1. Anthropometric indices are presented for representative samples of elderly people in South Wales, based on over 1500 subjects seen during community surveys.

2. Body mass index declined with age after 70 years in both men and women. Estimates of fat and muscle volume based on upper arm measurements also showed a decline with age, which was particularly steep for triceps skinfold thickness in women.

3. These indices are in general similar to results that have been reported from other surveys within the UK; they suggest that Welsh old people have less fat and muscle than elderly Americans.

1. The effects of unhydrogenated and partially-hydrogenated marine and rapeseed oils on the relative content of n-6 fatty acids in rat liver phospholipids were studied by gas–liquid chromatography.

2. The type of dietary oil strongly affected the pattern of n-6 fatty acids in the liver phospholipids even after a relatively short feeding period (3 weeks).

3. With diets deficient in linoleic acid, accumulation of the 20:3 n-9 fatty acid was observed in the animals receiving partially hydrogenated oils, but not in the animals receiving the unhydrogenated marine oil which contained relatively high amounts of polyunsaturated fatty acids of the n-3 family.

4. The results presented are in line with reports in the literature that dietary trans fatty acids may inhibit the desaturation–elongation enzyme systems of rat liver. The observed effects did not appear to be directly correlated to the dietary content of very-long-chain monounsaturated fatty acids.

1. The effects of differing degrees of experimental protein-energy malnutrition on the response of myofibrillar protein turnover rates to administration of corticosteroid has been studied in two experiments on rats. The basal control diet, offered ad lib. in each case, contained 40 g protein/kg, and other groups received diets containing 62.5, 95 or 220 g protein/kg at 0.67, 1 or 1.5 times the level of the control energy intake.

2. Daily administration of 25 or 30 mg corticosterone/kg body-weight after 18 d pre-feeding caused an increase in plasma protein, glucose and insulin concentrations, but a decrease in the corticosterone: insulin values. Liver size and protein content increased, as did the fractional excretion of dietary nitrogen as urea-N in all treated groups. However, whereas a fall in food intake and body-weight occurred in one experiment the reverse occurred in the other.

3. NT-Methylhistidine excretion was 12% lower for rats receiving 40 v. 220 g protein/kg diet and excretion was increased by only 57 v. 90% respectively, when the two groups of rats were given 30 mg corticosterone/kg per d. Rats which received 25 mg corticosterone/kg per d and up to 95 g protein/kg diet increased excretion of NT-methylhistidine by an average 35%.

4. The fractional degradation rate of myofibrillar protein (kd) was reduced by about 10% by the low-protein diet from 3.1 to 2.8%/d. During corticosterone treatment the increment in kd for rats on this diet was only 60% of that for rats receiving the 220 g protein/kg diet, i.e. an increase of 1.8 v. 3.0%/d. Energy restriction further reduced kd during low-protein intake but did not affect the response to the corticosterone. Variations in dietary protein from 40 to 95 g/kg had little effect on the increase in kd during steroid treatment. The effect of corticosterone on calculated synthesis rates (kg) differed markedly between experiments. While kg fell by 50–65% in rats which lost weight on treatment, it rose by up to 60% in rats where carcass non-collagen-protein accretion remained unchanged or increased, despite an increase in kd

5. Protein deficiency decreases the catabolic response to glucocorticoid, but the net metabolic response appears crucially dependent on changes in food intake or the stage of growth of the rat or both. A net anabolic response with increased fractional rates of myofibrillar protein breakdown, synthesis and accretion was observed in growing rats fed on relatively-low-protein diets and given 25 mg corticosterone/kg per d. This novel finding indicates that a particular role for cortisol in the adaptation to protein-energy malnutrition by humans should be ascribed only with caution.

1. Protein utilization in young men under circumstances of one or two periods of work and both adequate and surfeit energy intake was determined by nitrogen balance; protein intake was constant at the FAO/WHO (1973) safe level (0.57 g/kg body–weight).

2. Physical activity affected protein utilization negatively by increasing sweat and faecal N losses, and positively by supporting increased energy intake.

