Introduction: Nutrition clinical trials (NCTs) are pivotal in establishing causal links between nutritional interventions and chronic diseases. This review comprehensively examines prevalent clinical trial designs, emphasizing their strengths and limitations. The goal is to provide insights into the selection and optimization of these designs for dietary intervention studies. Methods: Various study designs in NCTs are explored, including quasi-experimental designs, double-blind Randomized placebo-controlled trials for nutrient/functional foods supplementation, community-based lifestyle interventions, pragmatic nutrition interventions, and field trial projects. The characteristics, advantages, and challenges of each design are discussed. Real examples are presented to illustrate how these designs can be tailored and optimized for dietary intervention studies. Results: Parallel Randomized clinical trials are acknowledged as the gold standard, despite requiring substantial sample sizes and having inherent limitations. Cross-over NCTs emerge as valuable for assessing temporary treatment effects while mitigating potential confounders and interpatient variability. However, they may not be suitable for acute diseases and progressive disorders, and attrition rates can be higher. Multi-arm Randomized designs offer increased study power with a lower sample size but necessitate more intricate design, analysis, and result reporting. Conclusion: In conclusion, each study design in NCTs comes with its set of strengths and limitations. The selection of an appropriate design should consider determinants and common considerations to provide robust evidence for establishing cause-and-effect associations or assessing the safety and efficacy of food products in nutrition research. This comprehensive understanding aids researchers in making informed choices when planning and conducting nutrition clinical trials.

Background Late onset sepsis is a frequent complication of prematurity, associated with increased mortality and morbidity. Probiotics may prevent late onset sepsis in premature infants. The aim of this study was to determine prophylactic effect of oral probiotics in prevention of late onset sepsis of very preterm infants. Materials and Methods This study was a Randomized, double blinded, placebo controlled trial. Eighty preterm infants born at < 32 weeks gestation weighing 1, 000-1, 500 gr randomly assigned in intervention and control groups. From soon after the start of feeds, intervention group received Pedilact drop, which was a probiotic and control group received distilled water (DW) as placebo, 1 drop per kg of body weight every 12 hours, made by Zist-Takhmir, Iran Company. After data collection incidence of late onset sepsis, mortality, time to establish full enteral feeding and duration of hospitalization were compared between two groups. Results Cause of hospitalization in all patients was respiratory distress and prematurity. The incidence of late sepsis and death in the intervention group was lower than the control group, which was significant. The mean time to establish full enteral feeding in the probiotic group was lower than the control group. No case of necrotizing enterocolitis was observed. There was no difference in terms of days of hospitalization among two groups (P>0. 05). Conclusion According to the results, usage of prophylactic probiotics can reduce the incidence of late onset sepsis and its mortality. By consuming probiotics preterm infants could reach the full enteral feeding in a shorter period of time, but the duration of hospitalization not reduced.

Background & aim: Fatigue is one of the most common complaints among pregnant women. Reflexology can be used to reduce the symptoms of fatigue. The purpose of this study was to measure the impact of foot sole reflexology on the intensity of fatigue in the first half of pregnancy. Methods: This Randomized clinical trial was conducted on 73 pregnant women with 8-20 gestational weeks who referred to urban health centers, Mashhad, Iran in 2018. The participants were randomly assigned to two groups of foot sole reflexology (n=36) and control (n=37) using a random number table. In the intervention group, in addition to routine care, foot sole reflexology was daily administered through a 20-minute session for 4 days. The control group only received routine care. The checklist of fatigue symptoms was daily completed by both groups up to seven day. The data were analyzed by SPSS software (version 25) using the Mann-Whitney U test, independent t-test, and analysis of covariance. Results: The results showed that although the mean score of severity of fatigue after the intervention decreased in both groups, compared to those reported before the intervention, there was no significant difference between the two groups (P=0. 87). Conclusion: In this study, foot sole reflexology did not reduce fatigue in the first half of pregnancy. However, as most pregnant women reported more relaxation in the reflexology group than the control group, further research in this topic is recommended in the future.

Background: The purpose of our study was to evaluate an inexpensive and available method to reduce mucous impactions in mechanically ventilated patients.Methods: This Randomized clinical trial was conducted on 40 mechanically ventilated patients aged 15-90 years. The patients were randomly allocated into two arms; 20 cases and 20 controls.The cases received N-acetylcysteine via their nebulizers, and the control group received normal saline three times a day for one day. We measured the density of respiratory secretion, plateau and peak airway pressures, and O2 saturation at baseline, 12 and 24 hours later.Results: Although the mean secretion density was significantly lower in the NAC group (F (1, 38)=8.61, P=0.006), but a repeated measures ANOVA with a Greenhouse-Geisser correction determined that the effect of NAC on mean secretion density did not differ significantly between time points (F (1, 38)=3.08, P=0.087). NAC increased O2 saturation significantly between time points (F (1.92, 73.1)=4.6, P=0.014). The plateau airway pressures were relatively stable throughout the study in the normal saline and NAC groups (F (1.95, 37.1)= 0.67, P=0.513). The peak airway pressure did not change significantly during the study in the normal saline and NAC groups (F (1.52, 56.4)=0.91, P=0.384).Conclusion: Considering the limitations of the study, nebulized NAC in mechanically ventilated patients was not effective more than normal saline nebulization in reducing the density of mucous plugs. The peak and plateau airway pressures were relatively stable throughout the study in both groups.