1. Yudkin's (1967) questionnaire on the dietary intake of sugar was given to 415 businessmen for self-administration.

1. The results showed an inverse relationship between sugar intake and relative weight (actual weight as a percentage of expected weight for height and age) and additional evidence suggests a direct relationship between sugar intake and adequate exercise.

2. The statement that ‘sugar was restricted’ was shown to be a factor of considerable importance affecting the reported level of sugar intake and should be taken into account when comparing different series.

3. The positive association between cigarette smoking and mean sugar consumption in this series was due to the low-sugar intake of ex-smokers.

4. In future studies on the role of sucrose in the aetiology of ischaemic disease, both smoking habits and levels of activity should be recorded.

1. Chicks and quail (Coturnix japonica) were used in the measurement of net protein utilization and true digestibility of nitrogen of isolated soya-bean protein and a mixture of casein and gelatin in zinc-deficient diets.

2. The net protein utilization values for both protein sources were increased when the diets were supplemented with Zn or with the disodium salt of ethylenediaminetetra-acetic acid, as was the true digestibility of nitrogen of the isolated soya-bean protein.

1. The amino acid incorporating activity of skeletal muscle ribosomes was studied in rats under various nutritional conditions using labelled amino acids.

2. Ribosomes were obtained from rats that were given a protein-free diet for 5 d followed by a high-protein diet containing casein, gelatin or wheat gluten for 16.5 h and from others that were given one of these protein-containing diets or one containing protein from polished rice for 6 d.

3. The level of isotope incorporation relative to RNA was somewhat higher when the protein source given for 16.5 h was a good-quality protein such as casein than with gelatin or wheat gluten, but fine discrimination between proteins was not considered to be feasible with this system.

4. In the rats that were given the protein-containing diets for 6 d the differences were more pronounced and the amino acid incorporating activity was correlated with the biological value of the protein.

1. The amounts of available cystine and tyrosine in the protein of different animal tissues showed a close correlation with the level of hydroxyproline, and may be estimated from hydroxyproline values by regression equations.

2. Estimates of ‘chemical score’ have been calculated from the content of hydroxyproline determined in a series of samples for which net protein utilization (NPU) for rats had also been determined. Chemical scores calculated as percentages of the total ‘essential+semiessential’ amino acid content of each material correlated closely with NPU, whereas scores calculated as percentages of total amino acids did not. ‘Methionine+cystine’ were calculated to be first limiting amino acids in every sample.

1. Sixteen Indian schoolboys, aged 12–14 years resident in Singapore, were tested for the determination of energy cost, pulmonary ventilation (PV) and oxygen consumption at rest and at various daily activities; their height, body-weight, pulse and blood pressure were also measured. An energy balance study was made by estimating from a diary of measured activities the 24 h energy intake and output.

2. PV and O2 consumption during running showed positive correlations(r = 0.4 and r =0.3 respectively) with mean post-exercise recovery pulse, O2 consumption and PV.

3. The daily mean calorie intake and output of the subjects were found to be 2108 kcal (8.85 MJ) and 1811 kcal (7.60 MJ) respectively.

4. The boys gained an average of 2.2 kg in weight and 0.7 cm in height in 2 months. They did not suffer from any mental retardation, they were physically fit, free from disease and did their daily routine work satisfactorily.

1. The effects of adding increasing supplements of urea to mainly barley diets for early-weaned lambs were investigated in two experiments. In the first experiment the passage of nutrients along the alimentary tract was studied by taking samples of abomasal, ileal and rectal contents and using a marker technique. In the second experiment, feed consumption and rate of gain were recorded over the growth period up to 40 kg live weight, and nitrogen balances were carried out. In the second experiment a barley-fish meal diet was also included.

2. The fermentation of organic matter in the rumen increased with the amount of urea in the diet and levelled off when the diet contained about 12% crude protein.

