Vitamin D Research

Vitamin D Analysis Shows Reduced Overall Mortality

 

Authors of a recent journal article in the Archives of Internal Medicine found a significant reduction in all-cause mortality in people who supplemented with vitamin D. The meta-analysis studied 18 randomized, controlled studies involving over 57,000 individuals over a mean of 5.7 years. With an average daily supplemental dose of 528 IU, people who took vitamin D for at least three years had an eight-percent reduction in mortality. The mechanism(s) by which vitamin D is protective are not known; however, lower vitamin D levels have been demonstrated to be correlated with increased risk of death from heart disease, cancers, and diabetes. It may be that vitamin D’s anti-proliferative and immune-regulating effects will be found to be the predominant mechanisms. “Given the high probability of benefit for at least some of the many conditions that have been associated with vitamin D deficiency, and the low likelihood of harm, it seems prudent that physicians measure 25-hydroxyvitamin D levels in their patients,” said Dr. Edward Giovanucci, of the Harvard School of Public Health, in an accompanying editorial.

Reference:
Autier P, Gandini S. Vitamin D supplementation and total mortality: A meta-analysis of randomized controlled trials. Arch Intern Med 2007;167:1730-1737

 

Vitamin D Protects Against Colds & Flu

It has long been observed that incidence of colds and influenza rises in the fall and winter months and wanes in the spring and summer. This is the opposite of serum levels of 25-hydroxyvitamin D, which increase in the summer and decrease dramatically as the amount of daylight diminishes. Research has shown adequate blood levels of vitamin D stimulate the genetic expression of antimicrobial peptides in human monocytes. These peptides demonstrate a broad spectrum of antimicrobial activity against viruses, bacteria, and fungi. Vitamin D also has other immune-modulating and anti-inflammatory activity.

An article published in the journal Epidemiology and Infection reports on a three-year study of 208 African-American postmenopausal women (who are at great risk of vitamin D deficiency) who were supplemented with vitamin D or placebo. For the first two years the active group received 800 IU daily, which was increased to 2,000 IU daily in the last year of the study. In the three years of the study 34 patients reported cold and flu symptoms, eight in the supplemented group and 26 in the placebo group (p<0.002). This showed that participants who got a placebo had a 300-percent greater risk of having a cold or flu, and that vitamin D supplementation provided a highly significant protective effect.

Reference:
Aloia JF. Epidemic influenza and vitamin D. Epidemiol Infect 2007;135:1095-1096.

 

Vitamin D Deficiency Increases Risk of Heart Attack, Stroke

Recent vitamin D research has found vitamin D receptors in heart muscle and many other tissues. This may partly explain the results of the Framingham Offspring Study, in which researchers analyzed vitamin D status (serum 25- hydroxyvitamin D [25-(OH)D]) in 1,739 individuals without cardiovascular disease to determine how levels might correspond with the incidence of cardiac events (MI, stroke). Baseline levels were assessed and participants were followed for a mean of 5.4 years. Researchers observed the incidence of cardiovascular disease and found it was correlated positively with serum 25-(OH)D status. Individuals who were seriously deficient (25-(OH)D < 10 ng/mL) had an 80% greater risk of having a cardiovascular incident, while deficient individuals with 25-(OH)D between 10-15 ng/mL had a 53% increased risk, compared to those with 25-(OH)D > 15 ng/mL. A serum 25-(OH)D level less than 30 ng/mL is considered deficient by most vitamin D experts. The authors concluded vitamin D deficiency is positively correlated with incident cardiovascular disease.

Reference:
Wang TJ, Pencina MJ, Booth Sl, et al. Vitamin D deficiency and risk of cardiovascular disease. Circulation 2008;117:503-511.

 

Vitamin D Levels May Affect Blood Pressure

The health benefits of maintaining an adequate serum level of 25’hydroxy vitamin D are numerous. A recent article in the American Journal of Clinical Nutrition hypothesized that systolic blood pressure levels might be influenced by serum levels of 25-hydroxyvitamin D, or 25(OH)D.

