A Paleolithic-type diet results in iodine deficiency: a 2-year randomized trial in postmenopausal obese women.

BACKGROUND/OBJECTIVES: Different diets are used for weight loss. A Paleolithic-type diet (PD) has beneficial metabolic effects, but two of the largest iodine sources, table salt and dairy products, are excluded. The objectives of this study were to compare 24-h urinary iodine concentration (24-UIC) in subjects on PD with 24-UIC in subjects on a diet according to the Nordic Nutrition Recommendations (NNR) and to study if PD results in a higher risk of developing iodine deficiency (ID), than NNR diet. SUBJECTS/METHODS: A 2-year prospective randomized trial in a tertiary referral center where healthy postmenopausal overweight or obese women were randomized to either PD (n=35) or NNR diet (n=35). Dietary iodine intake, 24-UIC, 24-h urinary iodine excretion (24-UIE), free thyroxin (FT4), free triiodothyronine (FT3) and thyrotropin (TSH) were measured at baseline, 6 and 24 months. Completeness of urine sampling was monitored by para-aminobenzoic acid and salt intake by urinary sodium. RESULTS: At baseline, median 24-UIC (71.0 µg/l) and 24-UIE (134.0 µg/d) were similar in the PD and NNR groups. After 6 months, 24-UIC had decreased to 36.0 µg/l (P=0.001) and 24-UIE to 77.0 µg/d (P=0.001) in the PD group; in the NNR group, levels were unaltered. FT4, TSH and FT3 were similar in both groups, except for FT3 at 6 months being lower in PD than in NNR group. CONCLUSIONS: A PD results in a higher risk of developing ID, than a diet according to the NNR. Therefore, we suggest iodine supplementation should be considered when on a PD.

Comparison of food habits, iron intake and iron status in adolescents before and after the withdrawal of the general iron fortification in Sweden.

BACKGROUND/OBJECTIVES: Sifted flour was fortified with carbonyl iron for 50 years in Sweden. This study evaluates changes in food habits, intake of iron, factors affecting iron absorption and iron status after the discontinuation of the general iron fortification in adolescents with the highest requirements. SUBJECTS/METHODS: A total of 2285 15- to 16-year-old students in 1994 (634 girls and 611 boys) and in 2000 (534 girls and 486 boys) in 13 schools in Gothenburg, Sweden, were included in two cross-sectional surveys assessing food habits with diet history interviews and iron deficiency defined with serum ferritin stores ⩽ 15 µg/l and no preceding infection. RESULTS: In girls, iron deficiency increased from 37 to 45%, while in boys, it was stable at 23%. Total iron intake decreased from 15.7 to 9.5 mg/day and 22.5 to 13.9 mg/day in girls and boys, respectively. Cereals were the main iron source. Among girls, the increase of fish and decrease of calcium intake may not counteract the effect of decreased intake of fortification iron. Among boys, more meat, less calcium and more vitamin C may have favoured the bioavailability of iron. CONCLUSIONS: The discontinuation of the general iron fortification resulted in a 39% decrease in total iron intake and iron deficiency increased substantially in girls. However, in boys no change in iron deficiency was observed. Whether this was a result of changed bioavailability of dietary iron or simultaneous changes of non-dietary factors remains to be explored.

Nutrition impact symptoms and body composition in patients with COPD.

BACKGROUND/OBJECTIVES: Anorexia or lack of appetite is common in chronic obstructive pulmonary disease (COPD) and may be caused or augmented by several symptoms affecting appetite and eating. We aimed to investigate and quantify the extent of nutrition impact symptoms (NIS) in patients with COPD and to explore relationships between NIS and fat-free mass depletion. SUBJECTS/METHODS: The results in this cross-sectional study are based on 169 COPD patients (62% female subjects). Body composition was assessed using bioelectrical impedance spectroscopy and the patients reported NIS by two newly developed questionnaires: the Eating Symptoms Questionnaire (ESQ) and the Disease-Related Appetite Questionnaire (DRAQ). RESULTS: Symptoms with the highest prevalence were dry mouth (71%), stomach ache (39%), pain or aches affecting appetite (36%) and constipation (35%). Problems with diarrhoea and feeling affected by smells were more severe among women compared with men (P<0.05). Thirty-six percent of the patients were depleted (fat-free mass index (FFMI) <15 kg/m2 for women and FFMI<16 kg/m2 for men). Depleted patients had more NIS (P<0.05) and also rated appetite and taste of food as worse compared with non-depleted patients (P<0.05). CONCLUSIONS: NIS are common in patients with COPD, and depleted patients have more severe symptoms. To investigate how these symptoms are best prevented and/or managed and whether NIS prevention/treatment can affect development of malnutrition in patients with COPD is a challenge for the future.

