Inferior Diet Research Articles

Imagined foodways and rejected biopedagogies: Rural children's perspectives of rural foodways

AbstractRural residency is an independent risk factor for being overweight, but little is known about why this is so. The purpose of our study was to gain insight into what Norwegian rural children say about a rural diet in comparison to an urban one. Child‐friendly methods were used. We found a discrepancy between what the children said they eat – traditional, ‘healthy’ foods, and what they ate – largely ultra‐processed foods. We explored this by using the frameworks of imagined foodways and biopedagogies. Their imagined foodways were rooted in notions of ‘traditional food’, connected to surrounding nature and a history of farming and hunting. Urban people were perceived as eating an inferior diet of very unhealthy and ultra‐processed foods of which they do not know the origin of. As a result, the children rejected specific health‐ and nutrition recommendations that were incompatible with their notions of traditional foods, leading to a more calorie dense diet than their urban counterparts. Our research adds to knowledge on what role a rural diet can play on the prevalence of overweight in rural areas, and how biopedagogies can be recontextualized within different cultural fields.

Ultra-processed food (UPF) intake in pregnancy and maternal and neonatal outcomes.

Ultra-processed food (UPF), as defined by the NOVA classification, is related to lower diet quality, which may adversely affect maternal health and neonatal outcomes. This study aims to describe nutrient intake of pregnant women by the share of UPF in the diet and to identify associations between UPF intake and maternal and neonatal outcomes. In this cross-sectional study, pregnant women (n = 206) were recruited upon arrival to the obstetrics ward for delivery, and asked to complete a Food Frequency Questionnaire (FFQ), and questionnaires regarding environmental exposures, and socio-demographic characteristics. Neonatal measurements and clinical data were obtained following delivery. UPF energy intake was expressed as absolute and in terms of percent from total energy. Women with high intake of energy from UPF were compared to those with low intake. Among 206 pregnant women, dietary intake of UPF ranged from 15.6% to 43.4% of total energy in the first and fourth quartiles of UPF consumption, respectively. Women in the fourth quartile of energy from UPF had lower intakes of vitamin C, beta-carotene, vitamin B6, and potassium, which is indicative of inferior diet quality. Percent energy from UPF was associated with maternal obesity (BMI ≥ 30) (OR = 1.06, 95% CI: 1.06, 1.10, p = 0.008) and shorter male infant ano-genital distance (AGD) (B = -1.9, 95% CI: -3.5, -0.24, p = 0.02). UPF intake during pregnancy is associated with undesirable maternal and neonatal outcomes and more research is needed to confirm these findings.

EXPERIMENTAL JUSTIFICATION OF THE PREVENTION OF PERIODONTAL BONE TISSUE DESTRUCTION IN OVARIOECTOMIZED RATS WITH CALCIUM-CONTAINING ADDITIVES

Purpose. Study of periodontoprotective properties of preventive complexes based on calcium, quercetin, vitamins, macro- and microelements in ovariectomized rats with alimentary deficiency of protein and calcium. Materials and methods. The study was conducted on 32 female rats in which pathology of periodontal bone tissue was simulated due to hipoestrogenicity; as well as the prevention of the said pathology with biologically active complexes based on calcium citrate from the shells of Black Sea oysters and "Minerol". Hypoestrogenicity was caused by bilateral ovariectomy, the negative effect of which on bone tissue was further complicated by a diet with a low content of calcium and protein. After 5 months, the animals were removed from the experiment; the degree of atrophy of the alveolar process was determined on the drugs; the content of acid and alkaline phosphatases, elastase, catalase and MDA was determined in the homogenate of the alveolar process. Results. The combination of ovariectomy and an inferior diet caused characteristic inflammatory-dystrophic changes in the bone tissue of the jaws, which are expressed in an increase in the activity of elastase, catalase, and MDA content in the alveolar bone homogenate. Also, under the condition of pathology, an increase in the degree of atrophy of the alveolar process, an increase in the activity of acid and alkaline phosphatases was observed, which indicates a violation of mineralization processes. Prophylactic administration of a complex based on calcium citrate from the shells of Black Sea oysters and a complex based on the biologically active additive "Minerol" showed a pronounced osteoprotective effect, which consisted in the decrease of the degree of the alveolar process atrophy and the reduction of the activity of markers of bone resorption and peroxidation lipids.

