He is professor in human nutrition and medicine at the University of Otago and consultant physician (endocrinology) at Dunedin Hospital.

[2] In 1988, Mann moved to New Zealand where he was appointed professor of human nutrition and medicine at the University of Otago,[2][4][5][6] and consultant physician (endocrinology) at Dunedin Hospital.

[9] In 2015 he was appointed director of Healther Lives – He Oranga Hauora, a National Science Challenge based at the University of Otago.

[11] Mann and his team at the University of Otago carried out a major review for the World Health Organization (WHO) of the scientific evidence on sugar and weight gain, published in 2013 in the British Medical Journal.

"[13] Mann and his coworkers at Otago carried out a "landmark" review, commissioned by the WHO and published in The Lancet in 2019.