Plasma thiocyanate has been reported to be high among cassava-eating populations such as that in Nigeria because of the cyanide content of cassava. Thiocyanate, which is secreted into the stomach contents of animals, has been demonstrated to catalyse the formation of nitrosamines (potent carcinogens) in the stomach from secondary amines and nitrite. The main source of the nitrite precursor in this environment is vegetables, primarily eaten as the chief supplier of proteins. The present study attempts to analyse the levels of nitrate and nitrite in vegetables commonly grown and consumed in Delta State, Nigeria. The nitrate and nitrite contents in green vegetable (Amaranthus spp.), bitter leaf (Vernonia amygdalina), pumpkin (Telfaria occidentalis) and water leaf (Talinum triangulare) grown in different localities of the state were determined by standard analytical procedures. The results show that those vegetables grown in the industrialised urban centres of the state had higher nitrate (223 (sd 71) mg/kg dry weight; P<0·05) and nitrite (12·6 (sd 1·7) mg/kg dry weight; P>0·05) levels when compared with the same species (188 (sd 77) mg nitrate/kg dry weight and 10·9 (sd 1·1) mg nitrite/kg dry weight) cultivated in less industrialised suburbs. We conclude that frequent consumption of such vegetables whose nitrate and nitrite contents are high by cassava-eating individuals might put them at risk of developing stomach cancer and other possible results of nitrate and/or nitrite toxicity. In order to avoid an outbreak in our communities, appropriate agencies should monitor and regulate the release of chemicals into the environment. In the meantime, the cultivation and consumption of vegetables grown in industrialised areas of the state should be discouraged.

Prevalence estimates of obesity in a national random sample of Spanish children and young people are presented in this paper, defined by age- and sex-specific BMI national reference standards for the 85th percentile (overweight) and 97th percentile (obesity), as well as by Cole et al. criteria. A random sample of 3534 people, aged 2–24 years, was interviewed between 1998 and 2000. The study protocol included personal data, data on education and socioeconomic status (SES) for the family, dietary assessment, anthropometric measurements and physical activity. The prevalence of obesity was 13·9 % (95 % CI 12·7, 15·1) considering Spanish reference standards as cut-offs. Obesity was significantly higher in boys (15·6 %) than in girls (12 %). The highest values were observed between 6 and 13 years of age. Using Cole's cut-offs, the estimated prevalence of obesity was 6·3 % (95 % CI 5·4, 7·5) with a similar pattern to that previously described by sex. Regarding sociodemographic factors, sex, age group, region, size of locality of residence, mother's level of education and family SES level were significant predictors for obesity in children and adolescents under 14 years. Among young people, the main sociodemographic predictors for obesity were geographical region and family SES level. Odds ratio for obesity was 1·27 for those with a more frequent consumption of buns, cakes and snacks, and 1·71 for those with more frequent consumption of sugared drinks. Adequate consumption of fruit and vegetables, usually having breakfast and regular sports practice had a protective effect. The available data show that obesity in Spain is a public health issue given its magnitude and increasing trends. Among Spanish children and young people, those at prepubertal age, particularly boys, can be identified as a group at higher risk for overweight and obesity, particularly children from lower SES families.

The objectives of the present study were to identify predictors of serum retinol concentration as well as to assess the prevalence of low serum retinol concentration, in both the whole population after correcting for the effect of serum C-reactive protein (CRP) (using multiple categories), and the healthy subgroup. A cross-sectional study of 579 apparently healthy children, aged 3–7 years from a Dhaka slum, Bangladesh, was conducted. The effects of age, gender, serum CRP and α1-antichymotrypsin, reported morbidity (during the previous 2 weeks), Ascaris lumbricoides and Trichuris trichiura infections, parental education, wasting, stunting and underweight on serum retinol were estimated using multiple linear regression. The mean serum retinol concentration was 0·84 (sd 0·27) μmol/l. Elevated serum CRP levels, reported diarrhoea, reported nasal discharge and T. trichiura infection were negative predictors of serum retinol, whereas maternal education was a positive predictor. Compared with a serum CRP level of <1 mg/l, CRP levels of 2 to <5, 5 to <10 and ≥10 mg/l were associated with 0·12, 0·16 and 0·32 μmol/l lower serum retinol, respectively. The prevalence of low serum retinol (<0·70 μmol/l) fell from 31·2 % to 15·6 % in the whole population, after correcting for the effect of CRP, and was 20·1 % in the healthy subgroup (CRP <2 mg/l). The prevalence of low serum retinol was high but overestimated due to the effect of CRP. Interventions are needed to address low serum retinol in Bangladesh. Controlling diarrhoea, nasal discharge and T. trichiura infection and improving maternal education may be important interventions. The use of multiple categories of acute-phase proteins and cut-off values that indicate elevated levels need further research.

