1. During the course of a nutritional survey on an Antarctic base, leucocyte ascorbic acid estimations (Denson & Bowers, 1961) were found to be significantly affected (P < 0.0001) by the leucocyte count measured during analysis.

2. The effect was significantly less (P < 0.05) when leucocyte levels were at or near saturation than when subsaturated.

3. This suggests that leucocytes share available ascorbic acid, especially in subsaturated subjects, and that assessment of nutritional status from the leucocyte ascorbic acid level should take account of the leucocyte count and the plasma ascorbic acid titre.

1. The effect of fortification of food with iron to provide 10 mg elemental Fe/child per d was studied in preschool children maintained on a cereal diet, over a 5-month period.

2. The absorption of 5 mg Fe as ferrous sulphate mixed in one meal was 3.3% of the test dose and when 3.3 mg was given with each of three meals over a 2 d period the corresponding value was 4.8%.

3. The mean absorption of a test dose of ferrous ascorbate studied in twenty-four children midway through the trial was 42%.

4. The only beneficial effect of Fe fortification in this time-period in the experimental group was the prevention of the decrease in packed cell volume which occurred in the control group.

1. Carbohydrate (CHO) oxidation was measured simultaneously in a group of five normal subjects after an oral load of 100 g naturally-labelled [13C]glucose, using indirect calorimetry and mass spectrometry.

2. CHO utilization, calculated from the results of indirect calorimetry, increased 30 min after the glucose load to reach a peak at 90 min. It then decreased to reach basal values at 380 min. Cumulative total CHO oxidation at 480 min was 83±8g, and CHO oxidized above basal levels, 37±3 g.

3. Enrichment of expired carbon dioxide with 13C began at 60 min and maximum values were observed at 270 min. At 480 min, cumulative CHO oxidation measured by use of [13C]glucose was 29 g. The difference from calorimetric values can be attributed in part to the slow isotopic dilution in the glucose and bicarbonate pools.

4. Thus, approximately 30% of the glucose load was oxidized during the 8 h after its ingestion and this accounts for a significant part of the increased CHO oxidation (37 g), as measured by indirect calorimetry.

1. A study amongst schoolboys in villages around Hyderabad, India, showed that almost all the boys had riboflavin deficiency, 61% had pyridoxine deficiency, and 9.4% had thiamin deficiency as judged by enzymic tests.

2. The prevalence of angular stomatitis was 41.3% and that of glossitis was 18.2%. Biochemical deficiency of riboflavin and pyridoxine was marginally higher in children with angular stomatitis with or without associated glossitis, than in children without oral lesions.

3. Treatment with B-complex vitamins (containing 4 mg riboflavin and 10 mg pyridoxine) daily for 1 month produced significant reduction in the prevalence of glossitis but had no effect on angular stomatitis. The latter responded to topical application of gentian violet.

4. Small but significant changes in erythrocyte enzymes occurred over the period of 1 month even without vitamin supplements.

5. Results suggest that while glossitis is a relatively early manifestation of riboflavin or pyridoxine deficiency or both, angular stomatitis has a more complex aetiology perhaps associated with infection.

1. Effects of dietary composition, energy restriction, and diabetes on hexose absorption were examined by feeding male rats isoenergetic, semi-synthetic diets of differing carbohydrate and protein content. Diets were carbohydrate, (g/kg): 890 sucrose; carbohydrate-protein, 500 sucrose, 390 casein; or protein, 890 casein. An additional group was fed on commercial rat chow ad lib.

2. Hexose (3-O-methyl-D-glucose) absorption was measured by luminal perfusion of the entire small intestine in situ. Absorption by the total small intestine, i.e. absorption per rat, and absorption per g dry weight of mucosa (specific absorption) were calculated.

3. When semi-synthetic diets were fed at 210 kJ/d to normal animals absorption depended on composition of diets: carbohydrate enhanced or protein suppressed hexose absorption. Dietary carbohydrate as glucose, dextrimaltose or starch gave the same hexose absorption response as sucrose.

4. When diets of normal rats were restricted to 118 kJ/d, specific absorption was independent of dietary composition and was incresed for all dietary groups to the level of the group fed on the carbohydrate diet at 210 kJ/d.

5. When diabetic rats were given 210 kJ/d, hexose specific absorption was the same for all diabetic groups independent of dietary composition and was equal to that of controls given carbohydrate, but greater than that of protein-fed controls.

