Deuterium dilution for the measurement of total body water (TBW) has been conducted using varying protocols for equilibration. We measured TBW from deuterium dilution in urine samples in twenty-eight subjects using three protocols: (1) early morning dosage without breakfast, measuring deuterium in a second voiding at 4h and 6h; (2) early morning dosage with breakfast with the same measurement times; (3) dosage as last consumption before overnight sleep, measuring deuterium in a second voiding at 10 h. Results were compared with TBW estimates from underwater weighing (UWW). Because UWW is an indirect measure of TBW, it is used as an independent reference method in order to compare only relative discrepancies between the two methods. TBW values in the fasted state were not significantly different from those obtained in the fed state. The urinary deuterium enrichment was higher at 4 h than at 6 h (resulting TBW differences: 0·6 (SD 0·4)I). At 4h and 6h, differences in TBW measurements from deuterium and densitometry were positively related to the amount of TBW, indicating incomplete equilibration in larger water compartments. At 10h no such relationship existed, indicating complete mixing of deuterium. It is concluded that 10h equilibration is preferable to the shorter 4h and 6h, for the determination of TBW.

The effect of dietary protein quality and quantity on fractional rates of protein synthesis (ks) and degradation (kd) in the skeletal muscle, liver, jejunum and skin of young growing chickens was studied. Chickens were either fasted overnight or were fed at frequent intervals, using continuous feeders, with equal amounts of a diet containing soya-bean meal as the sole protein source, unsupplemented, or supplemented with either lysine or methionine. Each of the three diets was provided at 2 or 0.9 × maintenance. On the higher intake, birds on the unsupplemented diet gained weight, lysine supplementation decreased and methionine supplementation increased body-weight gain (by −23% and + 22% respectively). Birds led at 0.9 × maintenance lost weight; supplementation with methionine or lysine did not influence this weight loss. None of the dietary regimens had significant effects on protein synthesis rates in any of the tissues, thus the mechanism whereby muscle mass increased in response to methionine supplementation appeared to be a decrease in the calculated rate of protein degradation. Similarly, on the 0.9 × maintenance diet the failure of the animals to grow appeared to be due to an increase in the rate of protein degradation rather than an effect on synthesis. Conversely, muscle ks was decreased in fasted chickens previously fed on the unsupplemented diet at 2 × maintenance, and in birds which had received the 0.9 × maintenance diet fasting resulted in a similar reduction in protein synthesis in muscle; ks in the liver and jejunum was also significantly decreased. The effect of fasting, unlike the effect of supplementation or restriction of the diet, appeared to be due to changes in the rate of protein synthesis.

Changes in tissue composition and protein synthesis ratio were studied in the major tissues of the body in young rats fed on lipid-rich, isonitrogenous purified liquid diets, a convenient method for inducing voluntary overfeeding under controlled nutritional conditions. Overfed rats showed faster growth induced by the energy excess. Analysis of tissue composition (protein, DNA and RNA contents) revealed that growth was due mainly to tissue hyperplasia in which protein and DNA contents increased in parallel. Fractional protein synthesis ratio measured in vivo by the flooding-dose method of phenylalanine showed a marked increase in all tissues. This change could be attributed to an increase in the ribosomal activity for protein synthesis in most tissues. Therefore, our results indicate that addition of a supplementary energy source (as lipids) to a well-balanced diet improves growth and protein synthesis in growing rats.

In order to determine how soya-bean proteins are digested and metabolized in the human intestine before colonic bacterial fermentation and to estimate their true digestibility, the gastro-jejunal behaviour of soya-bean proteins in water and in two other forms (a concentrated soya-bean-protein solution (isolate) and a drink composed of crude soya-bean proteins (soymilk)) was studied in humans. Experiments were carried out in eight healthy volunteers using a double-lumen steady-state intestinal perfusion method with polyethyleneglycol (PEG) as a non-absorbable volume marker. Gastric emptying and N and electrolyte contents of the jejunal digesta were analysed. Gastric half-emptying time (min) of the liquid phase after water ingestion (12·59 (SE 0·12)) was shorter (P < 0.05) than those for soymilk (37·74 (SE 11·57)) and isolate (36·52 (SE 11·23)). Electrolytic balances showed that for all meals, Na+, Cl− and K+ were secreted when Ca2+ was efficiently absorbed from the jejunal lumen. Gastro-jejunal N absorption for isolate and soymilk were 63 and 49% respectively, and were not significantly different from one another; after water ingestion, endogenous N was estimated to be 21 mmol. An estimate of the exogenous: endogenous values for the effluents was obtained from the amino acid compositions of soymilk and effluents after water or soymilk ingestion, indicating that 70% of the total N was exogenous and 30% endogenous. Under these conditions the endogenous fraction represented 31 mmol after soymilk ingestion and the gastro-jejunal N balance indicated that 54% of the soymilk was absorbed. This finding indicates that the true gastro-jejunal digestibility of soya-bean proteins is similar to that of milk proteins.