In this cross-sectional study, data from the National Health and Nutrition Examination Survey (1988-1992) was evaluated, and the authors found a significant association between age-associated blood pressure increase and serum 25(OH)D in white subjects. Deficient subjects (<50 nmol/L, or 20 ng/ml) had an age-related systolic blood pressure (SBP) increase of 0.50 mm Hg/year, insufficient subjects (50-79 nmol/L or 20-31.6 ng/ml) 0.48 mm Hg/y, and sufficient (>80 nmol/L or 32 ng/ml) subjects had an SBP increase of 0.40 mm Hg/y. “Participants who were vitamin D deficient and insufficient had significantly higher age-associated increases in SBP than did participants who were vitamin D sufficient (p=0.01).

In this population of 7,699 people 19 yrs of age or older, 61% of whites and 92% of blacks were found to have insufficient vitamin D levels as defined as a serum 25(OH)D level less than 80 nmol/L (32 ng/ml). This was of particular concern because 65% of the black participants had vitamin D levels checked in the summer or fall, when levels are typically highest. The researchers were unable to detect a correlation between blood pressure and vitamin D in these subjects because practically all were deficient.

Reference:
Judd SE, Nanes MS, Ziegler TR, et al. Optimal vitamin D status attenuates the age-associated increase in systolic blood pressure in white Americans: results from the third National Health and Nutrition Examination Survey. Am J Clin Nutr 2008;87:136-141.

 

High-Dose Vitamin D Shows Excellent Safety in MS Patients

Epidemiological studies have shown a significantly increased risk of developing multiple sclerosis (MS) in people who are vitamin D deficient, and have correlated increased symptomatology in MS patients with lower serum levels of 25-hydroxy vitamin D. To test the tolerability and safety of high doses of vitamin D in MS patients, researchers from the University of Toronto and two hospitals in Toronto gave 12 MS patients 1,200 mg elemental calcium along with increasing doses of vitamin D for 28 weeks. The starting dose was 28,000 IU per week, which was increased to 280,000 IU per week. Serum 25-OH vitamin D levels rose dramatically, to a mean of 154 ng/mL at the end of the study. This supraphysiological level was not associated with any negative effects on liver or kidney function, or on serum or urinary calcium levels. MS disease activity was not affected; however, the mean number of gadolinium-enhancing brain lesions was significantly decreased during the study. This is a groundbreaking study, as it demonstrates that a very high vitamin D oral dosage and the resultant very high serum 25-OH vitamin D level are safe in MS patients. This may stimulate researchers to use higher supplemental therapeutic vitamin D doses in the future, which will provide more safety and efficacy data regarding supplementation with this essential nutrient.

Reference:
Kimball SM, Ursell MR, O’Connor P, Vieth R. Safety of vitamin D3 in adults with multiple sclerosis. Am J Clin Nutr 2007;86:645-651.

 

Vitamin D Deficiency “Almost Universal” in Elderly Hip Fracture Patients

Researchers in Scotland report in the September 2005 issue of Current Medical Research and Opinion an “almost universal vitamin D inadequacy” in 548 elderly patients admitted to the hospital for hip fracture. Data was gathered over a four-year period at South Glascow University Hospital, and showed that 97.8 percent of hip fracture patients had low serum vitamin D, one-fourth being so low as to be undetectable. The lead author, Dr. Stephen Gallacher, stated that doctors “should do all they can to encourage their osteoporotic patients to adhere to their vitamin D supplementation.” Vitamin D is necessary for calcium regulation and deposition in bone, and vitamin D deficiency is a well-known risk factor for osteoporosis.

Reference:
Gallacher SJ, McQuillian C. Harkness M, et al. Prevalence of vitamin D inadequacy in Scotish adults with non-vertebral fragility fractures. Curr Med Res Opin 2005;21(9):1355-1362.

ARTICLES: Grant W, Holick W. Benefits and requirements of vitamin D for optimal health: a review. Altern Med Rev 2005;10(2):94-111.

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