Wellness Check: Nutrition

2 Minute Medicine is pleased to announce that we are launching Wellness Check, a new series dedicated to exploring new research evidence focused on wellness. Each week, we will report on articles examining different aspects of wellness, including (but not limited to) nutrition, sleep, reproductive health, substance use and mental health. This week, we explore the latest evidence-based updates in nutrition. 

Automated behavioral intervention for improving workplace diet did not prevent weight gain

1. Work-place behavioral interventions for improving diet choices and weight management can be automated and personalized based on cafeteria purchase history.

2. Personalized, automated behavioral intervention did not alter weight but improved diet choices during the 2-year observational period.

Evidence Rating Level: 1 (Excellent)

With the growing obesity epidemic in the US, effective and sustainable weight management interventions are urgently needed, especially at the workplace. However, most workplace interventions are short-term and based on biometric screenings or education regarding food choices. Therefore, interventions that can promote effective and long-term behavioral changes in diet choice and weight management are critically needed.

This randomized control trial tested the effectiveness of an automated, personalized behavioral intervention program in preventing weight gain and improving diet amongst 602 adult (124 men and 478 women) hospital employees. All participants purchased food from hospital cafeteria at least 4 times a week. Participants who were pregnant, had a history of eating disorder, weight loss surgery, or enrolled in another weight loss program were excluded. 299 participants were randomized to the intervention group and received automated emails twice a week containing personalized feedback and suggestions regarding cafeteria purchases and a monthly letter with peer comparisons and financial incentives for healthier food purchases. 303 participants were randomized to the control group and received a monthly letter with general healthy lifestyle tips. The primary outcome was change in weight.

The intervention group did not have a significant difference in weight change at 12 or 24-months follow-up. However, the intervention group made healthier purchases and had decreased calories purchased per day compared with control group. This study was limited in its generalizability and feasibility given there were predominant female participants and a prerequisite for a food purchase tracking system. Nonetheless, the observed long-term improvement in food choices and potential consequent benefits warrants further studies of automated, personalized work-place interventions.


Longer seated lunch time associated with more consumption of fruit and vegetables in children

1. Compared to 10-minuted seated lunch, 20-minuted seated lunch led to increased amount of fruit and vegetables consumed amongst children.

2. 20-minute lunch did not increase phone usage but increased rate of interaction among participants.

Evidence Rating Level: 1 (Excellent)

The National School Lunch Program aims to ensure children have access to and consume foods that are nutritious. However, such large-scale program also needs to consider broader areas such as food waste, food education, and eating behavior to be successful and sustainable. Regarding eating behavior, there is currently no federal policy for lunch time duration in the United States. Some observational studies have identified an association between seated lunch time and healthier eating behavior in children. However, a randomized trial that can better control for inherent variations in food preferences and eating environment is needed.

This randomized control trial assessed eating behavior, food waste, and dietary intake during 20-minute or 10-minuted seated lunch periods in 38 children. Participants were aged 8-14 years old, attended the same summer camp and observed for 20 study days. Each participant received one of 5 free lunch sets and were randomly assigned a 10 or 20-minute seated lunch time each day. The primary outcomes were amount of food and beverage consumed and wasted each meal. Staff also observed each participant’s level of talking and phone use during the lunch period. Compared to 10-minute seated lunch times, participants in 20-minute seated lunch times consumed significantly more and wasted significantly less fruits and vegetables. However, no difference was observed in consumption of entrees or beverages. Furthermore, phone use was similar in 10-minute and 20-minute lunches, but talking time was increased during 20-minute lunches. Overall, shorter lunch time seemed to disproportionately decrease consumption of fruit and vegetables.  This study was limited in sample size, age of children represented, and environmental context. Nonetheless, these findings highlight potential benefits of systemic policies around seated lunch time to improve food behavior and reduce food waste in school aged children.


Very-low-calorie diet leads to significant but reversible changes in gut microbiome

1. Very-low-calorie diet significantly altered composition of the gut microbiome in study participants, including an enrichment in pathogenic Clostridiodies difficile.

2. Stool samples from post-diet patients similarly induced weight loss in mice due to impaired nutrient absorption and enrichment in Clostridiodies difficile.

Evidence Rating Level: 1 (Excellent)

The gut microbiome plays an important role in health and disease and is greatly modulated by components and patterns of our diet. However, how our diet patterns, especially in the scenario of severe caloric restriction, affect our gut microbiome is poorly understood. This randomized control trial assessed the effects of severe caloric restriction on number, composition, and function of gut microbiome. 80 post-menopausal women who were overweight were randomized to either diet or stable weight control group for 16 weeks. Participants in the diet group consumed shakes with less than 800 calories a day.

Overall, dieting reduced the number of microorganisms present in the gut, diversity of the composition of gut microbiome, and number of metabolites produced by gut microbiota. To directly test whether gut microbiome alone can contribute to weight loss, stool samples from participants pre and after diet were transplanted into mice lacking gut microbiome. Mice receiving post-diet stool samples had rapid and sustained weight loss and decreased body fat. However, weight loss was found to be in part due to decreased efficiency of dietary energy intake and enrichment in Clostridioides difficile, a pathogenic bacterial strain that can cause severe colitis. This study was limited in the homogeneity of its patient population and the type of food supplied as part of the diet. Furthermore, this study did not assess how long after dieting observed changes could be sustained. Nonetheless, this study points to further need to better understand the interaction between diet, acute changes in diet pattern, and gut microbiome in health and disease.


Image: PD

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