Stretch-shortening cycle muscle power in women and men aged 18-81 years: Influence of age and gender.

This study explored the age-related deterioration in stretch-shortening cycle (SSC) muscle power and concurrent force-velocity properties in women and men across the adult life span. A total of 315 participants (women: n = 188; men: n = 127) aged 18-81 years performed maximal countermovement jumps on an instrumented force plate. Maximal SSC leg extension power expressed per kg body mass (Ppeak) was greater in men than in women across the adult age span (P < 0.001); however, this gender difference was progressively reduced with increasing age, because men showed an ∼50% faster rate of decline in SSC power than women (P < 0.001). Velocity at peak power (VPpeak) was greater in men than in women (P < 0.001) but declined at a greater rate in men than in women (P = 0.002). Vertical ground reaction force at peak power (FPpeak) was higher in men than in women in younger adults only (P < 0.001) and the age-related decline was steeper in men than in women (P < 0.001). Men demonstrated a steeper rate of decline in Ppeak than women with progressive aging. This novel finding emerged as a result of greater age-related losses in men for both force and velocity. Consequently, maximal SSC power production was observed to converge between genders when approaching old age.

A maternal diet of fatty fish reduces body fat of offspring compared with a maternal diet of beef and a post-weaning diet of fish improves insulin sensitivity and lipid profile in adult C57BL/6 male mice.

AIM: The maternal diet during pregnancy and lactation may affect the long-term health of the offspring. Our aim was to study how a fish or meat diet perinatal and after weaning affects body composition, insulin sensitivity and the profile of n-3 and n-6 polyunsaturated fatty acids (PUFAs) in breast milk, fat depots, skeletal muscle and liver in male adult mice offspring. METHODS: During gestation and lactation, C57BL/6 dams were fed a herring- or beef-based diet. Half of the pups in each group changed diets after weaning. In offspring, body composition measured by DEXA, plasma lipid profile and insulin sensitivity measured by euglycemic clamp or QUICKI were monitored to adulthood. Analysis of total FAs by GC-MS were performed in the diet, breast milk and in different tissues. RESULTS: At 9 week of age, offspring of herring-fed dams had less body fat than offspring of beef-fed dams. Mice fed herring after weaning had increased insulin sensitivity at 15 week of age, reduced total plasma cholesterol and triglyceride levels, and compared with beef-fed mice, larger interscapular brown adipose tissue depots. The FA composition of the maternal diet was mirrored in breast milk, and the herring diet significantly affected the FA profile of different tissues, leading to an increased content of n-3 PUFAs. CONCLUSION: A herring-based maternal diet reduces body fat in the offspring, but the insulin sensitivity, plasma lipids and amount of brown adipose tissue are affected by the offspring's own diet; the herring diet is more beneficial than the beef diet.

Energy expenditure in chronic obstructive pulmonary disease-evaluation of simple measures.