Phenotypic Plasticity of the Thermal Reaction Norms for Development in the Multicolored Asian Lady Beetle, Harmonia axyridis (Pallas) (Coleoptera, Coccinellidae)

Phenotypic plasticity of insect thermal reaction norms (TRNs) (the lower thermal threshold, coefficient of thermal sensitivity, and sum of degree-days) ensures precise adjustment of the seasonal cycle to local environments by changing the pattern of temperature-dependence of developmental rate. In different geographic populations the plasticity of TRNs can be manifested in different ways. We investigated the photoperiodic and diet-induced plasticity of TRNs, body mass and structural size (hind femur length) of the multicolored Asian ladybird, Harmonia axyridis, from native (Irkutsk) and invasive (Sochi) laboratory populations. Each population was tested in 16 experimental treatments that represented combinations of 4 temperatures (17, 20, 24, and 28°C), 2 photoperiods (10 and 16 h of light per day), and 2 larval diets (frozen eggs of the grain moth Sitotroga cerealella and larvae and adults of the green peach aphid Myzus persicae). The lady beetle eggs developed at a temperature of 20°C; first instar larvae were distributed among experimental treatments. We have demonstrated that under both photoperiodic regimes larval feeding on a low-quality diet (grain moth eggs) resulted in a disproportional (more strongly manifested at a low temperature) retardation of preimaginal development of individuals from both populations. The lower temperature thresholds for preimaginal development were also greater on the inferior diet. When fed on grain moth eggs, larvae from the Irkutsk population showed weaker temperature-sensitivity of development, whereas in the Sochi population the slope of the TRN did not differ between the two diets. In contrast, H. axyridis from Irkutsk showed practically no photoperiodic plasticity of TRN, whereas those from Sochi were sensitive to photoperiod on both diets. Under short-day conditions, the lower temperature threshold in the latter population was smaller and temperature-sensitivity was weaker so that at the temperatures of 17 and 20°C, development under short-day conditions was faster than that under long-day conditions, whereas at 28°C, on the contrary, it was slightly slower. In both studied populations the thermal plasticity of adult body mass and hind femur length was manifested in different ways and to varying degrees, depending on the larval photoperiodic conditions and diet. Adult body mass could decrease or increase with larval developmental temperature or show no change. Despite being maintained in the laboratory for many generations, the H. axyridis populations from Sochi and Irkutsk have retained differences in physiological responses to photoperiodic conditions and larval diet.

Food consumption and diet quality choices of Roma in Romania: a counterfactual analysis

This paper analyses the diet quality aspect of food security of Roma in Romania. We employed a modified Blinder-Oaxaca decomposition technique using Household Budget Survey data for the period 2004–2011. The estimates suggest that Roma have inferior diet diversity compared to the non-Roma. Around one-third of the diet diversity gap is explained by the differences in observed socio-economic factors, whereas the remaining part of the gap is attributed to unobserved factors. We argue that the unexplained component of the diet diversity gap is caused by the discrimination of the Roma on the labour market and by their specific informal institutions.

Radiation exposure and functional gastrointestinal disease.

