Arnold Peter Meiklejohn (1909 – 14 June 1961) was an English physician and academic, specializing in nutrition.

In 1938, he was elected as a Peabody Fellow of the Harvard Medical School and during the Second World War worked for the Rockefeller Foundation and as nutrition adviser to UNRRA. In 1945, shortly after the liberation of Bergen-Belsen concentration camp, Meiklejohn was put in charge of administering a starvation diet to the camp’s severely malnourished and dying inmates.

After the war, he became a lecturer in nutrition at the University of Edinburgh and in 1947, at the request of the Medical Research Council (MRC), assessed and reported on the state of nutrition of German civilians.

He wrote a number of papers on nutrition, particularly on errors of metabolism, and with Sir Stanley Davidson and R. Passmore was co-author of the textbook Human Nutrition and Dietetics (1959).

Peter Meiklejohn was born in Harpenden in 1909. He attended Gresham's School, where he was a contemporary of W.H. Auden, Stephen Spender, and John Pudney. From there, he was awarded a scholarship to Oriel College, Oxford, and in 1931 graduated BSc in physiology with first-class honours. He then gained admission to St Mary's Hospital, London, to study medicine, and in 1935 achieved his B.M., B.Ch.^[1] He was then a house physician in the St Mary’s Medical Unit, and in 1936 gained a Radcliffe Travelling Fellowship. In 1938, he was elected as a Peabody Fellow of the Harvard Medical School.^[2] For three years he worked with leading American physicians who included George Minot and William Bosworth Castle,^[1] and from 1939 to 1941 published papers in The New England Journal of Medicine on human nutritional deficiencies,^[2] writing often on errors of metabolism. In 1941, his paper "Is Thiamine the Anti-neuritis Vitamin?" was published in The Johns Hopkins Bulletin.^[1]

In 1941, Meiklejohn became a member of the Rockefeller Foundation Health Commission.^[2] He returned to live in England, and the 1942 edition of The Medical Directory gives his address as 15, Ox Lane, Harpenden, Hertfordshire.^[2]

During the Second World War, Meiklejohn became nutrition adviser to the United Nations Relief and Rehabilitation Administration (UNRRA).^[3][4]

After the war, UNRRA wound down its activities, and in 1946 Meiklejohn was appointed as a senior lecturer in nutrition at the University of Edinburgh, where he remained for fifteen years and became known for his well-prepared and entertaining lectures.^[1]

Also in 1946, following a severe winter and restricted imports, leading to German demands for more food, the British Medical Research Council sponsored a number of nutritional scientists including Robert McCance, Elsie Widdowson, and Meiklejohn to report on the German state of health. All three came to the same conclusion that the Germans might have lost some weight due to food shortages but were generally not malnourished, and after examining more than 2000 Germans, Meiklejohn reported that "many adults are likely to have benefitted from losing excess weight and its complications of high blood pressure, diabetes and gall stones".^[6] He disagreed with German studies of the nutritional state of its civilians, stating the "Germans are now grossly over exaggerating the effects of the food shortage".^[6]

In 1949, Meiklejohn received the degree of D.M. In the same year his publications earned him Membership of the Royal Colleges of Physicians of the United Kingdom.^[1] In 1950 he was elected a member of the Harveian Society of Edinburgh.

In 1954 he published a paper titled "The curious obscurity of Dr James Lind" in the Journal of the History of Medicine and Allied Sciences which contributed to the inspiration of research into James Lind following the bicentenary year of the Treatise he produced.^[20]

In 1959 he co-authored the acclaimed textbook Human Nutrition and Dietetics with Sir Stanley Davidson and R. Passmore.^[1]

In 1950, Meiklejohn was on the electoral register for Edinburgh West at 9, St Bernards Crescent, with Margaret L. Campbell-Renton. In 1960, he was at 8a, Fountainhall Road, in Edinburgh South, with Jean S. Meiklejohn.^[21]

Known as Peter, and not Arnold, Meiklejohn was married to Jean, and they had two sons, who were small boys at the time of his death on 14 June 1961, in an accident while fishing in a Highland river. He was 51.^[1]

His obituary in the British Medical Journal enumerated some of his quirks, saying; "He had many amusing and endearing foibles; there were his oddities of dress, his dilapidated motor-car, his inveterate snuff-taking, and his refusal to drink coffee at lunch as he said it disturbed his post-prandial nap-normally enjoyed on the floor of his room in the Department of Medicine with his head resting on a green velvet pillow specially designed for the purpose."^[1]