BACKGROUND/OBJECTIVES: Almost 50% of all chronic obstructive pulmonary disease (COPD) patients become underweight. One possible reason for nutritional treatment to fail could be miscalculation of patients' energy requirements. The aim of this study was, therefore, to evaluate simple measures that may be used to assess the energy requirement of COPD patients. SUBJECTS/METHODS: This cross-sectional evaluation study includes 68 COPD patients (42 women). Resting metabolic rate (RMR) was assessed by indirect calorimetry, while total energy expenditure (TEE) was assessed by a 7-day monitoring using the ActiReg. Simple measures to evaluate was body weight (kg) multiplied by 125 kJ (30 kcal), predicted RMR multiplied by 1.7 and two simple questionnaires. RESULTS: Mean physical activity level (PAL) from the ActiReg was 1.46. Calculation of energy expenditure multiplying body weight with 125 kJ resulted in a TEE of 8614 kJ compared with ActiReg 8317 kJ (P=0.10). To multiply predicted RMR by 1.7 resulted in a statistically significant overestimation of 1335 kJ (P<0.01). Both questionnaires showed a clear 'dose-response' regarding PAL from ActiReg in the different activity categories. CONCLUSIONS: This study shows that simple measures of energy expenditure could, on group level, assess COPD patient's energy needs. However, for individual assessment of energy need, more thorough procedures are necessary.

Thyroid volume in Swedish school children: a national, stratified, population-based survey.

BACKGROUND/OBJECTIVES: Sweden has had a salt iodination program since 1936. This first national surveillance study on iodine nutrition infers an adequate level of urinary iodine concentration (UIC 125 µg/l) and the aim is now to evaluate thyroid volume (Tvol) in the same national sample. SUBJECTS/METHODS: A stratified probability proportionate to size cluster sampling was used to obtain a representative national sample of Swedish children aged 6-12 years. Median Tvol obtained ultrasonographically and the prevalence of enlarged thyroid glands were compared with an international reference standard. Regional differences were evaluated through comparisons of Tvol between coastal and inland areas, urban and rural regions, and former goitre and non-goitre regions. RESULTS: Tvol was correlated with age, body surface area (BSA), weight, height and body mass index for both sexes (P<0.0001) but not with UIC. The most important predictors for Tvol were age (girls: P<0.0001, boys: P=0.001) and BSA (girls: P<0.0001, boys: P<0.01). Median Tvol was higher in Sweden than in the reference study (P<0.0001). The prevalence of goitre was higher in Sweden (correlated to age 22.3%, BSA 15.7%, weight 17.6%, height 12.9%) than in the international reference (correlated to age 2.5%, BSA 2.5%, weight 2.5%, height 2.5%) (P<0.0001). Thyroids were larger in boys from urban and former non-goitre areas. CONCLUSIONS: Tvols were higher in Swedish school children than in the international reference study although iodine intake is considered optimal in Sweden. These findings underline the importance of regular monitoring of iodine intake, especially with regard to the decreased intake of table salt that is likely to follow initiation of health campaigns.

Salt intake in young Swedish men.

OBJECTIVE: To measure dietary salt intake in a Swedish population. DESIGN: A cross-sectional study with measured 24 h urinary excretion of Na and K. Completeness of urine collection was assessed using p-aminobenzoic acid. The subjects were interviewed on their habitual food intake. SETTING: Sahlgrenska University Hospital, Gothenburg, Sweden. SUBJECTS: Eighty-six young men (age 18-20 years), randomly selected from the population of Gothenburg. Seven men were excluded due to incomplete urine collection. RESULTS: The mean excretion of Na and K over 24 h was 198 and 84 mmol, respectively (corresponding to 11.5 g NaCl and 3.3 g K). The mean 24 h excretion in the highest quartile of Na excretion was 297 mmol Na and 105 mmol K, and in the lowest quartile, 100 mmol Na and 68 mmol K. The mean Na:K ratio was 2.3, and respectively 3.2 and 1.8 in the highest and lowest Na excretion quartiles. Calculated energy intake did not differ between the highest and lowest quartiles of Na excretion, but body weight, BMI and the intake of certain foods known to be Na-rich did. CONCLUSIONS: Salt intake in young men was alarming high and even subjects in the lowest quartile of Na excretion did not meet present recommendations to limit salt intake to 5-6 g/d. At this point we can only speculate what the consequences of the high salt intake may be for CVD and stroke later in life. Regulation of the salt content in processed and fast food and in snacks is advocated, to curtail the salt burden on society imposed by the food industry.

Physical activity, sports participation and aerobic fitness in children who have undergone surgery for congenital heart defects.