The present study examined the association between dietary factors and metabolic syndrome in a 7-year follow-up of Japanese–Brazilians. In 1993, a survey estimated the prevalence of diabetes in a Japanese–Brazilian population aged 40–79 years. From 647 subjects studied at baseline, 394 (60·9%) participated in a second survey (2000); after exclusion of subjects with self-reported diseases, 23·4% (n 151) were included in the present analysis. Metabolic syndrome diagnosis was based on the National Cholesterol Education Program criteria modified for Asians. Food intake was assessed by a validated food-frequency questionnaire. At baseline, mean ages were 56·1 (sd 9·7) and 54·7 (sd 10·6) years for men and women, respectively. Similar cumulative incidence rates of the metabolic syndrome were found in both sexes (36·9 (95% CI 26·6, 48·1)% for men and 38·8 (95% CI 27·1, 51·4) % for women). In 1993, mean values of blood pressure, waist circumference for men and 2h plasma glucose for both sexes were higher among subjects who developed metabolic syndrome when compared with those who did not. Comparisons of nutrient intakes between subsets of subjects who developed or did not develop metabolic syndrome showed an association of protein intake with the syndrome only in men (96·4 (sd 56·8) v. 74·3 (sd 26·0) /; P<0·05). Odds ratios of the metabolic syndrome across tertiles of food groups intake showed that among men the highest tertile of red meat consumption was associated with a 4·7-fold increase in risk of developing the syndrome, after adjustments for confounders. However, the statistical significance of this model disappeared when saturated fatty acids were added. The data raised the possibility of a role of red meat consumption for the occurrence of metabolic syndrome in Japanese–Brazilian men. The present findings may have implications for the prevention of metabolic syndrome in this high-risk population.

Plasma phylloquinone (vitamin K1) concentration from non-fasted blood samples was examined by season, smoking status, socio-demographic factors and phylloquinone intake in a nationally representative sample of 1154 British individuals aged 19–64 years from the 2000–1 National Diet and Nutrition Survey. Geometric mean plasma phylloquinone concentration was 0·94 (95 % CI 0·88, 1·00) nmol/l, with 95 % of values in the range 0·10–8·72 nmol/l. Plasma phylloquinone concentrations of 530 men were significantly higher than those of 624 women (1·13 (95 % CI 1·04, 1·22) v. 0·81 (95 % CI 0·74, 0·88) nmol/l; P < 0·001), independent of other factors. Women aged 19–34 years had significantly lower plasma phylloquinone concentration than their older counterparts. Women were also found to have lower plasma phylloquinone concentrations during summer compared with winter and spring (each P < 0·01). In contrast, plasma phylloquinone concentration in men did not vary significantly by season or any of the socio-demographic or lifestyle factors. Plasma phylloquinone concentrations were positively correlated with phylloquinone intake in men and women (r 0·26 and 0·32 respectively; each P < 0·001). Overall, forward stepwise multiple regression analysis revealed that 8 % of the variation in plasma phylloquinone concentration was explained by phylloquinone intake, with a further 10 % of its variation explained by plasma concentrations of γ-tocopherol (6 %) and retinyl palmitate (4 %). After adjustment for age and corresponding nutrient intakes, plasma phylloquinone concentration was significantly associated (each P < 0·01) with plasma concentrations of total and LDL-cholesterol, α- and γ-tocopherols, retinyl palmitate, β-carotene, lycopene and lutein plus zeaxanthin in men and women.

