فصلنامه علوم تغذیه و صنایع غذایی ایران
سال چهارم شماره 2 (پیاپی 13، تابستان 1388)

High serum concentrations of systemic and vascular inflammation markers are two major risk factors for cardiovascular diseases in hemodialysis patients. The present study was designed to investigate the effects of dietary ω3-fatty acid supplementation on the serum systemic and vascular inflammation markers in these patients. The study was a double-blind randomized clinical trial. Forty hemodialysis patients were randomly assigned to either an ω3-fatty acid supplement or a placebo group. The patients in the ω3-fatty acid supplement group received 2080 mg ω3-fatty acids as 4 capsules, each containing 310 mg eicosapentaenoic acid and 210 mg docosahexaenoic acid, daily for 10 weeks, while the placebo group received 4 corresponding placebo capsules containing MCT oil. At baseline and the end of week 10 of the study, 7 ml blood was collected from each patient after a 12- to 14-hour fast before dialysis and serum sICAM-1, sVCAM-1, sE-selectin, sP-selectin, CRP, IL-6, TNF-α, malondealdehyde (MDA) and total antioxidant capacity (TAC) were measured. Serum sICAM-1 concentration decreased significantly in the ω3-fatty acid supplement group at the end of week 10, compared to the baseline value (P<0.05); the reduction was also significant in comparison with the decrease in placebo group (P<0.05). No significant differences were observed between the two groups with regard to the mean changes in the serum sVCAM-1, sE-selectin, sP-selectin, CRP, IL-6, TNF-α, MDA, and TAC concentrations. The results of the present study indicate that dietary ω3-fatty acid supplements can reduce serum sICAM-1 concentration in hemodialysis patients, but it has no effect on serum systemic inflammation markers and oxidative stress.

Traditional Iranian flat breads have been widely produced and consumed all over the country and still play a major part in nutrition of the people. Starch gelatinization, retrogradation and staling of flat breads are topics of considerable interest to cereal chemists and baking technologists. This study aimed to investigate the processes of gelatinization, retrogradation, and staling of two types of Iranian flat breads, namely, Lavash and Taftoon. Three different flours with protein contents of 12.56%, 11.52%, 11.28% and extraction rates of 90%, 86% and 58%, respectively, were selected and, after chemical and rheological testing, used to bake Taftoon and Lavash breads. Starch gelatinization and retrogradation of the breads were quantified using Differential Scanning Calorimetry (DSC) after 1 and 3 days of storage. In the endothermic curves, the area under the curve, temperature at the start, and crystallization peak were used as the main criteria. Bread staling was determined using the shear test by Texture Profile Analyzer on days 1, 3, 5, and 7 of storage. Enthalpy, temperature at the start, and the crystallization peak were lower in Lavash bread, which is an indication of a slower rate of gelatinization and retrogradation in this type of bread due to the shorter time of the baking process. The data also show that Lavash bread is softer than Taftoon, but the staling rate (which shows the rate of firming during storage) is lower in Taftoon. Although the temperature in baking Lavash bread is higher, starch gelatinization cannot be completed due to the shorter time of the baking process and, consequently, its rate of crystallization is lower than in Taftoon. Therefore, retrogradation rate is lower in Lavash than in Taftoon. In addition, Lavash bread is thinner and softer than Taftoon and, therefore, it loses moisture faster and stales and dries more quickly.

Information on the effects of different types of fat on insulin sensitivity is limited. The present study was designed to compare the effects of feeding a fish oil-containing diet, a diet containing an oil mixture based on the Iranian fat consumption pattern, and a standard diet from the fetal period till puberty on the serum glucose and insulin sensitivity in Wistar rats. Thirty female Wistar rats were randomly allocated to three dietary groups: a standard diet (containing soy bean-oil), a diet containing fish oil, and a diet containing an oil mixture based on the Iranian population fatty acid intake. Dams in each group were fed one of the diets during pregnancy and lactation, and in each case the pups born were weaned onto the same diet. Fasting serum glucose level (by photometry) and insulin (by ELISA) were measured in the pups and insulin sensitivity was calculated at puberty. Data were analyzed using SPSS software and the one-way ANOVA and Tukey tests. The fasting serum insulin level and insulin sensitivity in the fish oil-fed group were significantly lower (P=0.018) and higher (P=0.002), respectively, than in the other two groups. It seems a diet containing fish oil (rich in long chain omega-3 fatty acids) causes a higher insulin sensitivity, as compared to diets containing either soy bean oil (rich in omega-6 fatty acids) or mixed oil based on the Iranian dietary fatty acid pattern (rich in saturated fatty acids).