I read the study by Choi et al.1 with interest, which evaluated the impact of radiation exposure on functional dyspepsia (FD) and IBS. I think the author tried to evaluate the harmful effect of radiation exposure on gastrointestinal function, so they chose a subject that was expected to have the highest radiation exposure among medical workers or the general population. In practice, because of the long latent period and cumulative effect of radiation and various radiosensitivities of different human tissues and because we do not know the exact minimum level of radiation exposure that can cause functional or structural abnormalities in the human body, the International Commission on Radiological Protection recommends a much lower dose than the alleged harmful dose of radiation exposure. For example, <1.0 mSv/year of radiation exposure for the general population and <50 mSv/year and 100 mSv/5 years for radiation workers.2 This means that the dose of exposed radiation in this study subject was at a safe and acceptable level. Additionally, we can approach a similar conclusion from the fact that each abdominal CT exposed the subject to approximately 10.0 mSv radiation exposure3,4 and that in ordinary conditions, no one shows any radiation-related complications. We currently consider visceral hypersensitivity-central and peripheral sensitization-and psychoneuroimmune interaction were important pathophysiological factors of functional gastrointestinal diseases such as FD and IBS.5,6 This is all about neurons, one of the most radio-resistant human tissues. Because of these facts and ethical issues, it is impossible to study the effect of radiation on human health. Most human studies related to radiation exposure were based on several historical event in the 21st century such as the atomic bombings of Hiroshima and Nagasaki in World War II and the Chernobyl disaster. From these events, although exact doses are unknown, most people believe that radiation exposure is harmful to the human body. The author evaluated the psychological stress level and established that a high stress level was related to FD. Although there was no statistical significance among groups, the FD and IBS groups included more shift workers who slept poorly and engaged in less regular exercise and an inferior diet than the average study subjects. This finding suggests that psychological stress and lifestyle are more important than radiation exposure for subjects with FD and IBS with acceptable doses of radiation exposure. Fortunately (but unfortunately for the investigator), most countries strictly control radiation exposure. As a result, the maximum dose of radiation exposure cannot induce any physiologic damage to our body. As we saw in the results and conclusion, it is almost impossible to obtain positive findings (results) or obvious changes in the gastrointestinal system induced by radiation exposure in well-controlled conditions. Perhaps a much longer follow-up period is required. Therefore, in practice, these kinds of studies have an unavoidable fatal limitation. Even if it showed a negative conclusion, the theme of this study was never investigated before, so it was unique and valuable. Based on this study, I carefully propose a subsequent study with another high radiation exposure group such as health-screening examinees who regularly perform tests such as CT, PET, and mammography.

Microscopy Shows Neanderthals Ate Well

About 40,000 to 30,000 years ago, modern humans out-competed Neanderthals, and the Neanderthals became extinct. Some recent theories have speculated that Neanderthals had an inferior diet (predominately meat) that put them at a disadvantage. Evidence for plant foods is rare at sites occupied by Neanderthals, but this could be due to vagaries of preservation and insufficient attention to plant remains. In an ingenious study, Amanda Henry, Alison Brooks, and Dolores Piperno used microscopy to demonstrate that plants and cooked foods are present in dental calculus (the stuff the dental hygienist scrapes off your teeth) on the teeth of Neanderthals.

Effects of dietary protein level and source on the growth and survival of two genetic lines of specific-pathogen-free Pacific white shrimp, Penaeus vannamei

An eight-week trial compared the performances of two genetic lines of Penaeus vannamei, T-line and G-line, fed with different levels and sources of dietary protein. Both lines were originated from the same founder populations but had gone through genetic selection targeting different breeding goals for more than four generations. T-line was bred for fast growth and Taura syndrome viral disease resistance, and G-line was bred for fast growth and production yield under super-high density. Five dietary treatments were employed: two commercial diets and three semipurified diets (A, B, and C). The semipurified diets were formulated at similar levels of digestible energy. Diet A contained 35% crude protein (CP), from marine meals (fish, 15%, and squid, 15%). Diet C contained 35% CP from a reduced marine protein level from fish (11.5%) and squid meals (11.5%). Diet B contained only 20% CP but had the same level of marine protein as diet C. The two commercial shrimp feeds, containing 35% and 40% protein, served as reference diets. Three replicate tanks per dietary treatment were used. Each tank was stocked with 50 tagged shrimp (25 each of T-line and G-line) and 100 untagged shrimp, with average initial weight (IWT) of 10.4g, at a density of 107/m2.Diet significantly affected shrimp growth (p<0.0001) but did not interact with shrimp line. Shrimp fed either diet A or diet C grew over 25% faster than those fed diet B or either of the two commercial diets.Diets A and C yielded similar growth (0.30 to 0.33g/day) and survival rates (83 to 93%) to a harvest size of over 29g per shrimp, suggesting that the soy protein isolate that replaced part of the marine protein in diet C can serve as a good alternative protein source. Growth rates of the two shrimp lines were similar regardless of dietary protein levels or sources, but dietary plant protein level did interact with shrimp line when the measure was survival: T-line survived better than G-line on average when fed diet B, a nutritionally inferior diet containing 20% protein and no plant protein, but not when fed diet C, containing 35% protein, 15% of which was of plant origin (soybean). Microsatellite marker analyses quantified the genetic relationship of the two lines and confirmed that they were the most closely related of the lines derived from the same founding stock. This preliminary study provided information that will be useful for further studies of the relationship between dietary nutrition and genetics and for exploration of the potential of genetic selection for improving the efficiency of plant protein use in shrimp.

