1. The meat of the Indian species of crab was assessed for the quality of its protein with the use of protein-depleted adult rats.

2. The crab meat and casein had the same biological value, 88.

3. Crab meat supported a higher growth rate than casein in rats.

1. Body-weight, skinfold thickness and food intake were measured at regular intervals in twenty-five young men while on an Antarctic expedition.

2. The mean calorie intake over the year was 3600 kcal/man per day; 12.1% of these calories were supplied by protein, 39.8% by fat, and 48.1% by carbohydrate.

3. The calorie intake was equivalent to that which would be expected in a moderately active worker living in a temperate climate. The chemical composition of the diets did not differ from average values for young men in the United Kingdom.

4. There was a significant fall in food intake during the winter months, when the outside temperatures were greatly reduced and there was polar night. During this period the men were largely confined to the limits of the base hut and the levels of physical activity showed a marked fall.

5. During the year there was a gain in body-weight of 2.7 kg. Of this gain 2.5 kg occurred in the first 2 months.

6. Skinfold thickness followed the trend of the body-weights except for the April-May increment which was unaccompanied by a weight change. This dissociation could not be explained.

1. A series of experiments was carried out to determine the minimum essential amino acid requirements of the adult rat.

2. After testing four amino acid patterns taken from the literature, a basal pattern was formulated in which each amino acid appeared at the lowest level at which it was presented in any of the original diets.

3. Nitrogen balance was the main criterion used to judge any benefit arising from modest increases in individual amino acids tested in a modified Latin-square design. They were given at a protein level of 3.6% of the diet. Non-essential amino acids were in the same proportions as in whole egg.

4. It appeared that three amino acids, namely tryptophan, threonine and isoleucine, brought about more favourable balances when presented at concentrations higher than basal.

5. Reduced levels of each amino acid were then tested in order to ensure that no surpluses were present.

6. N retentions indicated that lysine, phenylalanine plus tyrosine, leucine and valine could be reduced below the basal level and still meet the needs of the rat for these amino acids.

7. When the pattern of amino acids arising from these latter trials was tested in combination, rather than as trios, pairs, or single changes, positive N balances gave confidence that these were minimal levels of the essential amino acids required for meeting the maintenance needs of adult rats.

8. Plasma proteins from the rats on the evolved pattern were found to be in no way different from those found for normal animals. This gave further support to the belief that the pattern was adequate for the rats.

1. The protein efficiency ratio of three protein sources was determined with rats by a depletion-repletion method. The sources were: a groundnut product, a methionine-supplemented groundnut product and lactalbumin.

2. Livers obtained from the test animals were assayed for arginase activity, and kidneys for transamidinase activity (glycine amidinotransferase).

3. The measurements indicated that there was an inverse relationship between arginase activity and the nutritive value of the dietary protein.

4. Transamidinase activity was also influenced by nutritive value. Only the unsupplemented groundnut product, which had the lowest nutritive value, failed to produce a significant increase of transamidinase activity over basal levels.

5. The findings are discussed from the standpoint of physiological function and needs. It is suggested that observed levels of arginase activity are not necessarily related to amounts of urea excreted; similarly, transamidinase activity may be well in excess of physiological requirements.

1. Forty-eight guinea-pigs were fed from weaning on a semi-synthetic diet free of retinol and carotenoids. Twenty-two of these animals received a twice-weekly supplement of methyl retinoate and fifteen received a twice-weekly supplement of retinyl acetate. The remaining eleven animals were fed on the vitamin A-free diet without supplementation.

2. At varying times throughout the experiment, animals died or were killed by chloroform inhalation. Testes and seminal vesicles were weighed and these tissues together with trachea, lungs, salivary glands, bladder, eyes and vagina were examined histologically.

3. The eleven guinea-pigs that received the unsupplemented diet developed signs of vitamin A deficiency after being fed on the diet for 3 or 4 weeks. Many epithelia showed a metaplastic change to the stratified squamous form often with keratinization.

4. The guinea-pigs given supplements of either methyl retinoate or retinyl acetate grew at a normal rate and developed none of the signs of vitamin A deficiency that appeared in the animals on the unsupplemented diet. Evidence of metaplastic change in epithelia was not seen in any of these animals.

5. Thirteen males were fed on the deficient diet and methyl retinoate. The testicles and seminal vesicles of these animals weighed less than those of the ten males fed on the deficient diet and retinyl acetate. The testes of the former showed severe histological degeneration of the seminiferous epithelium. The testes of the guinea-pigs fed on retinyl acetate were normal.

