1. Rat dams given a diet containing 100 g maize oil/kg for approximately 2 weeks before mating and during the first 14 d of gestation, were given the same diet or one containing 100 g hydrogenated coconut oil/kg (essential fatty acid (EFA)-deficient) in place of maize oil until parturition. After parturition the dams were given the same diets and all progeny were weaned to the maize oil diet at 21 d of age. Brain N-acetylneurammic acid (NeuNAc) content as well as neuraminidase (sialidase; (EC 3.2.1.18)) and cytidine monophosphate N-acetylneuraminic acid synthetase (CMP-NeuNAc synthetase) activities were measured at days, 7, 14, 21 and 168 in the progeny. Y-maze learning was measured at 168 d.

2. Brain weight was independent of dietary fat at all ages.

3. Lack of EFA in the maternal diet during gestation and lactation depressed ganglioside and glycoprotein NeuNAc levels and the activities of sialidase and CMP-NeuNAc synthetase.

4. Maternal dietary deprivation of EFA irreversibly impaired learning behaviour of the progeny. A relationship exists between early exposure to EFA deficiency and learning potential of the progeny.

1. This study investigated the subcellular localization of injected N-acetylneuraminic acid (NeuNAc) in brain. Forty pregnant rats were distributed into four groups. Two groups were given a 200 g casein/kg diel and the other two groups a 100 g casein/kg diet throughout gestation. One group from each of the low- and high-protein groups were given their respective diets for the first 11 d of lactation. On day 12 of lactation, 2·5 μCi [14]NeuNAc/kg body-weight were injected intraperitoneally into their pups. After 1 h the pups were killed, their brains removed and subjected to subcellular fractionation. On day 16 of lactation the other two groups were similarly treated.

2. In all groups of animals 80% of the [14C]NeuNAc incorporated into the brains was found in the synaptosomalfraction and the remainder distributed among the other subcellular fractions in proportion to their total NeuNA ccontent.

3. These results suggest that NeuNAc exerts its effects on behaviour via the synaptic membrane.

1. Differences in the extent of breakdown of phytate in wholemeal and white flours prepared from three wheats when the flours were made into bread using the three main UK commercial breadmaking processes were investigated.

2. The extent of breakdown (31–46% for wholemeal breads, 88–99% for white breads) was not proportional to the relative processing times involved (1–4 h). The importance of destruction of phytate in the oven is stressed.

3. The phytase (myo-inositol hexaphosphate phosphohydrolase. EC 3.1.3.8) activities of the wholemeal flours and of the yeast were determined. Re-examination of some information in the literature enabled the relative importance of these activities, and of the various stages of breadmaking, in determining the extent of hydrolysis of phytate to be assessed.

4. Average values for the molar ratio, phytate: zinc, of 22:1 and 0.8:1 were calculated for wholemeal and white breads respectively. The nutritional significance of these results is discussed.

1. Five groups of male Sprague Dawley rats were given for 6 months a diet with high protein and fat contents but a very low dietary fibre content (group B), and this diet mixed with (g/kg) 50 low-methoxyl pectin (groupL), 50 high-methoxyl pectin (group H), 50 guar gum (group G) and 200 wheat bran (group WB, corresponding to 100 wheat fibre) respectively.

2. The weight increment was significantly lower in group G than in the other groups. Assuming no energy value of the dietary fibre, the weight increment (/kJ) was the same in groups B, L and H, lower in group G and higher in group WB, indicating that a proportion of the bran fibre might in fact be available as a source of energy.

3. Wheat bran increased total plasma cholesterol and high-density-lipoprotein cholesterol after 6, 12 and 26 weeks. Group G had significantly lowered plasma cholesterol after 12 weeks. Pectin on the other hand did not significantly influence total or HDL-cholesterol levels. It is therefore possible that the plasma cholesterol lowering effect of pectin previously demonstrated in the rat is dependent on the presence of significant amounts of dietary cholesterol as our diets did not contain added cholesterol. Plasma triglycerides decreased with age but were similar in all groups.

