The iron-chelating potential of silybin in patients with hereditary haemochromatosis.

Milk thistle contains silybin, which is a potential iron chelator. We aimed to determine whether silybin reduced iron absorption in patients with hereditary haemochromatosis. In this crossover study, on three separate occasions, 10 patients who were homozygous for the C282Y mutation in the HFE gene (and fully treated) consumed a vegetarian meal containing 13.9 mg iron with: 200 ml water; 200 ml water and 140 mg silybin (Legalon Forte); or 200 ml tea. Blood was drawn once before, then 0.5, 1, 2, 3 and 4 h after the meal. Consumption of silybin with a meal resulted in a reduction in the postprandial increase in serum iron (AUC±s.e.) compared with water (silybin 1726.6±346.8 versus water 2988.8±167; P<0.05) and tea (silybin 1726.6±346.8 versus tea 2099.3±223.3; P<0.05). In conclusion, silybin has the potential to reduce iron absorption, and this deserves further investigation, as silybin could be an adjunct in the treatment of haemochromatosis.

Effect of dietary quercetin on oxidative DNA damage in healthy human subjects.

The effect of dietary intake of flavonols (predominantly quercetin) on oxidative DNA damage was studied in thirty-six healthy human subjects (sixteen men, twenty women). The study was a randomised crossover study, comprising two 14 d treatments of either a low-flavonol (LF) or high-flavonol (HF) diet with a 14 d wash-out period between treatments. Subjects were asked to avoid foods containing flavonols, flavones and flavanols during the LF dietary treatment period and to consume one 150 g onion (Allium cepa) cake (containing 89.7 mg quercetin) and one 300 ml cup of black tea (containing 1.4 mg quercetin) daily during the HF dietary treatment. A 7 d food diary was kept during each dietary period and blood samples were taken after each dietary treatment. Products of oxidative damage to DNA bases were measured in DNA from leucocytes. The study had more than 95% power to detect a change of 20% in DNA damage products Plasma vitamin C and plasma quercetin concentrations were also measured. No significant differences in intake of macronutrients or assessed micronutrients, measured DNA base damage products, or plasma vitamin C were found between the HF and LF dietary treatments. The plasma quercetin concentration was significantly higher after the HF dietary treatment period (228.5 (SEM 34.7) nmol/l) than after the LF dietary treatment period (less than the limit of detection, i.e. <66.2 nmol/l). These findings do not support the hypothesis that dietary quercetin intake substantially affects oxidative DNA damage in leucocytes.

Vitamin A and carotenoid status in rural China.

Vitamin A status of 260 groups of twenty-five males or twenty-five females, aged 35-64 years, surveyed in twenty-four provinces of the People's Republic of China, was assessed by measuring plasma retinol. retinol-binding protein and beta-carotene concentrations. Direct measurements of food intake over a 3 d period and questionnaire data on the frequency of consumption of vegetables, fruits, animal products and other dietary items were also used. Vitamin A status appeared to be low only in specific counties but in general was satisfactory or only marginally deficient. Plasma beta-carotene levels were strikingly low in comparison with Western levels despite generous vegetable consumption suggesting that intake of vitamin A precursors may have been adequate but not abundant enough to maintain high circulating plasma levels of beta-carotene. Plasma beta-carotene, for both males and females, was significantly correlated with the frequency of consumption of green vegetables. Plasma retinol, for males, was highly correlated with meat, fish, oil and alcohol consumption expressed both in quantity or frequency of consumption. Higher levels of plasma retinol, together with lower levels of plasma beta-carotene in males compared with females, suggest that men consume more animal products or may have higher retinol requirements and therefore a higher rate of conversion of beta-carotene to retinol.

Post-prandial thermogenesis with ephedrine, caffeine and aspirin in lean, pre-disposed obese and obese women.

