PEOPLE WHO INSTILLED FIBRE HYPOTHESIS IN BURKITTS MIND- PART 4 ALEC R. P. WALKER PhD, DSc (1913–2007)

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Alec Walker was a Scotsman, born in 1913. He had degrees in chemistry and physics. He emigrated to Southern Africa in 1938, joined the Municipal Department of Health, Johannesburg in 1939. He was interested in research on diseases related to diet, poor nutrition and prosperity.
                    
Lets see what is the contribution of Walker in fibre hypothesis in this post…

His first publication was in 1943 and till now he has written over 900 papers, letters and editorials. His last publication was on the health benefits of vegetable and fruit consumption in 2006 when he was 92 years.

Some of his interesting researches were….
ü  He was the first person to show that the body adapts to low Calcium intake by increasing absorption.
ü  He studied the prevalence of atherosclerosis and coronary heart disease in South African population.
ü  He published many papers on the role of fat, cholesterol and essential fatty acids in coronary vascular diseases.

Walker first mentioned about fibre in 1947. His interest was triggered by the widespread use of laxatives in many countries to correct what he calls as an ‘inadequate bowel movement’. He says the cause for this ‘as change in diet’. The introduction of roller milling towards the end of the nineteenth century, made the production of white bread with little fibre .

In 1954, he reported his research related to diet and atherosclerosis.  He studied the dietary fat intake and serum cholesterol in several hundred South Africans of different ethnic backgrounds. Interesting finding was black South Africans living in Johannesburg ate a higher fat intake than their rural counterparts, but their serum cholesterols were much lower than expected. He concluded as ‘Summarizing, of the dietary factors, our impression is that, apart from low fat intake, there is a factor or factors in the pattern of diet of the Bantu possibly related to its high fibre content which bears some responsibility for the low serum cholesterol values observed.’ This was an original observation and prompted Ancel Keys, of the University of Minnesota (USA) and many others to do experiments on cellulose and pectin and their effects on serum cholesterol.

Walker’s studies clearly indicate that fibre is related to atherosclerosis and coronary heart disease. Walker had read Wynder & Shigematsu’s 1967 paper on the possible environmental causes of large bowel cancer.They suggested that variation in contact time between faeces and bowel mucosa may be determined by diet. Walker started measuring transit time, the time taken for material to pass through the gut, in his African populations. Using a non-absorbable red dye, carmine, and later the technique of radio-opaque pellets, he showed that transit is much quicker in the South African blacks than their Caucasian counterparts and that bowel cancer is rarely seen in the black population.

By July 1970, he submitted a paper entitled ‘Diet, bowel motility, faeces composition and colonic cancer’ to the South African Medical Journal. He has reported his own work on bowel transit and earlier observations on diet together with ‘contributions’ by others to propose a role for fibre in the prevention of large bowel cancer.

Picture taken from  John H. Cummings and Amanda Engineer. Denis Burkitt and the origins of the dietary fibre hypothesis. Nutrition Research Reviews (2018), 31, 1–15

Walker suggested that the high-fibre diets of the Africans lead to faster transit of bowel contents and less degradation of large bowel constituents such as bile acids. His paper on the same was published in 1971, coinciding with one on a similar topic by Burkitt (Burkitt DP (1971) Epidemiology of cancer of the colon
and rectum. Cancer 28, 3–13).

Walker was a very humble and self-effacing man. Credit should be given to him for his early and original contribution to the fibre hypothesis. His interests were wide, his output of scientific papers was prodigious and to some extent his contribution has been undervalued. He met Burkitt for the first time in 1969 and they became colleagues. They went on to co-author six papers together. It may be that few months after they first met in 1969, lead to the development of the fibre hypothesis in Burkitt’s mind.

In the next post, we will see about one more important person who instilled fibre hypothesis in Burkitts mind.

References:
1.     John H. Cummings and Amanda Engineer. Denis Burkitt and the origins of the dietary fibre hypothesis. Nutrition Research Reviews (2018), 31, 1–15
                                                                                       Written by Dr.Priyavadhana



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