Diabetes is one of the most prevalent endocrine disorders. Considering the antidiabetic effect of soybean isoflavones, in this study the effect of daidzein, the most important isoflavone in soybean, on the serum glucose level, lipid profile, and paraoxonase activity in diabetic rats was investigted. Thirty six male Sprague Dawley rats were randomly divided into three groups: 1. healthy, 2. diabetic, and 3. diabetic, supplemented with daidzein. Diabetes was induced in rats by a single injection of streptozotocine (60mg/kg body weight, dissolved in 0.05 mol/l citrate buffer). It was confirmed when the fasting blood glucose level was above 250 mg/dl. For Group 3, the diet was supplemented with 600 mg diazdein/kg basal diet. The groups of rat were fed their respective diets for three weeks. Supplementation with daidzein had no effect on the fasting glucose level, but, as compared to the diabetic (control) group, it brought about a significant decrease in the triglyceride and low-density lipoprotein levels (P=0.0001). The high-density lipoprotein levels, too, increased in this group (P= 0.001). Daidzein had no effect on the paraoxonase enzyme activity, as compared to the control values. However, comparison of the initial and final levels of the activity of this enzyme in the daidzein-supplemented group indicated a positive effect of diadzein in preventing reduction of this enzyme's activity (P=0.0001). Daidzein may have a desirable effect on the lipid profile disorders, one of the most important complications of diabetes. It can also support the antioxidant system.

Appropriate nutrition is an essential prerequisite for effective improvement of athletic performance, conditioning, recovery from fatigue after exercise, and avoidance of injury. Nutritional supplements containing carbohydrates, proteins, vitamins, and minerals have been widely used in various sporting fields to provide a boost to the recommended daily allowance. The aim of this study was to investigate the effects of acute L-carnitine supplementation on anaerobic threshold and lactate accumulation during incremental exercise. The study was double-blind, randomized and crossover in design. The subjects were 12 randomly selected active male physical education students, 21.75±0.64 years old, with a mean body mass index (BMI) of 23.7±0.94, divided into 2 groups. They received orally either 2g of L-carnitine dissolved in 200 ml water plus 6 drops of lemon juice or a placebo (6 ml lemon juice dissolved in 200 ml water) 90 minutes before they began exercise on treadmill. They performed a modified protocol of Conconi test to exhaustion. Plasma lactate concentrations were recorded at rest and immediately after the test. One-way analysis of variance with repeated measurements was used for data analysis. The results showed that lactate accumulation immediately after exercise in the L-carnitine group (3.870±0.19) was significantly lower (p=0.000) than in the placebo (6.080±0.58) group. In addition, the intervention led to a higher increase (p=0.000) in the maximum oxygen consumption (50.54±1.48), as compared to the placebo group (45.16±1.51). The data also showed that the length of time required to reach the anaerobic threshold was higher in the L-carnitin group (19.14±0.65, vs 16.00±0.28 for the placebo group). There was no statistically significant difference between the 2 groups with regard to the respiratory exchange ratio. L-carnitine supplementation seems to cause a reduction in the blood lactate accumulation and delay anaerobic threshold in an incremental exercise, resulting in improved performance.

Mycotoxin contamination of agriculture commodities is a serious concern as regards human and animal health. Rice is a staple food and one of the major carbohydrate sources in the diet of Iranian people. There are reports on the contamination of rice with mycotoxins such as aflatoxins, citrinin, deoxynivalenol, fumonisins B1 and B2, fusarenon-X, nivalenol, ochratoxin A, sterigmatocystin, and zearalenone. In the present study, 100 samples of rice sold in several branches of three of the main chain stores in Tehran, Iran were collected and analyzed for ochratoxin A (OTA). Ochratoxin A was extracted from the samples with acetonitrile-water solvent and purified using the immunoaffinity column. HPLC with fluorescence detector was used to identify and measure the OTA, the detection and quantification limits were being 0.03 and 0.1 µg kg-1 respectively. The OTA content in all the 100 imported and domestic rice samples was 69%. The mean and range of OTA were 1.37±5.72 and 0.15- 46.79 µg kg-1, respectively. In the most samples OTA contamination were lower than the permitted thresholds in cereals according to the Institute of Standards and Industrial Research of Iran (ISIRI) standards. Considering the high contents of OTA in some of the rice samples on the one hand, and the high consumption of other foods contaminated with OTA on the other hand, the total intake of this toxic substance may exceed its Provisional Tolerable Daily Intake as determined by the Joint FAO/WHO Expert Committee on Food Additives. In order to control mycotoxin contaminations, taking pre- and post-harvest preventive measures (GAP, GHP, GSP, GMP and HACCP), as well as sharing experiences and collective effort of all the parties involved, are highly essential.

