Isabella Leitch

"It might seem an extremely easy matter to obtain accurate records of food consumed. Experience shows that it is not so. At the foot of the social scale there is a residue of housewives who are incapable of keeping accurate records, even with help and supervision. The work of Dr A. M. Thomson (unpublished) on shows that those unable to keep records are, almost certainly, worse fed than the more intelligent. In most surveys they swell the proportion of non-cooperators. But in all social and intellectual grades, vigilance is needed. Even highly intelligent scientists have been found grossly inaccurate in attempts to record what they ate the day before (Morrison, Russell & Stevenson, 1949)."

"A very large number of variables must be considered and either eliminated by matching or allowed for in the plan of any piece of research in . First the animals, including man: to be taken into account are breed, sex, age, size at birth and at completed growth, rate of growth or of production (milk, egg, meat), stage of reproductive life, previous dietary history, physical environment (e.g., temperature and humidity). Second, in diet there is a great complexity of s. Known to be of importance are about 20 s, 14 inorganic elements each in many different compounds, and 17 s of known structure; of s there are 10 sugars and 8 groups of s; 14 s, and as many s, innumerable pigments and aromatic substances, as well as many injurious and inert components, present in countless different foods. Add to which that a complete longitudinal study of human growth must take about 20 years, of growth in a pig at least 3 years and even in a rat 9 months; and that there is the reproductive span also, and old age beyond that. It is obvious that the number of possible questions is enormous and that no one man or one team in the whole of a lifetime can hope to cover by original research more than a minute part of any nutritional field."

"... Dr Isabella Leitch ... had a profound but often unacknowledged or unrecognizaed influence on nutritional science and scientists. Though a member of the since its formation, she never held office except as an editor of the first three volumes of the and the first five volumes of the . She contributed several papers of notable originality to its meetings and in 1979 the Society paid tribute by electing her as an Honorary Member. She was Director of the Commonwealth Bureau of Nutrition in Aberdeen from 1945 until her retirement in 1960; and as a member of staff of the Bureau since its formation was the driving force behind Nutrition Abstracts and Reviews for over 30 years."