The associations of habitual intake of sulfur amino acids, proteins and diet quality with plasma sulfur amino acid concentrations: The Maastricht Study.

BACKGROUND: Plasma sulfur amino acids (SAAs, i.e., methionine, total cysteine (tCys), total homocysteine (tHcy), cystathionine, total glutathione (tGSH) and taurine) are potential risk factors of obesity and cardiometabolic disorders. However, except for plasma tHcy, little is known about how dietary intake modifies the concentrations of plasma SAAs.

OBJECTIVE: To investigate whether intake of SAAs and proteins or diet quality are associated with plasma SAAs.

METHODS: Data from a cross-sectional subset of The Maastricht Study (n=1145, 50.5% men, 61 [IQR: 55, 66] years, 22.5% with prediabetes and 34.3% with type 2 diabetes) were investigated. Dietary intake was assessed with a validated food frequency questionnaire. Intake of SAAs (total, methionine and cysteine) and proteins (total, animal and plant) were estimated from the Dutch and Danish food composition tables. Diet quality was assessed with the Dutch Healthy Diet index, the Mediterranean Diet Score and the Dietary Approaches to Stop Hypertension score. Fasting plasma SAAs were measured with LC/MS-MS. Associations were investigated with multiple linear regressions with tertiles of dietary intake measures (main exposures) and z-standardized plasma SAAs (outcomes).

RESULTS: Intake of total SAAs and total protein was positively associated with plasma tCys and cystathionine. Associations were stronger in women and in those with normal body weight. Higher intake of cysteine and plant proteins was associated with lower plasma tHcy and higher cystathionine. Higher methionine intake was associated with lower plasma tGSH, while cysteine intake was positively associated with tGSH. Higher intake of methionine and animal proteins was associated with higher plasma taurine. A better diet quality was consistently related to lower plasma tHcy concentrations, but it was not associated with the other SAAs.

CONCLUSION: Targeted dietary modifications might be effective in modifying plasma concentrations of especially tCys, tHcy and cystathionine, which have been associated with obesity and cardiometabolic disorders.