Short-term Folinic Acid Supplementation Improves Vascular Reactivity in HIV-infected Individuals: a Randomized Trial

Design and participants This was a randomized, double-blind, placebo-controlled trial. Eligible participants were individuals with known HIV disease according to Centers for Disease Control revised criteria, aged 18 or over, on ART for at least 6 months, with undetectable viral load (less than 50 copies/ml), and CD4 counts more than 200 cells/mm3. Exclusion criteria were diabetes mellitus, any active infection, liver disease, renal disease, history of cardiovascular disease, or uncontrolled hypertension, pregnancy, use of illicit drug and mental illness that would compromise understanding and collaboration with the study. Patients currently using tobacco, taking any dietary supplement (such as folic acid or antioxidants) or women taking hormone replacement therapy were also excluded. All medications in regular use were maintained throughout the study period. The protocol was approved by the committee for ethics in research of the Hospital de Clínicas de Porto Alegre, and all participants gave written informed consent.

Study settings The study took place at the HIV outpatient clinic of the Hospital de Clínicas de Porto Alegre, a national reference center for HIV/AIDS in southern Brazil, from August 2009 to September 2011.

Interventions Participants were randomly assigned to a 4-week treatment with either folinic acid (n=15) or placebo (n=15). The study supplementation regimens consisted of the capsules containing 5 mg of folinic acid or placebo. Participants were provided with 1 bottle, which contained 30 capsules. Subjects were instructed to take 1 capsule daily, in the morning.

Outcomes The primary outcome measure was assessment of brachial artery vascular responses during reactive hyperemia. Secondary outcomes were the changes on the biochemical and hemodynamic variables.

Vascular measurements After an overnight fast, the assessments were performed in a temperature-controlled (20-22°C), quiet room, with subjects in the supine position. Throughout the protocol, blood pressure (BP) and heart rate were measured in the dominant arm using a calibrated oscillometric automatic device (Dinamap 1846 SX/P; Critikon, Florida, USA). Forearm blood flow was measured by venous occlusion plethysmography (D.E Hokanson, Washington, USA), in the nondominant limb, as previously described. In short, a rapid inflator cuff was used in the upper arm to occlude venous outflow and hand circulation was arrested by placing a cuff around the wrist. Reactive hyperemia (RH) was induced by placing a cuff in the upper-arm at 250 mmHg, and releasing after 5 min. All flow recordings were manually traced by an operator who was blinded to the groups, and time. The reproducibility of flow measurements in our laboratory has intraday and interday coefficients of variation of 6.9 and 9.2%, respectively. After 15 min of rest, 2.5 mg of sublingual isosorbide dinitrate (Isordil®, Sigma, Brazil), was administered as an endothelium-independent vasodilator. Five minutes later, endothelium-independent vasodilatation of the brachial artery was measured.