1. The retinol content of human liver tissue, obtained at autopsy from mortuaries in the London area, was determined in a group of 364 subjects.

2. Tissue samples from the central portion of the right lobe of the liver were saponified, extracted with light petroleum (b.p. 40–60°) and retinol assayed colorimetrically using the trifluoroacetic acid procedure.

3. The frequency distribution of retinol reserves was skewed to the right (positive skewness). The mean retinol content for the entire group was 252 mg/kg, with a median of 198 mg/kg and a range of 0–1201 mg/kg. Of the subjects, 49% had reserves in the range 100–300 mg/kg (regarded as the‘normal range’ for liver retinol) while 5% had reserves below 40 mg/kg (the arbitrary ‘cut-off’ point below which individuals are considered to be at risk). Only one subject had no detectable retinol reserves. On the other hand, 11 % of the subjects had reserves exceeding 500 mg/kg.

4. No sex-related differences were apparent, the median retinol reserves of male and female subjects being 190 and 202 mg/kg respectively.

5. Median retinol reserves varied markedly with age. They were relatively low (121 mg/kg) in infancy. but were approximately three times greater in childhood, adolescence and young adulthood. Thereafter, reserves declined gradually with increasing age to a low of 113 mg/kg in subjects over the age of 90 years.

6. When subjects were classified according to primary cause of death, the median reserves were as follows (mg/kg): accidental deaths 270, cancer 207, cardiovascular diseases 204, intestinal diseases 178, nervous diseases 164, hepatic diseases 158, respiratory diseases 141, sudden infant death syndrome 127.

7. Retinol reserves in London are substantially higher than those reported from North America and are exceeded only by those reported from New Zealand and Ghana. It is therefore concluded, from the results of this survey and also from official estimates of the dietary intake of retinol and provitamin A carotenoids, that vitamin A status in London, and probably also in the rest of Britain, is quite satisfactory.

1. The fermentative breakdown of dietary fibre from various sources in the intestinal tract was studied using rat balance experiments and gas–liquid chromatrographic analysis of dietary fibre monomers in feed and faeces.

2. On a basal diet with 690 g maize starch/kg but no added fibre, small but detectableamounts of polymeric glucose, rhamnose, arabinose, xylose, galactose, mannose and uronic acids, i.e. sugars occurring in dietary fibre, were excreted in faeces.

3. Dietary fibre in wheat bran was rather resistant to fermentation; 63% was recoveredin the faeces. Guar gum, on the other hand, was almost completely fermented, whereas 19 and 25% of the uronic acids in low and high methoxylated pectin respectively, were excreted in faeces. The various constituents of sugar-beet dietary fibre (approximately equal amounts of arabinose-based hemicellulose, pectin and non-starch glucan (cellulose)) showedquite variable availability for micro-organisms in that 6–12% of the arabinose, 17–25% of the uronic acids, and 52–58% of the cellulose were recovered in the faeces.

4. Faecal nitrogen excretion increased on addition of any one of the dietary fibre preparations studied, resulting in decreased true and apparent protein digestibility values.

5. The faecal dry weight increment was most pronounced when feeding bran and could then almost be accounted for by the remaining fibre and by protein. The less-prominent bulking effect ot guar gum and pectins, that were much more extensively fermented, could be only partly explained by dietary fibre and protein.

1. The capacity of the Chilean mixed diet to meet the daily protein and energy needs was tested in eight subjects aged from 20 to 31 years using the nitrogen balance method. This diet was tested at the protein levels of 0.40. 0.55 and 0.70 g/kg body-weight per d.

2. An egg reference diet providing 0.30, 0.45 and 0.60 g protein/kg per d was also assayed.

3. The mean daily energy intake was 207 kJ/kg per d according to subjects’previous intake and activity pattern.

4. The N balance response to each dietary protein level was taken as a measure of adequacy of protein intake, and regression analyses of N balance (Y) v. N intake (X) were calculated to estimate protein needs. The equations found were Y = 0.70X–68.7 for the egg diet, and Y = 0.74–92 for the mixed diet.

5. From these equations the mean protein requirements for equilibrium were estimated to be 0.61 g/kg for egg and 0.78 g/kg for the mixed diet.

6. If the coefficient of variation is 15, the protein requirement for N equilibrium of 97.5% of the population would be 0.8 g/kg per d for egg and 1.0 g/kg per d for the mixed diet.

