The relationship between diet and the development of chronic disease still remains a controversial area. One major difficulty is to obtain a valid estimate of habitual pattern and level of food consumption for each individual. There is, in fact, a voluminous and largely negative literature on the validity of dietary assessment methods. In the present paper the utility of the most frequently used dietary assessment method in epidemiological studies is discussed in terms of precision and accuracy.

The effects of the inclusion of raw and autoclaved whole faba beans (Vicia faba; RFB and AFB respectively) or faba bean fractions (cotyledons and hulls) in diets for growing broiler chickens (0–4 weeks of age) on performance, intestinal physiology and jejunal histological structure have been studied in three experiments. Significant decreases in body-weight as well as lower food consumption and higher food intake:weight gain ratio were observed in those animals fed on diets containing 250, 350 and 500 RFB'kg in the diet. Birds fed on AFB diets (500 g/kg) had significantly greater body-weights than chicks fed on RFB or raw faba bean cotyledons (RC). Significant increases in the relative lengths of duodenum, jejunum, ileum and caeca, pancreas relative weight, and intestinal transit time of birds fed on diets containing 250,350 and 500 g RFB/kg compared with control birds were observed. Including AFB (500 g/kg) in the diet significantly increased body-weight and significantly decreased pancreas weight compared with RFB (500 g/kg)-fed birds. The inclusion of RFB hulls had no effect on these variables. Dehulling or autoclaving of faba beans, or both, proved to have no significant effect on relative lengths of duodenum, jejunum, ileum and caeca, nor on caecal volatile fatty acid concentration in birds fed on 500 g faba beans/kg diet. Electron microscopy of the jejunal mucosa revealed discrete hyperplasia of polysomes and mitochondria1 swelling in those animals fed on AFB (500g/kg) or AC (4264g/kg). Pronounced strangulations were also observed along the microvilli, whose length was similar to that of control birds. The inclusion of RFB hulls, either autoclaved or raw, led to no ultrastructural changes in the enterocytes, as detected by electron microscopy. Birds fed on diets containing the cotyledons of RFB (RC, 426 4 g/kg) rather than whole RFB showed the same ultrastructural disorders as RFB (500 g'kg)- fed birds. The present study shows that factors other than those usually claimed, i.e. protease inhibitors, phytates, tannins and lectins, may be contributing to the low nutritional value of V. faba seeds for growing chickens.

The effect of long-term (10 weeks) treatment with growth hormone (GH) was investigated in twin lambs, one sibling being a control and the other treated with GH (0.1 mg/kg live weight per d). The lambs were fed on a concentrate-grass cube (9: 1 w/w) diet at a daily rate of 40 g fresh weightlkg Live weight. The average daily live-weight gain of the GH-treated lambs was 36% greater than that of the controls (307 v. 225 g/d, P < 0.01). The carcass composition of the GH-treated lambs changed: fat content was decreased (P < 001) and protein content was increased (P< 0.05) when expressed relative to carcass dry matter. The absolute weights and the weights when expressed relative to fleece-free empty body of some muscles were significantly increased in GH-treated lambs. The mean retention times of both particulate- and liquid-phase components of the digesta were unchanged by GH treatment, when calculated for the rumen or for the entire gastrointestinal tract. The feed conversion ratio was significantly greater (P < 0.01) in GH-treated lambs compared with controls. Nitrogen retained per g N intake was also significantly increased (P < 0.05) by GH treatment. Plasma urea concentrations were decreased (P < 005) and glucose concentrations were increased (P< 001) in GH-treated lambs, whereas non-esterified fatty acid concentrations were unchanged. Plasma insulin and total insulin-like growth factor-1 concentrations progressively increased in GH-treated lambs as treatment time continued. They were significantly correlated after week 4 of treatment. Two types of hepatic GH- binding site were detected, with high and low affinities for GH. The capacities of both binding sites were significantly increased (P < 0.05) in GH-treated lambs when expressed per unit microsomal protein but, when expressed per liver, only the capacity of the high-affinity site was increased.

