Newcastle Magnetic Resonance Centre, Institute of Cellular Medicine, Newcastle University, Campus for Ageing & Vitality, Newcastle upon Tyne NE4 5PL, UK. Electronic address: roy.taylor@ncl.ac.uk. Newcastle Magnetic Resonance Centre, Institute of Cellular Medicine, Newcastle University, Campus for Ageing & Vitality, Newcastle upon Tyne NE4 5PL, UK. Human Nutrition Research Centre, Institute of Health & Society, Newcastle University, Newcastle upon Tyne NE2 4HH, UK. Department of Computer Science, Lagos State University, Ojo, Lagos State, Nigeria. Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne NE2 4HH, UK. Institute of Cardiovascular and Medical Science, University of Glasgow, Glasgow G12 8TA, UK. Human Nutrition, School of Medicine, Dentistry and Nursing, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow G31 2ER, UK.