AIM: To investigate physical activity, sports participation and aerobic fitness in children who have undergone surgery for congenital heart defects. SUBJECTS AND METHODS: Children who had undergone surgery for congenital heart defects and healthy controls in the Gothenburg area were invited to participate in the study. All participants were aged 9-11 or 14-16 years. The activity monitor ActiReg was used to assess physical activity. Participants were interviewed about their participation in sports and performed a maximal exercise test on a bicycle with measured oxygen uptake. RESULTS: A total of 32 and 25 patients, and 61 and 45 controls, in the two age-groups were included, respectively. The patients had a wide range of severity of congenital heart defects. The physical activity level was similar in the patients and the controls. The rate of sports participation was high for both patients and controls; 80-94% of all participants took part in sports at least once a week. The majority of the patients were considered to have at least a moderate level of aerobic fitness. CONCLUSIONS: Although children who have undergone surgery for congenital heart defects have a similar level of physical activity compared with that of healthy children, some of them may require support to participate in exercise and vigorous physical activity.

Adequate iodine nutrition in Sweden: a cross-sectional national study of urinary iodine concentration in school-age children.

BACKGROUND/OBJECTIVES: Sweden has a long-standing salt iodization program; however, its effects on iodine intake have never been monitored on a national level. The objective of this study was to evaluate iodine nutrition in the Swedish population by measuring the urinary iodine concentration (UIC) in a national sample of Swedish school-age (6-12 years of age) children. SUBJECTS/METHODS: A stratified probability proportionate to size cluster sampling method was used to obtain a representative national sample of school-age children from 30 clusters. Spot urine samples were collected for UIC analysis using a modified Sandell-Kolthoff method. RESULTS: The median UIC of the children (n=857) was 125 microg/l (range 11-757 microg/l). The proportion of children with a UIC <100 microg/l was 30.0% and the proportion of children with a UIC <50 and >300 microg/l was 5.5 and 3.0%, respectively. CONCLUSIONS: The iodine nutritional status of the Swedish population is adequate. Iodized table salt remains the main dietary source of iodine in Swedish diet. Recommendations to reduce total salt intake in the population urge increased use of iodized salt in the production of processed foods. Pregnant and lactating women with high iodine requirements may still be at risk for low iodine intake. This study will serve as the basis for future monitoring of iodine nutritional status in Sweden.

Characteristics of under- and over-reporters of energy intake among 18-20-year-old males: the Gothenburg Osteoporosis and Obesity Determinants (GOOD) study.

OBJECTIVE: To identify and describe characteristics of the bias of reported energy intake of participants in the Gothenburg Osteoporosis and Obesity Determinants (GOOD) study. DESIGN: A validated diet history with a detailed questionnaire and an interview was used. Body fat was analysed by dual-energy X-ray absorptiometry. The ratio of energy intake (EI) to BMR was used to define under-reporters (EI:BMR<1.30), acceptable reporters (EI:BMR >or= 1.30 to <2.64) and over-reporters (EI:BMR >or= 2.64). SETTING: Sahlgrenska University Hospital, Gothenburg, Sweden. SUBJECTS: A total of 695 males (18-20 years). RESULTS: Sixty-eight per cent were classed as acceptable reporters, 22% as over-reporters and 10% as under-reporters. The under-reporters had higher BMI and body fat percentage than acceptable reporters (P<0.001), while over-reporters had lower BMI and body fat percentage (P<0.001). Over-reporters had more frequent use of protein supplements than acceptable reporters and higher physical activity. Over-reporters had a more regular and under-reporters a less regular meal pattern compared with acceptable reporters. CONCLUSIONS: Important knowledge of dietary reporting bias in a previously sparsely studied population has been provided. Over-reporting of energy intake was more common than under-reporting in the present population of young men and characteristics of under- and over-reporters were identified. The GOOD study was initiated with the central aim to determine environmental and genetic factors involved in the regulation of bone and fat mass, and the nutrient data of the acceptable reporters can be used for further investigation of the health effects of energy and nutrient intake.

The importance of bioavailability of dietary iron in relation to the expected effect from iron fortification.

