Son of a Royal Navy captain and engineer, Peter Cleave (as he was always known) was bom in Exeter and educated at Clifton College. Entering the Bristol Medical School at the age of sixteen, he passed his primary FRCS at eighteen but decided to be a physician. He finished his training at St Mary’s Hospital and went straight into the Royal Navy. There he was a medical specialist in various hospitals at home and abroad, ending up as surgeon captain and director of medical research until he retired in 1962.
In the 1970s Cleave received international acclaim as the father of the dietary fibre hypothesis, but for twenty years before that he had been an obscure and ridiculed writer. As a boy he had become convinced of the importance of diet to health. His desire to prevent as well as to treat disease was strengthened by his eight-year- old sister’s death from perforated appendicitis. At medical school he was taught by Rendle Short, who propounded that appendicitis is caused by lack of cellulose in the diet. At this time also he was profoundly influenced by the writings of Charles Darwin, and henceforth he built all his theories on the rock of the adaptation of species to their environment.
His great vision was to see that the human body must be maladapted to the artificial foods of civilization of which the most artificial were the refined carbohydrates, chiefly sugar and white flour. He reasoned that if man avoided unnatural foods he would surely avoid unnatural diseases, that is, diseases absent in wild animals or primitive communities. He spent his life gathering evidence and developing arguments to support this view, which culminated in his grand hypothesis of a range of diseases caused by maladaptation to the foods and drinks containing refined carbohydrate. These diseases included obesity, diabetes, coronary heart disease, peptic ulcer, dental caries, constipation, appendicitis and varicose veins. Since they all had a common cause he viewed them as a single master disease, the Saccharine Disease. His book of this name, published in 1974, sold many thousands of copies. His previous books were A Molecular Conception of Organisms and Neoplasms (3rd edition 1955); Fat Consumption and Coronary Disease (1957); On the Causation of Varicose Veins (1960); Peptic Ulcer (1962); and Diabetes, Coronary Thrombosis and the Saccharine Disease (1966), jointly with GD Campbell; (1969) jointly with GD Campbell and NS Painter. The last of these had a wide readership; the rest were ignored.
Cleave was slow to achieve recognition for several reasons. At a time when others were learning to trust only randomized trials and probability values he trusted in the lessons of nature and logical argument. He was recording differences in disease patterns over time and space long before the epidemiology of chronic diseases was a recognized discipline. He looked for big differences and had no use for statistical analysis. He painted with broad strokes on the biggest possible canvas when others were focussing on ever more minute areas of investigation.
At his own expense, he published his lofty ideas and findings in books, while ordinary mortals submitted humbly to peer review and the rule of editors. In his crusade he bombarded would-be converts with letters. His letters were always colourful. Sometimes they had the impact of grapeshot, if not a broadside. Sensitive colleagues and admirers became alienated. He expected complete loyalty and hated criticism.
Cleave’s most effective advocate was Denis Burkitt FRS, already famous in another field, and the meeting of the two men in 1967 was the turning point in the fortunes of Cleave’s hypothesis. Burkitt’s connections with 150 Third World hospitals enabled him to confirm many of Cleave’s epidemiological observations and even to add to his list of Western diseases which can be explained by refined carbohydrate. In articles and spell-binding lectures, Burkitt woke doctors and scientists all over the world to the idea that diets depleted of fibre are harmful to health.
The idea of fibre depletion is inherent in Cleave’s concept but he preferred to emphasize the dangers of sugar, the fibre depleted extract of sugar cane and sugar beet. Burkitt and his East African physician colleague, Hugh Trowell, tended to emphasize the positive virtues of a high intake of fibre and especially of bran. But Cleave was the pioneer here too because in 1941 he had been one of the first to advocate raw bran in medical practice. While serving on the battleship King George V he had sacks of bran brought on board to combat the constipation which was prevalent in the sailors, deprived of fresh fruit and vegetables. Bran was so effective the Cleave became known throughout the navy as ‘the bran man’. Research has shown that bran has other valuable properties and its use has spread widely. But it is a serious distortion of Cleave’s idea to call it the bran hypothesis. His message is not that we should add fibre to our food (unless we need a laxative) but that we should stop taking fibre out of it.
1979 was his annus mirabilis, when he was awarded the Harben gold medal of the Royal Institute of Public Health and Hygiene (previously awarded to Pasteur, Lister and Fleming) and the Gilbert Blane medal for naval medicine, which is awarded jointly by the Royal College of Physicians and Surgeons but never before to a retired man. A few months later, the Royal College of Physicians published its report Medical aspects of dietary fibre which largely vindicated Cleave’s theory and summarized the large body of research which it has stimulated. But the full implications of overnutrition, and the role of fibre-depleted foods in causing it, have not received the emphasis which Cleave believed they deserved. His last work, published in 1977, was an article entitled Overnutrition, now the most dangerous cause of disease in westernized countries.
Cleave was certainly one of the most original medical thinkers of the twentieth century. His rare combination of panoramic vision, piercing logic and bulldog tenacity deserves the title of genius. He had his weaknesses (he utterly rejected a role for animal fat in coronary heart disease) and many of his ideas will be modified, but he was a true pioneer who started a major revolution in scientific thought.
His main relaxations were gardening, which he did with military precision, originality and great success, and also fly fishing and pigeon shooting.
Cleave married twice and was survived by a medically qualified son and a daughter from his first marriage as well as by his second wife, Helen. He was always very close to his younger brother, Hugh, also a retired surgeon captain.
KE Heaton
[Brit.med.J., 1983, 287, 1145, 1480; Lancet, 1983, 2, 862; Times, 21 Sept 1983]