Size compensation in moth larvae: attention to larval instars

Environmental perturbations such as starvation and poor diet often prevent animals from attaining their optimal sizes. When the perturbation has a transient character, compensatory responses are expected in terms of faster growth or a prolonged developmental period. In the case of insect larvae, details of such responses are insufficiently known at the proximate level. Attention to responses at the level of particular larval instars should promote an understanding of insect developmental plasticity also in a more general context. To provide an instar-specific analysis of compensatory growth, larvae of the moth Orgyia antiqua (L.) are reared on inferior diet during one larval instar. Responses in growth parameters are recorded in the course of the manipulated instars, as well as at the level of the entire larval period. The negative relationship between development time and size in response to the inferior food quality, typical of the entire larval periods, is also observed within the manipulated instars taken separately. The manipulated larvae remain smaller than the larvae of the control group (significant in males only), even by the end of the subsequent instar during which all individuals are provided with superior host. In males, close to full size compensation by the time of pupation is achieved only by means of adding an extra larval instar. The inability of larvae to fully compensate during one and even two instars is considered as an indication of the presence of constraints on the within-instar growth pattern. An alternative, adaptational explanation for the incomplete compensation could be based on the cost of prolonged development period. Given the ecological context of the species' life history, such an explanation appears less likely.

Induction of reproductive diapause in Hippodamia convergens (Coleoptera: Coccinellidae) hinges on prey quality and availability

In the High Plains of western Kansas, USA, the convergent lady beetle Hippodamia convergens Guerin completes a spring generation feeding on cereal aphids in winter wheat before leaving fields in large numbers around the time of harvest. In late May, large aggregations of coccinellids form on wild sunflowers, Helianthus annuus, and certain other weeds, that appear to serve as important sources of water absorption for the beetles, and other beneficial insects, during the dry prairie summer. Adult beetles were collected from sunflower plants and held in four treatments: (1) access to water only, (2) access to sunflower stalks only, (3) eggs of Ephestia kuehniella provided ad libitum + water and, (4) greenbug, Schizaphis graminum Rondani provided ad libitum. Most females fed greenbug matured eggs in less than a week and only a few entered reproductive diapause. In contrast, more than half of the females fed Ephestia eggs, an inferior diet, entered reproductive diapause, and those that matured eggs required an average of almost three weeks to do so. Time to 50% mortality was 7 days for beetles receiving only water, and 12 days for those receiving only sunflower stalks, whereupon all survivors were fed greenbug. Even after feeding on greenbugs for a month, less than half of the surviving females in these two treatments produced eggs. We conclude that reproductive diapause is an important adaptation for improving H. convergens survival during summer when aphids are scarce, although females will forgo diapause if they have con- tinuous access to high quality prey.

Food competition between a large ruminant and a small hindgut fermentor: the case of the roe deer and mountain hare.

In this study, we demonstrate that the mountain hare and roe deer compete with each other. This was determined using "natural experiments" of populations found in sympatry and allopatry on the islands along the west coast of Norway. We demonstrate that both species occupy the same habitats, share the same food resources and that food availability is limited. Two browsing species as different in size as roe deer and mountain hare might be expected to partition the available vegetation (e.g. woody scrub) in terms of height above ground level. However, from the evidence collected, the feeding-height-separation hypothesis must be rejected as an explanation for ecological separation between roe deer and mountain hares because there was extensive height overlap in resource utilisation by both species and neither species changed its feeding height in response to the presence of the other. Total browse utilisation did not increase when both species were together; rather, species-specific browse utilisation declined when the other species was present. However, the foraging behaviour of each herbivore varied significantly between the allopatric and sympatric sites. When both herbivores were present, the clip diameter of shoots browsed by mountain hares declined to match those selected by roe deer, while roe deer switched from a browse-dominated diet to a diet dominated by winter-green gramineae. The change to smaller-diameter shoots likely resulted in the hare increasing its intake of digestion-inhibiting or toxic secondary metabolites, while the alternative choice of digging through the snow like roe deer to reach the winter-green gramineae is a practice considered energetically too costly for hares. On this basis, we conclude that the enforced switch to a nutritionally inferior diet by mountain hares at the sympatric sites may result in changes to growth rate and body size which consequently impact on mortality and may explain the competitive superiority of the roe deer.