1. An unsupplemented 4200 kJ (1000 kcal) diet emphasizing large quantities of relatively unrefined complex carbohydrates was evaluated among sixty obese adults for its effectiveness and nutritional adequacy in a long-term weight-control programme. Patients were followed individually as outpatients by a physician and dietician–an average of thirteen visits over 26 weeks. Assessment of health indices included anthropometric measurements, blood pressure, lipid levels and assays for seven vitamins, β–carotene and iron.

2. Weight loss averaged 8.2 kg or 24% of excess weight during the 6 months of active treatment. Over an average of 17 months of post-treatment follow-up, 44% of patients continued to lose weight and 92% remained below pretreatment levels.

3. Average skinfold thickness fell 7mm (p < 0·001) whereas muscle mass was maintained (arm muscle circumference+10mm, not significant; creatinine-height index + 3% of standard (Bistrian et al. 1975; not significant). Systolic and diastolic bleed pressure fell 7 and 5 mmHg respectively (P < 0·01). Total serum cholesterol and triglyceridesfell 200 and 660 mg/1 respectively (P < 0·01), while high-density-lipoprotein-cholesterol remained statistically unchanged. Mean serum levels of retinol, β-carotene, folate, vitamin B12, ascorbic acid, Fe and transferrin saturation, and activity coefficients for thiamin, riboflavin and pyridoxine were within normal limits after periods of treatment ranging from 5 to 84 weeks.

4. An earlier age of onset of obesity tended to be associated with greater weight lossduring treatment and lesser weight rebound during follow-up.

5. The results indicate that the experimental diet, without supplementation, was nutritionally adequate as well as effective for long-term weight control.

1. The energy metabolism of ad lib.-fed adult male Wistar rats receiving daily running exercise (0·9 km/d; 8° incline) on a motor-driven treadmill, over a period of 56 d, was compared with that of sedentary ad lib.-fed rats and sedentary restricted-fed rats of similar body-weight (approximately 420 g).

2. The metabolizable energy of the diet (Oxoid 41B) was 11·44 ± 0·05 kJ/g. This value was not affected by restricted feeding (70% ad lib.), exercise training or exercise itself.

3. Exercise-trained rats ate 5% more food than the sedentary ad lib.-fed rats but their equilibrium body-weight was 60 g lower than that of the latter group.

4. Resting metabolic rate, measured over 22 h in a respiration chamber was increased by 10% in exercise-trained animals.

5. Feeding increased energy expenditure (dietary-induced thermogenesis) and this effect was potentiated by performance of an exercise task.

6. Exercise-trained rats exhibited anticipatory rises in energy expenditure (approximately 40%) when placed on a stationary treadmill.

7. Treadmill work increased energy expenditure by a factor of 1·9–2·4.

8. The energy cost of the exercise, determined by respiration calorimetry was 66–80 J/g per km. These energy costs did not account for all the differences observed in food energy consumption of exercise-trained and sedentary rats of equal body-weight.

9. It is concluded that regular physical exercise increases energy expenditure by factors additional to the energy requirement directly related to the physical work. These factors include an increased resting metabolic rale in exercise-trained rats, increased dietary thermogenesis induced by exercise and anticipatory increases in energy metabolism during the period preceding exercise.

1. The obligatory nitrogen losses were measured in young adult males of the low socio-economic group, consuming an N-free diet at 192 kJ (46 kcal)/kg per d from day 1 to 10 and 243 kJ (58 kcal)/kg per d from day 11 to 18.

2. All subjects, except one, lost weight compatible with N loss.

3. A kinetic evaluation of the results showed that the asymptotically derived urinary N loss after stability had been reached was 35·8 mg N/kg per d. The mean time to stability was 6·5 d. The subjects showed a trend toward decline in N loss while consuming the high-energy N-free diet.

4. The obligatory faecal N loss for days 1–10 was 16·1 mg N/kg per d and 8 mg N/kg per d for days 11–18.

5. Based on the factorial approach the total obligatory N loss of our subjects, for the initial 10 d, was 57·5 mg N/kg per d.

1. Sixteen adult male volunteers were selected on the basis of body size and customary food intake: half could be described as‘lean’and habitually consuming large amounts of food (group mean ± SEM: 15·03± 1·13 MJ/d), the high-energy-intake group (HEI group), and half though‘lean’admitted to a weight problem and regularly consumed a lower than average food intake (group mean ± SEM: 6·90 ± 0·39 MJ/d), the low-energy-intake group (LEI group).