3. Urea supplementation had significant effects in increasing N retention and rate of live-weight gain and in decreasing feed conversion ratio, but supplementation beyond about 12% crude protein in dry matter had no further effect on these measurements. In each instance results with the barley–fish meal diet were better than the results with any of the barley-urea diets.

4. From the concentrations of diaminopimelic acid (DAPA) in abomasal fluid it was estimated that microbial protein was produced in the rumen at a rate of 15.6% g/100 g organic matter fermented. This ratio did not appear to alter significantly with urea supplementation, but the comparison depends on the assumption that the concentration of DAPA in the bacterial protein did not itself change with urea supplementation.

5. Using results from both experiments, it was calculated that the retained N on the urea-supplemented barley diets was approximately 47% of the amount of protein N absorbed in the small intestine.

6. It is suggested that barley diets for early-weaned lambs can with advantage be supplemented with non-protein N to increase the crude protein in the dry matter up to about 12%. When barley diets are given with a protein supplement the addition of non-protein N is unlikely to be beneficial unless the protein supplement is given in such a way that it is not subject to degradation to yield ammonia in the rumen.

1. Groups of lambs were killed immediately after birth; others were reared on a diet of cow's milk and were killed at 10, 20 and 30 d after birth. The concentrations of 18: 2ω6 (linoleic acid) were determined in cow's milk and the concentrations of 18:2ω6, 20:4ω6 (arachidonic acid) and 20: 3ω9 (Δ5, 8, 11 eicosatrienoic acid) were determined in the whole carcasses of the lambs.

2. The carcass of the newborn lamb contained only about 300 mg 18: 2ω6. During the first 20 d after birth, there were large increases in the 18: 2ω6 contents of the carcasses, and on the 10th and 20th days, their contents of 18: 2ω6 were similar to the dietary intakes of 18: 2ω6 at the corresponding time-intervals after birth.

3. The 20: 3ω9 to 20:4ω6 ratio in the carcass of the newborn lamb was about 1.6, but after 10 d the ratio had decreased to 0.38 in spite of the fact that 18:2ω6 contributed only about 1% of the total calories in the diet.

4. The minimum dietary requirements for essential fatty acids for young ruminants and for non-ruminent animals are compared.

1. ε-(γ-L-Glutamyl)-L-lysine was found to have a growth-promoting activity that was approximately equal to the equivalent quantity of L-lysine for both young rats and chicks receiving a lysine-deficient diet.

2. Small quantities of the compound were found in the plasma of the chicks and rats receiving it at the level of 0.4–0.5% on the diet, but none was detected in the rat urine and only a trace in the separated chick urine.

3. Direct intravenous infusion of glutamyl-lysine into rats resulted in higher plasma concentrations; it is suggested that hydrolysis of the ingested peptides may occur largely in the intestinal wall.

4. The findings are discussed in relation to the earlier hypothesis that the formation of glutamyl-lysine cross-linkages in severely heated protein provides an explanation of their reduced nutritional value.

1. The live-weight gain, carcass weight, edible carcass composition, efficiency of food conversion, and roughage intake were measured in three groups of calves fed for 87 d. After a 3-week feeding period on a common regimen, one group of calves was weaned on to a diet of dry whole-milk powder and chopped lucerne, the second group received a similar diet except that the whole-milk powder was reconstituted to a liquid milk, containing 12–15% dry matter. The third group was given the diet in the same manner as the second group except that the chopped lucerne was available ad lib.

2. The mean live-weight gains for the three groups were 37.7, 47.6 and 52.7 kg respectively, the differences between the dry-fed and the liquid-fed groups being highly significant.

3. Energy and nitrogen accretion in the edible carcass and efficiency of food conversion were superior in the second and third groups.

4. The third group ate larger quantities of roughage, though the difference did not reach significance.

5. The reasons for the superiority of the liquid milk diet are discussed in relation to the avoidance of ruminal fermentation of the milk.

