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More obese had less vitamin D, and after low calorie diet, vitamin D went up – June 2010

Vitamin D Rising Serum 25-Hydroxy-Vitamin D Levels after Weight Loss in Obese Women Correlate with Improvement in Insulin Resistance.

J Clin Endocrinol Metab. 2010 Jun 9. Epub ahead of print
Tzotzas T, Papadopoulou FG, Tziomalos K, Karras S, Gastaris K, Perros P, Krassas GE.
Department of Endocrinology, Diabetes, and Metabolism (T.T., F.G.P., K.T., S.K., K.G., G.E.K.), Panagia General Hospital, 55132 Thessaloniki, Greece; and Department of Endocrinology (P.P.), Royal Victoria Infirmary, Newcastle upon Tyne NE1 4LP, United Kingdom.

Objective: The objective of the study was to examine changes of 25-hydroxy-vitamin D (25OHD) and PTH blood levels 4 and 20 wk after low-calorie diet-induced weight loss.

Methods: Forty-four obese women (aged 40.6 +/- 11.4 yr, body mass index (BMI) 36.7 +/- 4.9 kg/m(2)) and 25 controls (BMI 22.9 +/- 1.5 kg/m(2)) were examined. Anthropometric and cardiometabolic parameters and 25OHD and PTH levels were determined at baseline and 4 and 20 wk after a low-calorie diet.

Results: At baseline, 25OHD levels were lower in obese compared with control subjects (17 +/- 6.0 vs. 23.8 +/- 8.7 ng/ml, P < 0.001), whereas no differences were found in PTH levels. In all women, a negative correlation was found between 25OHD levels and body weight (BW) (r -0.32, P < 0.001), BMI (r -0.37, P < 0.001), waist circumference (r -0.26, P < 0.05), and percent fat mass (r -0.38, P = 0.001) as determined by bioelectrical impedance analysis.

The 4-wk low-calorie diet (n = 37) reduced BW and led to significant improvements in the homeostasis model assessment (HOMA) index and lipid levels.

The 20-wk low-calorie diet (n = 26) resulted in reduction of BW and BMI by 10%, HOMA index (4.7 +/- 3.8 vs. 3.10 +/- 1.7, P < 0.01), and lipids levels (except high density lipoprotein cholesterol) and increase in 25OHD (15.4 +/- 6.0 vs. 18.3 +/- 5.1 ng/ml, P < 0.05), compared with baseline. PTH levels were unchanged. The increase of 25OHD levels was associated with the reduction of insulin levels and HOMA index (r -0.43, P < 0.05).

Conclusions: Blood 25OHD levels were low in obese women and correlated inversely with severity measures of obesity. Weight loss of 10% after low-calorie diet increased 25OHD levels, and this increase was mainly associated with improvement of insulin resistance. PMID: 20534751