The objective of the present study was to evaluate the oxidative susceptibility of LDL in human volunteers following supplementation with various low doses (<1 g/d) of n–3 polyunsaturated fatty acids (PUFA). Sixty-two healthy volunteers (thirty-seven males and twenty-five females, aged 19–63 years) were recruited to take part in a randomised placebo-controlled trial. Volunteers were required to take 0.9, 0.6 or 0.3 g n–3 PUFA as fish oil or placebo capsules daily for 16 weeks. Susceptibility of LDL to oxidative modification was assessed by measuring the production of conjugated dienes and thiobarbituric acid-reactive substances in LDL oxidised by Cu2+ (15 μM) OR 2,2″-AZOBIS(2-AMIDINOPROPANE) DIHYDROCHLORIDE (1 Mm) for 5 h. Plasma fatty acid and LDL-fatty acid composition, cholesterol levels and antioxidant concentrations were also measured. While post-treatment n–3 PUFA compositions of plasma and LDL reflected the capsule contents, no meaningful differences in antioxidant concentrations or cholesterol levels were observed between the groups. Supplementation with low doses of n–3 PUFA as fish oil did not influence the oxidative susceptibility of LDL. The results of the present study suggest that moderate dietary intakes of n–3 PUFA do not significantly influence the susceptibility of LDL to oxidative modification in vitro.

The present study was aimed at evaluating in patients with type 2 diabetes: (1) the glycaemic response to four starchy foods based on wheat, typical of the Italian diet; (2) the importance of some food characteristics in relation to their effects on postprandial glucose response. Seventeen patients with type 2 diabetes (eleven men and six women) participated in the study. All patients consumed, in random order and on alternate days, 50 g available carbohydrate provided by 90 g white bread and, according to a randomised procedure, an equivalent amount of carbohydrate provided by one (n 8) or two (n 9) of three other different test foods (g): pizza 85, potato dumplings 165, hard toasted bread 60. Foods had a similar nutrient composition. Plasma glucose response, measured for 180 min, was significantly lower after the potato dumplings than after white bread at 90 (P<0·05), 120 (P<0·01) and 150 (P<0·05) min. No difference was observed in postprandial plasma insulin response after the various test foods. The percentage of starch hydrolysed after 5 h in vitro hydrolysis with α-amylase was about 30 % lower for potato dumplings than for the other foods. However, no differences in the resistant starch content, the rate of diffusion of simple sugars added to a dialysis tube containing the food, and the viscosity of digesta were observed among the test foods. Scanning electron microscopy of potato dumplings showed a compact structure compatible with impaired accessibility of starch to digestive enzymes. In conclusion, carbohydrate-rich foods typical of the Italian diet which are often consumed as an alternative to pasta dishes are not equivalent in terms of metabolic impact in diabetic patients. Due to their low blood glucose response, potato dumplings represent a valid alternative to other starchy foods in the diabetic diet. Food structure plays an important role in determining starch accessibility to digestion, thus influencing the postprandial blood glucose response.