6. Fifteen guinea-pigs fed on the deficient diet and retinyl acetate were mated to normal males. Eleven were thought to have become pregant. Eight of these gave birth to twenty-four pups. One died in advanced pregnancy with five apparently normal pups in utero and one produced three living young and died with one still in utero. Sixteen guinea-pigs fed on the deficient diet and methyl retinoate were mated to normal males. Twelve were thought to have conceived but all resorbed their foetuses.

7. The vision of guinea-pigs fed on the synthetic diet and methyl retinoate deteriorated progressively, and after 150 days on the experiment the pupils did not respond to light. However, degeneration of the retina, such as had been seen in rats fed on a vitamin A-deficient diet containing methyl retinoate, was not seen in any of the guinea-pigs.

1. The effect of a penicillin-enriched diet (100 mg or 1000 mg penicillin-G/kg food) on the active transport of D-glucose and L-histidine has been investigated by the use of sacs of everted small intestine of normal young adult rats and golden hamsters. The antibiotic was given for up to several weeks.

2. The penicillin made no difference to the final concentration gradients of D-glucose or L-histidine achieved by rat small intestine, although with the hamster these appeared somewhat improved. Water entry into the serosal fluid remained unchanged.

3. The lengths and the dry weights of the small intestines of both species were not altered by the dietary regimen.

1. The effects of low-protein and protein-free diets on the levels of disaccharidase, peptidase and aldolase activities in the jejunal mucosa of rats were studied.

2. Maltase, palatinase and sucrase activities increased significantly after both types of feeding, although there was an initial fall with the protein-free diet.

3. The rise in lactase levels was, however, not so marked.

4. Glycyl-glycine and glycyl-leucine dipeptidase levels fell consistently with both diets.

5. Aldolase activities were generally unaltered, but tended to fall if the period of low-protein feeding was prolonged.

6. Enzyme levels rapidly returned to normal when the rats were given a normal diet after a period on a protein-deficient one.

7. It is suggested that the rise in disaccharidase and fall in peptidase levels are adaptive changes to the high-carbohydrate, low-protein diet, with diminished enzyme synthesis, due to lack of nitrogen, contributing to the lowered peptidase activities. The relevance of these results to disaccharide intolerance in chronic malnutrition, kwashiorkor and gastro-intestinal infection is discussed.

1. A critical analysis of the biological antioxidant theory of vitamin E function has been made and the implications of the theory have been tested.

2. When small amounts of [5-Me-14C]α-tocopherol were present in lipid systems subject to autoxidation in vitro, it was found that, whether the tocopherol was the sole antioxidant or was in synergistic combination with a secondary antioxidant (ascorbic acid), peroxidation did not occur without concomitant destruction of the tocopherol. This was so, whether a simple fat substrate or a liver homogenate (subject to catalysis) was used. The decomposition of tocopherol took place even when the secondary antioxidant was in large excess, as would occur under physiological conditions in the vitamin E-deficient animal, and accelerated as the induction period neared its end.

3. When [5-Me-14C,3H]α-tocopherol and ascorbic acid were used as a synergistic antioxidant couple in vitro, tocopherol recovered from the peroxidizing system always had the same isotopic ratio as the starting material. This means that regeneration of tocopherol by the secondary antioxidant cannot involve, as an intermediate, a tocopherol carbon radical formed by loss of hydrogen from the 5-methyl group. Such radicals probably dimerize before they can be regenerated. The same result was found when doubly labelled α-tocopherol was given to the rat and recovered later from its tissues.

4. In a series of experiments, rats were rigorously depleted of vitamin E for periods up to 7 months and then given as little as 50 μg [14C]D-α-tocopherol. They were then given, either by stomach tube daily or by dietary addition, large amounts of methyl linoleate or vitamin E-free polyunsaturated fatty acid methyl esters prepared from cod-liver oil and compared with controls given methyl oleate for up to 31 days. When the possibility of interaction between the lipid and tocopherol in the gut was eliminated, analyses of liver, kidney, testis, adrenal, adipose tissue, whole carcass and faeces showed that there was no effect of the polyunsaturated fatty acids on either the metabolism or recovery of [14C]α-tocopherol in any of the animals.

5. When interaction between the administered fatty acid esters and tocopherol in the gut was allowed to take place, a marked destruction of [14C]α-tocopherol in the tissues was observed in animals given the polyunsaturated esters. The importance of oxidative destruction of tocopherol in the gut before absorption was demonstrated in a nutritional trial, in which cod-liver oil and lard were compared and the degrees of resistance of rats' erythrocytes to dialuric acid-induced haemolysis was used as an index of vitamin E depletion.