Recent studies suggest that dexfenfluramine (D-fenfluramine), because of its pure serotonergic effect, may be a more potent anti-obesity agent, associated with fewer side-effects than the racemate DL-fenfluramine. The effect of dexfenfluramine on gastric emptying of a mixed solid and liquid meal was assessed with a double-isotope scintigraphic technique in eleven obese patients. Each subject took a placebo capsule on the morning and evening of the day before, and on the morning of the first gastric emptying measurement. Dexfenfluramine was then taken at a dose of 15 mg twice daily and gastric emptying measurements were performed at 5 and at 29 d after the initiation of active treatment. Dexfenfluramine significantly slowed gastric emptying of the solid meal at both 5 and 29d when compared with the placebo (P < 0.05) and also delayed emptying of solid food from the proximal stomach (P < 0.01), but no significant effect on liquid emptying was observed. No significant side-effects were reported and there was a marginal weight loss (P< 0.005) during treatment. We conclude that inhibition of gastric emptying may contribute to the efficacy of dexfenfluramine in the treatment of obesity.

The selective retention of particles in the reticulo-rumen and in the gastrointestinal tract distal to the reticulo-rumen was studied in fistulated sheep maintained on a roughage diet. Polyethylene glycol and plastic particles of different lengths (1 and 10 mm) and densities (092, 1.03, 1.22 and 1.44 g/ml) were either fed or were introduced into the omasum. The mean retention time in the reticulo-rumen (MRTRR) of 1 mm long particles with a density of approximately 1.0 g/ml was about 67 h, that is eight times longer than the MRTRR of fluid; the heavier particles were retained only three times longer than fluid. Particles with a length of 10 mm were retained in the reticulo-rumen 19–28 h longer than 1 mm long particles of the same density. Particles with a length of 10 mm were reduced to smaller particles (0.5–4 mm) due to rumination. Multiple regression analysis indicated that particle density and particle size accounted for 59 and 28% of the total variation of MRTRR respectively. The mean retention time distal to the reticulo- rumen (MRTGut) of 1 and 10 mm long particles with a density near 1.0 g/ml was 18–19 h, similar to that of fluid (16 h). The heavier particles were retained about 3–8 h longer.

Apparent and partial digestible energy values for α-amylase (EC 3. 2. 1. 1)-resistant, retrograde starches, isolated from cooked maize and pea starches (RMS and RPS respectively), were determined in male Wistar rats (about 180 g) during a 28–29 d balance period with ten animals per treatment. The starches were provided as supplements (100 g/kg diet) to a semi-synthetic basal diet (B), and their effects on the apparent digestibilities of nitrogen and fat, and on gains of live weight, fat and lean tissue were examined. Diet B alone was the control; sucrose (Su) and Solka-floc cellulose (SFC) were also examined for reference. Apparent digestibilities for Su, SFC, RMS and RPS were 1.0, 0.16, 0.98 and 0.89 respectively. Whereas the apparent digestibilities of gross energy, N and fat in the diet were unaffected by supplementation with Su, each was decreased by supplementation with SFC, RMS and RPS. Partial digestible energy values calculated from the intakes and faecal losses of energy in the basal and supplemented diets were 15, 12.4 and 0.8 kJ/g for RMS, RPS and SFC respectively. These values were smaller than corresponding apparent digestible energy values calculated from the apparent digestibility of the supplement and its gross energy value. Only the Su and starch supplements increased the intake of apparent digestible energy and the gain of live weight. Both starches and Su increased total energy (and fat) deposition to almost similar extents. It is concluded that the resistant starches contribute significant dietary energy, enhance growth and elevate fat deposition to extents almost similar to Su.

Ten subjects aged 19–35 years (four men and six women) underwent two measurements of 24 h energy expenditure (EE) in a whole-body respiration calorimeter, one at a temperature of 28° and one at 20°. Choice of clothing was allowed. Dietary intake was standardized and subjects were asked to follow the same pattern of activity during both measurements. Mean 24 h EE was significantly greater at the cooler temperature by 5.0 (SD 5.5) %, with individual differences ranging from 4.6% lower to 12.6% higher. The difference in EE at the two temperatures was similar during the day and the night and occurred even though subjects wore more clothes and used more bedding at 20°. No relationship was observed between response to 20° and body-weight status. In conclusion, the assumption that mild cold is unlikely to affect EE in subjects wearing normal clothing may be incorrect.