Individuals with diabetes receive more nutrition advice than other population segments yet little is known about how well they comply or differ in nutrient intake from the rest of the population. The present study determined the mean macronutrient intake, glycaemic index (GI), and glycaemic load (GL) of a cohort of 3654 older Australians, with and without diabetes. Fasting pathology tests, including plasma glucose, were obtained for 88% of the 3654 residents, and a 145-item semi-quantitative food-frequency questionnaire was completed by 2900 residents (89%) between 1992 and 1994. In total, 6% of participants had diagnosed diabetes. Valid food-frequency data were available for 2736 without and 164 individuals with diabetes. The GI and GL were calculated from a customised database of Australian foods. Individuals with diabetes consumed significantly more protein (V=0·001) and less sugars (P≤0·001) than the general population. Only seven individuals with diabetes (4·3%) met all macronutrient recommendations and only four (2·4%) met fibre recommendations as well. Those with diabetes had a lower mean GI (55 (sd 5) V57 (sd 4); P=0·007, respectively) and GL (122 (sd 26) V 134 (sd 24); P<0·001, respectively) than the general population. In conclusion, older individuals with diabetes living in Australia in the 1990s chose a diet that had significantly more protein and less sugars than those without diabetes. This difference had little impact on the average GI, but it led to a moderate reduction in the average GL. Only a small percentage, however, was able to meet nutritional recommendations for optimal diabetes management.

Since the last century, fortified and enriched foods are products whose original composition has been modified–through addition of essential nutrients–to satisfy specific population needs. For the fortification of foods to have a positive impact on nutritional status, the micronutrients added must be well absorbed and utilized by the organism (bioavailability). Diverse factors affect bioavailability, such as the nutritional status of individuals, the presence in the diet of substances which facilitate or inhibit its absorption, interactions among micronutrients, illnesses, and chemical characteristics of the compound used for fortification. In countries such as Chile, Venezuela and Mexico, important effects have been demonstrated in reducing iron deficiency anaemia in children under 5 years of age. In less than a decade, the salt iodization programme has also proven its effectiveness. Other programmes have fortified foods with Zn, vitamin A and folic acid, which are deficient in infants and children of many populations. In summary, food fortification is a low-cost, relatively simple strategy that may reach a wide range of people, and contribute to reducing the high prevalence of micronutrient deficiencies affecting children, especially in poor countries. The costs due to losses of human capital and their repercussions on health and future development are very high. Building links among academic researchers, politicians, food manufacturers and consumers is essential in order for food fortification to be efficacious and effective, and therefore should be considered as part of an integral strategy to combat micronutrient deficiencies.

The objective of the present study was to investigate the association between food patterns and anaemia among Chinese adults. It was a cross-sectional household survey undertaken in 2002. The sample contained 2849 men and women aged 20 years and above, and had a response rate of 89·0 %. Factor analysis was used to identify food patterns based on a food-frequency questionnaire. Logistic regression was used to relate food patterns to anaemia. A four-factor solution explained 30·5 % of the total variance. After adjusting for socio-demographic factors and four distinct food patterns, the ‘traditional’ (rice, vegetable, wheat flour), ‘sweet tooth’ (drinks, cake) and ‘healthy’ (whole grains, fruits, vegetables) patterns were independently associated with anaemia. ‘Traditional’ and ‘sweet tooth’ patterns were positively associated with anaemia, whereas the association with ‘healthy’ food pattern was negative. No association was observed between the ‘macho’ pattern (meat and alcohol) and anaemia. Compared with the lowest quartile (Q1) of the ‘traditional’ pattern, the highest quartile (Q4) had a higher risk of anaemia (men: odds ratio (OR) 2·60, 95 % CI 1·38, 4·88; women: OR 3·40, 95 % CI 2·14, 5·39). For the ‘sweet tooth’ pattern, compared with the lowest quartile (Q1), the OR of the highest quartile was 2·34 (95 % CI 1·47, 3·73) for men and 2·02 (95 %CI 1·31, 3·13) for women. The fourth quartile of healthy food was associated with a lower risk of anaemia (men: OR 0·50, 95 % CI 0·31, 0·79; women: OR 0·51, 95 % CI 0·34, 0·75). Women in the north had a higher risk of anaemia (OR 2·49, 95 %CI 1·80, 3·43). Food patterns were associated with anaemia in this area with a high prevalence of anaemia.