6. Similar experiments with [14Cα-tocopherol in weanling rats given large amounts of cod-liver oil methyl esters also showed little effect. Although there was a suggestion that prolonged feeding of partly peroxidized polyunsaturated esters could lead to a slight depression of tissue tocopherol concentrations, no significant differences were usually obtained.

7. Fourteen-day-old rats were given a vitamin E-deficient diet and received three weekly doses of 0.5 mg α-tocophcryl acetate. The dosage was stopped, the rats were then given a deficient diet containing 4% of either vitamin E-free linseed oil fatty acids or oleic acid, and the rate of their tocopherol depletion was measured by the erythrocyte haemolysis test. No effect of the polyunsaturated fatty acids was found. Nor was there any effect on the concentrations of ‘secondary antioxidants’ (glutathione and ascorbic acid) in liver, kidney, testis, muscle or adipose tissue.

8. The results of the experiments in vivo contrast strongly with those in vitro. They lead to the conclusion that lipid peroxidation, if it occurs in the living animal, is irrelevant to the problem of vitamin E function. This conclusion has been substantiated by a critical review of the literature on the quantitative aspects of the vitamin E-dietary fat relationship.

9. The effects of dietary fat stress in vitamin E-deficient animals are, we believe, due to two causes: (1) destruction of tocopherol in the diet or in the gastro-intestinal tract of the animal, and (2) the existence of an increased requirement for vitamin E for the metabolism of certain long-chain fatty acids. The specific effects of certain of these substances in producing or accelerating some vitamin E deficiency diseases may be related to the toxic states known to be induced in vitamin E-deficient animals by other stress factors.

1. The metabolism of small amounts of [5-Me-14C]D-α-tocopherol and [5-Me-3H]D-α- tocopherol has been studied in the vitamin E-deficient chick. Small doses of the labelled tocopherol were given to chicks, which were then subjected to stress by giving them diets formulated to produce encephalomalacia, exudative diathesis or muscular dystrophy.

2. Tocopherol concentrations in the cerebella and brains of chicks with incipient encephalomacia were the same as those in normal chicks in which the dietary fat stress was absent.

3. α-Tocopherol delayed the onset of encephalomalacia by a mean value of 3.5 days when its concentration in the cerebellum was about 2 × 10−7g/g of lipid. This concentration is considerably below the usual effective concentrations of antioxidants in vitro.

4. Selenium deficiency, under conditions leading to a high incidence of exudative diathesis, was not associated with lowered tocopherol levels and did not result in detectable destruction of tocopherol.

5. Nor was there any destruction of tocopherol or significant effect on its metabolism in the processes leading to muscular dystrophy: on the contrary, the affected muscles of dystrophic chicks, which had received a diet deficient in sulphur amino acids, contained significantly more tocopherol than muscles from control birds.

6. These results do not support the hypothesis that lipid peroxidation is a causative process in the aetiology of vitamin E-deficiency diseases in the chick. The relationships between unsaturated lipid, Se, sulphur amino acids and tocopherol in the chick require further exploration.

1. When weanling rats were given a vitamin E-deficient diet and 0.15% (w/v) silver acetate in their drinking water, there was a high incidence of liver necrosis and death after 2–4 weeks. This was prevented by 120 ppm D-α-tocopheryl acetate in the diet, was partially prevented by selenium at 1 ppm but not at 0.05 ppm and was only marginally prevented by 0.15% DL-methionhe.

2. All these effects were observed when the diet was free of fat and when it contained either methyl oleate or polyunsaturated methyl esters. The polyunsaturated lipid slightly increased the velocity of the terminal illness.

3. In spite of the ‘anti-vitamin E’ effect of Ag and the clear demonstration that α-tocopherol played a major part in preventing toxicity, experiments with tracer amounts of [5-Me-14C]-D-α-tocopherol showed that rather than there being any destruction of tocopherol in the critical period preceding the onset of disease, there was an increase in tocopherol in the liver due to Ag administation. The metabolism of tocopherol in the remainder of the animal was unaffected during the pre-necrotic phase.

4. The results are inconsistent with the view that the stress induced by Ag is caused by a pro-oxidant effect, either in the gastro-intestinal tract or in the tissues of the rat. They show that lipid peroxidation is not a causal factor in the aetiology of Ag-induced liver necrosis and suggest that stress in the vitamin E-deficient animal probably raises the requirement for tocopherol.

1. The activities of several lysosomal hydrolases were measured in the tissues of chicks suffering from nutritional muscular dystrophy, encephalomalacia or exudative diathesis.

