The Association Between Dietary Sulfur Amino Acid Intake and Markers of Vascular Health

Abstract

OBJECTIVEThe sulfur amino acid (SAA) methionine (Met) is a precursor to the SAAs cysteine (Cys) and its oxidized form, cystine (CySS). Previous research has found positive associations between plasma CySS levels and classic CVD risk factors (e.g., age, blood pressure, obesity). As dietary SAA can influence plasma levels of SAA, we hypothesized that increased intake of dietary SAAs would be associated with worsened markers of vascular health.SUBJECTS AND METHODSThis was a cross‐sectional study of 685 adults in the Emory/Georgia Tech Predictive Health Initiative cohort. Key markers of vascular health were assessed including arterial stiffness [via pulse wave velocity (PWV) and augmentation index (AIX)], flow mediated vasodilation (FMD), blood pressure (BP), and serum levels of triglycerides (TG), total cholesterol (TC), LDL‐C, and HDL‐C. Habitual dietary intake of Cys, CySS, Met and glutathione (GSH), a related sulfur‐containing antioxidant, were determined from the Block Food Frequency Questionnaire and corrected for energy intake. The relationships between dietary intake and markers of vascular health were assessed with Pearson correlations and multiple linear regression, adjusted for age, sex, race, BMI, smoking history, diabetes status, and history of CVD.RESULTSThe mean age was 48.2 yr (SD=10.8); 66% of subjects were female and 71% were white. Four percent of participants were current smokers, 8% reported a history of diabetes, and 7% reported a history of CVD. Reported dietary intake of total SAA was 39.6 ± 17.3 mg/kg/day, over twice the Recommended Dietary Allowance for total SAA. Pearson analyses showed no significant correlations of dietary SAA, reduced GSH, or total GSH with PWV, AIX, FMD, systolic or diastolic BP, or serum lipid levels. However, there was a positive association between total dietary GSH intake and HDL levels (r=0.11, p=0.006). After multivariate adjustment for demographic variables, dietary intake of Met was inversely associated with PWV (beta=−0.06, p=0.03). Dietary intake of Met (beta =−0.14, p=0.04), CySS (beta=−0.17, p=0.02) and total SAA (beta=−0.16, p=0.049) were inversely associated with serum TG levels. Dietary intake of GSH remained positively associated with serum HDL (beta=0.002, p=0.02).CONCLUSIONContrary to our hypothesis, higher dietary intake of Met (but not Cys or CySS) was associated with decreased arterial stiffness (PWV), while intake of individual and total SAA was not linked to AIX or FMD. Increased dietary intake of SAAs was also associated with decreased serum TG levels, and dietary GSH was positively associated with increased serum HDL. Further studies on the impact of dietary intake of SAA and GSH over time on markers of vascular health and oxidative stress in individuals at risk for CVD appear warranted.Support or Funding InformationEmory SURE program and NIH grants UL1 TR000454, K01 DK102851 (JAA), P30 ES019776 (ELB, TRZ, JAA) and K24 DK096574 (TRZ)