2. Energy expenditure was measured by open-circuit indirect calorimetry. Resting metabolic rate (RMR) was recorded. A meal (Complan, either 2·1 MJ or 4·2 MJ), ephedrine hydrochloride (0·25 mg and 0·50 mg/kg body-weight) or a water control were then administered and metabolic rate (MR) was measured for 4 h. Blood was collected before and 1 h after the meal or drug, and the serum analysed for various hormones and blood metabolites.

3. The size of the thermic response to feeding but not the time-course was related to meal size in both groups. MR increased by 21·6 and 28·6% in the HEI group and by 8·2 and 20·0% in the LEI group in response to the 2·1 and 4·2 MJ Complan meals respectively. Fasting insulin levels were similar in both groups but showed a significantly higher level in the LEI than HEI group after the Complan meals.

4. The mean RMR increased by 5·2 and 10·3% in the LEI in response to ephedrine and by 15·7 and 11·2% in the HEI groups after 0·25 mg and 0·50 mg ephedrine/kg respectively. The rise in serum-free fatty acids in response to ephedrine was significantly higher in the HEI group than in the LEI group.

5. These results suggest (1) the meal size required to promote a maximum thermic effect is smaller in energetically inefficient individuals (2) the sensitivity to a sympathomimetic drug is also increased in energetically-inefficient individuals.

6. We conclude that in energetically-efficient individuals both the thermic response to a meal and the sympathetic-mediated thermogenesis are lower than in energetically-inefficient ones.

1. The response of Lactobacillus casei was measured for a number of the monoglutamyl forms of folate derivatives.

2. At the concentrations of folate commonly used in the assay of folate vitamin in foods the response of L. casei to folic acid, (pteroyl glutamic acid) and 5-formyl-tetrahydrofolic acid was similar, but 5-methyl-tetrahydrofolic acid gave as little as half the response of folic acid.

3. The response was modified by altering pH but not by concentration of ascorbate.

4. These results have implications for the assays of foods for folate where mixtures of folate derivatives are present.

5. A modified procedure is suggested in which the monoglutamates give similar responses.

1. The amounts of iodine in nationally representative samples of prepared and cooked groups of foods and in a wide variety of individual foods and food products were determined colorimetrically. The amounts of erythrosine, a red food colour containing 577 mg I/g were also determined in selected foods and diets by high-performance liquid chromalography.

2. The average British diet was calculated to provide 323 μg I/d but only 255 μg if two fruit samples containing large amounts of glacé cherries were discounted. Of the total, 92 μg was derived from liquid milk. Meat and meat products provided 36 μgand cereal products 31 μg, but fresh fruitsand sugars, vegetables and beverages provided little I. Fish and fish products, though rich in I, contributed only 5% to the total intake.

3. Milk was the most variable as well as the most important individual source of I. Summer milk samples contained 70 μg/kg and winter milk 370 μkg on average. Milk products, including butter and cheese, and eggs were also rich in I.

4. Some processed foods contained erythrosine, particularly glacé cherries and some pink or red confectionery items, biscuits, cherry cake, canned strawberries and luncheon meat. However, none of these are major foods in the average household diet and erythrosine would therefore contribute little more than 10 μg I/d to most diets.

5. The average daily intake of I was lower than in similar studies in the USA, but wastwice the provisional UK recommended intake. This study provides no evidence that I intakes in the UK could be too low or loo high for health.

1. Studies were made on the lysine content of casein reacted with caffeic acid oxidized aerobically under alkaline conditions or enzymically with tyrosinase (EC 1.14.18.1).

2. Loss of fluorodinitrobenzene (FDNB)-reactive lysine was rapid at pH 10 and increased with time and the temperature of the reaction, with concentration of caffeic acid and with the oxygenation of the mixture. In presence of the enzyme mushroom tyrosinase, maximum reduction of reactive lysine occurred at pH 7 and was dependent on the reaction time and on the concentration of caffeic acid.

3. Reaction of α-formyl-L-[U- 14C]lysine with caffeic acid at pH 10 showed the rapid formation of five reaction products which appeared to polymerize gradually as the reaction progressed.

4. The nutritionally available lysine content of the casein-caffeic acid mixtures, as assayed with rats, was reduced after both alkaline and enzymic reactions, as were faecal digestibility, net protein ratio and net protein utilization. Biological value however was not reduced.