Despite the growing interest in dietary patterns, there have been few longitudinal investigations. The objective of the present study was to extend an earlier method of dietary pattern assessment to longitudinal binary data and to assess changes in patterns over time and in relation to socio-demographic covariates. A prospective national cohort of 1265 participants completed a 5 d food diary at three time-points during their adult life (at age 36 years in 1982, 43 years in 1989 and 53 years in 1999). Factor analysis identified three dietary patterns for women (fruit, vegetables and dairy; ethnic foods and alcohol; meat, potatoes and sweet foods) and two patterns in men (ethnic foods and alcohol; mixed). Trends in dietary pattern scores were calculated using random effects models. Marked changes were found in scores for all patterns between 1989 and 1999, with only the meat, potatoes and sweet foods pattern in women recording a decline. In a multiple variable model that included the three time-points, socio-demographic variables and BMI time-dependent covariates, both non-manual social class and higher education level were also strongly associated with the consumption of more items from the ethnic foods and alcohol pattern and the mixed pattern for men (P<0·0001) and the fruit, vegetables and dairy pattern and the ethnic foods and alcohol pattern for women (P<0·01). In conclusion, longitudinal changes in dietary patterns and across socio-economic groups can assist with targeting public health initiatives by identifying stages during adult life when interventions to improve diet would be most beneficial to health.

The relative importance of the usual diet in serum phospholipids in subjects with cystic fibrosis (CF) has been poorly studied. To compare the fatty acid profile in serum phospholipids from adult CF subjects with that of healthy subjects, and determine the role of the normal diet in this profile, we studied thirty-seven adult CF subjects with stable pulmonary disease and thirty-seven healthy controls matched for age, sex and nutritional status. A dietary questionnaire was obtained, anthropometric data were recorded, and the fatty acid profile measured by GLC. Compared with the controls, the percentages of myristic, palmitoleic and stearic acids and total MUFA were significantly higher in the CF group, and DHA, linoleic acid, total PUFA and n−6 fatty acids were significantly lower in the CF group. The CF subjects with worse pulmonary function and with pancreatic insufficiency had significantly lower levels of linoleic and n−6 fatty acids. The total energy intake was significantly higher in the CF subjects, although the energy distribution in the CF subjects and the controls was not different for the carbohydrates, lipids and proteins. No differences were detected in fat intake for MUFA (51 (sd 4) v. 52 (sd 4) %) or saturated fatty acids (33·5 (sd 5) v. 31·2 (sd 3·8) %), but the PUFA were slightly lower in the CF subjects (15·4 (sd 4·5) v. 17·4 (sd 4·2) %; P=0·02). The usual dietary intake of fatty acids by adult CF subjects does not appear to explain the difference in the fatty acid profile compared with controls. This suggests an abnormal fatty acid metabolism in CF subjects.

Anthocyanins from various vegetables and fruits have antioxidant activities, however, the bioactivities of coloured potato anthocyanins are not well studied. We examined the antioxidant capacities of pigmented fractions from purple potato flakes in vitro, and the antioxidant potentials of purple potato flakes in vivo. 1,1-Diphenyl-2-picrylhydrazyl radical scavenging activity of the pigmented fraction from Hokkai no. 92 (H92) potato flakes was higher than that from Kitamurasaki (KM) potato flakes. Extracts equivalent to 600 μg pigmented fractions from KM and H92 potato flakes inhibited linoleic acid oxidation in the order trolox>H92 ≥ KM>control. Rats were fed 25 % KM or H92 potato flake diets for 4 weeks. The major anthocyanin was identified as petanin. Control rats were fed a diet with cornstarch instead of potato flakes for 4 weeks. The serum antioxidant potential level in the H92 group was significantly higher than that in the control group. The degree of hepatic lipid peroxidation in the H92 group was significantly lower than that in the control group. Hepatic Cu/Zn-superoxide dismutase (SOD), Mn-SOD and glutathione peroxidase (GSH-Px) mRNA levels in the H92 group were significantly higher than those in the control group. Similar significant differences in Cu/Zn-SOD and Mn-SOD mRNA levels between the KM and control groups were found. The present results suggest that purple potato flakes have antioxidant functions with regard to radical scavenging activity and inhibition of linoleic acid oxidation, and that they improve the antioxidant potentials in rats by enhancing hepatic Mn-SOD, Cu/Zn-SOD and GSH-Px mRNA expression.

