Welcome to the September 2021 edition of Research Extracts. “The Extracts” is designed to keep busy practitioners and savvy consumers up to date on the latest research on diet, nutrients, botanicals, the microbiome, the environment, and lifestyle approaches to good health. Our medical team, which includes NDs, MDs, PhDs, RDs, an MS, and an LAc, has summarized the essence of several interesting recent studies.

In this issue you will find new studies on: (1) effects of being outdoors on the brain, (2) female athlete calorie restriction and urinary incontinence, (3) dietary effects on health and the microbiome, and (4) increased incidence of iron deficiency in the United States.

Does Spending Time Outdoors Change Your Brain?

Spending time outdoors, especially in nature, has been shown to have a positive effect on both physical and mental health. Previous studies show that as time spent outdoors increases, the risks of chronic disease and depressive symptoms in adults and children decrease. In addition, individuals living in urban areas tend to spend less time outdoors than those in rural areas, while living in an urban area is associated with decreased brain size, particularly in the dorsolateral prefrontal cortex (DLPFC). The purpose of this study was to determine the effects of spending time outdoors on grey matter volume in the brain’s DLPFC.

Six healthy adults ages 24-32 living in an urban environment were studied. Their brains were scanned with magnetic resonance imaging (MRI) twice weekly over 6-8 months. On days of MRI assessment, self-reported data were collected, including time spent outdoors, amount of free time, caffeine consumption, and physical exercise. Data from a physical activity tracking device and mood assessment questionnaire were also collected at each MRI visit.

There was a significant positive association between time spent outdoors and higher grey matter volume in the DLPFC. In addition, positive mood was predictable by the amount of time spent outdoors during the previous 24 hours. The authors note that, despite the small sample size, the findings are in line with previous studies on time spent outdoors and health, further emphasizing the importance of balancing indoor time with outdoor exposure.

Contributed by Jennifer Greer, ND, MEd


Not Eating Enough Calories Contributes to Urinary Incontinence in Female Athletes

Urinary incontinence is an inconvenient, unpleasant, and embarrassing condition. Unfortunately, the World Health Organization reports the prevalence of urinary incontinence might be as high as 36 percent and is twice as high in older women than in older men. Although some conditions can pose a risk to general wellness, most conditions associated with its underlying cause are harmless, age related, or lifestyle related. And although pregnancy, childbirth, and menopause can precipitate incontinence, female athletes comprise a growing population of women who regularly experience urinary incontinence. In fact, urinary incontinence is more common in female athletes than non-athletes.

A clinical syndrome called Relative Energy Deficiency in Sport (RED-S) encompasses many health and performance consequences. Low energy availability (LEA) is when calorie intake is insufficient to meet the needs of exercise energy expenditure while also supporting basic physiologic functions. This study sought to determine if LEA is associated with urinary incontinence (UI) in female adolescent or young adult athletes and to evaluate association with sport categories and UI prevalence.

Participants included 1,000 females, ages 15-30, who had never given birth. LEA was defined as meeting one or more of these criteria: (1) self-reported history of an eating disorder, (2) a high score on the Brief Eating Disorder in Athletes Questionnaire, and (3) a high score on the Eating Disorder Screen for Primary Care. UI was assessed using an adapted question set regarding the timing of UI onset and duration, and yes/no questions regarding UI during any of 36 subdivided sport activities.

A total of 165 (16.5%) of those surveyed reported a history of UI during exercise-related activities. A total of 572 participants studied experienced LEA and this group was twice as likely to experience UI during exercise. Athletes who participated in a high impact sport were 4.5-times more likely to experience UI than those who participated in ball sports. The study reveals the significance of LEA and participation in high-impact sports with the occurrence of UI in young female athletes. 

Contributed by Amanda Frick, ND, LAc


Research is Revealing the Bigger Picture of Diet, the Microbiome, and Health

As researchers study the broad impact of the microbiome (the array of microorganisms that live in and on the human body – mostly in the gut) on human health, they are taking a more specific look at the role of diet and how it influences this complex system. We are hearing more about how an individual food or compound influences the microbiome, but we eat a complex diet and when a dietary change is made it is more likely to be a recommendation for more general changes, such as “increase fiber” or “eat more vegetables.”

A recent Stanford University study (Wastyk, et al.) used a multiomic analysis to evaluate the impact of two types of diets – high fiber or high fermented foods – on the microbiome. Multiomics is a biological analysis approach in which the data sets of multiple “omes,” such as genomes, proteomes, transcriptomes, epigenomes, metabolomes, and microbiomes are used to study life. Also evaluated was how these recommendations impact inflammatory and immune responses.

In the 17-week study, 18 healthy adults were assigned to a high-fiber diet (increased by adding fiber from fruits, vegetables, legumes, grains, nuts, and seeds) and 18 other healthy adults were assigned to a high-fermented foods diet (by adding multiple sources of fermented foods, including yogurt, kefir, fermented cottage cheese, fermented vegetables, vegetable brine drinks, and kombucha). Comprehensive stool analysis looked at microbiome composition, function, and metabolic output. Blood samples evaluated the immune system, including measurements of circulating cytokine levels, cell-specific cytokine response signaling, and cell frequency and immune cell signaling.

In the end, both diets showed benefits in different ways. The high-fiber group had more density of their microbes (more bugs but not more diversity of microbes), as well as increased microbiome function and better degradation of fiber. The high-fermented food group had increased microbiome diversity and reduced markers of inflammation. Although not fully understood, microbiome diversity is associated with multiple positive health benefits, from better gut health and positive mood, to lower occurrence of diabetes, neurodegenerative disease, and much more (Deng, et al.)

This study provides insight into how some dietary recommendations can contribute to far-reaching health impacts. More data of this kind could allow clinicians to better personalize a dietary intervention to have the greatest overall impact on individual health.

How does your gut microbiome look? Do you have a highly diverse assortment of microbes? Find out this and much more with Thorne’s Gut Health Test.

Contributed by Jacqueline Jacques, ND


Iron deficiency on the rise in the United States

The incidence of iron deficiency anemia and associated mortality is on the rise in the United States. A new study analyzed the cause of this trend by evaluating data from 1999-2018. Laboratory files from the National Health and Nutrition Examination Survey (NHANES) were used to evaluate trends in serum iron; red blood cell hemoglobin, distribution, and volume; and daily dietary iron intake. Mortality rates were acquired from CDC records, and iron concentration in foods was obtained from the USDA.

Dietary changes with a reduction in red meat consumption accounts for many of the iron deficiency trends between 1999-2018. For example, during that time beef consumption went down 15.2%, while chicken consumption (lower in iron) went up 21.5%. Iron concentrations in certain foods also declined during this time. Overall dietary iron intake decreased by 6.6% in males and 9.5% in females. At this same time, incidence of iron deficiency anemia increased 10-106%, depending on the demographic examined. Mortality rates related to iron deficiency anemia as an underlying cause increased from 0.04 to 0.08 per 100,000 deaths, while mortality from other types of anemia decreased 25% during the same period.

The authors conclude that the increase in iron deficiency anemia is associated with a decrease in dietary iron consumption, caused by diminished iron levels in certain foods and decreased consumption of iron-rich foods.

Editor’s note: If you are a vegetarian or don’t include iron-rich foods in your diet for other reasons, then ask your health professional to test your iron levels and supplement if low.

Contributed by Kathi Head, ND