5. In metabolic studies using goat milk casein labelled with L-[3H]lysine and reacted with caffeic acid in the same way, the lysine–caffeoquinone reaction products were not absorbed by the rat but were excreted directly in the faeces.

6. The importance of the reaction of proteins with caffeoquinone and chlorogenoquinone (formed by the oxidation of caffeic and chlorogenic acids respectively) is discussed in relation to the production of sunflower protein, leaf protein and other vegetable-protein concentrates.

1. The hepatic uptake of indocyanine green (ICG) has been measured in rats receiving a 50 g protein/kg diet for 6, 12 or 20 d or a choline-deficient diet for 2 or 6 d.

2. There was no effect on ICG uptake on the choline-deficient diet, although all the rats developed an intense fatty infiltration of the liver by 6 d.

3. The rats on the 50 g protein/kg diet showed impaired uptake of ICG at 6, 12 and 20 d, which appeared to be related to the extent of fatty infiltration.

4. It is concluded that ICG uptake is predominantly a function of the periportal zone of the liver lobule, and therefore likely to be sensitive to insults that exert their predominant effect in this zone.

1. The relation between dietary carbohydrate:lipid ratio and the fuel mixture oxidized during 24 h was investigated in eleven healthy volunteers (six females, and five males) in a respiration chamber. Values of the fuel mixture oxidized were estimated by continuous indirect calorimetry and urinary nitrogen measurements.

2. The subjects were first given a mixed diet for 7 d and spent the last 24 h of the 7 d period in a respiration chamber for continuous gas-exchange measurement. The fuels oxidized during 2·5 h of moderate exercise were also measured in the respiration chamber. After an interval of 2 weeks from the end of the mixed-diet period, the same subjects were given an isoenergetic high-carbohydrate low-fat diet for 7 d, and the same experimental regimen was repeated.

3. Dietary composition markedly influenced the fuel mixture oxidized during 24 h and this effect was still present 12 h after the last meal in the postabsorptive state. However, the diets had no influence on the substrates oxidized above resting levels during exercise. With both diets, the 24 h energy balance was slightly negative and the energy deficit was covered by lipid oxidation.

4. With the high-carbohydrate low-fat diet, the energy expenditure during sleep was found to be higher than that with the mixed diet.

5. It is concluded that: (a) the composition of the diet did not influence the fuel mixture utilized for moderate exercise, (b) the energy deficit calculated for a 24 h period was compensated by lipid oxidation irrespective of the carbohydrate content of the diet, (c) energy expenditure during sleep was found to be higher with the high-carbohydrate low-fat diet than with the mixed diet.

1. The adsorption of bile salts from aqueous solution on to soya-bean flour, wheat bran, fine dry sawdust and lucerne (Medicago sativa) wasmeasured. Adsorption on to the residuum after the first three of these substances had been extracted with organic solvents, pronase or solvents, pronase and acid (to produce lignin) was also measured.

2. The removal of saponins from soya-bean flour did not affect bile salt adsorption, and bile salts were adsorbed on to lignin and on to wheat bran (deficient in saponins). Although our methods differed from Oakenfull & Fenwick (1978) we were unable to substantiate their conclusions that saponins are responsible for most bile salt binding to fibrous substances in vitro.

1. People with an ileostomy experience digestive problems with some foods. Why these foods are avoided is not known nor is it certain whether this interferes with the nutritional adequacy of their diet.

2. A detailed dietary assessment has therefore been made of thirty-seven subjects with ileostomies and a similar number of age-and sex-matched healthy controls. All food and drink eaten over 1 week was weighed and recorded. In addition, a larger group of seventy-nine ileostomy subjects and seventy matched controls answered a questionnaire designed to identify foods which upset them and which they avoided.

3. Total nutrient and energy intakes were similar in the two groups but the subjects with an ileostomy ate less dietary fibre (g/d; mean ± SD: ileostomy subjects 18·0±5·9, controls 20·9±5·5; P < 0·05) mainly due to lower fruit and vegetable intakes. Iron and vitamins A and C intakes were also less.

4. A majority of ileostomy subjects had a pattern of food intake different from the controls, taking more of their energy in the morning and less at night. A variety of food items upset more than half of them including nuts, pips, seeds, skins, onions, beetroot, lettuce, raw cabbage and carrot, peas, sweetcorn, mushrooms and dried fruit.

