Conjugated linoleic acids (CLA) are positional isomers of linoleic acid which have been suggested by some to possess antiatherosclerotic properties. To test this hypothesis, three groups of twenty C57BL/6 mice were fed on atherogenic diets containing: 5 g CLA/kg, 2·5 g CLA + 2·5 g linoleic acid/kg or 5 g linoleic acid/kg. All diets were fed for 15 weeks and contained (g/kg): triacylglycerol 145, free fatty acids 5, cholesterol 10 and cholic acid 5. At the completion of the experimental period, when data from both groups fed on CLA were combined, dietary CLA did not produce significant differences in body weight, serum total cholesterol concentration or serum HDL-cholesterol concentration. However, mice receiving CLA developed a significantly higher serum HDL-cholesterol: total cholesterol ratio and a significantly lower serum triacylglycerol concentration than controls. Despite causing a serum lipoprotein profile considered to be less atherogenic, the addition of CLA to the atherogenic diet increased the development of aortic fatty streaks. Considering the increased atherogenesis associated with dietary CLA in the present study, and the failure to demonstrate a significant beneficial effect of CLA in other animal studies, there is currently no conclusive evidence to support the hypothesis that CLA protect against atherogenesis.

It is hypothesized that the intake of long-chain PUFA (LC-PUFA) throughout pregnancy could protect against pre-eclampsia, pregnancy-induced hypertension or intra-uterine growth retardation, and is essential for optimal neural development. The objective of the present study was to systematically evaluate the effect of LC-PUFA supplementation of high-risk pregnant women's diets on pregnancy outcomes and growth measures at birth. We searched MEDLINE, EMBASE, CINAHL and the Cochrane Library through March 2006 and references in reviewed articles for randomized controlled trials (RCT) comparing LC-PUFA supplementation with placebo or no supplementation in women with high-risk pregnancies. We found no evidence that supplementation influenced the duration of pregnancy or the percentage of preterm deliveries < 37 weeks of gestation. However, compared with controls, supplementation was associated with a significantly lower rate of early preterm delivery ( < 34 weeks of gestation) (two RCT; n 291; relative risk 0·39 (95 % CI 0·18, 0·84)). There was no significant difference in the infant birth weight, the rate of low birth weight ( < 2500 g or < 10th percentile) and the recurrence of intra-uterine growth retardation. Other pregnancy outcomes (for example, the rate of pregnancy-induced hypertension, the rate of pre-eclampsia and the rate of Caesarean section) were also similar in both groups. In conclusion, the present data suggest that supplementation with n-3 LC-PUFA in women with high-risk pregnancies reduced the risk of early preterm delivery in the fatty acid-supplemented group compared with the placebo group, while no other effects on pregnancy outcomes were detected.

Epidemiological studies show that adherence to a Mediterranean diet (MD) increases longevity; however, few studies are restricted to Mediterranean populations or explore the effect of a MD pattern that directly incorporates olive oil. Therefore the relationship between adherence to the MD and mortality was studied within the the Spanish cohort of the European Prospective Investigation into Cancer and Nutrition (EPIC-Spain). The EPIC-Spain analysis included 40 622 participants (37·7 % males) aged 29–69 years who were recruited from five Spanish regions in 1992–1996. During a mean follow-up of 13·4 years, 1855 deaths were documented: 913 from cancer, 399 from CVD, 425 from other causes and 118 from unknown causes of death. Risk of all-cause and cause-specific mortality was assessed according to the level of adherence to a relative MD (rMED) score, measured using an 18-unit scale incorporating nine selected dietary components. A high compared with a low rMED score was associated with a significant reduction in mortality from all causes (hazard ratio (HR) 0·79; 95 % CI 0·69, 0·91), from CVD (HR 0·66; 95 % CI 0·49, 0·89), but not from overall cancer (HR 0·92; 95 % CI 0·75, 1·12). A 2-unit increase in rMED score was associated with a 6 % (P < 0·001) decreased risk of all-cause mortality. A high olive oil intake and moderate alcohol consumption contributed most to this association. In this Spanish cohort, following an olive oil-rich MD was related to a significant reduction in all-cause mortality, and reduced the risk of mortality from CVD. These results support the important role that the MD pattern has on reducing mortality in Mediterranean countries.

