Vitamin D Supports Immunity, Prevents Falls in the Elderly

VRP Staff

Two new studies have unearthed important findings about vitamin D3’s role in health. One study indicates vitamin D3 has antimicrobial actions that can protect against such bacterial infections as tuberculosis, while the other study finds that together with calcium it can limit the number of falls in the elderly.

In the one study, published in the journal Science, vitamin D3 triggered a key antimicrobial response in humans against Mycobacterium tuberculosis (TB).

In innate immune responses, activation of Toll-like receptors (TLRs) triggers direct antimicrobial activity against intracellular bacteria. The researchers in the current study have discovered that when TLR activates human macrophages, the expression of the vitamin D receptor is upregulated within these immune cells. Also upregulated in the immune cells was a gene that activates the enzyme that converts vitamin D to its active form. When vitamin D’s active form was added to the immune cells, this triggered the action of an antimicrobial peptide that helps kill intracellular TB. However, when the vitamin D receptor and vitamin D activating enzyme were inhibited, the antimicrobial peptide remained dormant.

In addition, the researchers observed that blood serum from African-American individuals, known to have increased susceptibility to tuberculosis, had low vitamin D levels. The serum from the African Americans was less efficient in triggering the antimicrobial peptide that kills TB. However, when researchers added vitamin D to serum samples from African-American subjects, it restored the antibacterial properties of the peptide that kills TB.

Based on these results, the study authors believe that “differences in ability of human populations to produce vitamin D may contribute to susceptibility to microbial infection.”

The findings also may help explain why African-Americans, who are often deficient in vitamin D, are more susceptible to TB.

The other study indicates vitamin D, when combined with calcium, may reduce the risk of falling in elderly women by 65 percent.

Although a recent meta-analysis found that vitamin D could reduce falls by more than 20 percent, little is known about whether supplemental vitamin D plus calcium citrate malate will lower the long-term risk of falling in elderly individuals.Vitamin D and calcium may be able to prevent falls because when the elderly fall, it is not the fall that breaks their hips but rather the hip snaps, resulting in a fall. The researchers decided to see whether the bone-strengthening effects of these two supplements could reduce the rate of falls.

Researchers studied the effect of 3 years’ supplementation with vitamin D3 and calcium on the risk of falling at least once in 199 men and 246 women 65 years or older who were living at home. Individuals received 700 IU of vitamin D3 plus 500 mg of calcium citrate malate per day or a placebo in a randomized, double-blind manner. Subjects were classified as less physically active if physical activity was below the median level.

In 3 years, 55 percent of women and 45 percent of men reported at least 1 fall. Vitamin D3-calcium significantly reduced the odds of falling in ambulatory older women by 46 percent. In less active women, vitamin D3 and calcium reduced falls by 65 percent. No reduction in risk occurred in men.

References:
Liu PT, Stenger S, Li H, Wenzel L, Tan BH, Krutzik S, Ochoa MT, Schauber J, et al. Toll-Like Receptor Triggering of a Vitamin D-Mediated Human Antimicrobial Response. Science. Published Online February 23, 2006. DOI: 10.1126/science.1123933

Bischoff-Ferrari HA, Orav EJ, Dawson-Hughes B. Effect of cholecalciferol plus calcium on falling in ambulatory older men and women: a 3-year randomized controlled trial. Arch Intern Med. 2006 Feb 27;166(4):424-30.