6. Thus, when two of the three stimuli (i.e. carbohydrate diet plus energy restriction or diabetes) were combined, the effect was not additive, and the response of hexose specific absorption to diabetes and energy restriction was the same: absorption was independent of dietary composition and was stimulated relative to controls fed on diets containing protein.

7. The pattern of response of total small intestinal hexose absorption to the stimuli of dietary composition, energy restriction and diabetes was similar to that of specific absorption.

8. Compared with groups given semi-synthetic diets, rats eating commercial rat chow ad lib. (approximately 286 kJ/d) showed increased mucosal mass and decreased specific absorption, but total absorption was similar to that of the carbohydrate and carbohydrate-protein-fed groups.

9. In a separate study in control rats, specific and total intestinal absorption of L-leucine did not respond to dietary composition, i.e. level of protein fed.

1. The absorption of an oral dose of paracetamol was measured in rats given either a basal fibre-free diet, or the basal diet with either pectin or bran added.

2. Urinary excretion of the oral dose was significantly greater during the first 8 h in the pectin-fed rats compared with those on basal diet, though cumulative excretion after 72 h was the same.

3. Free paracetamol levels in the plasma were significantly higher in the pectin-fed rats compared with those on basal diet at 30, 60, 90 and 120 min after the oral dose.

4. The plasma half-life of intravenously-injected paracetamol was shorter in the pectin-fed rats than in those on basal diet alone, but the antipyrine half-lives were not significantly different.

5. Pectin feeding had no effect on either the apparent volume of distribution of paracetamol and antipyrine, or on the rate of gastric emptying.

6. Perfusion of the whole length of the small bowel showed a significantly greater capacity for paracetamol absorption in the pectin-fed rats.

7. Bran had no effect on paracetamol absorption.

8. It was concluded that dietary fibre intake affects drug absorption and that the effect varies with the type of fibre. Unexpectedly pectin accelerates rather than retards absorption of paracetamol, though the mechanism of this effect is unknown.

1. The dependence of the rate of oxidative demethylation in the liver endoplasmic reticulum on the fatty acid composition of the endoplasmic reticulum has been studied by varying the lipid content of the diet.

2. The rate of oxidative demethylation was markedly dependent on the percentage of linoleic acid (18:2) incorporated into the membrane. Feeding diets containing (g/kg) 100 coconut oil, 100 lard or 100 maize oil caused respectively the incorporation of 7.6, 10.3 and 25.1% linoleic acid (18:2) and a demethylation rate of 3.26, 3.15 and 5.03 nmol formaldehyde/min per mg protein. Feeding 100 g herring oil/kg diet caused incorporation of only 5.1% C18:2 but also 27.2% ωw3 unsaturated fatty acids, including 8.7% eicosapentaenoic acid (20:5) and 17.0% docosahexaenoic acid (22.6) and caused a very high rate of oxidative demethylation (6.53 nmol formaldehyde/min per mg protein).

3. Destruction of the polyunsaturated fatty acids in herring oil by irradiation with 400 krad caused incorporation of a smaller quantity of ωw3 unsaturated acids into the endoplasmic reticulum and decreased the rate of oxidative demethylation (4.83 nmol formaldehyde/min per mg protein).

4. The inductive effects of phenobarbitone on oxidative demethylation were partially dependent on changes in the fatty acid composition of the endoplasmic reticulum. Phenobarbitone (100 mg/kg) increased the percentage of C18:2 from 25.1 to 29.4% in rats given a maize-oil diet, increased the percentage of C20:5 from 8.7 to 10.3% in rats given a herring-oil diet and decreased the percentage of arachidonic acid (20:4) and C22:6 in rats given a lard, maize-oil, herring-oil or irradiated-herring-oil diet.

5. Intraperitoneal α-tocopherol (50 mg/kg) increased the percentage of C20:4 from 11.1 to 13.1% in rats given a lard diet and from 5.9 to 7.3% in rats given a herring-oil diet.

6. It is concluded that dietary C18:2 is an important factor in the regulation of the rate of oxidative demethylation in the liver endoplasmic reticulum but this may be replaced effectively by dietary C20:5 ω3 and C22:6 ω3 acids. Oxidative demethylation is regulated by changes in the fatty acid composition of the membranes of the liver endoplasmic reticulum.

1. The effect of dietary fibre digestion in the human gut on its ability to alter bowel habit and impair mineral absorption has been investigated using the technique of metabolic balance.

2. Five healthy male students were studied for 9 weeks under controlled dietary conditions and during the last 6 weeks they took 36 g pectin/d. Bowel habit, transit through the gut, faecal fibre excretion, calcium balance and faecal composition were measured.