The aim of the present study was to describe the association of fast food consumption with BMI, energy intake and diet quality in a Mediterranean population. The subjects were Spanish men (n 1491) and women (n 1563) aged 25–74 years who were examined in 1999–2000, in a population-based cross-sectional survey in northeast Spain (Girona). Dietary intake was assessed using a FFQ that included four typical fast food items. Two dietary-quality indices, the Mediterranean diet score and the healthy eating index, were created. Height and weight were measured. Within the population studied, 10·1 % reported eating fast food at least once per month. Dietary energy intake and energy density were directly associated with frequency of fast food consumption. Multivariate logistic regression analysis adjusted for lifestyle and educational level showed an inverse association of frequency of fast food consumption with meeting the dietary reference intake (DRI) for energy (P = 0·001). The consumption of fast food more than once per week increased the risk of overall low diet quality (P < 0·001). BMI was directly associated with fast food consumption expressed in g/d (P = 0·025) and in kJ/d (P = 0·017). The risk of being obese increased with the frequency of fast food consumption (P = 0·046). Fast food consumption was associated with higher energy intakes, poor diet quality and higher BMI. The likelihood of not meeting the DRI for energy, and of being obese, increased with the frequency of fast food consumption.

Provided that they are scientifically substantiated, nutrition and health (NH) claims linked to food products can help consumers make well-informed food choices. The new European legislation on NH claims made on foods entered into force on 19 January 2007. The law sets out conditions for their use, establishes a system for their scientific evaluation, and will create European lists of authorised claims. An important aspect of this proposed legislation is that it states, in article 5.2, ‘the use of nutrition and health claims shall only be permitted if the average consumer can be expected to understand the beneficial effects expressed in the claim’. The present review examines consumer understanding of NH claims from a consumer science perspective. It focuses on the type of data and information that could be needed to provide evidence that the average consumer adequately understands a particular NH claim. After exploring several different methodologies, it proposes a case-specific approach using a stepwise procedure for assessing consumer understanding of a NH claim.

Quantification of lean body mass and fat mass can provide important insight into epidemiological research. However, there is no consensus on generalisable anthropometric prediction equations to validly estimate body composition. We aimed to develop and validate practical anthropometric prediction equations for lean body mass, fat mass and percent fat in adults (men, n 7531; women, n 6534) from the National Health and Nutrition Examination Survey 1999–2006. Using a prediction sample, we predicted each of dual-energy X-ray absorptiometry (DXA)-measured lean body mass, fat mass and percent fat based on different combinations of anthropometric measures. The proposed equations were validated using a validation sample and obesity-related biomarkers. The practical equation including age, race, height, weight and waist circumference had high predictive ability for lean body mass (men: R 2=0·91, standard error of estimate (SEE)=2·6 kg; women: R 2=0·85, SEE=2·4 kg) and fat mass (men: R 2=0·90, SEE=2·6 kg; women: R 2=0·93, SEE=2·4 kg). Waist circumference was a strong predictor in men only. Addition of other circumference and skinfold measures slightly improved the prediction model. For percent fat, R 2 were generally lower but the trend in variation explained was similar. Our validation tests showed robust and consistent results with no evidence of substantial bias. Additional validation using biomarkers demonstrated comparable abilities to predict obesity-related biomarkers between direct DXA measurements and predicted scores. Moreover, predicted fat mass and percent fat had significantly stronger associations with obesity-related biomarkers than BMI did. Our findings suggest the potential application of the proposed equations in various epidemiological settings.