3. Efficiency with which surfeit energy improved N utilization (mg N retained/added kJ) was greater under circumstances of increased activity.

4. Changes in body composition as determined by total body potassium and hydrostatic weighing supported the N retention values.

1. Sixty marasmic children and fifteen normal age-matched controls were investigated for the absorption of fats and proteins. Their duodenal juice samples were also analysed for bile salts and microflora.

2. A significant amount of malabsorption, with respect to both the dietary ingredients, was observed in the majority of the marasmic children.

3. The levels of conjugated bile acids in the duodenal juice samples of marasmic children were significantly lower as compared with those of normal controls, while the reverse was true for free bile acids and bacterial counts.

4. Significant correlations were observed between bile acid levels and fat absorption and also between microflora and free bile acids.

5. The pathophysiology of malabsorption in marasmus is discussed in the light of these findings.

1. Nicotine has been implicated as a causative factor in the intrauterine growth retardation associated with smoking in pregnancy. A study was set up to ascertain the effect of nicotine on fetal growth and whether this could be related to the actions of this drug on maternal adipose tissue metabolism.

2. Sprague-Dawley rats were mated and assigned to control and nicotine groups, the latter receiving nicotine in the drinking-water throughout pregnancy. Animals were weighed at regular intervals and killed on day 20 of pregnancy. Rates of maternal adipose tissue lipolysis and lipogenesis were measured. Fetal and placental weights were recorded and analysis of fetal body water, fat, protein and DNA carried out.

3. Weight gains of mothers in the nicotine group were less in the 1st and 2nd weeks of pregnancy, but similar to controls in the 3rd week. Fetal body-weights, DNA, protein and percentage water contents were similar in both groups. Mean fetal body fat (g/kg) was significantly higher in the nicotine group (96.2 (se 5.1)) compared with controls (72.0 (se 2.9)). Rates of maternal lipolysis were also higher in the nicotine group.

4. The cause of these differences and their effects on maternal and fetal well-being is discussed.

1. Male, Wistar rats (50–74 g) were given a semi-purified diet containing cholesterol (10 g/kg diet) for 4 weeks, groups of control and experimental animals killed, and the remainder of the cholesterol-fed animals given either a semi-purified cholesterol-free diet without a fibre source or a similar diet with pectin (50 g/kg diet) for 8 weeks. Animals were killed at 2-week intervals and serum and liver cholesterol and triglycerides, faecal neutral steroids and acidic steroids measured.

2. Animals given pectin had significantly lower serum cholesterol levels than animals given the basal diet after 4 and 6 weeks.

3. Both experimental groups efficiently decreased their liver cholesterol levels during regression.

4. Bile acid excretion was elevated in both groups, especially in rats receiving pectin, but neutral steroid excretion was unchanged.

5. The increase in bile acid excretion was primarily in the form of chenodeoxycholic acid and its metabolites.

6. This increased bile acid excretion is postulated to result from stimulation of the normal mechanism for increased steroid excretion in the rat, i.e. a change in the value of cholic: chenodeoxycholic acid or from a mechanism not yet elucidated.

1. Iron retention and its subsequent distribution from 3 g 59Fe extrinsically-labelled wholewheat flour in rats given a low (8 μg Fe/g)- or high (566 μg Fe/g)-Fe diet during the previous 3 d was measured (Expt 1). The mean (with se) proportion of Fe retained from wholewheat flour was 0.46 (0.04) in the group given the low-Fe diet and 0.15 (0.01) in the group given the high-Fe diet (P < 0.001). There was no difference in distribution of absorbed 59Fe in the tissues examined.

2. The procedure was repeated in rats given diets containing a range of Fe concentrations, groups 1–6 respectively: 8, 77, 136, 334, 566, 1270 μg Fe/g (Expt 2). The mean (with se) proportions of Fe retained in groups 1–6 respectively were 0.60 (0.02), 0.34 (0.02), 0.30 (0.02), 0.20 (0.20), 0.17 (0.02), 0.09 (0.01). Regression analysis showed that Fe retention was a function of the logarithm of the Fe concentration of the diet consumed before the test meal (R -0.997, P < 0.0001) where Fe retained (μg) = 95–28 log10 Fe concentration of diet.

