Lack of Vitamin D Linked to CVD Biomarkers, Inflammation

Marlene Busko

February 27, 2014

COLERAINE, UK — Older, healthy individuals who were deficient in 25-hydroxy vitamin D (vitamin D) tended to have higher levels of biomarkers linked with CVD and inflammatory conditions such as multiple sclerosis and rheumatoid arthritis, in an observational study[1].

More specifically, individuals who had a vitamin-D deficiency had significantly higher levels of interleukin-6 (IL-6) and C-reactive protein (CRP) and higher IL-6:IL-10 and CRP:IL-10 ratios, compared with their peers who were not deficient.

This is the first study to demonstrate that vitamin-D status is linked with markers of inflammation in a population of independently living, older adults and the first to investigate the link between vitamin D and inflammatory ratios, which may be more reliable measures of inflammation, Dr Mary Ward (University of Ulster, Coleraine, United Kingdom) told heartwire in an email.

"The results suggest that older adults with a deficiency in vitamin D may be at risk of having a more proinflammatory immune profile . . . which in itself may be a risk factor for [acute or] chronic disease development, [including] CVD, osteoporosis, and cognitive dysfunction," she said. "However, further research needs to be undertaken in order to confirm these findings."

The study was published online February 25, 2014 in the Journal of Clinical Endocrinology and Metabolism.

Vitamin-D Deficiency in an Elderly Cohort

Inadequate levels of vitamin D are common in older individuals and may be implicated in immune dysfunction, but few studies have investigated this in an exclusively elderly cohort, Ward and colleagues write.

The current observational study was part of the Trinity Ulster and Department of Agriculture (TUDA) aging cohort study in Northern Ireland, which was designed to investigate nutritional factors and gene-nutrient interactions in the development of chronic disease in adults over age 60—which is one component of the Irish-government-funded Joint Irish Nutrigenomics Organisation (JINGO) project

To investigate the link between vitamin-D status and markers of inflammation, the researchers analyzed data from 957 hypertensive participants in TUDA. The participants, with roughly equal numbers of men and women, had a mean age of 70.5 years. They had a mean blood pressure of 154 mm Hg/80 mm Hg, and about 90% were receiving at least one antihypertensive.

Compared with individuals with sufficient serum levels of vitamin D (>75 nmol/L), those who were deficient (<25 nmol/L) had significantly higher levels of the inflammatory biomarkers IL-6 and CRP, and they were more likely to have CRP:IL-10 and IL-6:IL-10 ratios above 2, where IL-10 is an anti-inflammatory biomarker.

"There is . . . an urgent need for further studies to ascertain with certainty the vitamin-D concentration that is optimal for immune function and the potential implications of increasing dietary recommendations for vitamin-D intake within the population," the researchers write.

Good Rationale, Good Cross-Section, but RCT Needed

"I think all of us now think that inflammation is a critical factor in a lot of disease . . . so there's some rationale for thinking about trying to reduce chronic inflammation with something as simple as vitamin D, and it may have a further effect on atherosclerotic risk of cardiovascular disease," Dr Clifford J Rosen (Tufts University School of Medicine, Boston, MA), an author of the Endocrine Society's scientific statement on nonskeletal effects of vitamin D[2], commented.

Strengths of the study by Ward and colleagues include that they looked at "an "older [population] with a good cross section of values for [vitamin D], and the deficiencies [were] really deficient; less than 25 nmol/L, which is less than 10 ng/mL, is really low, and those people [generally] have other comorbid conditions," Rosen added.

However, "until we do randomized trials, these observational studies really don't provide us with much insight," he cautioned. The Vitamin D and Omega-3 Trial (VITAL), a randomized clinical trial of 20 000 men and women, which is looking at hard outcomes and expected to be completed in June 2016, should provide a clearer picture of the role for vitamin D and omega-3 supplements in preventing cancer and CVD, he noted.

The researchers report no conflict of interest.

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