Recombinant glucagon-like peptide-1 (7–36)amide (rGLP-1) was recently shown to cause significant weight loss in type 2 diabetics when administered for 6 weeks as a continuous subcutaneous infusion. The mechanisms responsible for the weight loss are not clarified. In the present study, rGLP-1 was given for 5d by prandial subcutaneous injections (PSI) (76nmol 30min before meals, four times daily; a total of 302·4nmol/24h) or by continuous subcutaneous infusion (CSI) (12·7nmol/h; a total of 304·8nmol/24h). This was performed in nineteen healthy obese subjects (mean age 44·2 (sem 2·5) years; BMI 39·0 (sem 1·2)kg/m2) in a prospective randomised, double-blind, placebo-controlled, cross-over study. Compared with the placebo, rGLP-1 administered as PSI and by CSI generated a 15% reduction in mean food intake per meal (P=0·02) after 5d treatment. A weight loss of 0·55 (sem 0·2) kg (P<0·05) was registered after 5d with PSI of rGLP-1. Gastric emptying rate was reduced during both PSI (P<0·001) and CSI (P<0·05) treatment, but more rapidly and to a greater extent with PSI of rGLP-1. To conclude, a 5d treatment of rGLP-1 at high doses by PSI, but not CSI, promptly slowed gastric emptying as a probable mechanism of action of increased satiety, decreased hunger and, hence, reduced food intake with an ensuing weight loss.

1. The entry rates of urea into the urea pool of the body fluids have been measured in sheep given rations varying in crude protein percentage from 3.5 to 27.3.

2. Results obtained with a single injection and with continuous infusions of [14C]urea were essentially the same.

3. The difference between the entry rate and the rate of excretion of urea in the urine was taken to indicate the quantity of urea degraded in the alimentary tract.

4. Plasma concentrations and urea entry rates were significantly and linearly related.

5. The relationship between excretion rate and plasma urea concentration was best described by a cubic equation.

6. Degradation of urea in sheep was found to be extensive in all the animals studied; as the protein intake increased, the quantity of urea degraded also increased but the percentage of urea entering the body pool that was degraded was decreased. Animals given a ration containing 3.5% crude protein degraded 76–92% of the urea entering the body pool.

7. A rectilinear relationship was found between pool size and plasma urea concentration. The urea space in animals given low-protein rations was significantly less than in animals on high-protein rations.

8. The effects of starvation for 2, 4 and 6 days on urea metabolism in sheep were investi-gated. In a11 the sheep starved for 2 days there was a significant increase in urea pool size, but the entry rate was markedly depressed indicating a retention of urea in the body pool on starvation.

9. A significant amount of nitrogen was found to go through the system: rumen ammonia → portal blood ammonia→blood urea→rumen ammonia.

10.Urea excretion rate, urea clearance by the kidney, urine flow rate and the ratio of the concentration of urea in urine to that in plasma (urea U:P ratio) were also examined.

11. There were significant correlations between urine flow rate and urea excretion and between plasma urea concentration and urine flow rate.

Understanding the interactions between hydrogen producers and consumers in the rumen ecosystem is important for ruminant production and methane mitigation. The present study explored the relationships between rumen protozoa, methanogens and fermentation characteristics. A total of six donor sheep harbouring (F, faunated) or not (D, defaunated) protozoa in their rumens (D animals were kept without protozoa for a period of a few months (D − ) or for more than 2 years (D+)) were used in in vitro and in vivo experiments. In vitro the absence of protozoa decreased NH3 and butyrate production and had no effect on methane. In contrast, the liquid-associated bacterial and methanogens fraction of D+ inocula produced more methane than D −  and F inoculum (P < 0·05). In vivo fermentation parameters of donor animals showed the same trend on NH3 and butyrate and showed that D+ animals were high methane emitters, while D −  were the lowest ( − 35 %). The concentration of dissolved dihydrogen measured after feeding followed the opposite trend. Methane emissions did not correlate with the relative abundance of methanogens in the rumen measured by quantitative PCR, but there was a trend for higher methanogens concentration in the solid-associated population of D+ animals compared with D −  animals. In contrast, PCR-denaturing gradient gel electrophoresis profiles of methanogens' methyl coenzyme-M reductase A gene showed a clear clustering in liquid-associated fractions for all three groups of donors but fewer differences in solid-associated fractions. These results show that the absence of protozoa may affect differently the methanogen community and methane emissions in wethers.