3. Rats were given a low-, medium- or high-Fe diet (8, 136 or 1270 μg Fe/g respectively) for 1 or 2 d instead of 3 d before measuring Fe retention from 3 g wholewheat flour (Expt 3). The mean (with se) proportions of Fe retained in rats given the low-, medium- or high-Fe diets for I d were 0.45 (0.02), 0.25 (0.02) and 0.13 (0.01) (P < 0.001) and for 2 d 0.47 (0.03), 0.31 (0.03) and 0.18 (0.02) (P < 0.001). There were no significant differences in Fe retention from animals given similar diets for 1 or 2 d before the test meal. As in Expt 2 regression analysis showed a highly-significant relationship between Fe retention and the logarithm of the previous dietary Fe concentration in both sets of groups.

4. It was concluded that the amount of Fe retained by rats from a 3 g meal of wholewheat flour depended on the previous dietary Fe intake. Only one meal in the previous 24 h was required to influence the ‘mucosal setting’ since there was no difference in response between rats preloaded for 1 or 2 d before the test meal.

1. The contribution of the fortification of flour with calcium carbonate to the Ca intake of 375, 11–14-year-old Northumbrian children has been calculated.

2. Mean Ca intakes were above those currently recommended for children of this age. The fortification of flour supplied 16% of the total Ca intakes.

3. Without the fortification, the percentage of these children with intakes below the recommended intake would be more than double. This would include the majority of girls (particularly those of social classes III, IV and V).

4. The recommendation to stop fortifying flour with calcium carbonate should be reviewed.

1. Heats of combustion and energy equivalents of cytoplasmic ATP have been estimated for glucose, 101 food proteins and 116 food fats based on amino acid and fatty acid composition data from food composition tables and the heats of combustion and energy equivalents of cytoplasmic ATP of each individual amino acid, fatty acid, glycerol and glucose. The isodynamic equivalents of carbohydrate, fat and protein at the biochemical level have been investigated.

2. Heats of combustion of food proteins and fats derived from compositional data were within 1 % of published values obtained by calorimetry.

3. Cytoplasmic ATP equivalents for glucose, fat and protein range from 9·0 to 14·7, 8·6 to 14·6 and 6·4 to 13·2 mol cytoplasmic ATP/MJ of metabolizable energy respectively, depending on the choice of mitochondrial proton stoichiometries for these estimations. The range is extended further when considering the level and type of mitochondrial ‘uncoupling’.

4. Isobioenergetic relationships between the efficiencies of glucose (G) and fat (F) (F = 1·05 G-0·9) and glucose and protein (P) (P = G(1·02–0·19f)-(1.8+0·5f)) energy conversions (wheref is the fraction of protein oxidized via gluconeogenesis) were obtained and were essentially independent of the choice of mitochondrial proton stoichiometry and the level and type of uncoupling of oxidative phosphorylation.

5. Potential errors in previous estimates of ATP yield from protein are shown to be as much as -17·6 to < 118%; accounting for the efficiency of mitochondrial oxidative phosphorylation narrows this to between -7·9 and 17·4% and accounting for the fraction of protein oxidized via gluconeogenesis limits this further to between - 7·9 and 11·1%. Remaining uncertainty is attributed mostly to lack of knowledge about the energy cost of substrate absorption from the gut and transport across cell membranes.

6. Coefficients of variation (cv) in the cytoplasmic ATP yield/g protein and /g protein nitrogen for the 101 food proteins were large (0·033 and 0·058 respectively). This is attributed mostly to variation in the metabolizable heats of combustion (cv 0·033 and 0·053 respectively) and to a much smaller extent in the efficiency with which cytoplasmic ATP equivalents are generated/MJ of metabolizable energy (cv 0·01).