The present paper compares the effects of two monounsaturated oils, extra virgin olive oil (EVOO) and high-oleic acid sunflower oil (HOSO), on serum and LDL peroxides, eicosanoid production and the thrombogenic ratio (thromboxane (TX) B2:6-keto-prostaglandin F1α) in fourteen non-obese post-menopausal women. The subjects, mean age 63 (SD 11) years, were assigned to two consecutive oleic acid-rich 28 d dietary periods. EVOO and HOSO represented 62 % of the total lipid intake and were used as the only culinary fat during the first and second dietary periods respectively. Serum peroxides, plasma α-tocopherol and TXB2 levels in stimulated platelet-rich plasma (PRP-TXB2) were significantly higher (P<0.01, P<0.001, and P<0.05 respectively) after the HOSO diet than after the EVOO diet. The relationship between the serum cholesterol level (<6.21 mmol/l or ≥6.21 mmol/l) and the type of dietary oil on eicosanoids, peroxides and α-tocopherol were evaluated by two-way ANOVA. Dietary oil significantly affected (P<0.05) the PRP-TXB2 level, whereas serum and LDL peroxides were significantly affected (P<0.001 and P<0.01 respectively) by the serum cholesterol level. The plasma α-tocopherol level was significantly affected by the serum cholesterol level and the type of dietary oil (both P<0.001). No significant relationships were found between serum cholesterol levels, serum peroxide or LDL peroxide levels, plasma α-tocopherol concentrations or α-tocopherol intakes with eicosanoid production or the thrombogenic ratio due to dietary changes. However, in spite of their higher α-tocopherol levels, hypercholesterolaemic subjects showed increased peroxidation in serum and LDL in comparison with normocholesterolaemic subjects on the HOSO diet in comparison with the EVOO diet. These findings suggest that differences in the type of minor compounds, as well as in the concentration of linoleic acid, in both these monounsaturated oils may play an important role in modulating eicosanoid production and lipoprotein peroxidation when they constitute a large proportion of the diet of post-menopausal women.

Evidence of the impact of maternal nutritional status on pregnancy outcome is increasing. However, reference values for vitamin and homocysteine concentrations in maternal blood during normal pregnancy are scarce, and are lacking for the preconceptional period and early pregnancy. Thus, in a longitudinal study we evaluated vitamin and homocysteine concentrations in 102 nulliparous women with an uneventful singleton pregnancy and normal outcome not using supplements. The physiological changes in vitamin and homocysteine concentrations in blood were determined from the preconceptional period throughout pregnancy until 6 weeks post-partum. The vitamins evaluated comprised retinol, thiamin, riboflavin, pyridoxal 5′-phosphate, folate in serum and erythrocytes, vitamin B12 and α-tocopherol. The plasma homocysteine concentration was also measured, considering the essential roles of folate, vitamin B6 and vitamin B12 in homocysteine metabolism. The concentrations of retinol, thiamin, pyridoxal 5′-phosphate serum folate and vitamin B12 decreased during pregnancy. In contrast, the concentrations of riboflavin, α-tocopherol, and folate in erythrocytes increased or showed only minor changes. Homocysteine concentrations also remained approximately constant during pregnancy. These observations emphasize the importance of preconceptional and post-partum concentrations of vitamins in the evaluation of pregnancy-induced changes. These data have provided valuable reference values for vitamins and homocysteine before, during and after pregnancy in order to contribute to better diagnosis of maternal deficiencies and to study further the relationship between maternal vitamin status and adverse course and outcome of pregnancy.

Infant formula based on pea (Pisum sativum)-protein isolate has been suggested as an alternative to soyabean formula in countries where soyabean is not a native crop, or when soyabean protein cannot be used due to allergic reactions or intolerances. In the present study, Fe absorption from experimental infant formulas based on pea-protein isolate was measured in healthy non-anaemic young women. The influence of phytic acid and ascorbic acid on Fe absorption was evaluated, using a stable-isotope technique based on incorporation of Fe stable-isotope labels into erythrocytes 14 d after administration. Geometric mean Fe absorption increased from 20·7 (+1SD 41·6, -1sd 10·3) % to 33·1 (+1sd 58·6, -1sd 18·7) %; (P<0·0001; n 10) after enzymic degradation of virtually all phytic acid. Doubling the molar ratio Fe : ascorbic acid from 1 : 2·1 to 1 : 4·2 in the infant formula with native phytic acid content also increased Fe absorption significantly (P<0·0001; n 10); geometric mean Fe absorption increased from 14·8 (+1sd 32·1, -1sd 6·8) % to 22·1 (+1sd 47·2, -1sd 10·4) %. These results confirm the inhibitory and enhancing effects of phytic acid and ascorbic acid respectively on Fe absorption, but also indicate relatively high fractional Fe absorption from the pea-protein-based formulas. After adjusting for differences in Fe status, our data indicate that Fe absorption from dephytinised pea protein might be less inhibitory than dephytinised soyabean protein as measured in a previous study ().