3. During the control period only 15% of the dietary fibre ingested was excreted in the stools and when pectin was added to the diet there was no increase in fibre excretion. Stool frequency and mean transit time were unchanged by pectin but stool wet weight increased by 33% and faecal excretion increased (%) for fatty acids 80, nitrogen 47, total dry matter 28 and bile acids 35. Ca balance remained unchanged.

4. It may be concluded from these results that dietary fibre is largely metabolized in the human gut and dietary pectin completely so. This could explain its lack of effect on bowel habit and Ca balance. Other changes in the faeces may be related to an increase in bacterial mass.

1. Intakes of magnesium, copper, zinc, vitamin B6, vitamin B12 and folic acid in Britain were calculated by applying the values selected for the 4th edition of McCance and Widdowson's The Composition of Foods (Paul & Southgate, 1978) to the amounts of food recorded in the National Food Survey made during 1976 (Ministry of Agiculture, Fisheries and Food, 1977).

2. National average intakes were (/person per d): Mg 249 mg, Cu 1.51 mg, Zn 9.1 mg, vitamin B6 1.36 mg, vitamin B12 6.6 μg, free folic acid 105 μg and total folic acid 190 μg. Corresponding intakes (/person) in families with four or more children were 10–20% lower.

3. A comparison of intakes with those recommended in Canada (Department of National Health and Welfare, 1976) and the USA (National Research Council, 1974) or by WHO (1973) indicated that for folic acid average values were particulary low, and only for vitamin B12 were the recommendations significantly exceeded.

4. Contributions from alcoholic drinks and confectionery were also calculated and found, on average, to be significant for Cu, vitamin B12 and folic acid.

5. The losses of B-vitamins which might occur on cooking are discussed.

1. Four human subjects on strictly controlled diets were given a fibre supplement, 25 g Ispaghula husk (Isogel)/d, for 3 weeks.

2. Replicate diets and faeces were collected during two 5 d balance periods. The first period served as control for the second which occurred after the supplement had been fed for 2 weeks.

3. Diets and faeces were analysed for total solids, gross energy, total nitrogen, fat, available and unavailable carbohydrates.

4. Three of the four subjects showed a considerable increase in faecal bulk; total faecal weight was more than doubled in two subjects. In two subjects the increase was brought about mainly by extra fibre in the faeces accompanied by a higher proporation of faecal water whereas in one subject it was also an increased excretion of nutrients. One subject showed very little change in faecal bulk.

5. High values for the apparent digestibility of fibre were found during the control period; from 0.70 to 0.80. There was more variation during the experimental period when apparent digestibility of total fibre ranged from 0.47 to 0.82. Values arrived at for the minimum apparent digestibility of the fibre supplement were generally high; one subject appeared to digest Isogel completely. Isogel was degraded preferentially to the food-derived fibre; in particular, cellulose in the faeces was increased during the experimental period.

6. Only one subject showed distinct decreases in the apparent digestibility of energy, N and fat in the diet. The results do not therefore agree with the generally held view that increased fibre in the diet decreases the apparent digestibility of the other nutrients.

1. The influence of the dose and the form in which guar gum was given on the degree of ‘flattening’of blood glucose curves was studied in five subjects using meals of bread and soup containing 5 or 10 g guar gum.

2. When 5 g guar gum was added to bread the peak increase of blood glucose was reduced by 41% (P < 0.002), with 5 g guar in soup, the reduction was 54% (P < 0.001) while a reduction of 68% (P < 0.001) was seen with 10 g guar gum (5 g in bread and 5 g in soup). The corresponding reduction in insulin peak increases were 37% (P < 0.002), 50% (P < 0.001) and 65% (P < 0.001) respectively.

3. The difference between the two 5 g doses was not significant with respect to the reduction of the peak increases in blood glucose and serum insulin; however the difference between the 5 g dose in bread and the increases in blood glucose and serum insulin; however the difference between the 5 g dose in bread and the 10 g dose was significantly different (P < 0.002 for glucose, P < 0.01 for insulin).

4. The results indicate that as little as 5 g guar gum may reduce the glycaemia following a 45 g carbohydrate meal, but perhaps due to earlier and more complete mixing, guar gum is most effective when added to the liquid phase of the meal.