Persian clover and maize silage. III. Rumen fermentation and balance of nutrients when clover and silage are fed to lactating dairy cows

Six rumen fistulated dairy cows, at various stages of lactation, were housed in metabolism stalls on a total of nine occasions in three experiments in which various combinations of Persian clover (Trifolium resupinatum) and maize (Zea mays) silage were offered. These experiments considered some aspects of digestion of Persian clover and Persian clover/maize silage diets in order to understand the good milk yield responses attributed to maize silage measured in previous research. Rumen ammonia concentrations and nylon bag degradation rates suggested that the cows made better use of one or both feeds when Persian clover and maize silage were offered together than they did when Persian clover was offered alone. While Persian clover and maize silage appeared to be a substantially inferior diet in terms of apparent in vivo digestibility coefficients and availability of nutrients when compared with Persian clover offered alone, milk yields were unaffected. In addition, no matter how much maize silage was offered, milk fat content remained constant. These results were attributed to an improved balance of absorbed nutrients.

Fecundity, autogeny, and the larval environment of the pitcher-plant mosquito, Wyeomyia smithii.

Pupae and fourth instar larvae of a southern (30°N, Alabama, USA) population of Wyeomyia smithii Coq. (Diptera: Culicidae) were collected from pitcher plants. Adults which emerged were maintained without food then dissected to determine their egg clutch size. Among females which matured eggs, fecundities were negatively correlated with larval densities in individual pitchers. The mean autogenous fecundity of the overwintering generation did not differ from a summer sample. Adults unable to mature eggs comprised 6-39% of samples, depending on whether collected as pupae or fourth instar larvae. Fecundity was negatively correlated with time to adult eclosion among larvae maintained on unrenewed pitcher contents in the laboratory.Cohorts from this population were reared in artificial containers from egg hatch to adulthood at a single density and a superior or inferior diet. On the superior larval diet, all females survived to reproductive age, and all but one (>99%) produced eggs autogenously. On the inferior diet, survivorship to adult eclosion was significantly less, a high proportion of females died before reaching reproductive age, and only 19% of survivors matured eggs without blood. Protracted larval development induced by the inferior diet did not influence the probability of autogeny among females that survived to reproductive maturity.The relationship between larval environment and reproductive strategies is contrasted across the geographic range of W. smithii. Bloodfeeding occurs among southern populations where density dependent constraints on preimaginal growth are constantly severe. The loss of hematophagy among northern populations may have been facilitated by periods of density independent larval growth.

Pathophysiology of ovine fascioliasis: The influence of dietary protein and iron on the erythrokinetics of sheep experimentally infected with Fasciola hepatica

Worm-free sheep were fed diets with a high or low protein and iron content and infected with 1,000 F. hepatica metacercariae. The adult fluke burdens of the sheep on each diet were similar, but animals on the poorer plane of nutrition developed an earlier and ultimately more severe anaemia and as a result had to be necropsied earlier. By measuring the attendant changes in blood volume and erythrokinetics, it was found that the underlying cause of the anaemia in all animals was a combination of haemodilution, intra-hepatic and biliary haemorrhage, and its earlier appearance and faster development in the poorer-fed group was a refelection of the earlier onset of these changes in association with a faster rate of fluke migration. The ultimate degree of anaemia was not related to the severity of biliary haemorrhage, but rather to the animals' erythropoietic capacity. This was substantially lower in the sheep maintained on the poorer diet, which unlike their better-fed counterparts, became iron deficient by virtue of their inability to replace from the diet iron lost in the faeces as a result of haemorrhage. It was concluded that this difference was primarily a reflection of the better appetite and hence iron intake of the supplemented sheep, but differences in the efficiency of dietary iron utilization, possibly related to protein intake, may also have been involved. In a further experiment involving sheep infected with 600 metacercariae, there was no evidence of haemodilution. When provided with a diet of high protein and iron content, these animals were able to maintain constant, albeit reduced PCV values in the face of substantial biliary haemorrhage. However, when switched to an inferior diet, the same degree of haemorrhage produced a sharp fall in PCV, suggesting that erythropoiesis was adversely affected by reduced protein and iron intake.

