- Extra vitamin D from sun exposure is destroyed by the body.
- At least 2,000 IU of vitamin D per day for 18 months is required for toxicity.3
- The current no-adverse-effects level (NOAEL)4 of vitamin D per day is 2,000 IU.4
- A recent paper stated that the NOAEL should be 10,000 IU/day.5
The reason vitamin D deficiency is so often overlooked is that there are often no symptoms until levels are severely depressed.
Vitamin D Deficiency Signs and Symptoms2,3,6,7,8
- ricketts in children and infants (knock-knees, enlarged joints, a "pigeon" chest, bulging forehead, a "pot" belly, and bowed limbs);
- osteomalacia in adults;
- tendency to fracture bones easily;
- muscle twitching and convulsions (tetany);
- low-serum calcium;
- gnawing bone pain;
- increased risk to breast, prostate and colon cancer; and
- increased risk of falling.
Conversely, by taking a dietary history and analyzing supplements, vitamin D toxicity is much easier to catch.
Vitamin D Toxicity Signs and Symptoms8
- high serum calcium;
- excessive thirst;
- appetite loss;
- weight loss;
- nausea and vomiting; and
- alternating diarrhea and constipation.
References
- Code of Federal Regulations, Title 21, Volume 3, Part 184, 2003.
- Plehwe WE. Vitamin D deficiency in the 21st century: an unnecessary pandemic? Clinical Endocrinology. 2003;59: 22-24.
- Liebman B. Vitamin D deficiency: The silent epidemic. Nutrition Action. 1997;24(8):1-6.
- Boik J. Natural Compounds in Cancer Therapy. Oregon Medical Press. 2001.
- Vieth R. Vitamin D supplementation, 25-hydroxyvitamin D concentrations and safety. Am J Clin Nutr. 1999;69(5): 842-56.
- Malabanan AO, Holick MF. Vitamin D and bone health in postmenopausal women. J Women's Health. 2003;12(2): 151-6.
- Studzinski GT, Moore DC. Sunlight - can it prevent, as well as cause, cancer? Cancer Research. September 15, 1995; 55:4014-22.
- Ensminger AH, Ensminger ME, Konlande JE, Robson JR. Encyclopedia of Foods and Nutrition. CRC Press: Boca Raton, Fla. 1995.
G. Douglas Andersen, DC, DACBSP, CCN
Brea, California
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