Welcome to the October 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.

We are adding a new regular column – a Mental Health Moment. In this issue you will find new studies on: (1) effect of aerobic exercise on gut bacteria, (2) effect of dietary flavonoids on blood pressure and gut bacteria, (3) sleep and obesity, and (4) a Mental Health Moment: pre-diabetes and mood.

Aerobic Exercise Alters Gut Bacteria in Healthy Young Men

Exercise and gut bacterial content are both associated with chronic diseases, such as obesity, diabetes, cardiovascular disease, and colon cancer. Recent research has found that exercise can positively impact the gut microbiome in individuals who have chronic diseases. However, there is less evidence to support exercise as an agent for altering gut bacteria in healthy individuals.

Healthy men ages 20-45 were recruited to participate in a study measuring this effect. Participants were not following any type of restrictive diet and had been living a sedentary lifestyle with no changes in activity, body weight, or diet in the previous six months. Fecal and blood samples, cardiorespiratory fitness testing, body composition, and a 48-hour dietary recall were collected at baseline and at week 12. Participants were randomized into two groups:  control (no exercise) and exercise (aerobic training three times per week for 10 weeks).

The exercise group saw significant improvement in cardiorespiratory fitness, although neither group experienced changes in body composition, plasma metabolic markers, or dietary habits. This allowed changes in gut microbiota to be associated with the exercise intervention alone, and improvements in cardiorespiratory fitness were associated with positive changes in gut microbiota leading to improved bacterial diversity.

Contributed by Jennifer Greer, ND, MEd

Dietary flavonoids benefit blood pressure via microbiome effects

Flavonoids provide the wonderful color to many of the fruits and vegetables we eat. And how many times have you heard that a healthy diet includes a colorful plate of fruits and vegetables? So, it should be no surprise that we regularly see studies showing specific health benefits from flavonoid-rich diets.

In this study, the relationships between dietary flavonoid intake, blood pressure, and make-up of the gut microbiome were examined in a group of 904 German adults. Dietary intakes for the previous year were assessed using a food frequency questionnaire. Seated blood pressure (BP) was taken three times with 3-minute intervals between each. The average of the second and third BP was recorded. The content of the gut microbiome was assessed using gene sequencing of stool samples. Each participant also completed a questionnaire regarding age, gender, smoking status, medications, and physical activity.

Eating flavonoid-rich foods led to decreases in systolic blood pressure (SBP). The specific foods most associated with significant decreases in blood pressure included berries, apples, and red wine. And it didn’t require baskets of berries or barrels of wine. As little as 1.5 servings of berries daily decreased SBP mg 4.1 mmHg and slightly less than three glasses of wine a week decreased SBP an average of 3.7 mmHg.

The other portion of the study looked at the connection between gut microbiome content and the effect of flavonoid intake on blood pressure. The researchers conclude that microbiota content of the gut microbiome contributes to 15 percent of the effect of flavonoids on blood pressure. This is likely due in part to the prebiotic nature of certain flavonoid-containing fruits. Examples of their effect on the microbiome include greater microbial diversity (a good thing) associated with intakes of wine and berries and decreased abundance of Parabacteroides with intakes of apples, pears, and berries. 

Check out the Thorne product that contains flavonoid prebiotics from blueberries, pomegranate, and green tea.

Contributed by Kathi Head, ND


Associations of diet quality and sleep quality with obesity

With the prevalence of obesity reaching almost epidemic status across all ages, genders, and ethnicities, scientists are performing epidemiological studies to better understand potential mechanisms. There are established associations of poor sleep affecting food intake, hormones that regulate satiety (leptin) and appetite (ghrelin), and subsequent energy balance through high calorie, high carbohydrate foods. Similarly, poor sleep is also associated with decreased physical activity. This Korean study looked at associations of sleep, diet, and obesity in adults. 

In this study, 1165 adults (737 men, 428 women), ages 19-64 provided demographics, lifestyle, alcohol, and physical activity information via a questionnaire as part of a larger study. They were divided into three sleep groups: (1) >7 hours; considered adequate, (2) >5 hours with poor quality sleep, or (3) ≤5 hours of good quality sleep using the Pittsburg Sleep Quality Index questionnaire. Diet quality was assessed using the Recommended Food Score questionnaire. Obesity was defined as BMI >25; 44 percent of males and 18 percent of women were obese. Note: This is not a conventional definition of obesity in relation to BMI – which usually refers to a BMI of 25-30 as overweight and BMI over 30 as obese.

The results showed, on average, 43 percent of men and 41 percent of women slept less than seven hours a day; however, 54 percent of women reported poor sleep quality compared to 49 percent of men. Overweight/obesity was associated with higher rates of insufficient sleep and poor quality sleep in women, but not in men. Also interesting was, after adjusting for covariates, women with poor sleep quality were at higher risk (about two times) for obesity than women with good sleep quality.

Researchers associate the gender-based differences of sleep and obesity to leptin and other metabolic hormones implicated in the sleep-wake cycle and food intake behavior in women, because this finding is similar to other studies. The bottom line: adults, women in particular, who receive less than adequate sleep on a habitual basis might be at a significantly higher risk for obesity than those who receive adequate sleep.

Explore Thorne’s Sleep Products 

Contributed by Laura Kunces, PhD, RD


Mental Health Moment

Introducing our new column, Mental Health Moment, which provides timely insights into research focused on diet, nutrition, and natural products for mental-emotional wellness. Take a moment with us – you might find something that makes a difference.

Prediabetes and Mood – New Data Suggests a Connection

Most of us know there is a connection between what you eat and how you feel, although the reality is that it’s complicated. Humans often find their eating is influenced by mood – for example, you eat more when you are bored, crave sweet foods when you are sad, or lose your appetite when you feel stressed. Although it might be less obvious, the opposite is also true – what we eat and the health effects of our diets can also impact how we feel. If we can understand this connection, then we might be able to help individuals better manage their moods by making diet and lifestyle changes.

A new study in the American Journal of Psychiatry1 finds a link between prediabetes – sometimes referred to as insulin resistance – and depressed mood. Over a 9-year period, 601 healthy adults who were free of mood disorders at the start of the study were tracked for new onset of depression or anxiety. Researchers monitored them for markers related to insulin resistance, including waist circumference, blood fats (like cholesterol and triglycerides), and fasting blood sugar.

Over the course of the study, 14 percent developed depression. When the data was analyzed looking for links with prediabetes, the following was found:

  1. Elevated blood sugar led to a 38-percent increased risk of depression
  2. High-waist circumference (sometimes called central obesity) was associated with an 11-percent increased risk
  3. An elevated ratio of triglycerides-to-HDL cholesterol was associated with an 89-percent increased risk 
  4. There was no significant difference between men and women

The researchers suggest that positive findings for tests that screen for prediabetes might be a reason to also screen or monitor for depression. More research is needed to determine if managing insulin resistance through diet, lifestyle, and/or medication proves beneficial for individuals experiencing related mental-emotional changes.

Try Thorne’s Weight Management at-home test to check your blood sugar metabolism.

Contributed by Jacqueline Jacques, ND