The time-course effects of two diets containing raw (RSF) or heated (HSF) soya-bean flour on the digestive enzyme levels in the pancreas and in pancreatic juice were investigated in growing rats fed, alternately, on RSF or HSF diets for two 4-week periods. These values were compared with those obtained in a control group fed on a casein diet. RSF and HSF diets lowered N balance (84.8 (SE 0.9), 82.6 (SE 0.8) and 79.9 (SE 0.8) % with control, HSF and RSF diets respectively, at the third week). However, they increased protease activities compared with the control diet (3-fold for trypsin (EC 3.4.21.4) and chymotrypsin (EC 3.4.21.1) activities in pancreas contents and outputs with the RSF diet; 2-fold for trypsin in pancreas contents and outputs and by 60% for chymotrypsin contents with the HSF diet). The poorer nutritional N utilization might be attributable to soya-bean flour heat-stable (lectins) and heat-labile components (trypsin inhibitors). The decrease in lipid apparent digestibilities in RSF and HSF diets (97.0 (SE 0.8), 91.1 (SE 09) and 90.4 (SE 0.7) % with control, RSF and HSF diets at the seventh week) were correlated with a diminution in apparent lipase (EC 3,1.1.3; measured without addition of exogenous colipase), potential lipase (measured with addition of saturated amounts of exogenous colipase) and colipase activities. Compared with control values, gains in potential and apparent lipase outputs were diminished by nearly 40% and gain in colipase outputs by 60% with RSF and HSF diets. These results show clearly that heated or raw soya-bean flours have a significant inhibitory effect on lipase digestive enzyme activities in the pancreas and in its secretion, which might explain impaired lipid digestibility.

In order to study the influence of pancreatic enzyme secretion on the intestinal absorption of mediumchain fatty acids (MCFA), three growing pigs (mean body-weight 61 kg) with ligated and severed pancreatic ducts were fitted with a permanent fistula in the duodenum and with two catheters in the portal vein and carotid artery respectively. An electromagnetic flow probe was also set up around the portal vein. A mixture of octanoic and decanoic acids, esterified as medium-chain triacylglycerols, together with maltose dextrine and a nitrogenous fraction was continuously infused for 1 h into the duodenum. Samples of blood were withdrawn from the two vessels at regular intervals of time for 8 h and further analysed for their non-esterified octanoic and decanoic acid contents. The concentrations of non-esterified octanoic and decanoic acid in the portal blood increased slowly after the beginning of each infusion, reaching about 10 times higher values than the basal level. Only 26% of octanoic acid infused in the duodenum and 27% of decanoic acid were recovered in the portal flow throughout each experiment. The possible mechanisms underlying the appearance of MCFA in the portal blood in the absence of pancreatic enzyme secretions and the importance of duodenal absorption of MCT in such physiological conditions have been discussed.

In a controlled clinical trial we have recently shown that patients with rheumatoid arthritis (RA) improved after fasting for 7–10 d and that the improvement could be sustained through 3.5 months with a vegan, diet and 9 months with a lactovegetarian diet. Other studies have indicated that the inflammatory process in R A can be reduced through manipulation of dietary fatty acids. A switch to a vegetarian diet significantly alters the intake of fatty acids. Therefore, we have analysed the changes in fatty acid profiles of the plasma phospholipid fraction and related these changes to disease activity. The concentrations of the fatty acids 20: 3n-6 and 20: 4n-6 were significantly reduced after 3.5 months with a vegan diet (P < 0.0001 and P < 0.01 respectively), but the concentration increased to baseline values with a lactovegetarian diet. The concentration of 20: 5n-3 was significantly reduced after the vegan diet (P < 0.0001) and the lactovegetarian diet periods (P < 0.01). There was no significant difference in fatty acid concentrations between diet responders and diet non-responders after the vegan or lactovegetarian diet periods. Our results indicate that the changes in the fatty acid profiles cannot explain the clinical improvement.

Apparent Mg absorption, that is Mg intake minus faecal excretion, was found to be greater in rats fed on diets containing fructose instead of glucose. This effect of fructose was accompanied by enhanced urinary excretion and diminished retention of Mg. True Mg absorption was then determined with the use of oral and intraperitoneal administration of tracer doses of 28Mg. True Mg absorption was significantly greater in rats fed on fructose. There was no significant effect of fructose v. glucose on faecal excretion of endogenous Mg. It was hypothesized that fructose enhances the solubility of Mg in the ileal lumen and thereby facilitates its absorption. The distribution of Mg between the solid and liquid phases of the ileum was determined in rats fed on either glucose or fructose. Fructose reduced the amount of Mg in the solid phase but raised both the amount and the concentration of Mg in the liquid phase. We conclude that the dietary-fructose-induced stimulation of Mg absorption in rats is caused by a raised solubility of ileal Mg. but the mechanism by which fructose exerts this effect and why it was not associated with a decrease in faecal excretion of endogenous Mg remain unknown. Dietary fructose v. glucose did not systematically affect the apparent absorption of Ca and P.