OBJECTIVE: To determine whether or not aspirin further potentiates the greater post-prandial thermogenesis induced by ephedrine with caffeine. DESIGN: Determination of the acute metabolic rate response to the following treatments: 1050 kJ liquid meal (M); meal plus ephedrine (30 mg) and caffeine (100 mg) (MEC) or meal plus ephedrine, caffeine and aspirin (300 mg) (MECA). SUBJECTS: Lean, pre-disposed obese and obese women (n = 10 each group). MEASUREMENTS: Pre- and post-treatment metabolic rate determinations via indirect calorimetry. Post-treatment measurements made at 20 min intervals for a total of 160 min. RESULTS: In all groups, metabolic rate increased significantly more following the MEC or MECA, compared to the meal only (p < 0.05). The obese group had a significantly greater absolute increase in metabolic rate following the MECA and MEC compared to both the lean and pre-disposed obese groups (p < 0.05). Metabolic rate remained elevated at the end of the 160 min following all treatments. CONCLUSION: Aspirin does not further potentiate the acute thermic effect of ephedrine and caffeine with a meal. However, the full thermogenic response was not measured and longer duration studies are necessary to confirm these results.

Effect of habitual exercise on daily energy expenditure and metabolic rate during standardized activity.

To assess whether long-term habitual exercise affects energy expenditure even on a nontraining day, 24-h energy expenditure (24-h EE) and metabolic rate of sedentary, moderately active, and highly active males (n = 10 per matched group), were measured in a room respirometer on two separate occasions: sedentary and standardized mild-exercise protocols. Twenty-four--hour EE was greatest in the highly active group, second highest in the moderately active group, and lowest in the sedentary group on both experimental days (sedentary day: 9908 +/- 344, 9328 +/- 357, and 8669 +/- 227 kJ/d; exercise day: 11915 +/- 395, 11609 +/- 328, and 11063 +/- 370 kJ/d, respectively). Differences were significant between the 24-h EE (P < 0.01), waking (P < 0.03), and sleeping metabolic rate (P < 0.01) of the highly active group compared with the sedentary group. However, when expressed per unit lean body mass (LBM), group values on both experimental days were not significantly different. Therefore, we found no evidence that habitual exercise, at a high or moderate level, leads to a significant prolonged stimulation of metabolic rate per unit active tissue. However, the increased LBM associated with exercise does increase daily energy expenditure by 8-14%.

Aspirin potentiates the effect of ephedrine on the thermogenic response to a meal in obese but not lean women.

The effect of ephedrine (30 mg) and aspirin (300 mg) on the acute thermogenic response to a liquid meal (250 kcal) was investigated in lean and obese women (n = 10 each group). Resting metabolic rate (RMR) was measured prior to each of the following treatments: meal only (M), meal plus ephedrine (ME) or meal plus ephedrine and aspirin (MEA). Eight post-treatment measurements of metabolic rate were made over a total of 160 minutes. Rise in post-treatment metabolic rate was compared to the baseline RMR. Following the M treatment, the mean increase in metabolic rate was 0.17 +/- 0.01 and 0.13 +/- 0.02 kcal/min in the lean and obese groups respectively, with the corresponding rises being 0.21 +/- 0.02 and 0.19 +/- 0.02 kcal/min following the ME, and 0.23 +/- 0.03 and 0.23 +/- 0.01 kcal/min following the MEA. The increase in post-prandial thermogenesis with the ephedrine or ephedrine plus aspirin was significant in the obese group (P less than 0.03 and P less than 0.001 respectively) but not the lean. Furthermore, the post-treatment rise in metabolic rate, following the MEA treatment compared to the ME, was significantly greater for the obese group (P less than 0.05) but not the lean. It was concluded that aspirin potentiates the stimulatory effect of ephedrine on the thermogenic response to a meal in obese but not lean women.

Normal caffeine consumption: influence on thermogenesis and daily energy expenditure in lean and postobese human volunteers.

