Biological variation is evident in all aspects of nutrition, particularly total daily energy expenditure (TDEE) and basal metabolic rate (BMR). The impact of ethnicity on biological variation on certain aspects of energy metabolism has been investigated. Predictive equations to estimate BMR were published by the FAOIWHOIUNU (1985) in a report entitled EllerK}' and Protein Requirements. Since its publication, serious concern has been expressed on the validity of these equations, largely because the analysis appears to be based on a biased and incomplete analysis of the world literature on BMR. Using an expanded database (n=10,004) and stringent selection criteria the global BMR data has been re-analysed and new predictive equations presented. The robustness of the new equations were tested by comparing their predictive accuracy with those of existing ones. The BMR of 77 women aged 18-30 years were found to be best described by the newly developed Oxford Brookes equations and the Henry & Rees (1991) equations for tropical peoples (P<0.05 and NS respectively). Furthermore, the new expanded data base was used to plot nonnal curves for BMR for individuals which compared ethnic differences. It was observed that when BMR is expressed per kilogram of body mass, ethnic differences are diminished. The necessity to estimate TDEE in various ethnic groups prompted the evaluation of a non-invasive easy to use technique. Heart rate monitoring as a means of estimating TDEE is reviewed and compares favourably to the use of activity diaries. Whilst highly variable, heart rate monitoring is acknowledged as a valuable tool in the estimation of energy expenditure and activity in individuals and populations Ethnic differences in energy intake in a migrating student population were assessed. Malaysian students recently arrived in the UK were requested to keep food diaries in order to detect changes in their diets. Particular emphasis was placed on changes in the energy densities of food consumed and their effect on body weight and energy balance. After 6 months, it was observed that energy balance was maintained despite the energy density of food consumed in the UK being significantly (P<0.05) more energy dense than food consumed in their native Malaysia. This illustrates the precise way in which the human body can maintain energy balance. Anthropometric differences were compared in 553 individuals from 4 ethnic groups in a study investigating the ann-span and height relationship. Differences were found between the ethnic groups (P<O.OI). The use of ann-span as a proxy for height should be used with caution. It is imperative that more global data collected under strict control is required before human biological variation can be attributed to true ethnic differences and not merely individual variation.
Reeves, Sue L.
Supervisors: Henry, Jeya
Faculty of Health and Life Sciences
Year: 1997
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