1. A new in vitro method using the intestinal fluid of the pig for predicting the digestibility of diets was proposed.

2. A 0.5 g sample of pig diet was placed in a 100 ml Erlenmeyer flask, 20 mg pepsin (EC 3.4.4.1) in 10 ml 0.75 M-hydrochloric acid was added, and the mixture was incubated for 4 h at 37°. Then, after neutralization with 0.2 M-sodium hydroxide, 10 ml of intestinal fluid was added and incubated for an additional 4 h at 37°. This fluid was obtained from a pig fitted with a simple cannula in the upper jejunum. After the two-stage incubations, the contents of the flask was centrifuged for 10 min at 1250 g and the residue transferred to preweighed filter paper for dry matter (DM) and crude protein (nitrogen × 6.25; CP) determinations. The in vitro DM and CP digestibility was calculated on the basis of the original DM and CP content of the diet respectively.

3. The intestinal fluid could be stored at ∓ 20° for 60 d without losing its activity on DM and CP digestion.

4. A high correlation was found between this in vitro method and the standard in vivo procedures, for seven diets commonly used for growing or adult pigs, when diets were ground to pass through a 1 mm screen for the in vitro experiment, but there was an obvious dissimilarity between the two methods, especially in the case of CP: DM, Y = 1.04X +0.0806 (r 0.98, P < 0.001); CP, Y = 1.70X − 0.6092 (r 0.98, P < 0.001), where Y and X are in vivo and in vitro digestibility respectively.

5. This method is rapid and reproducible and particularly suited for the evaluation of a large number of samples. Since this method assesses only stomach and small intestinal digestion, it therefore may require further modification when used for diets which include large amounts of crude fibre. Also, depending on the needs of the investigator, the addition of a correction factor for endogenous faecal nitrogen loss may be required.

1. Four sheep, each fitted with a rumen fistula and a re-entrant cannula at the proximal duodenum were fed a semi-purified diet containing urea as the only nitrogen source. The quantities of total protozoal amino acid-N (TPAN) present in the rumen and entering the duodenum were determined when the mean rumen dilution rate (D) was low (0.034/h) and when D was increased to 0.078/h by the intraruminal infusion of artificial saliva.

2. Increasing the dilution rate had no significant effect upon the proportions of TPAN present in the total microbial amino acid-N (TMAN) of the rumen fluid and duodenal digesta. With both dilution rates the mean proportion of TPAN in the duodenal TMAN (0.24) was markedly less than the equivalent proportion (0.45) found in the rumen fluid.

3. The daily flow of TPAN, as measured at the duodenal cannula at both dilution rates was equivalent to only 41 % of the flow of TPAN as predicted from measurements of rumen outflow, indicating that a substantial proportion of rumen protozoal protein was retained within the rumen.

1 A series of experiments were conducted to investigate the effects of dietary retinol status on chickens ingesting aflatoxin B1. The effects of dietary supplementation with biotin and α-tocopherol were also examined.

2. Aflatoxin B1 levels greater than I mg/kg diet had a detrimental effect on ‘liveability’, body-weight gain, food intake and food conversion efficiency. When fed for more than 2 weeks aflatoxin increased relative liver weight and liver lipid concentration. These effects were less pronounced with avitaminotic A chickens.

3. A synergistic effect on hydropericardium development was observed between aflatoxin B, and retinol. This effect was not observed when the dietary level of α-tocopherol was increased tenfold.

4. The specific activities of certain hepatic lipogenic and amino acid-metabolizing enzymes were influenced by aflatoxin ingestion. A reduction in lipogenic enzyme activity was observed before a reduction in the activities of amino acid-metabolizing enzymes.

5. Liver fatty acid composition was significantly influenced by aflatoxin B1. The extent of these changes was reduced by the inclusion of additional dietary biotin.

1. Two experiments were conducted with lambs sustained entirely by intragastric infusion of volatile fatty acids (VFA), protein, minerals and vitamins.

2. In the first experiment to determine the effects of VFA on nitrogen retention four mixtures of VFA (B, C, D and E) were used containing acetic, propionic and butyric acid in the following molar proportions respectively: 45,45 and 10; 55,35 and 10; 65,25 and 10; 75, 15 and 10.The level of infusion was 836 kJ/live weight0.75 per d and the design was a 4 × 4 Latin square with 14 d periods. There were no significant differences in the N balance between the different mixtures of VFA though mixture B tended to give the highest N retention.

3. Thirty-two lambs were used in the second experiment for measurements of heat production in closed- circuit respiration chambers. Six mixtures of VFA were used. These included mixtures B-E from Expt I and in addition two mixtures (A and F) containing acetic, propionic and butyric acid in the following molar proportions respectively: 35, 55 and 10; 85, 5 and 10. The heat production was measured both at 450 and 900 kJ/W0.75 per d, except for mixture F, where it was not possible to achieve a rate of infusion in excess of 675 kJ/W0.75 per d.