The increasing consumption of junk foods by adolescents is associated with adverse health consequences. The purpose of this study was to identify determinants of unhealthy snack consumption among female adolescents using an integrative method based on the theory of planned behavior. The sample included 90 female adolescents aged 12-15 years, from 2 guidance schools in Tehran, selected by systematic sampling. In the qualitative phase of the study, which was of a phenomenology type, the data were collected through 9 focus group discussions. After obtaining parental consent, in each discussion session a moderator followed a topic outline developed based on the theory of planned behavior (TPB). Data analysis was done using the framework method. The quantitative phase consisted of a cross-sectional study on 790 female adolescents aged 12-15 years old from 10 schools, selected using a randomized stratified cluster sampling method. Data on social cognition (based on TPB) and food consumption (using a 48-item food frequency questionnaire) were collected and analyzed using the multiple regression method. In both phases of the study there was a broad range of factors, some of them contradicting each other, influencing selection of snacks by the adolescents. Taste was identified as the most important factor influencing their attitude towards junk foods consumption. The major predictors of behavior of the adolescents were found to be easy access to junk foods, personal taste preferences, peer pressure, media advertisements, and low price of unhealthy snacks (p<0.05). The most influential individuals in snack choice, based on the qualitative phase findings, were peers, while quantitative findings identified parents as the most influential. Applying an integrative approach provided a comprehensive insight into the underlying factors of junk food consumption by adolescents. Intervention programs with due consideration of these factors can help reduce unhealthy snack food consumption in this vulnerable group.

To define overweight and obesity in children, body mass index (BMI) reference standards are used. Presently four reference standards can be used to determine obesity among children in Iran: CDC-2000 standard, IOTF-2000 standard, the recent (2007) WHO growth references for school-age children and adolescents, and finally, the Iranian reference cutoffs, developed in 1999. So far there has been no study in Iran on identifying the best BMI reference standard for Iranian obese children. This study was conducted to identify the most suitable BMI reference standard to define obesity among Iranian children, as compared with triceps skin fold thickness. A total of 6818 school-age children (6-11years old) were recruited from 3 Iranian cities, namely, Ahwaz, Kazeroon, Orumiyeh, and Yazd by random cluster sampling. Age, sex, weight (to the nearest 0.1 kg), height (to the nearest 0.1 cm) and triceps skinfold thickness (TSF, to the nearest 0.1 mm) were determined and BMI was calculated. Obesity was defined as a BMI ≥ 95th percentile of CDC, WHO, and the Iranian reference standard. With regard to the IOTF standard, cutoff points (for boys and girls) were chosen as percentiles that matched the adult cutoffs of BMI of 30 at 18 years of age. The 95th percentile of TSF for each age/sex group was determined in each city and 5% of the pupils with the highest TSF (true obese children) were selected. Analysis was done on data gathered on 6700 subjects. Based on TSF, approximately 5% of the children were identified as obese. Proportions of obese children according to CDC, IOTF, WHO, and the Iranian reference standard were 5.4%, 3.9%, 6.3%, and 13.6%, respectively. Kappa values showed moderate agreement between the 4 reference values and TSF among the children (0.44-0.60). Overall, the Iranian reference standard showed the lowest agreement (0.44). Sensitivities and specificities of the 4 reference standards were, respectively, 61% and 97.5% for CDC, 98.8% and 55% for IOTF, 97% and 69.2% for WHO, and 90.4% and 90.3% for the Iranian reference values. The Iranian reference proved to have the lowest positive predictive value (PPV+) and efficiency. Despite the high sensitivity of the Iranian reference standard, its PPV+ (prevalence rate of disease), the most important diagnostic character of a method, and its efficiency were low in comparison with the other standards. Based on the findings of this study and features of the recent WHO growth reference values, we recommend the use of the WHO reference in future studies to assess obesity in children.