The inhibiting effect of Ca on non-haem-Fe absorption is well established. Presentstudies showed that Ca inhibited haem-Fe absorption to the same extent when the same amount of Ca (165 mg Ca as CaCl2) was added to a meal. Attempts were made to examine the mechanism for this inhibition in the present studies. Meat is the only known dietary factor influencing haem-Fe absorption. The present studies were designed to examine whether Ca interfered with the enhancing effect of meat on haem-Fe absorption. We found that the inhibition was the same whether biosynthetically radio-Fe-labelled haemoglobin wasgiven in meals with or without meat. The haem-Fe absorption ratio with: without added Cawas 0.59 (SE 0.07) when Ca was added to a hamburger meal, and 0.052 (se 0.03) when added to a wheat roll. These values were not significantly different (t 0.95; P = 0.35). The inhibition of haem-Fe absorption by Ca is, thus, a direct effect on theabsorption of haem-Fe and not an indirect counteracting effect of the well-known enhancing effect of meat on haem-Fe absorption. Control studies were conducted to ensure that haem-Fe had not been degraded to non-haem-Fe during preparation of the foods. Since Ca inhibits the absorption of haem- and non-haem-Fe to the same extent, the present results strongly suggest that Ca interferes with the transport of Fe through the mucosal cell, andata late stage, is common for haemand non-haem-Fe transport. The observations that Ca strongly interferes with the absorption of both haem- and non-haem-Fe have important nutritionalimplications.

Farmed salmon feeds have changed from purely marine-based diets with high levels of EPA and DHA in the 1990s to the current 70 % plant-based diets with low levels of these fatty acids (FA). The aim of this study was to establish the impacts of low dietary EPA and DHA levels on performance and tissue integrity of Atlantic salmon (Salmo salar). Atlantic salmon (50 g) in seawater were fed fourteen experimental diets, containing five levels (0, 0·5, 1·0, 1·5 and 2·0 %) of EPA, DHA or a 1:1 EPA+DHA plus control close to a commercial diet, to a final weight of 400 g. Lack of EPA and DHA did not influence mortality, but the n-3-deficient group exhibited moderately slower growth than those fed levels above 0·5 %. The heart and brain conserved EPA and DHA levels better than skeletal muscle, liver, skin and intestine. Decreased EPA and DHA favoured deposition of pro-inflammatory 20 : 4n-6 and 20 : 3n-6 FA in membrane phospholipids in all tissues. When DHA was excluded from diets, 18 : 3n-3 and EPA were to a large extent converted to DHA. Liver, skeletal and cardiac muscle morphology was normal in all groups, with the exception of cytoplasm packed with large or foamy vacuoles and sometimes swollen enterocytes of intestine in both deficient and EPA groups. DHA supplementation supported normal intestinal structure, and 2·0 % EPA+DHA alleviated deficiency symptoms. Thus, EPA and DHA dietary requirements cannot be based exclusively on growth; tissue integrity and fish health also need to be considered.

A cross-sectional study was conducted within the Spanish cohort of the European Prospective Investigation in Cancer and Nutrition to assess the principal food sources of vitamin C, vitamin E, α-carotene, β-carotene, lycopene, lutein, β-cryptoxanthin and zeaxanthin in an adult Spanish population. The study included 41 446 healthy volunteers (25 812 women and 15 634 men), aged 29–69 years, from three Spanish regions in the north (Asturias, Navarra and Guipúzcoa) and two in the south (Murcia and Granada). Usual food intake was estimated by personal interview through a computerized version of a dietary history questionnaire. Foods that provided at least two-thirds of the studied nutrients were: fruits (mainly oranges) (51 %) and fruiting vegetables (mainly tomato and sweet pepper) (20 %) for vitamin C; vegetable oils (sunflower and olive) (40 %), non-citrus fruits (10 %), and nuts and seeds (8 %) for vitamin E; root vegetables (carrots) (82 %) for α-carotene; green leafy (28 %), root (24 %) and fruiting vegetables (22 %) for β-carotene; fruiting vegetables (fresh tomato) (72 %) for lycopene; green leafy vegetables (64 %) for lutein; citrus fruits (68 %) for β-cryptoxanthin; citrus fruits (43 %) and green leafy vegetables (20 %) for zeaxanthin. In conclusion, the main food sources of nutrients with redox properties have been identified in a Mediterranean country. This could provide an insight into the interpretation of epidemiological studies investigating the role of diet in health and disease.