1. Protein turnover and muscle composition has been studied in rat skeletal muscle throughout development in a relatively-fast-growing rat strain.

2. Muscle growth involved an increase in the total DNA and in the DNA-unit size as indicated by protein: DNA. As a result of the latter increase together with no change in RNA: DNA, the RNA concentration fell throughout development.

3. Rates of protein synthesis measured in vivo by the continuous intravenous infusion method fell throughout development from 15.6%/d at 25 d to 4.46%/d at 320 d, and these changes reflected mainly the fall in RNA concentration, since there was no marked change in the rate of protein synthesis per unit RNA.

4. The rate of protein degradation, measured as the difference between rates of protein synthesis and growth, fell from 9.82%/d at 25 d to 4.46%/d at 320 d.

5. When these changes in protein turnover throughout development are compared with measurements made previously in a slow-growing strain it would appear that the faster growth was achieved as a result of increased efficiency of protein synthesis (defined as net synthesis: over-all synthesis) and this occurred mainly because of lower rate of protein degradation.

1. Male Wistar rats were meal-fed for at least 10d a control semi-synthetic diet containing no guar gum, or one of three similar test diets containing 3, 10 or 20 g dry guar gum/kg.

2. Rats were killed 6 h after feeding, and contents of stomach, small and large intestine were collected separately. The apparent viscosities of stomach and smalt intestine contents from animals fed on diets containing 10 and 20 g guar gum/kg were increased relative to control animals, but large intestine contents were unchanged

3. In the second part of this study, male Wistar rats were anaesthetized and two consecutive lengths of jejunum were perfused, initially with Ringer only (control) or Ringer plus 5 or 6g guar gum/1 (test). Following this pre-perfusion, both segments were perfused with Ringer containing glucose (10 mM), [3H]glucose and [14C]inulin, and the rate of glucose absorption was determined

4. The rate of glucose absorption was decreased relative to control values in segments pre-perfused with both 5 and 6g guar gum/I solution, but this reduction was significant only in the instance of the 6g/l solution (P< 0.001)

5. These results provide evidence to support previous assumptions that ingestion of guar gum will increase the apparent viscosity of the contents of the stomach and small intestine. We propose that a possible mechanism by which guar reduces post-prandial glycaemia is a reduction of glucose absorption from the smali intestine, resulting from an increase in viscosity of the contents

1. The feasibility of intrinsically labelling poultry meat with the stable isotopes 68Zn and 70Zn was investigated.

2. Chickens (I-d-old) were gavaged with solutions of 68Zn and 70Zn several times over a 42 d period.

3. Isotopic analysis of edible tissues has shown that they were significantly enriched with respect to the gavaged isotope and that the extent of isotopic enrichment achieved was sufficient to permit their use in human feeding experiments designed to investigate availability of native Zn from such food models.

4. The absolute efficiency of retention of the stable isotopes from gavage solutions in the edible tissues has been calculated to be 2–3%.of the administered dose; methods have been suggested to enhance this value, based on considerations of utilization of dietary Zn.

1. Water-holding capacity (WHC) of dietary fibre is usually considered as the amount of water held but the manner in which water is held by the fibre matrix may be more relevant in understanding the role of fibre in nutrition.

2. A method used to determine WHC under physiological conditions has been adapted to determine how strongly water is held by fibre. Solutions of compounds, such as polyethylene glycol, of known osmotic potential are used to generate a suction pressure across a dialysis membrane containing a fibre sample. The WHC at each suction pressure can then be determined.

3. The method can be applied to water-soluble and water-insoluble sources of fibre. Fibre sources studied included potato fibre concentrate, bran and gum arabic.

4. Results are comparable to other similar systems of WHC measurement for gels and suggest that vegetable fibre has water-holding properties more akin to a true gel than bran. Bran has very poor water-holding properties.

