Nutritional Immunology and Inflammation
To 1) examine the burden of vitamin B12 deficiency, 2) determine the effects of recombinant growth hormone and rosiglitazone on vitamin B12 status, and 3) investigate vitamin B12 status as a risk factor for changes in insulin sensitivity (SI) and visceral adipose tissue (VAT), among HIV-infected patients with insulin resistance and visceral adiposity participating in a randomized controlled trial.
Methods : Participants were 72 HIV-infected adults (median [IQR]: 48 [43, 53] y) with insulin resistance and visceral adiposity who participated in a 12-week randomized trial of recombinant growth hormone (GH) and rosiglitazone (R). Venous blood samples were collected at baseline, 4, and 12 weeks, and samples were centrifuged, processed, and stored < -80ºC until analysis. Total vitamin B12, methylmalonic acid (MMA), homocysteine, and serum folate were measured in a subset. Vitamin B12 deficiency and insufficiency were defined as < 148.0 pmol/L and < 221.0 pmol/L, respectively. Elevated MMA was defined as >0.26 µmol/L.Generalized estimating equations were used to evaluate the effects of treatment on vitamin B12 status. Generalized linear models were used to assess the associations of vitamin B12 concentrations with SI and VAT.
Results : A total of 2.3% of patients were vitamin B12 deficient and 13.6% were vitamin B12 insufficient at baseline (median [IQR]: 419.8 [287.0, 538.6] pmol/L); 5.4% had elevated MMA concentrations. The GH+R intervention significantly lowered vitamin B12 concentrations at 4 (β: -66.6, 95% CI: -119.6, -13.6, p=0.01) and 12 (β: -73.3, 95% CI: -117.8, -28.7, p=0.001) weeks, compared to placebo. The GH-only intervention significantly lowered vitamin B12 concentrations at 12 weeks (β: -89.1, 95% CI: -143.0, -35.3, p=0.001), compared to placebo. Vitamin B12 concentrations did not significantly change in the R-only group. There were no significant changes in MMA concentrations. Vitamin B12 concentrations at baseline were not significantly associated with changes in SI or VAT (p >0.05).
Conclusions : The prevalence of vitamin B12 deficiency was low in HIV-infected individuals with insulin resistance and visceral adiposity. However, interventions containing recombinant growth hormone decreased vitamin B12 status during follow-up.
Funding Sources : BG was supported by NIH/NCATS Grant # TL1-TR-002386
Division of Nutritional Sciences, Cornell University