The modification of microbiota composition to a ‘beneficial’ one is a promising approach for improving intestinal as well as overall health. Natural fibres and phytochemicals that reach the proximal colon, such as those present in various nuts, provide substrates for the maintenance of healthy and diverse microbiota. The effects of increased consumption of specific nuts, which are rich in fibre as well as various phytonutrients, on human gut microbiota composition have not been investigated to date. The objective of the present study was to determine the effects of almond and pistachio consumption on human gut microbiota composition. We characterised microbiota in faecal samples collected from volunteers in two separate randomised, controlled, cross-over feeding studies (n 18 for the almond feeding study and n 16 for the pistachio feeding study) with 0, 1·5 or 3 servings/d of the respective nuts for 18 d. Gut microbiota composition was analysed using a 16S rRNA-based approach for bacteria and an internal transcribed spacer region sequencing approach for fungi. The 16S rRNA sequence analysis of 528 028 sequence reads, retained after removing low-quality and short-length reads, revealed various operational taxonomic units that appeared to be affected by nut consumption. The effect of pistachio consumption on gut microbiota composition was much stronger than that of almond consumption and included an increase in the number of potentially beneficial butyrate-producing bacteria. Although the numbers of bifidobacteria were not affected by the consumption of either nut, pistachio consumption appeared to decrease the number of lactic acid bacteria (P< 0·05). Increasing the consumption of almonds or pistachios appears to be an effective means of modifying gut microbiota composition.

The objectives of the present study were to assess the intake of different food groups in French children aged 3–17 years (n 1455), and to analyse trends since a dietary survey undertaken 8 years ago. Dietary intake was evaluated using data from the 2006–7 cross-sectional INCA2 national dietary survey (étude Individuelle Nationale sur les Consommations Alimentaires), based on a 7 d food record. Dietary intake (percentage of subjects consuming the food group and amount eaten) was assessed for thirty-nine food categories. We observed variations in food consumption by age, sex, North–South regional gradient, seasonal period and educational level of the responding parent. Trends in dietary intake between 1999 and 2007 were determined by comparing the INCA1 (n 1126) and the INCA2 surveys. Both surveys had been carried out using the same methodology. The findings showed a decrease in energy intake in children aged 3–14 years, due to a reduction in the consumption of foods of animal origin and sweetened products. In adolescents aged 15–17 years, energy intake remained rather stable; during this 8-year period, the consumption of meat decreased, whereas the consumption of savoury snacks such as sandwiches and hamburgers significantly increased. These trends occurred during a time of growing concern about overweight and the associated co-morbidities in France. A number of public health measures were implemented over this period to improve dietary habits and physical activity patterns in children and adults. The periodic monitoring of dietary patterns through the INCA surveys is an essential part of the surveillance network in France.