7. It is concluded that the current understanding of biochemical energy transduction is sufficient to permit only a crude estimate of the energy equivalents of cytoplasmic ATP but that these equivalents vary by less than 5% between both different food proteins and different food fats. Isobioenergetic equivalents for carbohydrates, fats and protein which could be applied to modify the Atwater conversion factors are possible but require first an accurate quantification of the energy equivalent of cytoplasmic ATP for glucose in vivo, and an indication that oxidative phosphorylation is similarly efficient in different individuals.

1. Between September 1979 and July 1981, 405 northern-English children, initially aged 11–12 years, each recorded all food and drink consumed on five occasions on each of three consecutive days. Sugars and nutrient intakes were calculated using food tables.

2. The average total sugars intake was 118 g/d or 21% of the energy in take and 43% of the carbohydrate intake; these percentages were similar for both sexes, all social class groups and surveys.

3. Sugars were found to be derived from a variety of food sources with confectionery being the single largest source.

4. Sugars were fairly evenly consumed over the average day with a high amount in foods eaten between meals. Snacks accounted for 65% of the sugars intake but only 46% of the energy intake.

5. Sugars intake and snacking therefore seem to have been major components of the eating habits of these children. If dietary changes towards lower sugars intakes are to be achieved a vigorous, informed health education campaign is necessary together with effective labelling of manufactured foods, the development of new products and the modification of some existing ones.

1. Residual antigenic protein in heat-denatured cow's milk whey and in two commercial infant milk formulas was determined using enzyme-linked immunosorbent assays specific for β-lactoglobulin, α-lactalbumin, bovine serum albumin, bovine IgG1 and α-casein. This immunochemical assessment of antigenicity was related to the capacity of the preparations to sensitize immunologically when fed to guinea-pigs for 2 weeks. Antibody production was measured and the susceptibility of the animals to systemic anaphylaxis was assessed by injecting them intravenously with heated or unheated milk proteins.

2. Whey protein that had been heated at 100° or 115° for 30 min was extensively denatured and, in contrast to pasteurized whey, failed to sensitize guinea-pigs for anaphylaxis. Antibody production was undetected or very low. The proteins in SMA powder and SMA Gold Cap liquid concentrate were less denatured and animals given these formulas prepared according to the maker's instructions produced relatively high levels of antibodies to β-lactoglobulin and α-casein and a majority developed anaphylaxis when injected intravenously with these products.

3. As well as failing to sensitize, whey that had received severe heat treatment did not, in most cases, elicit anaphylaxis when injected into animals that had been sensitized with unheated milk.

4. Discrimination between antibodies of the IgG1 and IgG2 subclasses specific for β-lactoglobulin showed that IgG1, the principal anaphylactic antibody in guinea-pigs, was preferentially depressed in animals drinking heat-denatured milk preparations.

5. The results suggest that heat denaturation of whey protein may be a logical and simple strategy for producing a hypoallergenic baby milk. Nevertheless, the value of experiments in guinea-pigs for predicting results in man is uncertain and the proposal awaits assessment in clinical trials.

1. Effects of a feeding programme on maternal weight, triceps and subscapular skinfolds during pregnancy and lactation were assessed in a marginally undernourished population of rural Taiwan. Mothers participated during two pregnancy and lactation periods. At 3 weeks after the delivery of the first infant, one group of 114 mothers began consuming a nutrient-dense supplement (A), while another group of 111 received a placebo (B).

2. There was no significant A–B difference in pregnancy weight gain (A 7.52 kg, B 7.75 kg) or in mean maternal weight, triceps or subscapular skinfolds at any time during pregnancy or lactation. Despite a general trend toward moderate weight loss during lactation, one-third of mothers in both groups gained weight. Highly significant increases in weight and skinfold thicknesses from one lactation period to the next characterized both groups.

3. The absence of demonstrable supplement-effects on maternal anthropometry concomitant with increments in infant birth weight supports the notion that infants can benefit from maternal supplementation without changes in maternal nutritional status.

1. A new method has been developed for the study of zinc metabolism in man using the stable isotope 67Zn. The technique involves intravenous infusion of the isotope followed by measurements of the plasma and faecal enrichments over a period of days.

