 Intervention: Subjects will be randomly allocated to receive 5g of NWT-03 and placebo, once daily, on separate occasions, for a period of 4 weeks and with a washout period between the two interventions of typically 4 weeks. However, this period may be shortened by 2 weeks or extended by 8 weeks, depending on the availability of the subject. Total study duration will be 10 - 16 weeks, depending on the duration of the washout period. 