BACKGROUND: The most common method of combating iron deficiency is iron fortification, especially in developing countries. However, few studies have shown a significant effect on iron status following iron fortification of low bioavailability diets. OBJECTIVE: To investigate how iron fortification and dietary modifications affect iron absorption and rates of changes in iron stores. METHODS: Research has made it possible to predict both iron absorption and the effects of iron fortification and diet modifications on iron stores using recently developed algorithms. Iron absorption and rate of change in iron stores were calculated from nine diets representing a broad range of iron bioavailability and iron contents. The calculations were related to the main target group for iron fortification, that is, women of reproductive age having empty stores but normal haemoglobin concentrations. RESULTS: As the only measure, iron fortification has practically no effect on iron status if the original diet has low bioavailability. However, after dietary modifications such a diet shows a positive effect on iron stores. The combined action of fortification (6 mg/day) and modest bioavailability changes in a low bioavailability diet results approximately in 40 and 70% greater increases in iron stores than through iron fortification or dietary modification alone. CONCLUSIONS: It is difficult to achieve good effects on iron status from iron fortification as the only measure if the diet has low bioavailability. Both dietary modifications as well as iron fortification are required to improve effectively the iron status of a population.

Subjects heterozygous for genetic loss of function of the thiazide-sensitive cotransporter have reduced blood pressure.

Gitelmans syndrome (GS) is an inherited recessive disorder caused by homozygous or compound heterozygous loss of function mutations of the NaCl cotransporter (NCCT) gene encoding the kidney-expressed NCCT, the pharmacological target of thiazide diuretics. An observational study estimated the prevalence of GS to 19/1,000,000, in Sweden, suggesting that approximately 1% of the population carries one mutant NCCT allele. As the phenotype of GS patients, who always carry two mutant alleles, is indistinguishable from that seen in patients treated with high-dose thiazide diuretics, we aimed at investigating whether subjects carrying one mutated NCCT allele have a phenotype resembling that of treatment with low-dose thiazide diuretics. We screened first-degree relatives of 18 of our patients with an established clinical end genetic diagnosis of GS for NCCT loss of function mutations and identified 35 healthy subjects carrying one mutant allele (GS-heterozygotes). Each GS-heterozygote was assigned a healthy control subject matched for age, BMI and sex. GS-heterozygotes had markedly lower blood pressure (systolic 103.3 +/- 16.4 versus 123.2 +/- 19.4 mmHg; diastolic 62.5 +/- 10.5 versus 73.1 +/- 9.4 mmHg; P < 0.001) than controls. There was no significant difference between the groups either in plasma concentration or urinary excretion rate of electrolytes, however, GS-heterozygotes had higher fasting plasma glucose concentration. Similar to patients being treated with low-dose thiazide diuretics, GS-heterozygotes have markedly lower blood pressure and slightly higher fasting plasma glucose compared with control subjects. Our findings suggest that GS-heterozygotes, the prevalence of which can be estimated to 1%, are partially protected from hypertension through partial genetic loss of function of the NCCT. However, as our study had a case-control design, it is important to underline that any potential effects on population blood pressure and risk of future cardiovascular disease need to be examined in prospective and population-based studies.

Capturing the onset of the common cold and its effects on iron absorption.

Hypoferremia is a well-known response to infections and inflammatory disorders. It seems to be managed by the key mediator of iron kinetics, hepcidin. There are several studies on induced-acute phase reactions. However, to our best knowledge there are no previous published reports on the outbreak of a common cold and its initial effect on iron kinetics. The objective of this case report is to describe such an observation. From an apparently healthy state in the morning we observed, in a 28-year-old male, every hour for 6 h the outbreak of a common cold and the modulations in the levels of serum iron (S-Fe) and interleukin-6 (IL-6). Despite a 100 mg oral iron loading there was a substantial reduction in S-Fe, which seemed to precede the IL-6 peak. Interestingly, this observed succession is in conflict with the proposed infection chain of order in which IL-6 stimulates hepcidin induction.

Measurements of eosinophil activation before and after food challenges in adults with food hypersensitivity.

