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. 

Adequate sleep may reduce energy intake and weight in overweight adults

1. In this study, individualized sleep hygiene counseling was sufficient to extend bed duration in participants with habitual insufficient sleep duration.

2. Furthermore, extension in sleep duration was associated with decreased daily energy intake and weight loss.

Evidence Rating Level: 2 (Good)

Obesity is a rising public health concern affecting both adults and children. Habitual sleep insufficiency (<7 hours) has been associated with adverse health consequences and has also been shown to be a risk factor for obesity. However, it is not clear if extending sleep can directly modify energy intake and weight in adults who are overweight.

This randomized control trial looked at the effect of sleep extension on daily energy intake and weight in a group of 80 adults (21-40 years old) who were overweight (BMI of 25-29.9) and were habitually sleeping less than 6.5 hours per night for the past 6 months. Participants were randomized to either individual sleep hygiene counseling aimed to extend sleep to 8.5 hours, or their usual habitual sleep schedule (control group). Sleep-wake patterns were continuously monitor by wrist actigraphy. Those with obstructive sleep apnea, insomnia, or working night shift were excluded. The primary outcome was change in daily energy intake after two-weeks.

Results demonstrated that the intervention resulted in extension of sleep by an average of 1.2 hours. Compared to the control group, the group with sleep extension had decreased daily energy intake (-270kcal) and reduced weight (-0.87kg). However, this study was limited by the short study period (2-week) and small sample size. Therefore, whether the changes in sleep duration and consequently, changes in decreased energy intake and weight, can be sustained over time and in participants from more diverse socioeconomic backgrounds will need to be studied. Nonetheless, the result of this study suggest the potential benefit of encouraging sufficient sleep as a lifestyle intervention for obesity. 

Weight loss and lifestyle interventions significantly decrease obstructive sleep apnea severity

1. In this study, comprehensive lifestyle interventions significantly decreased severity of obstructive sleep apnea at end of intervention up to 6 months after.

2. More than 50% of patients in the intervention group no longer required continuous positive airway pressure therapy both at end of intervention and 6 months after.

Evidence Rating Level: 1 (Excellent)

Obesity is a rising public health crisis and is a risk factor for multiple medical conditions. Specifically, it is the leading cause of obstructive sleep apnea (OSA), which affects up to 936 million adults. However, whether strategies targeting obesity such as weight loss and lifestyle interventions can directly improve OSA severity has not been well-studied.

This randomized control trial was conducted in Granada, Spain, from April 1^st, 2019, to October 23^rd 2020. The study looked at the effect of multi-faceted weight loss and lifestyle intervention on OSA severity and associated morbidity in 89 obese (BMI>25), Spanish men aged 18 to 65 years with moderate to severe OSA receiving continuous positive airway pressure (CPAP) therapy. 40 participants were randomized to receive usual care (CPAP therapy alone) and 49 to receive usual care along with 8-week lifestyle interventions such as nutritional behavior counseling, aerobic exercise, sleep, and alcohol and tobacco cessation. Patients enrolled in weight loss programs or with any psychological/psychiatric disorder were excluded. The primary outcome was changes in OSA severity as measured by apnea-hypopnea index (AHI) at end of intervention and 6 months after intervention. Secondary outcomes were changes in sleep-related outcomes, body weight, cardiometabolic risk, and health-related quality of life.

Results demonstrated that compared to the control group, patients in the intervention group had greater decrease in AHI (51% reduction) at the end of intervention and sustained decrease (57%) at 6 months after intervention. A proportion of patients in the intervention group were able to stop using CPAP therapy at end of intervention (45%) and an even higher proportion by 6 months after intervention (61.8%). Patients in the intervention group also had improved secondary outcomes including weight loss (mean difference between group of -6.8kg) and improved blood pressure (mean different between group of -6.4mmHg). However, this study was limited by homogeneity of patient population, making generalization to female or non-Spanish patients difficult. However, the results strongly support the inclusion of lifestyle interventions as future therapeutic strategy for OSA.

Green Mediterranean diet reduced age-related brain atrophy

1. In this study, participants over the age of 50 had more brain atrophy within 18-months compared to younger participants.

2. Furthermore, participants on the Green-Mediterranean diet had reduced brain volume loss compared to participants on a standard Mediterranean diet or healthy diet.

Evidence Rating Level: 1 (Excellent)

Longstanding research has shown that the Mediterranean diet is associated with lower mortality and risk of cancer, cardiovascular, and metabolic diseases. Based on the Mediterranean diet, the green-Mediterranean diet replaces red-meat completely with plant-based proteins and further supplement foods rich in polyphenols, such as Mankai. However, very few clinical trials have evaluated the effectiveness of the green-Mediterranean diet in providing further health benefits.

This randomized control trial looked at the effect of Green-Mediterranean (Green-MED) diet compared to traditional Mediterranean diet (MED) or normal healthy diet (HDG) on degree of age-related brain atrophy. 294 middle-aged patients (mean age 51 years old, 88% men) with abdominal obesity were randomized 1:1:1 to each group. Patients with kidney or liver dysfunction, active cancer, or pregnant were excluded. Change in brain volume, particularly the hippocampus, was assessed using whole-brain MRI 18-months after initiation of diet. The primary outcome was degree of hippocampal volume loss.

Compared to the HDG group (-1.3%), both MED (-0.78%) and green-MED (-0.8%) participants had attenuated atrophy of the hippocampus. Specifically, reduced red-meat consumption and increased consumption of high-polyphenol foods such as walnuts (both MED and green-MED) and Mankai (just green-MED) all individually associated with attenuated hippocampal volume decline. However, this study was limited by its small sample size and male-predominant participants, suggesting that the results may not be generalizable to females, younger people, or people without obesity. Nonetheless, given the environmental impact of animal-based food production, whether this diet can also have health benefits on a more general population would be of interest, and also have far-reaching implications on environmental sustainability.

Image: PD

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