The effect of two levels of fishmeal substitution (50 (FM1) and 150 (FM2) g/kg) of a grass silage control diet (C) on the rumen digestion of organic matter and nitrogen, and the small intestinal disappearance of amino acids was examined in young growing cattle each equipped with simple PVC cannulas in the dorsal sac of the reticulo-rumen, the proximal duodenum and the terminal ileum. The silage was a primary growth of perennial ryegrass (Lnlium pevenne) (+formic acid) with a total N content of 22 g/kg dry matter (DM) (diet C). Fishmeal substitution increased this to 26 (diet FM1) and 34 (diet FM2) g/kg DM. On diets C and FM1, approximately 0.71 of digestible organic matter intake was apparently digested in the rumen, but this was significantly (P < 0.05) reduced on diet FM2 (0.60). Whilst duodenal flows of non-ammonia N and total amino acids were significantly (P < 001) increased at the highest level of fishmeal inclusion only, the synthesis of microbial N was significantly (P < 0.001) reduced by fishmeal inclusion, and feed N degradability declined progressively in response to increased fishmeal. Both levels of fishmeal addition caused a significant (P< 0.05) reduction in the fractional outflow rate of water from the rumen, and on the highest level of fishmeal significant (P< 0.05) increases in rumen ammonia concentration and rumen propionate molar proportions were observed. The net effect of the highest level of fishmeal substitution was to increase amino acid absorption from the small intestine by 0.47 compared with the control diet (P< 0.05), but due to an elevated ileal flow of amino acid no such effect was detected at the lowest level of fishmeal substitution. Composition of the absorbed amino acid fraction was relatively unaffected by the treatments imposed, despite large changes in the composition of the duodenal protein. The apparent non-linearity of response to fishmeal substitution is discussed and the amino acid supply findings are compared with the protein retention findings obtained in an earlier study by Gill et al. (1987). By two methods of calculation it was estimated that the amino acid N fraction disappearing from the small intestine was utilized with an efficiency of between 0.51 and 0.53 and no apparent effects due to diet or level of amino acid supply were detected.

The influence on protein accretion and whole-body protein turnover of changing dietary protein quality while maintaining constant energy intake was studied by varying the degree of lysine supplementation of a lysine-deficient barley-based diet given to growing pigs. Measurements of nitrogen metabolism and whole-body protein turnover, using both classical and 15N end-product methods following a single dose of lsqb;15N]glycine, were made in 49-kg male pigs given diets containing 109 g lysine-deficient protein/kg supplemented to make them (1) 'deficient', (2) 'adequate' and (3) 'in excess' with respect to lysine. The 15N dose and protein intake values used to calculate amino N flux from the cumulative urinary excretion of 15N in urea and ammonia were corrected respectively for apparent digestibilities of [15N]glycine and total N determined in a separate experiment in pigs fitted with simple ileal cannulas. N retention and biological value were significantly increased by lysine supplementation of the deficient diet to the 'adequate' level, but were not further increased by the higher level of supplementation. Rates of growth paralleled these changes. The poorer biological value of the unsupplemented diet 1 was shown also in a significantly higher excretion of urea N compared with diets 2 and 3. N digestibility was not markedly influenced by the level of lysine supplementation. Both whole-body protein synthesis and degradation increased markedly on 'adequate' supplementation of the diet with lysine, but did not increase further with an excess of lysine. It is concluded that the increase in protein accretion rate observed on supplementation of the diet with lysine was due to a greater increase in the rate of protein synthesis than of degradation, rather than a decrease in degradation rate.

The relations between the urinary excretion of acid-soluble peptide (ASP)-form amino acids, the rate of whole body protein synthesis and plasma immunoreactive insulin-like growth factor-1/somatomedin C concentration were investigated in rats. The urinary ASP-form leucine plus valine excretion correlated well with the rate of whole body protein synthesis and with the plasma immunoreactive insulin-like growth factor-1 concentration. The results provide further evidence for the hypothesis that urinary excretion of ASP is an excellent index of the status of protein metabolism in animals.

