Vitamin D Status and Components of Metabolic Syndrome in Older Subjects from Northern Finland (Latitude 65°North)

Abstract

Introduction: Vitamin D deficiency has been linked to the increased risk of several chronic diseases, especially in people living in the Northern Latitudes. The aim of this study was to assess the vitamin D status in older subjects born in 1945 in Northern Finland (latitude 65°North), and to examine its associations to components of metabolic syndrome (MetS). Methods: In this cross-sectional study, we invited 904 subjects born in 1945 from the Oulu region (Oulu45 cohort), out of an original cohort of 1332 subjects. In the cohort, plasma 25 hydroxyvitamin D (25OHD) levels were determined by an enzyme immunoassay of 263 men and 373 women, with a mean age baseline of 69±0.5 years old. We assessed the participants’ usage of vitamin D supplements, as well as their lifestyle factors, using a questionnaire. Results: Nearly 80% of the subjects had low vitamin D levels [either vitamin D deficient (<50 nmol/L) or insufficient (50 – 75 nmol/L)], and only 20% of the participants had sufficient vitamin D levels (>75 nmol/L) (based on the American Endocrine Society guidelines). The low vitamin D status was associated with a high prevalence of MetS; a significantly higher number of subjects with MetS (41%) had low vitamin D levels in comparison to the non-MetS subjects (38%) (p ≤ 0.05). The subjects under vitamin D supplementation had a significantly lower incidence of MetS (42.6% vs 57.4%) and its components in comparison to the non-supplemented subjects (p ≤ 0.05). Conclusions: Low vitamin D levels are a risk factor for MetS amongst other lifestyle factors, such as dietary habits and physical inactivity, among older subjects in the Northern Latitudes (65°North). Optimal supplementation of vitamin D, along with rich dietary sources of vitamin D, are highly recommended for older subjects as a means to positively affect, e.g., hypertension, insulin resistance, and obesity, as components of the MetS.

Serum Vitamin D Concentration ≥75 nmol/L Is Related to Decreased Cardiometabolic and Inflammatory Biomarkers, Metabolic Syndrome, and Diabetes; and Increased Cardiorespiratory Fitness in US Adults

“…Earlier studies relating serum vitamin D with MetS yielded mixed results. Our results of low vitamin D relation with high prevalence of MetS is in agreement with recent findings [31,32]. Two studies on middle-aged population reported an inverse relationship between 25(OH)D and triglycerides and blood pressure [33,34].…”

Impact of sunshine on the risk of gestational diabetes mellitus in primiparous women

“…Further, the individual daily sunshine hours during the first trimester of pregnancy were calculated for each woman individually. Our study observations endorse previous study findings that seasonality with different amounts of sunshine has an association with well-being and health [31,32].…”

Role of Vitamin D in the Metabolic Syndrome

“…Serum concentrations of vitamin D vary widely among different geographic areas, largely attributable to differences in sun exposure, a key source of vitamin D [ 15 ]. Thus, the frequency of hypovitaminosis, and therefore the potential risk of developing diabetes or MetS is higher in populations living further from the equator, and differences in clothing habits, skin color, and the use of sunscreen also play a role [ 29 ]. With regard to specific populations, vitamin D deficiency in postmenopausal women seems to be associated with a higher risk of MetS, hypertriglyceridemia, and lower HDL levels [ 26 ].…”