Fibre-mediated physiological effects of raw and processed carrots were investigated in twenty-four young women under strict dietary control in two randomized crossover studies. For 3 weeks between 405 and 688 g of either raw frozen, blanched or canned carrots (first study), or raw or raw frozen carrots (second study) were consumed in addition to a low-fibre basal diet. Carrots provided 15 g dietary fibre (DF)/d. Total DF intake was 16.0 to 1.90 g (control periods) and 31 to 34 g (experimental periods). Faecal bulking effects of raw and processed carrots were similar (between 2.4 and 3.7 g additional stool/g carrot fibre in the diet). Faecal excretion of dry matter, fibre, and protein also increased significantly during carrot consumption. Fermentability of carrot fibre constituents was high (91–94%) and independent of processing, in spite of differences in the distribution of soluble and insoluble fibre and in the texture of raw and processed carrots. There was no effect of either type of carrot on serum total and high-density-lipoprotein-cholesterol or on faecal bile acid excretion.

Ninety preselected children, aged between 8 and 14 years, living in two rural West African (Gambian) villages, were randomly divided into three groups, matched for age and sex. One group received a placebo (lactose) tablet, one received riboflavin (5 mg) on 5 d every week, which was sufficient to correct an endemic riboflavin deficiency, and one received a multivitamin supplement (Protovit; Hoffmann La Roche), on 5 d every week, together with FeSO4 (200 mg) once weekly, and the supplements were given for 1 year. Neuromuscular tests, including arm tremor and manipulative skills, were performed on three occasions: once just before the introduction of the supplements; again 6 weeks after commencing the supplements; and again 1 year later. Venous blood samples were collected at the same time as the first two sets of neuromuscular tests. These samples were used for haematology and nutrient status indices: plasma ferritin, ascorbic acid, cyanocobalamin and pyridoxal phosphate, and erythrocyte tests for folate status, for riboflavin status (erythrocyte glutathionc reductase activation coefficient) and thiamine status (erythrocyte transketolase activation coefficient). The riboflavin in both supplements achieved a clear-cut response in biochemical status, which was dose-dependent. The pyridoxine, ascorbic acid and Fe components of the multivitamin also affected the associated biochemical indices. Although overall the arm tremor and related neuromuscular function tests did not respond significantly to the supplements, significant improvement was seen in the boys for the arm-tremor test in both the supplemented groups.

Zn deficiency is hypothesized to produce poor resistance to injury involving oxidative stress. This could occur by impairing Zn antioxidant function(s) or by indirectly limiting adaptive protective mechanisms such as a rise in acute-phase proteins. The present study examined rats fed diets adequate or moderately low in Zn (4 or 25 μg/g diet) for 9 d. The lower intake produced a mild Zn deficiency based on body weight, plasma Zn and plasma alkaline phosphatase (EC 3.1.3.1) activity. Galactosamine injection, an oxidative stress, produced much more liver injury in the mildly Zn-deficient rats. However, injury was strongly inhibited in rats from each dietary group by an acute-phase response due to turpentine-induced leg inflammation. Mild Zn deficiency did not prevent a rise in levels of the acute-phase protein caeruloplasmin (EC 1.16.3.1), but did limit the usual inflammation-induced rise in hepatic levels of metallothionein, a Zn protein with possible antioxidant function. In conclusion, high degrees of galactosamine-induced hepatitis were associated with mild Zn deficiency, but the liver injury was blocked by prior stimulation of an acute-phase response, regardless of Zn status.

Women (n 160) aged 50 to 65 years were asked to weigh their food for 4 d on four occasions over the period of 1 year, using the PETRA (Portable Electronic Tape Recorded Automatic) scales. Throughout the year, they were asked to complete seven other dietary assessment methods: a simple 24 h recall, a structured 24 h recall with portion size assessments using photographs, two food-frequency questionnaires, a 7 d estimated record or open-ended food diary, a structured food-frequency (menu) record, and a structured food-frequency (menu) record with portion sizes assessed using photographs. Comparisons between the average of the 16 d weighed records and the first presentation of each method indicated that food-frequency questionnaires were not appreciably better at placing individuals in the distribution of habitual diet than 24 h recalls, due partly to inaccuracies in the estimation of frequency of food consumption. With a 7 d estimated record or open-ended food diary, however, individual values of nutrients were most closely associated with those obtained from 16 d weighed records, and there were no significant differences in average food or nutrient intakes.