He is a leading researcher into the immune and endocrine aspects of depression – specifically, the role of gut microbiota in stress-related disorders. He is also an authority on bowel health, the pharmacology and neurobiology of affective disorders, and many other fields of psychiatry.

Dr Dinan has published over 500 papers and numerous books on pharmacology and neurobiology. His work has made an impact on both sides of the Atlantic, as evidenced by his position as a Fellow of the Royal Colleges of Physicians and Psychiatrists, and a Fellow of the American College of Physicians.

In 1995, Dr Dinan won the Melvin Ramsey Prize for his research into the biology of stress. His research has been funded by bodies such as Science Foundation Ireland, the Health Research Board and the European Union.

In 2019, he was ranked by Expertscape as the number 1 global expert on the microbiota and also listed in the top 100 Global Makers and Mavericks.