BACKGROUND: Objective assessment of inflammatory reactions in the gastrointestinal tract could be useful in the diagnosis of food hypersensitivity. The aim of the present study was to investigate the involvement of eosinophils and mast cells in the inflammatory response of patients with food hypersensitivity before and after food challenges. METHODS: Eleven patients (4 with IgE-mediated allergy and 7 without) with food hypersensitivity and positive double-blind, placebo-controlled food challenge were subjected to food challenge in a single-blinded fashion. Four subjects with no known food hypersensitivity were recruited as controls. Placebo was given after a 1-week washout period followed by an active dose. Stool, urinary and serum samples were collected and symptoms were recorded in a diary. Fecal samples were analyzed for eosinophil protein X (F-EPX) and tryptase; urinary samples for EPX (U-EPX) and leukotriene E4 (U-LTE4) and serum samples were analyzed for eotaxin and food-specific IgE antibodies. RESULTS: Patients with IgE-mediated food allergy had increased levels of F-EPX compared to controls and tended to have lower serum levels of eotaxin compared to non-allergic patients and controls. U-LTE4 was significantly higher in allergic patients compared to non-allergic patients after challenge. Moreover, F-EPX correlated to U-LTE4 (p = 0.011). Reported symptoms, abdominal pain, distension, flatulence and nausea were similar in the allergic and non-allergic patients. CONCLUSION: The results strongly indicate that eosinophils are activated in the gastrointestinal tract of food-allergic patients but not in patients with non-allergic food hypersensitivity. Due to the inconsistent pattern of symptoms after placebo and active food challenge, it was not possible to relate the levels of inflammation markers to the recorded symptoms.

Energy expenditure in underweight chronic obstructive pulmonary disease patients before and during a physiotherapy programme.

OBJECTIVE: To investigate how total daily energy expenditure (TEE) changes when underweight patients with chronic obstructive pulmonary disease (COPD) enters a physiotherapy programme. DESIGN: Prospective intervention study. SETTING: Sahlgrenska University Hospital, Göteborg, Sweden. SUBJECTS: Fifteen patients with severe COPD and BMI<21 kg/m(2) were recruited consecutively at the outpatient COPD unit at the Department of Respiratory Medicine. Fourteen patients completed the whole study. INTERVENTION: TEE was assessed by the doubly labelled water method in a 2-week control period and during 2 weeks of physiotherapy. Energy intake was assessed using 7-day dietary record during control and physiotherapy period. RESULTS: Mean TEE during physiotherapy period was 500 kJ (6%) lower than during control period but the difference was not statistically significant. Ten of the 14 patients had lower and four had higher TEE. Mean energy intake during the physiotherapy period did not change from the control period (7700 vs 7600 kJ/day). CONCLUSIONS: Since underweight patients with COPD may show variable TEE during physiotherapy compared to a control period, an assessment of individual energy requirements is recommended.

Dietary problems in patients with severe chronic obstructive pulmonary disease.

BACKGROUND AND AIMS: Low body weight and low fat-free mass-index (FFMI) are common in patients with severe chronic obstructive pulmonary disease (COPD). Several factors seem to contribute. The aims of the present observational study were to investigate dietary problems in patients with severe COPD and to compare dietary problems to nutritional status, energy intake and smoking habits. METHODS: Nutritional status was assessed in 73 stable outpatients using body mass index and FFMI by single-frequency bioelectrical impedance. Lung function, smoking habits, energy intake and dietary problems were also assessed. RESULTS: The most frequently reported dietary problems were 'anorexia', 'dyspeptic symptoms other than diarrhoea', 'slimming', 'fear of gaining weight', 'dyspnoea', 'diarrhoea', 'depression, anxiety, solitude'. Smoking habits and gender had impact on the kind of dietary problems reported. Reporting two dietary problems correlated to low FFMI, whereas reporting one or more dietary problems correlated to decreased energy intake. CONCLUSION: Dietary problems are common in the group studied and related to smoking habits and gender. Dietary problems affect energy intake and FFMI negatively. It is important to recognize dietary problems and to offer intervention of the dietary problems as a part of the dietary intervention.

Obesity, dietary pattern and physical activity among children in a suburb with a high proportion of immigrants.

