Risk Group

Reasons

Reference

Pregnant women

Methionine is metabolised to homocysteine and raised plasma homocysteine is associated with birth defects, pre-eclampsia, spontaneous abortion and placental abruption.

15, 16

Schizophrenic patients

Schizophrenic patients given 10–20 g methionine daily developed functional psychoses.

17

Patients with pre-existing cancer

Animal studies have shown that restriction of methionine intake blocks division and metastasis of tumour cells.

18,19

Ischaemic heart disease (IHD), peripheral vascular disease (PVD), stroke

Methionine is metabolised to homocysteine – raised homocysteine levels are associated with IHD, PVD and stroke.

20-22

Patients with chronic liver disease

The liver has an impaired ability to metabolise methionine.

22