2. In dystrophic breast muscle, β-glucuronidase was raised five- to six-fold, cathepsin fourfold and acid phosphatase 1.5-fold. No change was found in the subcellular distribution of β-glucuronidase.

3. Chicks with encephalomalacia showed no changes in the β-glucuronidase, β-galactosidase, acid phosphatase or β-acetylglucosaminase activities of cerebellum or brain. Subcellular distribution of β-glucuronidase and β-galactosidase in these tissues was also unchanged.

4. In exudative diathesis, hydrolases were found in the exudate, and there was increased activity in the subcutaneous tissue first showing haemorrhages. Increased hydrolytic activity was found in liver, spleen and kidney. Breast muscle was not always affected by the exudative condition, but, when it too degenerated, its hydrolase activity increased.

5. β-Glucuronidase activity was measured in the serums of chicks suffering from each of the three deficiency diseases. None of the diseases caused a rise in activity.

1. Activities of β-glucuronidase, β-galactosidase, acid phosphatase and cathepsin were measured in the uterine contents of normal rats during gestation and of vitamin E-deficient rats during foetal resorption.

2. β-Glucuronidase activity reached a peak value on days 11 and 12, falling to lower values by day 14. Deficient rats showed slightly greater mean values than normal rats on days 11 and 12, but not after that time.

3. Vitamin E deficiency did not affect the activities of β-galactosidase, acid phosphatase and cathepsin, all of which showed a slow decrease during pregnancy.

4. The supernatant fraction of homogenates of uterine contents from deficient rats showed increased β-glucuronidase and β-galactosidase activity from day 14 to 17, suggesting some degree of rupture of the lysosomal membrane.

5. β-Glucuronidase and acid phosphatase activities were raised in the uteruses of some deficient rats towards the end of pregnancy, but serum β-glucuronidase was unaffected.

6. Changes in lysosomal hydrolases were not so marked during gestation–resorption as in some other vitamin E deficiency states, such as muscular dystrophy in the chick and rabbit.

1. The activities of several lysosomal hydrolases have been measured in tissues of rats with nutritional liver necrosis. Incipient or actual liver necrosis did not alter total, free or unsedimentable activities of cathepsin, β-glucuronidase, β-galactosidase or acid phosphatase of liver and kidney. Free hydrolytic activity towards p-nitrophenyl phosphate was slightly raised in liver, and serum β-galactosidase and β-glucuronidase were moderately elevated. These results suggest that lysosomal hydrolases are not directly implicated in the causation of liver necrosis.

2. Testicular degeneration was studied with reference to changes in β-giucuronidase activity. This enzyme activity, total, free and unsedimentable, was raised in deficient rat testis at 6 months old and did not decline even after a year. Raised values were also found in serum.

1. Among a series of 343 children with severe primary malnutrition there were 248 for whom, on admission, there were reliable records of age, weight, height, liver size, severity of oedema, skin lesions and angular stomatitis, and concentration of total serum protein, haemoglobin and sodium. For eighty-four of these children the serum bilirubin concentration was also known.

2. The correlations of these characteristics of the children on admission, with mortality, and with the rate of recovery were investigated.

3. Age, weight, oedema and haemoglobin concentration were not significantly related to mortality or to rate of recovery. A multiple regression analysis showed that an increased serum bilirubin concentration and a decreased serum sodium concentration indicated a bad prognosis, and these two factors contributed almost the whole of the multiple correlation coefficient of 0.63 with respect to mortality and 0.59 with respect to speed of rccovery.

4. We conclude that in our series of children death was more closely associated with liver failure or overhydration than with protein depletion, and suggest that the administration of ton much protein or water to an acutely ill malnourished child may precipitate death.

5. This analysis shows that the mortality observed in our series cannot be adequately explained by any combination of the characteristics considered above; there must, therefore, be other factors of importance for which we do not have suitable measurements.

1. The effect of dietary protein level and supplementation with thyroxine on the liver storage of vitamin A, on the fraction of liver vitamin A in the alcohol form, and on the plasma levels of vitamin A and proteins has been studied in chicks.

2. Liver storage was reduced by lowering the dietary protein level.

3. Protein restriction lowered the percentage of vitamin A found in the liver as retinol.

4. Thyroxine increased both vitamin A storage and the fraction of the total vitamin A as retinol, this effect being dependent on dietary protein level.

5. Plasma vitamin A and plasma protein contents were lowered to a highly significant extent by protein restriction. This drop was essentially caused by reduction of the albumin fraction in chicks fed on a 5% protein diet and by a reduction of β- and γ-globulins in chicks fed on a 10% protein diet.