BACKGROUND: Obesity among children is a growing problem. Interventions should be planned to meet needs in different cultural settings. The objective of this study was to explore dietary patterns, physical activity and perceptions of relationships between life-style and health among children in a suburb with low socio-economic status and a high proportion of immigrants and refugees. METHODS: All children (n = 114) in Grades 5 and 6, aged 11 to 12 years, at a local Swedish school were invited, 112 participated. Food and exercise habits and perceptions on health and body image were assessed by a validated questionnaire and an interview. Height and weight were measured and risk for passing BMI 25 and 30 kg/m(2), respectively at the age of 18 was calculated. RESULTS: Thirty-one percent of the children were obese or overweight. Thirty-four percent spent more than 3 h daily watching TV or using computer, a behaviour, which clustered with excess intake of sweet drinks and habitually skipping breakfast. Only about half of the children believed that their life-style could affect their health. The results show that low socio-economic status and migration are proxies for overweight and obesity. CONCLUSIONS: Obesity, unhealthy living and a low awareness of relations between life-style and health call for action, for culturally sensitive prevention and treatment approaches.

Double-blind placebo-controlled challenges for peanut allergy the efficiency of blinding procedures and the allergenic activity of peanut availability in the recipes.

BACKGROUND: A firm diagnosis of double-blind placebo-controlled food challenge (DBPCFC) would facilitate the diagnosis in patients with uncertain history of reaction. Guidelines are lacking for an upper provoking dose and how to hide high concentrations of peanuts. AIM: To develop and evaluate a double-blind recipe with minimum 10% of peanut. To compare the recipe with published recipes regarding blindness, taste, texture and immunoglobulin (Ig)E antibody binding to peanut. METHODS: A recipe (I) with 10% of peanut was developed evaluated and used in DBPCFC. The challenges were followed by development of a concentrated recipe (II) (15% peanut, 25% fat). Recipe II was compared with the only published recipe (III) (11% peanut, 7% fat) regarding taste, texture and availability of peanut. Recipe IV (12% peanut, 10% fat) was developed using the same methods. The binding of IgE in the recipes was measured using an inhibition method. RESULTS: During challenges, one patient reacted after 4 g, emphasizing the need for blinding recipes containing high doses of peanut. Evaluation between recipes II and III, only recipe II was regarded as blind by the taste panels. A tenfold lower availability of peanut protein in the recipe II was found at 50% of inhibition. Recipe IV had a better IgE binding that did not differ from the original peanut extract. CONCLUSION: The peanut taste and texture can be hidden in a challenge medium. The fat content was important for the availability of the allergenic protein in challenges. The availability of allergens must be taken into consideration when used for DBPCFC.

Physical activity questionnaire for adolescents validated against doubly labelled water.

OBJECTIVE: To validate a physical activity questionnaire for adolescents (PAQA) adapted from the International Physical Activity Questionnaire (IPAQ). DESIGN: Energy expenditure was measured during a 14-day period with doubly labelled water (DLW). PAQA was administered as an interview at the end of the period, asking for physical activity in school, during transportation and leisure-time, during a habitual week. Energy expenditure (EE(PAQA)) was calculated as the product of total physical activity + sleep and predicted resting metabolic rate, and was compared to energy expenditure from DLW (EE(DLW)), thermic effect of feeding excluded. SETTING: Participants were recruited from grade 9 in a compulsory school in Göteborg, Sweden. All data were collected at school, and distribution of DLW and measuring of resting metabolic rate were performed at Sahlgrenska University Hospital. SUBJECTS: A total of 33 adolescents (16 girls, 17 boys) 15.7 (0.4) y performed all measurements. RESULTS: : For the whole group, PAQA underestimated energy expenditure by 3.8 (1.7) MJ (P<0.001). There was a strong correlation (r = 0.62, P<0.001) between EE(PAQA) and EE(DLW), but not for boys (r = 0.42, P = 0.090) and girls (r = 0.33, P = 0.22) separately. CONCLUSIONS: PAQA is not able to predict energy expenditure in Swedish adolescents, largely explained by the amount of unreported time. The ability to rank adolescents energy expenditure is questioned because of the gender effect, although we found a strong correlation for the whole group.