The present study was conducted to determine the iodine concentration in Norwegian-produced milk and a selection of dairy products. The iodine concentration of eighty-five samples of milk and dairy products was analysed by inductively coupled plasma–MS. Low-fat milk and organic milk were sampled from nineteen and seven different locations in Norway, respectively, during the summer and winter season of 2000. Other milk and dairy products were chiefly collected during the summer season. Low-fat milk from the summer season had significantly lower median iodine concentration (88 μg/l, range 63–122 μg/l) compared with low-fat milk from the winter season (232 μg/l, range 103–272 μg/l). The median iodine concentration of organic summer milk (60 μg/l) was significantly lower than the iodine concentration of organic winter milk (127 μg/l). There were no significant differences in the low-fat-milk samples with regard to geographical sampling location. Whey cheese (Tine Gudbrandsdalsost) iodine concentration was significantly higher (803 μg/kg) than the median iodine concentration in casein cheeses such as Jarlsberg and Norvegia of 201 and 414 μg/kg, respectively. With a recommended iodine intake of 150 μg/d for adults, a daily intake of 0.4 litres milk meets the requirement with 25% during the summer and more than 60% during the winter season. Thus, milk and dairy products are important determinants of iodine intake in Norway.

The beneficial association of the Mediterranean diet (MedDiet) with longevity has been consistently demonstrated, but the associations of MedDiet components have not been accordingly evaluated. We performed an updated meta-analysis of prospective cohort studies published up to 31 December 2017, to quantify the association of adherence to MedDiet, expressed as an index/score (MDS) and of its components with all-cause mortality. We estimated summary relative risks (SRR) and 95 % CI using random effects models. On the basis of thirty studies (225 600 deaths), SRR for the study-specific highest/lowest and per 1sd MDS increment were 0·79 (95 % CI 0·77, 0·81, Ι2=42 %, P-heterogeneity 0·02) and 0·92 (95 % CI 0·90, 0·94, Ι2 56 %, P-heterogeneity <0·01), respectively. Inversely, statistically significant associations were evident in stratified analyses by country, MDS range and publication year, with some evidence for heterogeneity across countries overall (P-heterogeneity 0·011), as well as across European countries (P=0·018). Regarding MDS components, relatively stronger and statistically significant inverse associations were highlighted for moderate/none-excessive alcohol consumption (0·86, 95 % CI 0·77, 0·97) and for above/below-the-median consumptions of fruit (0·88, 95 % CI 0·83, 0·94) and vegetables (0·94, 95 % CI 0·89, 0·98), whereas a positive association was apparent for above/below-the-median intake of meat (1·07, 95 % CI 1·01, 1·13). Our meta-analyses confirm the inverse association of MedDiet with mortality and highlight the dietary components that influence mostly this association. Our results are important for better understanding the role of MedDiet in health and proposing dietary changes to effectively increase adherence to this healthy dietary pattern.

The present study was performed to further investigate the adaptive component of thermogenesis that appears during prolonged energy restriction. Fifteen obese men and twenty obese women underwent a 15-week weight-loss programme. During this programme, body weight and composition as well as resting energy expenditure (REE) were measured at baseline, after 2 and 8 weeks of energy restriction (-2929 kJ/d) and drug therapy (or placebo), and finally 2–4 weeks after the end of the 15-week drug therapy and energy restriction intervention, when subjects were weight stable. Regression equations were established in a control population of the same age. These equations were then used to predict REE in obese men and women at baseline, after 2 and 8 weeks, as well as after the completion of the programme. In both men and women body weight and fat mass were significantly reduced (P < 0.05 in all cases) while fat-free mass remained unchanged throughout the programme. At baseline, REE predicted from the regression equation was not significantly different from the measured REE in men, while in women the measured REE was 13 % greater than predicted. After 2 weeks of energy restriction, measured REE had fallen by 469 and 635 kJ/d more than predicted and this difference reached 963 and 614 kJ/d by week 8 of treatment in men and women respectively. Once body-weight stability was recovered at the end of the programme, changes in REE remained below predicted changes in men (-622 kJ/d). However, in women changes in predicted and measured REE were no longer different at this time, even if the women were maintaining a reduced body weight. In summary, the present results confirm the existence of adaptive thermogenesis and give objective measurements of this component during weight loss in obese men and women, while they also emphasize that in women this component seems to be essentially explained by the energy restriction.