A purified pancreatic α-amylase inhibitor (α-AI) from white beans (Phaseolus vulgaris) was administered orally (100m/g body weight dissolved in 9g NaC/) for 22d to non-diabetic (ND) and type 2 diabetic (neonatal diabetes models n0-STZ and n5-STZ) male Wistar rats. Mean glycaemia (mmo/) declined from day 4 of the α-AI administration in ND rats (5·48 (sem 0·08) v. 4·39 (sem 0·13); P<0·05), n0-STZ diabetic rats (7·94 (sem 0·42) v. 5·56 (sem 0·32); P<0·01) and n5-STZ diabetic rats (17·34 (sem 2·58) v. 11·93 (sem 1·96)), until the end of treatment: ND (5·22 (sem 0·21) v. 3·97 (sem 0·06); P<0·01); n0-STZ (8·10 (sem 0·19) v. 5·21 (sem 0·30); P<0·01); and n5-STZ (16·36 (sem 2·14) v. 7·69 (sem 1·34); P<0·01). There was a decrease in water intake (m/) in the α-AI-treated diabetic rats: n0-STZ (30 (sem 0·10) v. 22 (sem 1·50); P<0·01) and n5-STZ (76 (sem 5·04) v. 57 (sem 4·85); P<0·01). Food intake (/) decreased in all three groups: ND (23 (sem 0·31) v. 20 (sem 0·03); P<0·05); n0-STZ (22 (sem 0·55) v. 16 (sem 0·98); P<0·01); and n5-STZ (31 (sem 0·58) v. 23 (sem 1·20); P<0·01). The enterocyte sucrase and maltase activities (/ proteins) were high (P<0·01) in the untreated diabetic rats, n0-STZ (45 (sem 4) and 152 (sem 10), respectively) and n5-STZ (67 (sem 12) and 151 (sem 10), respectively) with respect to the ND rats (24 (sem 2) and 74 (sem 10), respectively). After α-AI treatment, enzyme activities declined in both diabetic rats, n0-STZ (21 (sem 2) and 85 (sem 11); P<0·01) and n5-STZ (28 (sem 7) and 75 (sem 19); P<0·05), to values close to those in the ND rats. In conclusion, α-AI significantly reduced glycaemia in both the ND and diabetic animals and reduced the intake of food and water, and normalized the elevated disaccharidase levels of the diabetic rats.

Although studies in Caucasian populations have reported the beneficial effects of intakes of fruit and vegetables on bone mass, limited data are available in the Asian populations. We examined the association of the intake of fruits and vegetables with bone mineral density (BMD) in a population-based cross-sectional study of 670 postmenopausal Chinese women aged 48–63 years. Habitual dietary intakes were assessed using a food frequency questionnaire. BMD at the whole body, lumbar spine and left hip were measured with dual-energy X-ray absorptiometry. Univariate regression analyses showed that the total intake of fruits and vegetables was significantly associated with greater BMD at the whole body, lumbar spine (L1–L4), total hip, trochanter and intertrochanter. An independently positive association between fruit and vegetable intake and BMD at the whole body (P=0·005), lumbar spine (P<0·001) and total hip (P=0·024) remained even after adjusting for age, years since menopause, body weight and height, dietary energy, protein and Ca, and physical activities. A daily increase of 100 g fruit and vegetable intake was associated with 0·0062 (95 % CI 0·0019, 0·0105) g/cm2, 0·0098 (95 % CI 0·0041, 0·0155) g/cm2 and 0·0060 (95 % CI 0·0011, 0·0109) g/cm2 increases in BMD at the whole body, lumbar spine and total hip, respectively. In conclusion, greater fruit and vegetable intake is independently associated with better BMD among postmenopausal Chinese women.

School meals have changed during the last decades. The traditional service style with on-site food preparation has shifted towards catering delivery services. Vending machines, school cafeterias and other ways of food distribution are widely used in many schools, particularly in secondary schools. From a health promotion approach, the quality and quantity of food and beverages consumed while in school have an enormous potential impact on the health and well-being of young people. Most children spend a significant part of their lives in school. Additionally, school meals supply 30–35 % of daily energy intake and provide an important contribution to nutrient intake. School life is a critical period in the acquisition and practice of healthy behaviours. Environmental interventions in schools, to increase availability and access to healthy foods such as fruit and vegetables, have proved to be effective. School meals should make high-quality foods available which allow nutrient requirements to be met, consistent with dietary guidelines and offering a positive nutritional experience. School meals should be part of the educational process in the life of the school.