6. Thyroxine supplementation of the diet lowered to a highly significant extent plasma protein content; this reduction was caused by a dramatic fall in the level of plasma albumin. The β- and γ-globulins were concomitantly increased.

1. Samples of whale, meat, fish, groundnut and soya-bean meals and skim-milk powders were assayed microbiologically with Tetrahymena pyriformis W and Streptococcus zymogenes for available methionine and available lysine.

2. Detailed collaborative studies on the assay of available methionine with Strep. zymogenes were conducted on the effects of dry- or wet-grinding the test meals, the use of crude or purified papain for predigesting the ground meals and the use of optical density or titratable acidity as criteria of bacterial growth response.

3. Wide differences were observed in the available methionine and available lysine contents of a variety of meals in the preliminary studies, with a promising measure of interlaboratory agreement in the assay of available methionine with Strep. zymogenes.

4. As a result of detailed collaborative studies a provisional method is proposed for the assay of available methione with Strep. zymogenes, adopting dry-grinding and predigestion with an agreed level of papain in the preparation of the meals. No general recommendation could be offered on the comparative merits of optical density and titratable acidity as criteria of bacterial growth response.

1. Eleven groups of male rabbits (eight to eleven per group) were given ad lib. a diet consisting of 61 parts of a low-fat basal ration to which were added: for groups 1–3, 20 parts maize oil; for groups 4–7, 20 parts butterfat; and for groups 8–11, 0.47 parts maize oil and 43.1 parts wheat starch. Different types of roughage were added to the 61 parts of basal ration as follows: for groups 1, 4 and 8, 19 parts ground wheat straw; for groups 2, 5 and 9, 19 parts Solkafioc; for groups 3, 6 and 10, 19 parts of shredded cellophane; and for groups 7 and 11, 14 parts shredded cellophane and 5 parts peat.

2. After the rabbits had been given the experimental diets for a period of 40 weeks, the plasma cholesterol levels were determined. The animals were then killed and the degree of atheromatous degeneration was determined after the aortas had been stained with Sudan IV.

3. Elevated levels of plasma cholesterol and extensive atheromatous degeneration were observed in the rabbits given the diets containing 20% butterfat (groups 4–7) and in those given the diets containing 48% starch (groups 8–11). Lower levels of plasma cholesterol and only slight atheromatous degeneration were observed in the rabbits given the diets containing 20% maize oil (groups 1–3).

4. The levels of plasma cholesterol and the degree of aortic atherosis were influenced very markedly by the nature of the dietary roughage. Plasma cholesterol levels and degrees of aortic atherosis tended to be higher when cellophane was the roughage component than when wheat straw was the roughage component of the diet. The replacement of part of the cellophane of the diet by peat reduced the level of plasma cholesterol and the degree of aortic atherosis.

5. The possible mechanisms by which the nature of the dietary roughage influences plasma cholesterol levels are discussed.

1. The total polyunsaturated fatty acid (PUFA) content of tissues of vitamin E-deficient rats and chicks has been measured by the lipoxidase method.

2. Vitamin E deficiency did not depress total PUFA in rat liver, kidney, heart, spleen, brain, adrenal and adipose tissue during experimental periods up to 13 months.

3. Liver PUFA was not depressed by deficiency of vitamin E and selenium in rats at 9 weeks or 8 months of age.

4. Rats given a muscular dystrophy-producing diet (containing oxidized cod-liver oil) showed a severe depletion of PUFA in muscle, but not in kidney or adipose tissue.

5. Exudative diathesis induced in chicks by a deficiency of vitamin E and Se did not depress liver PUFA.

6. It is considered that in vitamin E deficiency there is no general decrease in PUFA due to peroxidative loss. Changes of a more specific nature occur, as found by other workers.

1. One hundred and ten weanling rats were distributed between five dietary groups in randomized blocks. Each block was constructed from within a litter and each member of the block received a different diet.

2. The main features of the diets were: group I (twenty-six rats) 72% sucrose, group 2 (sixteen rats) 72% uncooked maize starch, group 3 (sixteen rats) 72% roll-dried maize starch, group 4 (twenty-six rats) 36% sucrose and 36% uncooked starch, group 5 (twenty-six rats) 36% sucrose and 36% roll-dried starch.

3. The animals were killed after 20 days on the diets and assessed for dental caries. The rats of group 1 (sucrose) had significantly more caries than all other groups, the rats of group 2 (uncooked starch) had significantly less caries than any of the other groups. Roll-dried starch (group 3) produced significantly more caries than uncooked starch (group 2). The mixture of uncooked starch and sucrose (group 4) was significantly more cariogenic than the mixture of roll-dried starch and sucrose (group 5).