Twenty-three British Friesian bull calves at approximately 7 d of age were allocated to one of four treatments: controls untreated (five calves), a group (Clen) given 1 mg clenbuterol/kg diet (five calves), a group (GH) given a daily subcutaneous injection of 3.5 mg bovine pituitary growth hormone (GH) (five calves) and a group (Clen + GH) given a combination of clenbuterol as in the Clen group with GH as in the GH group (seven calves). All calves were given milk-substitute at levels adjusted weekly according to metabolic live weight. The animals were slaughtered over the weight range 150–170 kg. Samples of semimembranosus and triceps muscles were excised a t slaughter. Treatment with GH produced approximately a threefold increase in mean daily serum GH concentration. Calves given Clen + GH were heaviest a t slaughter and the combined treatment produced a significantly higher (P < 0-01) feed conversion ratio. Administration of clenbuterol either alone or in combination with GH increased the cross-sectional area of both fast twitch glycolytic (FG), and fast twitch oxidative glycolytic (FOG) fibres in both muscles. In contrast GH produced little change in fibre size in semimembranosus muscle, although FOG fibres in triceps were slightly larger than in controls. Neither Clen nor GH resulted in any change in fibre percentage frequency in either muscle. Treatments involving clenbuterol produced a significant decrease in muscle glycogen concentration. Muscles from all three treatment groups tended to show small increases in protein and RNA concentration compared with the controls. Muscles from animals treated with GH alone exhibited an increase in DNA concentration not seen in muscles from the two other treatment groups. Overall, the differential response to the two agents suggested that clenbuterol does not mediate its effects via the GH axis, and that an additive response in terms of protein anabolism may be achieved from the use of a combination of clenbuterol plus GH.

The present paper reports the influence on plasma lipids of isoenergetic diets containing 30 YO of energy as fat, with a polyunsaturated: saturated fat ratio of 4.00 or 0.25, consumed for 8 weeks by twenty-five young normolipidaemic males. Approximately 70 % of the fat energy was provided by the test fats: soya-bean fat and coconut fat. During the soya-bean-fat-eating period the total plasma cholesterol level fell significantly compared with baseline values (P < 0.001) and during the coconut-fat-eating phase total plasma cholesterol level increased significantly compared with the soya-bean-eating period (P < 0001).On the soya-bean-fat diet, high-density-lipoprotein (HDL)-cholesterol decreased by 15 YO (range 6–35 YO) and plasma triacylglycerols decreased by 25 YO (range 13–37 YO). Results of the present study show that even when the proportion of total fat in the diet is low, a high intake of linoleic acid lowers both total plasma cholesterol and HDL-cholesterol, while a high intake of saturated fat elevates both these lipid fractions. Application of regression formulas to the present findings indicates that short-chain saturated fatty acids have a neutral effect on serum cholesterol

The purpose of the present study was to test the hypothesis that the already well-established mitochondria1 lesion in fatty acid oxidation in riboflavin-deficient experimental animals, might be accompanied by an alteration in vivo in the kinetics of oxidation of labelled adipic acid. This dicarboxylic acid was chosen for testing as a metabolic probe because a block in its oxidation was already apparent from urine analysis of riboflavin-deficient animals, whereas the oxidation of medium- or long-chain monocarboxylic acids seemed to be little affected by deficiency in vivo. Female adult Norwegian hooded rats fed on purified diets containing either 15 mg riboflavin/kg diet (controls) or about 0.4 mg/kg (riboflavin-deficient) received an intragastric dose of either [l,6-I4C] adipic acid or [l-'4C] octanoic acid. Expired carbon dioxide was then collected in an alkaline trap over 3 h, for determination of radioactivity.This test was repeated at intervals for up to 2 weeks following riboflavin repletion of the deficient animals, and in riboflavin-dosed controls. Whereas the rate and extent of ['4C]octanoic acid oxidation was not significantly affected by the deficiency or repletion, the extent of [I4C]adipic acid oxidation was markedly and significantly increased during repletion of the deficient animals. The time-course indicated a temporary overshoot, followed by a slow return to the control values over 1–2 weeks. Adipate oxidation was also much less affected by a preceding period of overnight starvation, than was octanoate oxidation. Thus, adipic acid (or a related metabolic probe) may have appropriate properties for the design of a functional test of fatty acid oxidation efficiency, during riboflavin deficiency or allied metabolic conditions in human subjects.