5. Differences in WHC between fibre sources are more apparent if WHC is considered as fibre concentration (g fibre/g water).

6. Differences in the water-holding properties could be important in determining fibre activity in the gut.

1. A method of studying zinc absorption in rats has been developed in which binding of radioactive Zn to the intestinal mucosa and absorption into the carcass was determined at different times after administration by stomach tube.

2. This technique has been used to evaluate different hypotheses concerning the control of Zn absorption and to examine the processes by which this occurs.

3. The proportion of radioactive Zn absorbed into the carcass was found to be dependent on the Zn status of the animals but that found within the small intestinal wall was independent of this, indicating the existence of two mechanisms of Zn absorption.

4. One of these two mechanisms has been shown to be induced by a low dietary Zn content while the other was shown to be insensitive to this. This latter mechanism predominated in rats of normal dietary Zn status and a study of the characteristics of this process indicated that the quantity of Zn absorbed was proportional to the dietary Zn content over the normal range of intake. This implies that normally Zn homeostasis in rats is achieved through variations in Zn excretion. The additional mechanism of Zn absorption only becomes fully active at levels of dietary Zn below 0.24 μmol/g diet.

1. One thousand individuals were asked whether they avoided any foods. Of the 560 replies 33% stated that they avoided one or more foods because they caused ‘unpleasant physiological reactions’.

2. Adverse reactions to one of thirteen foods were reported by 1–4% of the respondents and it is suggested that this number might be regarded as a standard with which to compare reactions to novel foodstuffs. A total of sixty-seven foods were specifically mentioned as a cause of an adverse reaction.

1. Brain hypothalamic concentrations of serotonin and norepinephrine have been implicated in the control of food intake. During pregnancy and lactation a rat dam's food consumption is increased and so a study was performed to ascertain whether this was associated with changes in the hypothalamic content of serotonin and norepinephrine.

2. In the first experiment, forty-eight Sprague Dawley rat dams were given a diet containing 250 g casein/kg adlib. After 2 weeks, eight were killed and their hypothalamic analysed for the previously-mentioned neurotransmitters. The rest were mated and continued on the diet. On each of days 7, 14 and 20 of gestation, day 14 of lactation and 2 weeks after weaning of their pups a further eight dams were killed and their hypothalami assayed as described previously. Food intake was monitored throughout the experimental period.

3. The increased food intake of the dams during gestation and lactation increased to the same extent as elevations in hypothalamic norepinephrine content and depressions in serotonin content. After lactation food intake returned to pre-pregnancy levels as did the hypothalamic levels of norepinephrine and serotonin.

4. By using the same experimental design but limiting the increase in food intake in pregnancy and lactation to half the expected amount the same changes were found in hypothalamic norepinephrine and serotonin contents.

5. The possibility of hypothalamic neurotransmitter contents controlling food intake is discussed.

1. The fractional rate of protein synthesis (FSR) in tissues of nine growing lambs (4–5 months of age) was estimated following continuous infusion of L-[4,5–3H]leucine for a period of 7 h. Minimum and upper estimates of FSR were obtained assuming that the specific radioactivity (SRA) of leucine in blood plasma and tissue homogenate respectively defined that of leucyl tRNA.

2. Mean upper estimates of tissue protein FSR (/d) were skin 0·35, longissimus dorsi muscle 0·05, biceps femoris muscle 0·04, liver 0·54, rumen 0·79, cardiac muscle 0·09. Minimum estimates of tissue protein FSR ranged from 0·03 (muscle) to 0·15 (liver).

3. Plasma leucine flux was closely related to body protein content and dietary leucine absorption (r 0·94).

4. The rate of whole-body protein synthesis (WBS) derived from plasma leucine flux corrected for oxidation and localized recycling of leucine into protein was similar to that calculated from the sum of daily protein synthesis in individual tissues using the upper estimate of FSR, i.e. 610 g/d v. 581 g/d.