We validated doubly-labelled water (DLW) by comparison to indirect calorimetry and food intake–mass balance in eight Labrador dogs (24–32 kg) over 4 d. We used several alternative equations for calculating CO2 production, based on the single- and two-pool models and used two alternative methods for evaluating the elimination constants: two-sample and multiple-sampling. In all cases the DLW technique overestimated the direct estimate of CO2 production. The greatest overestimates occurred with the single-pool model. Using two samples, rather than multiple samples, to derive the elimination constants produced slightly more discrepant results. Discrepancies greatly exceeded the measured analytical precision of the DLW estimates. The higher values with DLW probably occurred because the dogs were extremely active during the 1 h in each 24 spent outside the chamber. Estimates of CO2 production from food intake–mass balance, which include this activity, produced a much closer comparison to DLW (lowest mean discrepancy 0·3 % using the observed group mean dilution space ratio and an assumption that the mass changes reflected changes in hydration for all except one animal). We recommend an equilibration time of 6 h and use of the two-pool model based on the observed population dilution space for future studies of energy demands in dogs of this body mass.

Variations in energy balance, body composition, and nutrient partitioning induced by high-fat feeding, cold exposure or by concomitant high-fat feeding and cold exposure were studied in young Wistar rats. Changes in hepatic metabolism as well as in serum free triiodothyronine and leptin levels were also evaluated. Rats were exposed to either 24 or 4°C and fed either a low- or high-fat diet (10 % or 50 % energy respectively) for 2 weeks. Relative to low-fat feeding at 24°C, both energy intake and expenditure were increased by high-fat feeding or by cold exposure, and these changes were accompanied by increased serum triiodothyronine levels. In response to concomitant high-fat feeding and cold exposure, serum triiodothyronine tended to be further elevated, but no further increases in energy intake or energy expenditure were observed. Independently of diet, the increased energy expenditure in cold-exposed rats was not completely balanced by adaptive hyperphagia, with consequential reductions in protein and fat gain, accompanied by marked decreases in serum leptin. Furthermore, unlike high-fat feeding at 24°C, cold exposure enhanced hepatic mitochondrial oxidative capacity both in the low-fat- and high-fat-fed groups. It is concluded that in this strain of young Wistar rats, despite similarly marked stimulation of energy expenditure by high-fat feeding at 24°C, by cold exposure and by concomitant high-fat feeding and cold exposure, an increased hepatic oxidative capacity occurred only in the presence of the cold stimulus.

The effects of ambient temperature (T; 12–29°C), body weight (BW; 30–90 kg) and metabolisable energy intake (ME) on components of energy balance were studied in seven groups of Piétrain × Large White barrows kept in a respiratory chamber. In Expt 1 (groups 1, 2 and 3), T varied in a cyclic way from 22°C to 12°C and then from 12°C to 22°C with three or four consecutive days at each of 22, 19, 16, 14 and 12°C. Similarly, in Expt 2 (groups 4, 5 and 6), T varied from 19 to 29°C and then from 29 to 19°C with three or four consecutive days at each of 19, 22, 25, 27 and 29°C. In both experiments, pigs were offered feed ad libitum. In Expt 3, pigs (group 7) were exposed to the thermic conditions of Expt 1 but their feed allowance was adjusted on a BW basis to the ad libitum intake recorded at 19 and 22°C in Expt 1. Groups 1, 2, 4, 5 and 7 were used over two successive cycles with initial average BW of 37 kg at cycle 1 (four pigs per group) and 63 kg at cycle 2 (three pigs per group). Groups 3 and 6 were studied at an intermediary stage of growth; their initial BW was 45 kg. The O2 and CO2 concentrations, physical activity and feed intake were continuously and simultaneously measured and used to calculate total heat production (HP; HPtot), HP due to physical activity (HPact), activity-free HP (HP0), and thermic effect of feed. HP was modelled as a non-linear function with T, BW and ME as predictors. Results indicate that all components of HP were proportional to BW0·60. Physical activity was minimal between 19 and 27°C (8 % ME). The estimated lower critical temperature was 24°C. Between 24 and 12°C, total thermic effect of feed decreased from 31 to 16 % ME, but the short-term thermic effect of feed (5·1 % ME) remained constant. Equations for prediction of HPtot, HPact and HP0 according to BW, T and ME are proposed and evaluated according to literature values; values for the feed cost of thermoregulation in pigs are proposed.