2. A procedure for the analysis of Zn isotopes in plasma and faeces is described which requires the separation of Zn from other elements using the chelator dithizone before analysis by thermal-ionization mass spectrometry.

3. The stable isotope technique has been used in conjunction with a metabolic balance study to obtain measurements of Zn absorption and gastrointestinal secretion in a normal subject. Preliminary measurements of the size of the exchangeable pool of Zn have been made as have estimates of the rates of plasma and whole-body Zn turnover.

4. Following an increase in dietary Zn the body appeared to respond in two ways. The gastrointestinal secretion of Zn increased immediately, but only by a relatively small amount. The absorption of Zn initially increased in proportion to the increase in dietary levels but then decreased within 4 d by an amount sufficient to restore Zn balance.

1. The effects of incorporating Fybogel (3·5 and 7 g doses), Metamucil (7 g) or guar gum (2·5 and 14·5 g doses) in a drink containing 50 g glucose on plasma glucose, plasma insulin and gastric emptying were studied in thirty-eight normal volunteers. In addition, the effects of Fybogel (7 g) on glucose tolerance, plasma insulin and gastric emptying were measured in fourteen non-insulin-dependent diabetics.

2. Both doses of guar gum significantly lowered plasma glucose and plasma insulin responses to the oral glucose load in normal subjects, although 14·5 g guar gum did not delay the half-time for gastric emptying.

3. Neither Fybogel nor Metamucil had significant effects on plasma glucose responses in normal subjects. In addition, Fybogel (at either dose) had no significant effects on plasma insulin levels, or on gastric emptying in normal subjects or on plasma glucose and insulin responses in diabetic patients.

4. The viscosity of ispaghula solutions (Fybogel) was lower than that of guar gum solutions.

1. Non-haem-iron absorption from a variety of cereal and fibre meals was measured in parous Indian women, using the erythrocyte utilization of radioactive Fe method.

2. The present study was undertaken to establish whether alteration of the phytate and polyphenol contents of sorghum (Sorghum vulgare) affected Fe absorption from sorghum meals, and to assess the influence of fibre on Fe absorption.

3. Removing the outer layers of sorghum grain by pearling reduced the polyphenol and phytate contents by 96 and 92% respectively. This treatment significantly increased the geometric mean Fe absorption from 0.017 to 0.035 (t 3.9, p < 0.005).

4. The geometric mean Fe absorption from a sorghum cultivar that lacked polyphenols (albino sorghum) was 0.043, which was significantly greater than the 0.019 absorbed from bird-proof sorghum, a cultivar with a high polyphenol content (t 2.83, p < 0.05).

5. Fe was less well absorbed from the phytate-rich pearlings of the albino sorghum than from the pearled albino sorghum (0.015 v. 0.035 (t 8.4, P < 0.0005)). Addition of sodium phytate to a highly Fe-bioavailable broccoli (Brassica oleracea) meal reduced Fe absorption from 0.185 to 0.037.

6. The geometric mean Fe absorption from malted sorghum porridge was 0.024 when 9.5 mg ascorbic acid were added and 0.094 when the ascorbic acid was increased to 50 mg (t 3.33, P < 0.005). This enhancing effect of 50 mg ascorbic acid was significantly depressed to 0.04 by tea (t 38.1, P < 0.0005).

7. Wheat bran significantly decreased the geometric mean Fe absorption from white flour from 0.116 to 0.043 (t 7.2, P < 0.0005).

8. Some of the constituents of the dietary fibre complex, such as apple pectin, guar gum, gum tragacanth and microcrystalline cellulose did not inhibit Fe absorption. On the other hand, hemicellulose and lignin decreased absorption. The geometric mean absorption of Fe given with hemicellulose was 0.079 v. 0.269 with microcrystalline cellulose (t 2.95, P < 0.05). Addition of cocoa, which contains approximately 280 g lignin/kg, reduced the geometric mean Fe absorption from milk from 0.075 to 0.035 (t 2.7, P < 0.05).

