Increasing levels of vitamin D could boost heart health, says a large study from the US that also calls for studies to assess a direct benefit of vitamin supplements.

"This is the first study, to our knowledge, to demonstrate a significant association between low vitamin D levels and CVD risk factors in a nationally representative sample," wrote lead author David Martins from Charles R. Drew University of Medicine and Science.

"Previous studies suggesting similar associations between low serum vitamin D levels and CVD risk factors were limited to subpopulations and small study samples," he added.

While very few health authorities have made, contrary to the scientific evidence, recommendations for the general public to take vitamin supplements (save folate during pregnancy to reduce the risk of neural tube defects in babies), this latest study is going to make it difficult for recommendations to not be made. It is particularly important to supplement with vitamin D during the winter months in colder climates or for people where exposure to the sun is very limited or negligible.

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Abstract: http://archinte.ama-assn.org/cgi/content/abstract/167/11/1159

Prevalence of Cardiovascular Risk Factors and the Serum Levels of 25-Hydroxyvitamin D in the United States

Data From the Third National Health and Nutrition Examination Survey

Authors: David Martins, MD, MS; Myles Wolf, MD, MMSc; Deyu Pan, MS; Ashraf Zadshir, MD; Naureen Tareen, MD; Ravi Thadhani, MD, MPH; Arnold Felsenfeld, MD; Barton Levine, MD; Rajnish Mehrotra, MD; Keith Norris, MD

Arch Intern Med. 2007;167:1159-1165.

Background  Results of several epidemiologic and clinical studies have suggested that there is an excess risk of hypertension and diabetes mellitus in persons with suboptimal intake of vitamin D.

Methods  We examined the association between serum levels of 25-hydroxyvitamin D (25[OH]D) and select cardiovascular disease risk factors in US adults. A secondary analysis was performed with data from the Third National Health and Nutrition Examination Survey, a national probability survey conducted by the National Center for Health Statistics between January 1, 1988, and December 31, 1994, with oversampling of persons 60 years and older, non-Hispanic black individuals, and Mexican American individuals.

Results  There were 7186 male and 7902 female adults 20 years and older with available data in the Third National Health and Nutrition Examination Survey. The mean 25(OH)D level in the overall sample was 30 ng/mL (75 nmol/L). The 25(OH)D levels were lower in women, elderly persons (60 years), racial/ethnic minorities, and participants with obesity, hypertension, and diabetes mellitus. The adjusted prevalence of hypertension (odds ratio [OR], 1.30), diabetes mellitus (OR, 1.98), obesity (OR, 2.29), and high serum triglyceride levels (OR, 1.47) was significantly higher in the first than in the fourth quartile of serum 25(OH)D levels (P<.001 for all).

Conclusions  Serum 25(OH)D levels are associated with important cardiovascular disease risk factors in US adults. Prospective studies to assess a direct benefit of cholecalciferol (vitamin D) supplementation on cardiovascular disease risk factors are warranted.

Author Affiliations: Department of Medicine, Charles R. Drew University of Medicine and Science, Los Angeles, Calif (Drs Martins, Zadshir, Tareen, and Norris and Mr Pan); The David Geffen School of Medicine, University of Calfornia, Los Angeles (Drs Martins, Felsenfeld, Levine, Mehrotra, and Norris); Department of Medicine, Harvard Medical School, Boston, Mass (Drs Wolf and Thadhani); Department of Medicine, VA Greater LA Healthcare System, Los Angeles (Drs Felsenfeld and Levine); and Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, Torrance, Calif (Dr Mehrotra).