4. The energy required for maintenance was determined to be 0.45±0.02 MJ/kg live weight0.75 per d regardless of the mixture used.

5. The efficiency of utilization for fattening (kf) values for the six mixtures were 0.78, 0.64, 057, 0.61, 0.61 and 0.59 for mixtures A, B, C, D, E and F respectively. Only mixture A was significantly better utilized than the other mixtures. This mixture also gave the most efficient N utilization.

6. It is concluded from this evidence that differences in k, for diets normally given to ruminants cannot be attributed to differences in utilization of volatile fatty acids.

A technique is described for feeding young sheep for long periods entirely by the infusion of volatile fatty acids into the rumen and protein and other essential nutrients into the abomasum. When the energy infused was twice the estimated requirement for maintenance, growth rate and nitrogen retention were essentially the same as in normally-fed sheep.

1. A comparative study was made of two biological techniques for assessing protein quality in wheat and barley, and in a soya-bean-protein isolate both as received, and after being heat damaged by autoclaving. Amino acid digestibility was determined by the ‘ileal’ analysis technique while amino acid availability was measured in growth assays. Some chemical and microbiological tests were also done.

2. Heat treatment of the soya-bean-protein isolate caused little change in amino acid composition but the digestibility of all amino acids and the availability of lysine and methionine were severely reduced, lysine being most affected. The reduced availability of lysine was not entirely attributable to impaired digestibility.

3. The amino acids in wheat and barley were highly digestible. The availability of methionine and lysine in barley and of methionine in wheat was high, whereas the availability of lysine in wheat was apparently much lower.

4. The results showed that for methionine, digestibility values are a fair measure of the availability. In heat-damaged soya-bean-protein isolate however, digestibility of lysine over-estimated the availability, indicating that amino acid digestibility may sometimes provide a misleading indication of nutritional value.

1. The food intake, pancreas weight and trypsin (EC 3.4.21.4) and α-chymotrypsin (EC 3.4.21.1) activities in the pancreas were measured in rats during pregnancy and lactation and after the young were weaned.

2. All the quantities measured increased significantly during lactation and had returned to their original values by 4 weeks after weaning. Food intake and pancreas weight were highest after the second week of lactation. Total trypsin and α-chymotrypsin activity, and the activity per g tissue, fell during pregnancy and rose during lactation, reaching a maximum I week after weaning.

3. From these and other results it is suggested that the hypertrophy and hypersecretion of pregnancy and lactation are initiated by changes in insulin secretion and mediated by the trophic effects of gut hormones, and that differences in the nature and timing of the response may be controlled by nutrient availability.

1. A study has been made of the zinc, copper, iron, manganese, protein (nitrogen x 625) and phytic acid contents of nineteen soya-bean-based textured-vegetable-protein (TVP) meat-extenders and meat-substitutes and of three ‘ready-prepared’ canned meals containing TVP.

2. Phytate analysis was performed using a newly-developed method based on Holt's (1955)procedure. This method enabled the phytate content of milligram quantities of TVP to be estimated, with an SD for six replicates of 3%.

3. The Fe, Cu and Mn contents (mg/kg) of the meat-extenders or meat-substitutes varied, wzith values of 59.4–144, 14.1–19.7 and 19.5–29.1 respectively. The protein content of these products was approximately 500 g/kg.

4. The phytate content of the meat-extenders and meat-substitutes ranged from 11.0to 20.2 g/kg and the Zn content from 35.0 to 49.4 mg Zn/kg. The calculated molar ratio, phytate:Zn varied from 25 to 42.

5. The trace element, phytate and protein contents of the ‘ready-prepared’ canned meals were 30–50 %: lower than the meat-extenders and meat-substitutes.

6. Cooking the ‘ready-prepared’ meals as specified by the manufacturers was without effect on the trace element or phytate content.

7. When TVP was fed to rats as the only protein source, they had significantly lower growth rates and plasma Zn concentrations than rats given an egg-albumen-based diet of similar Zn content (14.5mg Zn/kg). Supplementation of the TVP diet with Zn (100 mg Zn/kg) significantly increased growth rate and plasma Zn concentration whereas Zn supplementation of the albumen diet was without effect.

8. The possible implications of consumption of TVP products in relation to Zn status of the human population is discussed.