The aim of the present study was to determine the association between the maternal experience and changes in adiposity measured by BMI, percentage body fat (PBF) and waist:hip ratio (WHR). In a cross-sectional study, 203 women were recruited at health care and educational facilities in Brasilia, Brazil. These women were divided into three groups: fifty-three nulliparous (no full-term pregnancy); sixty-three primiparous (one full-term pregnancy); eighty-seven multiparous (two or more full-term pregnancies). Socio-economic, behavioural, reproductive and dietary data were collected. All the women were measured for weight, height, skinfold thicknesses and waist and hip circumferences. Analysis of covariance was used to measure the differences among the three groups in relation to BMI, PBF and WHR, controlling for the following covariates: age; socio-economic status; use of oral contraceptives; smoking; energy intake level; cooking oil intake; physical activity level; lactation score; parity. The three groups of women differed significantly for BMI (P=0·04), PBF (P=0·0008) and WHR (P=0·0001). Multiparous women presented higher BMI (P=0·01) and PBF (P=0·03) compared with primi- and nulliparous groups. PBF was also associated with age and high socio-economic status. Primi- and multiparous women showed a higher WHR than nulliparous women (P<0·0001). Age and smoking habit were also factors associated with higher WHR.

Enhancing the n-3 polyunsaturated fatty acid (PUFA) content of beef is important in view of the generally saturated nature of fatty acids in ruminant meats and the negative effect this can have on human health. This study examined the effects of different sources of dietary n-3 PUFA on the performance of steers and the fatty acid composition of m. longissimus thoracis muscle and associated subcutaneous adipose tissue. Animals were fed ad libitum on grass silage plus one of four concentrates (60:40 forage:concentrate on a DM basis) containing differing sources of lipid: Megalac (16:0), lightly bruised whole linseed (18:3n-3), fish oil (20:5n-3 and 22:6n-3) and a mixture of linseed and fish oil (1:1, on an oil basis). Diets were formulated so that total dietary oil intake was 6 %, approximately half of which was from the experimental test oil. Linseed feeding not only increased the levels of 18:3n-3 in muscle phospholipid from 9·5 to 19 mg/100 g muscle but also enhanced the synthesis of 20:5n-3, the level of which increased from 10 to 15 mg/100 g muscle. Linseed also increased the proportion of 18:3n-3 in muscle neutral lipid and in adipose tissue lipids by a factor of 1·64 and 1·75 respectively. Fish oil feeding doubled the proportion of 20:5n-3 and 22:6n-3 in muscle phospholipids. The proportion of 18:1 trans in muscle neutral lipid was higher on the n-3 PUFA diets than the control diet, 0·04 and 0·02 respectively. Despite the implied modification to rumen metabolism, lipid source did not affect feed intake, growth rate, cold carcass weight or carcass fatness, but carcass conformation score was higher on fish oil treatments (P<0·05). However, total muscle fatty acid content was not different between treatments and ranged from 3·5–4·3 % of tissue weight. The increase in n-3 PUFA in the meat produced by feeding linseed or fish oil lowered the n-6:n-3 ratio but had little effect on the P:S ratio.