Liver Lipids of Lactating Bovine: Fatty Acid Composition

The quantity and composition of the hepatic lipids of two groups of lactating cows, maintained on low-protein, low-energy, and high-protein diets were compared in the initial and sixth week of lactation. The lipid of livers from animals on the inferior diet was almost twice that of animals on the high-protein diet in the first week of lactation. However, within six weeks the lipids of livers from both groups of cows were comparable. The fatty acid analyses revealed that the lipids from cows on the low-protein, low-energy diets contained higher quantities of saturated and short-chain fatty acids than from cows maintained on the high-protein corn diet.

COMPARISON OF TISSUES FROM SOLID- AND HOLLOW-STEMMED SPRING WHEATS DURING GROWTH: II. FOOD VALUES DETERMINED WITH THE PALE WESTERN CUTWORM, AGROTIS ORTHOGONIA MORR. (LEPIDOPTERA: NOCTUIDAE)

Lyophilized stem tissues of Rescue and Thatcher wheat were inferior to lyophilized Thatcher sprouts or young leaves as diets for newly hatched or fifth-instar larvae of the pale western cutworm. Pith from solid-stemmed Rescue wheat was an inferior diet to either Thatcher stem or Rescue wall. Most newly hatched larvae lived for periods in excess of 24 days on pith diets but did not molt. Older stem tissues were nutritionally inferior to younger stem tissues. Neither the qualitative nor quantitative composition of 80% ethanol-soluble carbohydrates from the stems, leaves, and sprouts accounted for their relative value as diets for the cutworm. The amino acid composition of ethanol extracts and hydrolyzates of the different plant tissues was generally similar. Some differences were present and therefore amino acid composition cannot, as yet, be ruled out as a factor influencing the diets. Differences in the asparagine content of the plant tissues do not appear to be responsible for their effects on the larvae. There was no simple relationship between the ethanol-soluble nitrogen content of the tissues and their value as diets. The results suggest that a relatively high ethanol-soluble carbohydrate: total nitrogen ratio is an attribute of the tissues that were poor diets for the pale western cutworm.

Quantitative nutritional studies with water-soluble, chemically defined diets. IX. Further studies on d-glucosamine-containing diets

The effect of incorporating d-glucosamine at various levels into the water-soluble, chemically defined diet No. 26 fed ad libitum to rats has been compared with that observed earlier under the same conditions when the inferior diet No. 3 was employed. As before, a linear graphical relationship between growth and food intake was observed which, by extrapolation, permitted a calculation of the average daily requirement of food for the maintenance of body weight over the entire course of the experiment. On the superior diet, No. 26, there was ( a) a slightly higher maintenance requirement, and ( b) appreciably less depression in the growth rate at equal levels of glucosamine, than on diet No. 3. No toxic symptoms were evident, and it is apparent that the dietary glucosamine simply exerts a self-limiting effect on food intake. Force-feeding of diet No. 26 containing 8 and 12% of glucosamine to rats bearing the transplanted Walker tumor resulted in no symptoms of toxicity nor any effect upon tumor or carcass growth. Observations on the cyclic daily weight fluctuations of animals ingesting soluble diets as compared with Purina Chow are described.

Quantitative nutritional studies with water-soluble, chemically defined diets. I. Growth, reproduction and lactation in rats

Mixtures of purified l-amino acids, salts, vitamins (B and C), and d-glucose were prepared in 50% aqueous solution and offered, together with a separate supplement of fat-soluble vitamins in corn oil to weanling rats. The tyrosine and cystine components were present in the form of ethyl l-tyrosinate. HCl and ethyl l-cysteinate. HCl, respectively. Calcium and phosphorus were present in the form of the soluble calcium fructose 1,6-diphosphate, and iron appeared in the form of the complex salt, ferrous ammonium sulfate. Potassium and magnesium appeared as the respective gluconates. With these precautions to maintain solubility, the diet solutions were stable and water-clear almost indefinitely. Tests for the presence of microorganisms in diet solutions not sterilized but in which the amino acid and calcium fructose diphosphate components had been carefully crystallized prior to solution revealed complete sterility 0n standing at 37 ° for at least 4 weeks. No bulk was provided in these soluble diets, nor was a training period necessary for their ready imbibition. The intestinal contents were considerably reduced as compared with similar animals on a chow diet, and fecal excretion was scanty and infrequent. The teeth of these animals and the entire length of the gastrointestinal tract were free of any pathologic lesion, gross or microscopic. The diets contained roughly 20% amino acids and 80% glucose, equivalent per gram to 4 cal., or per milliter to 2 cal. The animals grew well at a rate of over 4 g. per day on a diet the “non-essential” amino acid ratios of which were modeled after that of casein. Lesser growth was obtained with diets modeled after other animal proteins, with diets containing fewer “non-essential” amino acids, and with diets modeled after casein but containing dl-amino acids, all however with the same or greater total nitrogen. At maturity the animals on a diet limited in “non-essential” amino acids were mated and produced satisfactory litters which were nursed to weaning. The young, which were smaller than normal, were divided into two groups, one fed on the same diet and the other on that with a full complement of “non-essential” amino acids. Animals on the latter diet recovered rapidly from their bad start and grew at a faster rate than did their litter mates. On mating within each group at the same time, the animals on the superior diet yielded satisfactory litters which were nursed to weaning while those on the inferior diet now showed no pregnancies at all.