Single-dose oral administration of 100 mg caffeine increased the resting metabolic rate of both lean and postobese human volunteers by 3-4% (p less than 0.02) over 150 min and improved the defective diet-induced thermogenesis observed in the postobese subjects. Measurements of energy expenditure (EE) in a room respirometer indicate that repeated caffeine administration (100 mg) at 2-h intervals over a 12-h day period increased the EE of both subject groups by 8-11% (p less than 0.01) during that period but had no influence on the subsequent 12-h night EE. The net effect was a significant increase (p less than 0.02) in daily EE of 150 kcal in the lean volunteers and 79 kcal in the postobese subjects. Caffeine at commonly consumed doses can have a significant influence on energy balance and may promote thermogenesis in the treatment of obesity.

A low-budget and easy-to-operate room respirometer for measuring daily energy expenditure in man.

Accurate assessment of energy requirements of humans under various physiological, pathological, and environmental conditions is hampered by the high cost of techniques for measuring daily energy expenditure. A room respirometer novel in its novel in its low cost of construction and simplicity of operation is described, together with an appreciation of errors and assumptions. It is suitable for measurements of daily energy expenditure in humans with an accuracy of +/- 1.5% and can be reproduced without difficulty in both developed and developing countries.

Lower metabolic rates of post-obese versus lean women: thermogenesis, basal metabolic rate and genetics.

Components of daily metabolic rate (thermogenesis, BMR and net exercise) were compared between 16 women predisposed to obesity (post-obese) and 16 naturally lean controls of matching age, weight and height, at three levels of activity, in a whole-body respirometer. At all levels of activity, the mean metabolic rate of the post-obese was 15 per cent lower than that of the lean controls. Expenditure on net exercise showed the same relationship, but BMR was only 10 per cent lower, while thermogenesis was 50 per cent lower. The latter was partly due to the smaller food intake of the post-obese and also to a lower thermogenic response. In absolute terms BMR accounted for less than half of the difference in total energy expenditure between the post-obese and the lean (45 per cent). Thermogenesis accounted for approximately 40 per cent of the difference, and 15 per cent after adjusting for the different energy intakes. Significantly more post-obese subjects had a family history of obesity (88 per cent) than lean subjects (38 per cent). Within the post-obese and lean groups there was a consistent trend at each level of activity for those with a family history to have lower metabolic rates, indicating that family history of obesity has an influence on energy expenditure over and above personal history of obesity.

Metabolic rate during and after aerobic exercise in post-obese and lean women.

The effect of aerobic exercise (cycling on bicycle ergometer for four 10-min periods/60-80 per cent max VO2) on energy expenditure following the activity was investigated in 16 post-obese and 16 lean control women over 24 h and shorter periods. In addition, net energy expenditure during aerobic exercise was compared to that during prolonged mild activity (stepping for four 30-min periods at 12 steps/min). The measurements were made in a room respirometer. Aerobic exercise did not significantly stimulate the 24-h resting metabolic rate of either the post-obese (3 per cent, 50 kcal) or lean controls (2 per cent, 30 kcal), nor was there any significant stimulation over shorter periods: during waking hours RMR was non-significantly increased by 5 per cent in both the post-obese and lean controls. Sleeping expenditure remained the same in the post-obese and was decreased by 2 per cent in the lean controls. All subjects found the aerobic exercise to be quite uncomfortable, yet in both groups the net cost was smaller than that of prolonged mild exercise which was found to be acceptable (post-obese: aerobic 180 kcal, mild 250 kcal; lean controls: 220 kcal, 290 kcal). It is suggested that prolonged mild activity (eg, as in walking frequently) is more appropriate in increasing energy expenditure as a means of preventing or controlling obesity. Total expenditure at each level of activity is also expressed as multiples of BMR calculated from FAO/WHO/UNU (1985) prediction equations and from measured sleep values. The results show that the equations overestimated BMR in the post-obese.

The daily metabolic rate of the post-obese and the lean.