Proper nutrition during pregnancy may be important for maternal health and fetal growth and development. In Finland, targeted recommendations are given to guide pregnant women in their food choice and dietary supplement use so that they may obtain adequate nutritional status and meet the increased need for nutrients. The aims of the present study were to examine food choices, nutrient intake and dietary supplement use of pregnant Finnish women in association with demographic variables. One thousand and seventy-five families were invited to a birth cohort study during 1998–9. Mothers of 797 newborns completed a validated 181-item food-frequency questionnaire from which the food and nutrient intakes were calculated. The information about supplement use was collected concerning the whole pregnancy. The results of the present study suggest that healthy food choices are rather common among pregnant Finnish women and the choices are positively correlated with age and education. Nutrient supplements were used by 85 % of the women. Supplements were favoured by the older and well-educated women and by those who had normal weight before pregnancy. Of the women in the present study, 31 % received vitamin A-containing supplements, although it is not recommended during pregnancy. Taking food and supplementation into account, the intake of vitamin D did not meet the dietary recommendation and folic acid intake was below recommendation in 44 % of the women. Therefore there seemed to be unnecessary nutrient supplementation and at the same time lack of relevant supplementation among these pregnant women.

The object of the present study was to investigate the levels of serum transferrin receptor (sTfR) and its response to Fe supplementation in Fe-deficient children and the role of sTfR in detecting Fe deficiency and assessing the efficacy of Fe supplementation. According to the diagnostic standard, 1006 children, aged 6–14 years in Fangshan district, Beijing, Peoples Republic of China, were divided into four groups: normal; Fe store depletion (IDs); Fe deficiency erythropoiesis (IDE); Fe deficiency anaemia (IDA). sTfR was determined and transferrin receptor-ferritin (TfR-F) index was calculated in 238 children, sixty-four normal and 174 Fe deficient. Children were administered a NaFeEDTA capsule containing 60 mg Fe once per week for the IDs and IDE groups and three times per week for the IDA group for nine consecutive weeks. The parameters reflecting Fe status and sTfR were determined before and after Fe supplementation. The levels of sTfR and TfR-F index in Fe-deficient children were significantly higher than those in the normal group. The receiver operating characteristic curve showed that sTfR has proper diagnostic efficacy for functional Fe deficiency. After Fe supplementation, the level of sTfR was significantly decreased in children with IDs, but not in children with IDE and IDA, while TfR-F index was significantly decreased in Fe-deficient children. sTfR is a reliable indicator for detecting functional Fe deficiency, and TfR-F index is a sensitive parameter for assessing the efficacy of Fe supplementation.

Liquid enteral formulas are commonly used as a sole source of nutritional support of patients in hospital and community settings. Their effect on appetite has important consequences for dietary management of such patients and is likely to be affected by the formula composition. The aim of the present study was to compare appetite within healthy subjects consuming both a standard formula and one supplemented with pea-fibre (10g/l) and fructo-oligosaccharide (FOS; 5g/l) as a sole source of nutrition. Eleven healthy subjects consumed a standard formula or a pea-fibre/FOS formula as a sole source of nutrition for 14d in a double-blind, cross-over trial. Appetite was recorded using standard 100mm lines anchored at each end by a phrase denoting the most extreme appetite sensation. Consumption of the pea-fibre/FOS formula resulted in higher mean fullness (46 v.37mm, P=0·035), minimum fullness (13 v. 9mm, P=0·024) and minimum satiety (12 v. 8mm, P=0·012) compared to the standard formula. As there were no differences in macronutrient intake between formulas, these differences are likely to be due to supplementation with pea-fibre and FOS. The effect on appetite of the composition of an enteral formula, both with respect to nutrient content and functional components such as pea-fibre and FOS, may be an important aspect to consider in the dietary management of patients consuming enteral formula as a sole source of nutrition.