The lipid distribution and fatty acid (FA) composition of total lipids, polar lipids and free fatty acids (FFA) were determined in liquid-associated bacteria (LAB) and solid-adherent bacteria (SAB) isolated from the rumen contents of seven dairy cows fitted with rumen fistulas. Two experiments, arranged according to a 4 x 4 and 3 x 3 Latin Square design, were performed using two basal diets consisting of one part hay and one part barley-based concentrate, and five lipid-supplemented diets consisting of the basal diet plus (g/kg dry matter): 53 or 94 rapeseed oil, 98 tallow, 87 soya-bean oil or 94 palmitostearin. For all diets used, total lipids were 1.7–2.2 times higher in SAB than in LAB (P < 005); this probably resulted from a preferential incorporation of dietary FA adsorbed onto food particles. Addition of oil or fat to the diets did not modify the polar lipid content but increased the FFA content of SAB and LAB by 150%. Lipid droplets were observed in the cytoplasm in SAB and LAB using transmission electron microscopy, which suggested that part of the additional FFA was really incorporated into the intracellular FFA rather than associated with the cell envelope by physical adsorption. Linoleic acid was specifically incorporated into the FFA of SAB, which emphasized the specific role of this bacterial compartment in the protection of this acid against rumen biohydrogenation.

Less frequent iron supplementation may be equally as beneficial to Fe-deficient subjects as routine daily supplementation because of the short-term suppressive effect of oral dosing with large amounts of Fe on subsequent Fe absorption. In the present study, the possibility that the administration of an Fe supplement every 2nd or 3rd day may be as effective in improving Fe status as a daily supplement was investigated in anaemic rats. Anaemic rats were given a 4 mg Fe supplement every day, on alternate days or every 3rd day, as a single dose with a midday meal or as a multiple dose with a morning, midday and evening meal. A low-Fe diet (13 mg/kg) was given at all other times. After 7 d, erythrocyte count, packed cell volume, mean cell volume, haemoglobin concentration and total liver Fe were measured and compared with those of meal-fed rats which had not been given any supplemental Fe. Rats which received a supplement every 3rd day, a total supplement of 12 mg, had a similar Fe status to those receiving a daily supplement, a total supplement of 28 mg. Administration of the supplement as a multiple, rather than as a single dose did not improve recovery from the Fe deficiency. It is suggested that less frequent supplementation with a smaller total amount of Fe, should be considered in human subjects. Such a regimen would minimize unpleasant side-effects of oral Fe therapy, decrease the risk of adverse effects of Fe on the absorption of other essential minerals and substantially cut the cost of supplementation programmes.

The effectiveness of EDTA compounds on iron fortificants for potential use in Egyptian balady bread was tested in sixty SpragueDawley weanling male rats by the haemoglobin regeneration efficiency (HRE) method. To confirm HRE-derived findings, eight groups of ten animals were repleted with a modified American Institute of Nutrition (1977; AIN) 76A diet, fortified with ferric phosphate, electrolytic Fe, carbonyl Fe or ferrous sulphate, with and without ascorbic acid. Results without ascorbic acid were comparable to findings of a human study by Forbes et al. (1989). Bioavailability of EDTA-enhanced fortificants, FeSO4 + Na2EDTA and NaFe(III)EDTA, was compared with that of FeSO4 in six groups of ten animals repleted with a ground Egyptian bread meal or a casein-based AIN diet fortified with one of the three compounds. Addition of either EDTA compound significantly increased bioavailability of Fe in Egyptian balady bread. When present in the less inhibitory casein meal, however, FeSO4 + Na2EDTA fortification was significantly less effective than NaFe(1II)EDTA or the reference FeSO4. Results indicate that NaFe(I1I)EDTA may be the fortificant of choice in a mixed diet. Further study of EDTA- enhanced Fe fortificants is needed.

Fifteen adult women were given diets in which the intake of complex carbohydrates was increased from 20 to 30 g over a 12 week period. Metabolic balances were carried out, iron and zinc absorption tests performed using stable isotopes, and Fe and Zn status monitored. Although effects on bowel function were observed, the changed diet had no influence on any of the previously described variables. It was concluded that a moderate increase in cereals, fruit and vegetables did not have an adverse effect on Fe or Zn nutrition.