Free-living energy expenditure was estimated by doubly-labelled water (DLW) and continuous heart-rate (HR) monitoring over nine consecutive days in nine healthy men with sedentary occupations but different levels of leisure-time physical activity. Individual calibrations of the HRenergy expenditure (EE) relationship were obtained for each subject using 30 min average values of HR and EE obtained during 24 h whole-body calorimetry with a defined exercise protocol, and additional data points for individual leisure activities measured with an Oxylog portable O2 consumption meter. The HR data were processed to remove spurious values and insert missing data before the calculation of EE from second-order polynomial equations relating EE to HR. After data processing, the HR-derived EE for this group of subjects was on average 0.8 (SEM 0.6) MJ/d, or 6.0 (SEM 4.2) 'YO higher than that estimated by DLW. The diary-respirometer method, used over the same 9 d, gave values which were 1.9 (SEM 0.7) MJ/d, or -12.1 (SEM 4.0) 'YO lower than the DLW method. The results suggest that HR monitoring can provide a better estimate of 24 h EE of groups than the diary-respirometer method, but show that both methods can introduce errors of 20 'YO or more in individuals.Energy expenditure: Doubly-labelled water: Heart-rate monitoringThe possibility that heart-rate (HR) monitoring may provide an alternative to whole-body calorimetry or doubly-labelled water (DLW) as a measure of 24 h energy expenditure (EE) is an attractive one due to the low cost of the HR monitors and the acceptability of HR monitoring for a wide range of subjects. The development of monitors which store minuteby-minute HR data for periods of 24 h or more has renewed interest in the method as it is now possible to estimate EE on a minute-by-minute basis rather than deriving a single value based on a mean daily HR. However, initial hopes that the relationship between HR and EE could be established for groups of subjects have not been realized, and the need for individual calibration of HR-EE relationships has been clearly established (Bradfield et al. 1970;Kalkwarf et al. 1989;Li et al. 1993). This requirement increased the complexity of the method, although the cost remains much less than that of DLW. Investigators differ in the mathematical model used to predict EE from HR, although it is generally agreed that an approach which takes account of the difference in the gradient of the relationship between HR and EE at low-and high-intensity activity is needed.
A study was performed in a rural Mexican community and in Mexico City to investigate possible differences in non-starch polysaccharide (NSP) intakes. One hundred and fourteen women (My-five rural and fitty-nine urban) and forty-three men (twenty-four rural and nineteen urban) completed 24 h r d questionnaires for three consecutive days with NSP intakes being estimated from a specially prepared set of new food composition tables. Potential underestimation of intakes was assessed by estimating individual BMR and dividing the estimated energy intakes by BMR to give a ratio. Excluding severe underrecording (ratio < 1.01) suggested NSP intakes of 2143 and 17.3 g/d in rural men and women and 17.7 and 15.6 g/d in urban men and women respectively. NSP sources differed, with a marked fall in intake from pulses in the urban areas but a compensatory increase of tortilla intakes and a rise in NSP-rich fruit consumption. Both soluble-and insoluble-NSP intakes were higher in rural areas. NSP intakes scaled by probable energy intakes of moderately active adults in developing countries suggest that NSP intakes in Mexico are similar to adjusted values in Africa, i.e. 26.9 g/d in Mexico Y. 28.5 g/d in Africa in rural men and 22.9 v. 21.0 g/d respectively in rural women. The NSP : energy density ratio (g/MJ) of the rural diet conformed with the World Health Organization (1990) goal. Data available on urban and rural communities for three countries showed that in each case the intake of NSP was lowest in the urban community.Non-starch polysaccharide intakes: Dietary fibre: AdultsThe importance for health of adequate NSP intakes is becoming widely accepted by national committees concerned with public health in the Western world. Analyses have been made, for example, of the possible effects of diets low in NSP on the incidence of metabolic diseases such as overweight and obesity (Weinsier et al.
Investigations on light soils from 1977 to 1981 revealed important effects and interactionsof husbandrymethods and fertiliser placement on barley growth and yield which were largely due to their effects on Mn availability to the crop. Thus combine-drilling an acidifying fertiliser (but not a non-acidifying fertiliser) with the seed rather than broadcasting it, was very effective in controlling Mn deficiency and increasing yield substantially on Mn deficient sites. Soil compaction was beneficial where the fertiliser was broadcast, primarily because it forced shallow sowing of seed and thus kept the seminal roots near the acidifying fertiliser. Deep sowing of seed greatly reduced yield when fertiliser was broadcast but not when fertiliser was placed near the seed. These effects and interactions explain why poor crops were frequently associated with loose seedbeds, deep sowing and broadcast fertilisers.
The validity of 7 d weighed records of diet obtained for pre-menopausal Mexican women was assessed by two independent methods: the energy intake:BMR (EI:BMR) and the dietary N:urinary N (DN:UN). For the latter, complete urine collections are required and completeness was assessed from measurements of para-aminobenzoic acid (PABA) excretion. There were forty-six adult female subjects in the study, thirty-four were from Mexico City and twelve were from a rural population in the Central Highlands, Mexico. However, data were rejected from five urban women for whom the PABA excretion data suggested incomplete urine collection on four or more days. BMR was measured with Oxylog portable O 2 consumption meters, and physical activity level was assessed from a self-completed activity diary. An approximate relationship between the EI:BMR ratio and the DN:UN ratio suggested that the rejection limits on the EI:BMR ratio recommended by Goldberg et al. (1991) are wider than the limits on the DN:UN ratio recommended by Bingham & Cummings (1985). Using the recommended cut-off points for EI:BMR but wider limits for DN:UN, twenty-one and twenty-five women respectively had acceptable intake records by the two methods, and sixteen of them by both methods. In conclusion the modification of the DN:UN limits to 0´92 and 1´70 to set acceptable intake values makes the use of measurements of N and energy balance comparable. Urine values with PABA recoveries greater than 100^15 % should be rejected, as should UN values validated by less than 3 d. Validation: Food intake: MethodologyAn ongoing problem in nutritional research is the uncertain validity of methods for assessing habitual food intake. The 7 d weighed diet record method is often the reference method, as it uses prospectively collected data with precise information on quantity and food type (Bingham et al. 1988). To validate it in free-living individuals is difficult, because it relies on information supplied by the subjects. Validation against some external criterion should therefore be built into the protocol of any planned dietary surveys (Bingham & Cummings, 1985). Isaksson (1980) proposed the use of 24 h urinary N excretion (UN) to validate protein intake; cut-off limits for the UN:dietary N (DN) ratio of 0´7±0´9 were proposed by Bingham & Cummings (1985). Completeness of urine collections may be assessed reliably by the para-aminobenzoic acid (PABA) method (Bingham et al. 1983). Doubly-labelled water ( 18 O and 2 H) measurements of energy expenditure (EE) have been used to assess bias in estimates of energy intake (EI) as measured by the 7 d weighed diet record procedure. These studies have highlighted the problem of under-reporting. Goldberg et al. (1991) proposed validating intakes by detecting unlikely values of the EI:BMR ratio, which we call intake physical activity level (IPAL), assuming a common value for physical activity level (PAL) of 1´55 Â BMRX Using this approach, Black et al. (1991) found that 64 % of published studies using dietary intake records fell below ac...
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