Ca and P are both essential nutrients for bone and are known to affect one of the most important regulators of bone metabolism, parathyroid hormone (PTH). Too ample a P intake, typical of Western diets, could be deleterious to bone through the increased PTH secretion. Few controlled dose–response studies are available on the effects of high P intake in man. We studied the short-term effects of four P doses on Ca and bone metabolism in fourteen healthy women, 20–28 years of age, who were randomized to four controlled study days; thus each study subject served as her own control. P supplement doses of 0 (placebo), 250, 750 or 1500mg were taken, divided into three doses during the study day. The meals served were exactly the same during each study day and provided 495mg P and 250mg Ca. The P doses affected the serum PTH (S-PTH) in a dose-dependent manner (P=0·0005). There was a decrease in serum ionized Ca concentration only in the highest P dose (P=0·004). The marker of bone formation, bone-specific alkaline phosphatase, decreased (P=0·05) and the bone resorption marker, N-terminal telopeptide of collagen type I, increased in response to the P doses (P=0·05). This controlled dose–response study showed that P has a dose-dependent effect on S-PTH and increases PTH secretion significantly when Ca intake is low. Acutely high P intake adversely affects bone metabolism by decreasing bone formation and increasing bone resorption, as indicated by the bone metabolism markers.

The importance of the seasonal variation of calcitropic hormones to growing skeleton has not been established. We studied whether there exists a seasonal variation in calcitropic hormones, bone mineral density (BMD) and bone remodelling markers in early puberty girls. One hundred and ninety-six girls, mean age 11·4 (sd 0·4) years, in Tanner stage 2 (early puberty) and 3 (mid-puberty) were studied during September to March. The BMD was measured from the lumbar vertebrae and the left femur by dual-energy X-ray absoptiometry. Their serum 25-hydroxyvitamin D (S-25-OHD), serum intact parathyroid hormone (S-iPTH), serum osteocalcin, urinary pyridinoline and urinary deoxypyridinoline were analysed from fasting samples. The concentration of S-25-OHD and serum osteocalcin differed among months (p<0·01), reflecting a seasonal variation. The parathyroid hormone correlated negatively with S-25-OHD (r −0·325, p<0·001). Moreover, the BMD in the femur (p=0·047) and to a lesser extent in vertebrae (p=0·057) differed between months in early puberty girls but this was not seen in mid-puberty. Seasonal variation in S-25-OHD and bone remodelling markers accompanied by negative correlation between S-25-OHD and S-iPTH was seen in this cross-sectional study of adolescent girls. In addition, the seasonal rhythm contributed 7·0–7·6% difference in the BMD of lumbar vertebrae and left femur in early puberty girls. This variation should be avoided since it could hamper peak bone mass attainment.

The effects of two bovine β-casein peptides on the urokinase plasminogen activator (u-PA) system and superoxide anion (SA) production by porcine macrophages and neutrophils activated by phorbol myristate acetate (PMA) were investigated. Macrophages and neutrophils were obtained from fourteen weaned piglets and were cultured in vitro for 24h with or without one of two chemically synthesised peptides: tripeptide leucine–leucine–tyrosine (residues 191–193 of β-casein) (LLY) and hexapeptide proline–glycine–proline–isoleucine–proline–asparagine (residues 63–68 of β-casein). Following incubation, cells were stimulated with 80μM-PMA. Total cell-associated u-PA, membrane-bound u-PA, free u-PA binding sites along with SA production were determined after stimulation with PMA. Both peptides suppressed the u-PA system and SA production of PMA-stimulated macrophages isolated from piglets during weeks 1–2 after weaning. Only the tripeptide LLY suppressed the u-PA system and SA production of PMA-stimulated neutrophils during the same time period. None of the peptides tested had any effect (P>0·05) on the u-PA system and SA production of PMA-stimulated macrophages and neutrophils isolated from the same piglets during weeks 5–6 after weaning. Thus, peptides are effective only in the early post-weaning period. Using cyclic AMP analogues that are highly specific activators of protein kinase A (PKA) or exchange protein directly activated by cyclic AMP-1 (Epac-1), we found that activation of PKA, but not Epac-1, was responsible for the downregulation of the u-PA system, whereas activation of PKA an/r Epac-1 was responsible for the downregulation of SA system in both macrophages and neutrophils.