1. Peripheral blood leucocytes from human male volunteers and from male rats were incubated in vitro in the presence of 14C-labelled linoleic acid ([14C]LA) or 3H-labelled arachidonic acid ([3H]AA). The time-course of [14C]LA and [3H]AA incorporation into human leucocyte total lipids was maximal at 80–90% of the initial dose within 20–30 min of dosing the cells.

2. Compared with mixed leucocytes, isolated polymorphonuclear leucocytes were only marginally different in the differential incorporation of [14C]LA and [3H]AA into total lipids.

3. In human leucocytes, [14C]LA was incorporated initially into triglycerides but predominantly into phosphatidylcholine thereafter. In the rat, [14C]LA remained as the free acid (63%), with lesser amounts entering the phospholipids (9%), monoglycerides-diglycerides (12%) and triglycerides (< 1%).

4. Utilization of [14C]LA by the Δ6-desaturase was only a minor route of its metabolism in both human and rat leucocytes.

5. 3H-labelled prostaglandins E2 and F2α accounted for up to 30% of the radioactivity released into the incubation medium from human leucocytes incubated with [3H]AA for 60 min.

6. Stimulation of phagocytosis in the human leucocytes with latex beads or with unopsonized zymosan did not alter the differential incorporation of [14C]LA or [3H]AA into the leucocyte lipid fractions.

1. The effect of the administration of oestrone sulphate on tryptophan metabolism has been assessed in rats in order to determine whether and to what extent inhibition of tryptophan metabolism by oestrogens may be a factor in the aetiology of pellagra, and might explain the reported twofold excess of females over males in many outbreaks of pellagra.

2. Feeding ovariectomized rats for 1 week on a diet containing 15 mg oestrone sulphate/kg led to significant inhibition of kynurenine hydroxylase (EC 1.14.13.9), kynureninase (EC 3.7.1.3) and 3-hydroxyanthranilate oxidase (EC 1.13.11.6). There was also a significant increase in plasma tryptophan, suggesting decreased activity of tryptophan oxygenase (EC 1.13.11.11). This inhibition of tryptophan metabolism will result in a considerable reduction in the synthesis of the nicotinamide nucleotide coenzymes (NAD and NADP) from tryptophan.

3. When ovariectomized rats were maintained for 4 weeks on a diet providing no preformed niacin and only a marginally adequate amount of tryptophan (1030 mg/kg), the addition of oestrone sulphate to the diet led to a significant reduction in the liver content of nicotinamide nucleotides and the urinary excretion of the end-product of NAD metabolism, N1-methyl nicotinamide.

4. It is suggested that when the diet is only marginally adequate in tryptophan and niacin, inhibition of tryptophan metabolism by endogenous or administered oestrogens may be an additional factor in the development of pellagra.

1. Gum arabic (GA) is a water-soluble polysaccharide (molecular weight approximately 850000) containing rhamnose, arabinose, glucuronic acid and galactose.

2. The metabolism of GA has been studied in the rat. Adult male Wistar rats were given GA incorporated into either an Oxoid breeders (OB) diet or an elemental (Elem) diet.

3. Intestinal contents were examined for precipitable GA using acidified ethanol. GA was found from stomach to small intestine but not in the caecum, colon or rectum.

4. Caecal excision and restoration of intestinal continuity resulted in GA recovery from stomach to rectum.

5. Excreted methane, hydrogen and volatile fatty acids (VFA) were measured as indicators of bacterial activity in the caecum and colon. Methane excretion increased on the OB+GA diet and H2 concentrations remained unaltered. The Elem diet abolished gas production. When the animals were given the Elem+GA diet, H2 and methane were only produced after 28 d. Faecal VFA increased with increasing GA intake, acetate concentration increased and butyrate concentration decreased with increasing GA dosage. Significant decreases in concentrations of VFA were found from caecum to left colon and from left colon to faeces.

6. It can be concluded that GA degradation occurs in the caecum and is associated with increased methane excretion, increased VFA concentrations and changes in the proportions of various VFA in the faeces.