5. The estimate of WBS derived from plasma leucine flux directly (241 g/d) was similar to that calculated from the sum of minimum estimates of daily protein synthesis in individual tissues (214 g/d).

6. The ratio, intracellular leucine SRA:plasma leucine SRA tended to increase with increasing dietary leucine absorption in all tissues although these factors were only significantly correlated (P < 0·05) in cardiac muscle, skin and rumen. Such relationships suggest an increased exchange of plasma leucine with intracellular leucine with increased food intake.

7. It was estimated that the energy cost of protein synthesis accounted for approximately 42% of daily heat production.

1. Erythrocytes (RBC) from control and marginally riboflavin-deficient subjects were fractionated into nine fractions using a discrete density gradient.

2. Glutathione reductase (NAD(P)H: glutathione oxidoreductase; EC 1.6.4.2) activity and aspartate aminotransferase (EC 2.6.1.1) activity (with and without the appropriate co-enzymes) reduced glutathione, methaemoglobin, sulphaemoglobin and oxyhaemoglobin and susceptibility to peroxide were measured in RBC in the different fractions.

3. Glutathione reductase and aspartate aminotransferase activities and concentrations of reduced glutathione and oxyhaemoglobin all declined with age, while melhaemoglobin, sulphaemoglobin and susceptibility to peroxide increased with age.

4. The only significant differences noted in the RBC from marginally-riboflavin-deficient subjects by comparison with controls, were lower glutathione reductase activities and higher concentrations of methaemoglobin.

5. The role of riboflavin in those sytems controlling RBC integrity is discussed.

1. Four groups of six rabbits were given purified diets in which the dietary variables were protein source (isolated soya-bean protein or cow's-milk protein) with or without saponin supplementation (10 g/kg).

2. Rabbits given soya-based diets showed significantly lower serum concentrations of triglyceride and cholesterol (P < 0·01). The latter changes were confined to the cholesterol fractions of β-lipoproteins.

3. These changes in serum cholesterol were associated with a significantly increased excretion of acid and neutral sterols in animals given soya-bean protein.

4. There was no evidence to suggest that the effect of dietary protein source on serum lipids and the excretion of total and individual sterols was influenced by saponin supplementation.

5. These results do not support the hypothesis that the hypocholesterolaemia associated with plant proteins is due to the presence of saponins.

1. Bread alone and supplemented with guar gum at three levels (50, 100 and 150 g/kg) was given to eleven non-diabetic subjects, and blood glucose and serum insulin were determined preprandialy, and at 30 min and 60 min after commencement of the meal. The satiating effect, up to 120 min, of the guar bread and its acceptability to the same group of normal volunteers was also studied.

2. No significant differences in blood glucose were observed between control and guar breads at 30 min and 60 min, apart from 100 g guar/kg bread at 30 min (P < 0·05). A significant difference in serum insulin was indicated between: control and 50 (P < 0·02) and 150 (P < 0·02) guar/kg breads at 30 min; control and 50 (P < 0·05), 100 (P < 0·001) and 150 (P < 0·05) guar/ke breads at 60 min.

3. There were no significant differences in the satiety scores for control and guar breads. Significant increases in satiety attributed to 150 g guar/kg bread were found when compared to: 50 g guar/kg bread immediately after eating (P < 0·05), 100 g guar/kg bread at 60 min (P < 0·02) and 50 and 100 g guar/kg breads at 120min (both P < 0·05).

4. There was a positive correlation between hedonic score and relative replacement of guar (r 0·62, P < 0·001, n 44) and from the regression line it was found that 50 and 100 g guar/kg breads produced hedonic scores close to a neutral response of 5, whereas 150 g guar/kg bread at a predictive score of 6·3 appeared to be unacceptable to our subjects.

5. Guar bread at the 100 g/kg level (59 g guar/kg bread) reduced the serum insulin by 48% at 60 min and is found to be an acceptable food product at this level of incorporation. However, more information is required to demonstrate the possible satiating potential of guar bread.