Plasma taurine and cysteine levels following an oral methionine load: relationship with coronary heart disease.

Objective: To test the hypothesis that endogenous synthesis of taurine from methionine is impaired in people with coronary heart disease (CHD).

Design: Nested case-control.

Subjects: Indian Asian and white European males aged 35-60 y. Both racial group included patients with CHD and healthy controls. Samples from 20 subjects in each of the four groups were selected at random.

Intervention: Fasting blood samples were taken before and 6 h after consumption of methionine (100 mg/kg body weight)

Measurements: Plasma concentrations of taurine, cysteine, pyridoxal-5-phosphate and 4-pyridoxic acid.

Results: Fasting plasma taurine values were higher in Indian Asian cases than controls, but not significantly different between European cases and controls. Postload taurine values were higher in cases than controls in both racial groups (P=0.002). Fasting plasma cysteine was higher in cases than controls (P=0.002) and higher in Indian Asians than Europeans (0.007), but there were no significant differences between any of the groups in postload cysteine values, nor in plasma pyridoxal-5-phosphate or 4-pyridoxic acid.

Conclusions: Taurine production from methionine was not impaired in patients with CHD, but fasting plasma cysteine was higher in CHD cases than controls.