Daily metabolic rates of 16 post-obese women and 16 matched, lean controls were measured at three different levels of activity in a room respirometer. Both groups had similar height, weight, age, and other anthropometric indices. Results show that the post-obese have metabolic rates approximately 15% lower than their controls at any level of activity. They also eat less. Slimmed-down, obese women have a normal body composition. For both groups, aerobic exercise did not have a prolonged stimulatory effect on metabolic rate after the exercise had finished. Mild exercise was more effective than aerobic exercise in increasing daily metabolic rate because it could be comfortably sustained for a longer time. Implications of these findings are discussed in relation to the etiology and treatment of obesity.

Validation of a field technique for the measurement of energy expenditure: factorial method versus continuous respirometry.

The field technique for measuring daily energy expenditure, using activity diary plus short-term indirect calorimetry, was validated with a room respirometer. Eleven male and 14 female subjects spent 24-h periods in the respirometer and kept an activity diary to the nearest minute. Subsequently, the energy cost of the recorded activities was measured in duplicate, and 24-h expenditure was calculated. Over the 42 24-h measurements the mean value by the factorial field method was within 1% of that from continuous indirect calorimetry. However, the error in individual daily expenditure ranged from -17% to +25%. Correction of the error involved in using calculated BMR for the cost of sleeping resulted in a 5% mean underestimation of the daily value. The factorial method is, therefore, too inaccurate for the estimation of individual daily expenditures but provides a close estimate of the true energy expenditure for population groups.

Problems with the use of "weight for height" tables.

Two sets of "weight for height" reference data that are widely used internationally for children and adolescents (NCHS) and for adults (Fogarty) show a marked discontinuity such that young adults might be considered obese by one set and underweight by the other. In view of the need for continuous data for the nutritional assessment of populations, a compromise set of reference values is proposed, calculated from the NCHS data, which is considered the more reliable of the two sets. The proposed values are a single set, which may be applied to all ages and to both sexes: they are close to the Fogarty data for tall adults but for shorter adults there remains a discrepancy, which may represent an error in the Fogarty data.

Racial differences in the energy cost of standardised activities.

The assumption is currently made by international organisations that individuals of the same size living in the same environment and having the same mode of living will have the same energy requirements whatever their race. Reports of very low energy intakes are frequently doubted. To investigate possible racial differences the energy cost of standardised activities was measured in European, Asian, and African males under the same experimental conditions. Subjects were closely matched for height, weight and Quetelet index. The energy cost of each activity, lying, sitting and standing, was significantly higher, by 10-17%, in Europeans as compared to Asians and Africans, between whom no differences were found. Whether these differences are morphological or metabolic is discussed. It is concluded that differences in energy requirements do exist over and above those due to body size and activity.

The nutritional effects of tooth loss.

In view of the high prevalence of edentulousness in developed countries, the evidence is reviewed for the effects of tooth loss on nutrition and health in the following categories of effects: mortality; food choice and nutrient intake; gastrointestinal irritation; digestion and nutrient absorption; nutritional status. The evidence indicates reduced consumption of meat, fresh fruit, and vegetables, and total energy resulting in lower Hb and vitamin C levels, increased gastrointestinal irritation and increased mortality from choking but no striking differences in digestion or nutritional status. However, most studies are not carefully controlled for other social and health factors.

The energy expenditure of female carpet weavers and rural women in Iran.

The energy cost of individual activities and the daily energy expenditure of female carpet weavers and villagers were measured in Iranian villages and in the town of Isfahan as part of a series of studies to assess the validity for the population of past and present FAO recommended energy allowances. The energy cost of typical activities was measured by indirect calorimetry using Max-Planck respirometers. Daily energy expenditure was assessed using these figures combined with a 24-hr activity diary. The results of standard activity values are compared with other published values for Europeans and populations of countries with hot climates. The mean daily energy expenditure for both groups was in the order of 2000 kcal/day, below but close to the FAO recommendations which appear valid for rural women in a large part of the country but are probably an underestimate for areas where the participation of women in agriculture is greater.