The composition of breast milk of south African Bantu mothers

Two hundred and sixty-six samples of breast milk mainly from urban South African Bantu mothers have been analysed. In respect of total solids, ash, protein, fat, lactose, calcium and phosphorus, it has been found that mean valyes closely approximate to corresponding means given for the milks of British and American mothers. The composition of the milks does not appear to be influencd by the tribal group of the mothers, by their habitual diet (largely composed of maize, bread, legumes), nor by their nutritional state. Their capacity to breast-feed is almost invariable, moreover, impressions suggest that the yield is satisfactory at least for the first 6 months. It is submitted that either the rôle of diet in lactation is over-emphasized, or that the body has a greater capacity to adapt itself to an inferior diet than is usually accepted.

INSECT NUTRITION

Summary1. Recent work has disclosed the nature of many of the accessory growth factors required by insects. Most of the species which have been studied appear to require only one fat‐soluble factor, cholesterol. Cholesterol can be replaced by certain other related sterols, depending on the species of insect, but it cannot be replaced by sterols of the vitamin D group. A fundamental difference evidently exists between insects and vertebrates with respect to their requirements for fat‐soluble growth factors. On the other hand, the water‐soluble growth factors for insects which have thus far been determined are all identical with the water‐soluble vitamins of the B group required by vertebrates. It seems probable that all insects require these substances, and the necessity of one or more for normal growth has already been demonstrated for species of the orders Hemiptera, Coleoptera, Lepidoptera, and Diptera. Some species of insects which contain intracellular symbionts have been found to develop normally on diets deficient in some of the B vitamins. If such insects are artificially freed of their symbionts they then require in their diet all the water‐soluble factors which are required by related species which naturally are free of symbionts.2. Various salts are essential constituents of the diet for most insects. For several species, calcium has been found to have especially striking effects, but Drosophila melanogaster appears to be able to develop without calcium. Insects differ somewhat in their carbohydrate requirements. Some species, like the mealworm Tenebrio molitor, can develop only on a diet containing a preponderance of carbohydrate over protein. Little is known concerning the amino‐acid requirements of insects, but they are certainly at least as extensive as those of the vertebrates.3. Because of the difficulties attending nutritional work with the large groups of leaf‐feeding and parasitic insects, it has not yet been possible to obtain information concerning the chemical nature of their specific nutrients. Such information may turn out to be of special interest and importance, especially in its relation to the peculiar host‐parasite specificities which exist in these groups of insects. Distinct effects have been reported of different natural foods on the development and reproductive capabilities of such insects, as well as of others more amenable to experimental manipulation. The fecundity of an insect may be affected by its food as a larva as well as by its food in the adult stage. In one case it has been found that the food of the parent insect as an adult profoundly affected the development of its offspring, so much so that offspring fed on a superior diet, but descended from parents fed on an inferior diet, grew less well than offspring fed on an inferior diet but descended from parents fed on a superior diet.4. Food selection appears to be determined in most cases by characters of the food which have no direct connexion with fundamental nutritional requirements.5. The polymorphism of aphids, paedogenetic flies, and certain other insects, and the queen and worker castes of the honey‐bee, are greatly influenced, if not primarily determined, by nutritional factors. Such factors may also be of importance in caste determination among the ants and termites. In no case has the nature of these forms determining dietary factors been discovered.