5. On the basis of the results it is possible to formulate general dietary advice for people with an ileostomy.

1. Two groups, each of six rabbits, were fed on semi-purified diets containing either 400 g casein or 400 g soya-bean protein/kg for 20 d and then the diets of the two groups were crossed-over.

2. Just before the cross-over, the serum cholesterol concentration (mean ± SE) was 3068 ± 592 and 800 ± 143 mg/l for the groups fed on casein and soya-bean protein respectively.

3. Changes in the serum cholesterol concentration were observed 1 d after crossing-over the diets. By 10 d, the cholesterol levels in the two groups had also crossed-over.

4. The changes in serum cholesterol level after the cross-over were reflected in the very-low-density lipoproteins (VLDL) and low-density lipoproteins (LDL).

5. Lipoprotein protein concentrations in the LDL changed in the same way as cholesterol. In the VLDL however, the protein concentration decreased in both groups after the change in diet.

6. The cholesterol:protein values for the LDL and VLDL markedly increased in the rabbits changed from the soya-bean-protein diet to the casein diet, reaching a maximum 2 d after the cross-over. In the animals switched from casein to soya-bean protein, the values progressively declined.

7. The source of dietary protein exerts a rapid effect on the composition of both the VLDL and LDL which is proposed to be attributed to changes in the number and size of lipoprotein particles.

1. Most subjects who have their large intestine removed and an ileostomy formed lead a healthy life after operation, although they are prone to a variety of metabolic problems. In order to determine the factors likely to lead to these metabolic disturbances a detailed assessment of ileostomy output and composition and of dietary intake in relation to nutritional and metabolic status has been made in a group of ileostomy patients living at home.

2. Thirty-six volunteers with established ileostomies (twenty-six ulcerative colitis (UC) patients and ten, Crohn's colitis (CC) patients) made a 24 h collection of urine and ileostomy effluent and kept a 7 d record of dietary intake and the frequency with which they emptied their ileostomy bag. Blood was collected for haematological and biochemical indices of nutritional status and height, weight and skinfold thickness were measured.

3. Effluent output for the whole group was 760±322 g/day (range 273–1612) and was very closely related to effluent sodium output (R 0·98). Stepwise multiple regression analysis of dietary and other variables identified the amount of ileum resected as the main determinant of both effluent output and effluent sodium. The CC group had significantly greater effluent output (1084±340 g/d) compared with the UC patients (635±215g/d) (P < 0·001); and excreted significantly more nitrogen, carbohydrate and sodium than the UC group.

4. The CC patients particularly showed evidence of salt depletion. The mean (±SD) 24 h urine Na loss for CC patients was 31±30 mmol and for UC patients 67±34 mmol (P < 0·01) with five of the ten CC patients v. four of the twenty-six patients with UC having raised urinary or plasma aldosterone levels.

5. All subjects had normal haematological and biochemical indices of nutritional status in the blood. Height and percentage body fat were also within the normal range when compared with a control population matched for age, sex and occupation, but patients with an ileostomy weighed on average 4·1 kg less than the controls.

6. These studies show that patients with an ileostomy come within the range of the normal population for most nutritional indices although are at increased risk of salt depletion. Effluent volume, which is probably the determining factor in most metabolic complications of ileostomy, is related more to the extent of the small bowel resection than to diet.

1. The phospholipid intake by eight healthy women was studied by the duplicate-portiontechnique, i.e. chemical analyses of duplicates of the food consumed. Their intake of phospholipids was 1·5–2·5 mmol lipid-phosphorus/d, which correspondsto 0·023–0·059 mmol lipid-P/g dietary fat and 0·24–0·45 mmol lipid-P/MJ respectively.

2. Choline phosphoglyceride constituted 480–700 mmol/mol and ethanolamine phosphoglyceride 170–240 mmol/mol total lipid-P. Most of the choline in nature occurs as choline phospholipids, the intake of which ranged between 0·91–1·85 mmol/d or 0·15–0·33 mmol/MJ.

3. Palmitate, stearate, oleate, and linoleate were the four major fatty acids both in choline phosphoglyceride and ethanolamine phosphoglyceride. Significant amounts of highly unsaturated, C20 and C22 fatty acids were also observed. It was calculated that 13–33 mg/g total dietary fatty acids was consumed as phospholipids. Together with bile phospholipids, dietary phospholipids and their degradation products may be important in the digestion and absorption processes.