1. Weanling (24-d-old) rats of a black and white hooded strain were allowed free access for 28 d to a diet containing 5% casein supplemented with methionine, and sucrose as the carbohydrate. Controls were fed on a 25% casein diet with a corresponding reduction in sucrose. Animals given the deficient diet were killed either at 52 d of age or after subsequent rehabilitation on the 25% casein diet when aged 140 d. These animals were compared with controls killed at these two ages and at the start of the experiment.

2. The skeletons were X-rayed, skeletal maturity was determined according to a scoring system, and various bones were measured. The forebrain and cerebellum were analysed for cholesterol and DNA and the brain stem for cholesterol only. The DNA content of the paired quadriceps muscles and the livers was also determined.

3. On the low-protein diet the body-weight rose by 7 g compared with the control value of 115 g. On rehabilitation, the body-weight of the previously malnourished group showed the expected growth spurt, but failed to attain that of the controls at 140 d.

4. With the exception of the pelvis width, all the bones grew a little during the period on the low-protein diet. After rehabilitation, the hind limb, pelvis, iliac and spine lengths and the bi-iliac width remained smaller than these measurements in the corresponding controls, whereas there was no difference in the length of the fore limb, width of the pelvis or in the bone maturity score.

5. The forebrains and cerebellums of the malnourished rats did not increase in weight, whereas some increase occurred in the brain stem. The concentration of cholesterol in the forebrains of the deficient animals was the same as that in controls of the same age, but on rehabilitation the concentration did not rise to the control value. The concentration of cholesterol in the cerebellum and brain stem of the deficient rats was lower than in controls of the same age but, whereas that in the cerebellum attained an almost normal level on rehabilitation, that in the brain stem remained significantly lower. The low-protein diet prevented the normal increase in cerebellum DNA and the amount remained low in the rehabilitated animals.

6. The experimental diet caused a complete cessation of growth of the quadriceps muscles, and even after rehabilitation they weighed less than their controls. The DNA content, however, was not significantly lower.

7. The low-protein diet did not permanently affect either the weight or DNA content of the liver.

1. The results of a previously reported controlled trial of vitamin supplementation of elderly hospital patients, in which capillary resistance was measured by the Hess test, were examined and analysed statistically.

2. Capillary resistance was reduced during successive 3-monthly tests over a period of 12 months and the reduction was related to leucocyte ascorbic acid concentration.

3. It is postulated that the rate of recovery from capillary trauma inflicted by the test was dependent upon the function of ascorbic acid in the hydroxylation of proline to hydroxyproline during collagen synthesis.

1. Nitrogen intakes, and N output in urine, faeces and sweat have been measured in six young Tanzanian men who were accustomed to a hot climate. The measurements were done while the subjects were receiving first a normal and then a low-N diet; and when they were performing moderate physical work, and had undergone a period of acclimatization.

2. When the subject were acclimatized and working on a normal diet, their sweat output increased, with a fall in its N concentration. Total sweat N loss increased from an average of 0.10 to 0.71 g/d.

3. The effect of the low-N diet was to decrease both the sweat N concentration, and the rate of increase of total N loss in sweat, as sweat volume increased.

4. It is estimated that maximum sweat N losses would not exceed 1 g/d on an adequate diet, or 0.5 g/d on a low-protein diet. Our results provide no basis for recommending extra protein allowances to cover sweat N losses for workers in tropical climates.

1. Propane-1:2-diol (loog/d) was infused through a cannula into the rumen of sheep receiving a ration of hay and dried grass. The concentration of volatile fatty acids, propanediol, lactic acid and of added polyethylene glycol, and the pH of the rumen contents were measured. The energy metabolism of the sheep was also determined.

2. Most of the propanediol disappeared from the rumen within 4 h of its infusion. The infusion of propanediol resulted in a 10% decrease in the concentration of total volatile acids; the concentration of acetic acid decreased by about 30%, that of propionic acid increased by up to 60% and there was no change in the concentration of butyric acid.

