Vitamin D

From the December 2006 The “G”Note

Vitamin D has been making a splash in the news recently. There are numerous recent articles in scientific journals on the benefits of vitamin D. Below are a few of the articles and a synopsis of them. Some are readily available at your local public library or are free online. Researchers are gearing up to do more research on vitamin D as more research is necessary.

American Journal of Physical Medicine & Rehabilitation November 2006, vol. 85 #11: pp.916-923. Kelly M. Heath & Elie P. Elovic.

Vitamin D deficiency can be the result of inadequate exposure to the sun, insufficient dietary intake, or absorption problems. The authors note that vitamin D deficiency can present as musculoskeletal pain: proximal muscle weakness, back pain, and muscle and bone pain. Numerous studies have found that increasing vitamin D intake – sun light and/or supplementation – increases muscle strength and reduces pain.

They state that vitamin D is absorbed either through the skin via sunlight (UV B) or ingested in food or supplements. Through sunlight-dermal absorption, there is activation of precursor 7-dehydrocholesterol and the formation of previtamin D3. In the liver, previtamin D3 is hydroxylated into 25-dehydroxyvitamin D which is hydroxylated in the kidneys into 1,25 dihyroxyvitamin D or cacitriol. Through the GI tract, ingested vitamin D is present as vitamin D2 and D3. These forms of vitamin D are absorbed in the small intestine and transported to the liver where they follow the aforementioned hydroxylation process.

The current minimum daily requirement of vitamin D is 200 IU (5 μg) up to age 50 years, 400 IU (10 μg) between age 50 and 70 years, and 600 IU *15 μg) over age 70 years. Most consider these levels much too low. Sun exposure can provide around 100% of the MDR in 15 to 30 minutes. Dark skin or tanned skin requires longer exposure than light skin. Dietary sources include fish liver oils, flesh of fatty fish, eggs from vitamin D fortified hens, and fortified milk and cereals. Studies of milk drinker found the same rate of deficiency as those who don’t drink milk.

In studies of Canadian women during the winter and Muslim women in Denmark, supplementation of 400-500 IU did not satisfy the vitamin D deficiencies that were found. Sunlight seems to be important, unless supplementation is higher than the levels taken in these studies. Crohn’s disease and celiac sprue reduce the absorption of nutrients, such as, vitamin D. Stapling and shortening the GI tract is becoming more common and is a cause of vitamin D deficiency. Obesity can lead to deficiency because fat-soluble vitamins are stored in fatty tissue.

Osteomalacia, and of course, rickets are severe manifestations of deficiency. Musculoskeletal pain is associated with vitamin D deficiency. In a study, 93% of patients who presented with nonspecific musculoskeletal pain had vitamin D deficiency. Of these, 100% of those under age 30 years were deficient and 55% of these were severely deficient. Other studies of muscle pain and/or proximal muscle weakness found the majority (often over 90%) with vitamin D deficiency. Back and lower extremity pain has been shown to respond very well to those with vitamin D deficiency.

One pain mechanism is thought to be deficiency reduces calcium phosphate levels which results in poor mineralization of the collagen matrix of bone. The matrix becomes hydrated and the expansion causes pressure under the periosteum. The periosteum has a rich sensory nerve supply. A mechanism for muscle weakness is calcidiol binds to vitamin D-dependent receptor in muscles. When deficiency of vitamin D is present, there are fewer receptors for calcidiol to bind to.

Science News November 11, 2006; vol. 170: pp.312, 317. Janet Raloff. The Antibiotic Vitamin: Deficiency in Vitamin D May Predispose People to Infection.

This article begins with a story of a psychiatrist, John J. Cannell, who works at a maximum security psychiatric hospital in Atascadero, California. Influenza was affected about 10% of the inmates in April 2005 – it is likely that the inmates received flu shots. The 32 of the inmates under his care had mingled with inmates in other wards, many of whom developed the flu, none developed the symptoms of flu. What was different about his patients? All had been receiving high doses of vitamin D which was boosting their level of cathelicidin, a natural antimicrobial in the body. A July 2005 article in FASEB Journal found that vitamin D elevates production of leukocytes. A finding years ago was that children with rickets had a tendency for infections.

