An adult male, 45 yrs old, has a chief complaint of pitting oedema in ankles, BP 120/80; lab investigations serum urea 29.8 mg%, serum creatinine 1.2 mg%, serum uric acid 7.8 mg%, serum TSH 5.7 uIU/ml. Oedema disappears at rest by night.

History of drug treatment: lithium 300 mg bd -400 mg bd since 15 years, propranolol 10-40 mg/day 10 years, quetiapine 100 mg 2 years, amisulpride 50-100 mg since 3 months. What should be the dietary advice to be given to this patient?