3. The methane production of the sheep decreased by about 9% after the infusion of propanediol and there were increases in the oxgyen consumption, carbon dioxide production and heat production of the animals; each of these increases was equivalent to about 40% of the theoretical value for the complete metabolism of 100 g propanediol.

4. It is concluded that, when propanediol is introduced into the rumen, a proportion is metabolized in the rumen and a large proportion is absorbed directly. Our thanks are due to Dr J. H. Moore for helpful discussions, to Mr D. R. Paterson, Mr J. R. McDill and Mr C. E. Park for looking after the animals and to Miss K. M. Graham, Miss A. T. McKay and Mrs C. E. Ramage for performing the analyses.

1. The effects of intraduodenal infusions of sterculic acid, a naturally occurring inhibitor of desaturase activity, on the yield and composition of milk were examined in a lactating goat.

2. Sterculic acid administration increased the percentage of stearic acid in milk fat, reflecting inhibition of mammary desaturase activity. Milk yield was not affected, but milk fat output decreased. Possible explanations are discussed.

3. No evidence was obtained for an alternative pathway of oleic acid synthesis from acetate.

1. A study was made on the folate content of goat's milk in relation to stage of lactation, and on the interrelationship between blood and milk folate concentrations in the dam and in the kid.

2. In seven goats the folate concentration in the colostrum at parturition ranged from 136 to 300 ng/ml, and averaged 205 ng/ml. The concentration fell sharply during the early days of lactation and by day 14 it averaged only 9.5 ng/ml. This pattern of rapid decline in milk folate concentration with advancing lactation was little affected by daily provision of folic acid parenterally in relatively large amounts.

3. The colostrum and milk contained a minor whey protein that combined strongly with folate, and presumably acts as a trapping mechanism to accumulate the vitamin from the plasma into the milk. The milk folate concentration determined by the rate of milk secretion in relation to the availability of free folate in the blood plasma.

4. At parturition the plasma folate concentration in the kids was very low – about 1 ng/ml – but by day 2 it had increased to about 28 ng/ml. This folate was protein-bound and accompanied by an excess of free binder protein. It appeared that the folate-protein complex from the colostrums was transmitted intact into the kids' blood circulation.

5. The possible importance of the folate-binding protein in regulation of folate metabolism is discussed.

1. In malnourished, compared with recovered children, fasting blood glucose concentrations were low and there was impaired peripheral glycolysis as shown by a failure of blood lactate to rise after glucose was injected intravenously.

2. Homogenates of muscle biopsies from malnourished and recovered children produced equal amounts of lactate when incubated anaerobically with various substrates, but when compared with homogenates of biopsies from normal children the pattern suggested an impairment of glycolysis.

3. The rate of glucose disappearance after intravenous glucose was slow in the malnourished child and there was possibly diminished sensitivity to exogenous insulin.

4. Isocaloric diets relatively high or low in fat were fed to children who had recovered from malnutrition. Glucose tolerance, insulin sensitivity, fasting plasma insulin and insulin response to intravenous glucose were all the same in children on either diet.

1. Four hundred and fifty patients who were treated for megaloblastic anaemias in northern Finland were grouped according to the month of diagnosis.

2. Only slight seasonal variation was detectable in the occurrence of megaloblastic anaemia.

3. During the first half of the twentieth century the seasonal variation in occurrence of megaloblastic anaemia was pronounced. The decrease in the variation is most likely related to the more even distribution throughout the year of the supply of foods containing folate and vitamin B12.

1. The equation used for calculating heat production of ruminant animals is expressed in a new form, convenient for application to open-circuit calorimetry.

2. It is shown that in open-circuit calorimetry the possible error involved in making the assumption that respiratory quotient is equal to unity is small compared with the possible error involved in neglecting methane production.

3. In open-circuit calorimetry heat production can be predicted with accuracy to within ± 2% solely from the measurement of oxygen concentration and ventilation rate.