At McGill University, researchers found that a form of vitamin D, 1,25-D, elevates cathelicidin levels. 1,25-D enters cells and binds to DNA. This activates the peptides, cathelicidin and beta-defensin 2. Another researcher in Stockholm, applied an ointment that mimics 1,25-D to the skin and cathelicidin gene activity increased substantially where the ointment was applied. A UCLA study that uses Mycobacterium tuberculosis found that macrophages in the presence of the TB bacteria developed vitamin D receptors that can convert produced. Higher levels of vitamin D obviously enhances the process. The same UCLA group is studying the effects of vitamin D – initially, exposure to the sun, and in a second study, the use of a 1,25-D analog – on wound healing.

Rather than running for flu shots as many people do, which has many side effects and is of questionable effectiveness as we know, some sunlight and/or vitamin D supplementation (along with their adjustments), may be much more effective.

Nutrition Action Health Letter November 2006; vol. 33 #9. Bonnie Liebman. Are You Deficient?

In the introduction, the author states that osteoporosis, muscle weakness, periodontal disease, diabetes, insulin resistance, arthritis, multiple sclerosis, and cancers of the breast, colon, pancreas, and prostate may respond to increasing the intake of vitamin D.

Our ancestors relied on sunlight to obtain vitamin D. As more people moved away from the equator, other sources of vitamin became necessary. The only darker skin people who have been able to satisfactorily meet their need for vitamin D are the Inuit who live on fatty fish which are high in the vitamin.

In a meta-analysis study, a 26% lower risk of hip fractures was found in those who took 700 to 800 IU/day of vitamin D compared to those on placebo. Some studies did not find elevated serum vitamin D in the elderly who received vitamin D. It is thought that compliance might have dropped in those studies as was found in one British study.

In a study of older women, vitamin D improved protein synthesis which resulted in muscle growth. Higher serum D levels helped the elderly do better on tests of strength and balance.

Associations have been found between vitamin D deficiency and periodontal disease. In one study, older people who received 700 IU/day of vitamin D and 500 mg/day of calcium had 60% less tooth loss than those who received placebo.

Animal and test tube studies found vitamin D to have a significant effect on cancer. A breast cancer study found a lower risk of breast cancer in women of 60 years who had high serum vitamin D levels. Another study of women found a lower risk of colon cancer if the vitamin D level was high at the time of entry into the study. A study found that among 46,000 men and 75,000 women, those who received at least 600 IU/day had a 40% lower risk of pancreatic cancer than those receiving less than 150 IU/day.

A 75% lower risk of diabetes was found in non-Hispanic whites with the highest levels of serum vitamin D compared to those with the lowest levels. In a study of those 65 years or older, 1/3 were pre-diabetic, fasting blood sugar levels rose during the 3 years that they were taking 700 IU/day of vitamin D and 500 mg/day of calcium.

How much should be taken? The recommended minimum levels should be increased from the 200 IU/day for those 50 years and under, 400 IU for 51 to 70 years, and 600 IU over age 70 years. The highest safe daily level of 2,000 IU was based upon a poor study of six patients in India. Serum vitamin D was not checked on these patients. In a current study, 4,000 IU/day is being given to pregnant women and 6,000 IU/day to breastfeeding women. More than 2 years in this study, no adverse events have been noted. The article states that the primary risk of too much vitamin D is a too high absorption of calcium which may cause kidney damage. The researcher of the womens’ study did not find excessive urine calcium levels with doses of vitamin D of up to 10,000 IU/day. Kidney stones are another slightly increased risk. In a study, women were given 400 IU/day of vitamin D and 1,000 mg/day of calcium. They found a slightly increased risk of kidney stones. It is thought that the women were actually getting 800 IU/day of D and 2,200 mg/day of calcium as they continued to take their usual supplements and the vitamin D/calcium pills were unmarked. Because of the prevalence of D deficiency, some researchers recommend 1,000 IU/day, particularly for the elderly to get serum D levels up to 75 nanomoles/liter of blood and 2,000 to 4,000 IU/day for most people, unless one is prone to kidney stones. It is thought that 90 nanomoles/liter of blood might be better serum blood level. A light skin person in a bathing suit can make 20,000 to 30,000 IU in 30 minutes.

This article recommends that if you get vitamin D from supplements, take it in the form of vitamin D3 or cholecalciferol rather than D2 or ergocalciferol.

Conclusions
This is a small sampling of recent articles on vitamin D. A lot more research needs to be done on the effects of vitamin D. The minimum daily requirements are obviously too low for most people. The risk of taking higher levels of vitamin D are less than what we’ve been told. It appears that we can conclude that most people need to increase their intake of vitamin D, either through sunlight, food, or supplements; or through a combination of these. It is also important to have an adequate supply of calcium and magnesium.