Few other aspects of food supply and metabolism are of greater biological importance than the feeding of mothers during pregnancy and lactation, and of their infants and young children. Nutritional factors during early development not only have short-term effects on growth, body composition and body functions but also exert long-term effects on health, disease and mortality risks in adulthood, as well as development of neural functions and behaviour, a phenomenon called ‘metabolic programming’. The interaction of nutrients and gene expression may form the basis of many of these programming effects and needs to be investigated in more detail. The relation between availability of food ingredients and cell and tissue differentiation and its possible uses for promoting health and development requires further exploration. The course of pregnancy, childbirth and lactation as well as human milk composition and the short- and long-term outcome of the child are influenced by the intake of foods and particularly micronutrients, e.g. polyunsaturated fatty acids, Fe, Zn and I. Folic acid supplementation from before conception through the first weeks of pregnancy can markedly reduce the occurrence of severe embryonic malformations; other potential benefits of modulating nutrient supply on maternal and child health should be further evaluated. The evaluation of dietary effects on child growth requires epidemiological and field studies as well as evaluation of specific cell and tissue growth. Novel substrates, growth factors and conditionally essential nutrients (e.g. growth factors, amino acids, polyunsaturated fatty acids) may be potentially useful as ingredients in functional foods and need to be assessed carefully. Intestinal growth, maturation, and adaptation as well as long-term function may be influenced by food ingredients such as oligosaccharides, gangliosides, high-molecular-mass glycoproteins, bile salt-activated lipase, pre- and probiotics. There are indications for some beneficial effects of functional foods on the developing immune response, for example induced by antioxidant vitamins, trace elements, fatty acids, arginine, nucleotides, and altered antigen contents in infant foods. Peak bone mass at the end of adolescence can be increased by dietary means, which is expected to be of long-term importance for the prevention of osteoporosis at older ages. Future studies should be directed to the combined effects of Ca and other constituents of growing bone, such as P, Mg and Zn, as well as vitamins D and K, and the trace elements F and B. Pregnancy and the first postnatal months are critical time periods for the growth and development of the human nervous system, processes for which adequate substrate supplies are essential. Early diet seems to have long-term effects on sensory and cognitive abilities as well as behaviour. The potential beneficial effects of a balanced supply of nutrients such as I, Fe, Zn and polyunsaturated fatty acids should be further evaluated. Possible long-term effects of early exposure to tastes and flavours on later food choice preferences may have a major impact on public health and need to be further elucidated. The use of biotechnology and recombinant techniques may offer the opportunity to include various bioactive substances in special dietary products, such as human milk proteins, peptides, growth factors, which may have beneficial physiological effects, particularly in infancy and early childhood.

1. The concentrations of volatile fatty acids (VFA) in the rumen and caecum were compared when sheep were given barley or dried grass. The molar proportions of VFA in the caecum resembled those in the rumen except that the proportions of isobutyric and isovaleric acids were higher in caecal than in rumen fluid indicating an extensive breakdown of protein during fermentation in the caecum.

2. The capacity for starch digestion in the large intestine was studied in two sheep receiving dried grass. Starch was infused into the caecum, the amount given increasing by daily increments of 20 g until 300 g daily were infused. Infused starch in excess of 138 g daily largely appeared in the faeces, indicating a limited but substantial capacity for starch fermentation in the large intestine. The infusion caused a marked increase in the molar proportion of butyric acid.

3. Determinations made with a single sheep showed that the infusion of starch into the caecum caused large changes in the microflora, and species similar to Butyrivibrio became prevalent. The viable count on a starch medium was increased by 83 % by starch infusion.

4. The infusions of starch increased the excretion of nitrogen in the faeces from 5.8 to 9.0 g daily. Using a fractionation procedure it was shown that when 100 g of starch were fermented in the large intestine the 'bacterial and endogenous debris' nitrogen increased by about 1.0 g. When starch was given orally to two sheep the increase in this fraction was about 0.4g nitrogen/100 g starch digested.

5. It is suggested that dietary factors that cause changes in the site of fermentation from the rumen to the caecum will render less microbial nitrogen available to the host animal per unit of carbohydrate fermented and decrease the apparent digestibility of nitrogen.