Welcome to the March 2024 issue 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 and wellness. Our medical team, including NDs, MDs, PhDs, RDs, an MS clinical nutrition, an MS biology, and an LAc, summarizes the essence of several interesting recent studies.

In this issue: (1) Mental Health Moment: Vitamin C and kiwifruit improve mood, (2) lentils for improvement of metabolic biomarkers, (3) beans improve metabolism via the microbiome, and (4) how microbiome diversity supports immunity.

Mental Health Moment: Kiwifruit, Vitamin C, and Improved Mood

Proper nutrition not only keeps us physically healthy, but it also impacts neurological health and mood. Vitamin C is an important antioxidant nutrient and a cofactor for neurotransmitter and hormone synthesis. Although many foods contain vitamin C, kiwifruit is a particularly rich source. Adequate vitamin C in the diet promotes healthy cognitive functioning and mental health. However, previous research has not clearly identified the time frame needed for vitamin C intake to improve mood. 

This 8-week trial explored the effects of vitamin C supplementation on mental health in 155 participants with a low vitamin C level. A 2-week lead-in period was followed by a 4-week intervention and 2-week washout. During the intervention period, participants were assigned daily to: (1) a chewable 250-mg vitamin C tablet, (2) two kiwifruits (providing 250 mg vitamin C), or (3) a chewable placebo. At each of the five check-in visits during the study, fasted blood samples were taken to measure serum vitamin C levels. Participants self-reported their level of energy/fatigue, mood, wellbeing/flourishing, sleep, and physical activity every other day throughout the study via a smartphone survey. 

Overall, while both the kiwifruit and vitamin C tablet intervention groups saw improvements in mood compared to control, the kiwifruit group saw more significant effects on vitality, mood, and flourishing. Initial improvements were typically seen in the first few days of increased vitamin C intake but had more consistent improvements after at least two weeks of consumption. Increasing vitamin C’s serum level provided relatively quick positive impacts on mental health and wellbeing.

Note: Support your own vitamin C level with Thorne’s Vitamin C with Flavonoids, Ascorbic Acid, or Buffered C Powder, all of which provide higher amounts of vitamin C than used in the present study.*

Contributed by Carly Duffy, MPH, RD

Reference

Daily Lentil Consumption for 12 Weeks Improves Metabolic Health Markers

Lentils are an excellent source of protein and fiber, and the USDA suggests that adults consume 1.5 cups (~300 grams) of lentils or other cooked pulses weekly. Few studies, however, have compared how long-term lentil consumption in higher amounts might impact blood sugar, cholesterol, and markers of inflammation compared to meat-based meals, particularly in populations at risk for metabolic diseases.

A group of 38 overweight or obese men and women (average body mass index 34.4; average age 47 years) were enrolled in a 12-week study and randomized to receive either a pre-made lunch consisting of 140 grams of cooked green lentils daily (~0.7 cups), totaling 980 grams weekly, or a poultry-based (chicken or turkey) lunch with no lentils. Meals were formulated to have similar protein and caloric content, and participants were advised to follow their regular eating patterns for their other daily meals. 

Study participants were selected based on having metabolic risk factors, including increased waist circumference (male ≥40 inches; female ≥35 inches) and elevated triglycerides (≥150 mg/dL) following a high-fat “test” meal that consisted of 58.3 grams (~4 tbsp) of salted butter on whole wheat bread, totaling 50 grams of fat, 54 grams of carbohydrates, and 12 grams of protein.

Blood samples and body composition were analyzed at baseline, and a variety of dietary intake surveys were used to identify potential differences between groups. Weekly surveys were used to assess for gastrointestinal side effects and compliance.

At the end of the 12-week trial, participants were instructed to avoid alcohol or strenuous exercise for 24 hours and visit the lab in the morning following a 10-12 hour fast. After fasting blood samples were taken, participants consumed the high-fat “test” meal and additional bloodwork was performed.

Although no body composition changes were found, the group who consumed lentils for 12 weeks had statistically significant reductions in various cardiometabolic blood markers compared to the poultry-meal group after the test meal, including reductions in fasting levels of total- and LDL cholesterol, as well as a significant reduction in blood sugar levels and markers of inflammation (IL-17 and IL-1β). 

Because the high lentil intake did not increase gastrointestinal discomfort compared to controls, the authors conclude that long-term lentil consumption offers several benefits to metabolic health and should be considered as a dietary strategy to modulate cholesterol, as well as post-meal blood sugar and inflammatory responses.

Note: Thorne’s Metabolic Health features botanical extracts – curcumin and bergamot phytosomes – to help maintain optimal cholesterol and blood sugar levels, as well as support for fat metabolism and maintaining a healthy weight.*

Contributed by Carina Toledo, MS, MHI, CNS

Reference

And if you need additional persuasion for the health benefits of legumes, here’s another study.

Eating Beans Modulates the Gut Microbiome and Improves Immune/Inflammatory Biomarkers

Although beans are growing in dietary popularity lately, in part due to their affordability, beans are also a recommended dietary staple thanks to their macro- and micro-nutrient content. A high-quality source of dietary fiber, beans provide prebiotic fuel for healthy gut microbes and add benefit to overall health. The BE GONE trial was conducted to determine whether introducing beans into the diet could shift the gut microbiome in a way that would improve outcomes in obesity-related conditions.

Participants in the study included adults, ages 30 and up, with obesity and a history of either precancerous polyps of the colon/rectum or colorectal cancer with completed treatment and return to normal bowel habits. The trial was a crossover style in which the participants maintained their normal diet without beans for four weeks before being randomized to two groups. The first group added beans to their usual diet for eight weeks, followed by an additional eight weeks of their usual diet without beans. The second group completed both phases in the reverse order. Participants provided a stool sample for microbiome testing at baseline and every four weeks during the trial. Fasting blood labs were completed every four weeks.

Adding one cup of beans to the daily diet improved the gut microbiome and related inflammatory and immune biomarkers in eight weeks. Upon return to the usual diet without beans, improvements in the gut microbiome were rapidly reversed. The authors note that while robust changes in diet and lifestyle would be even more beneficial, adding a cup of beans per day to the diet is an easily accessible, helpful step toward improving immune and metabolic health.

Note: Thorne’s Gut Health Test provides insights into the makeup of your individual gut microbiome and includes dietary recommendations for optimizing your health.

Contributed by Jennifer L. Greer, ND, MEd

Reference

How the Microbiome Boosts Immunity

If you have an interest in microbiome discussions and what makes for a healthy one, then you have probably seen the word “diversity” used in terms of the health of the microbiome. Diversity refers to the number of different bacterial species and the abundance of each – in general, the greater the diversity, the healthier your microbiome.

This study looked at the importance of microbiome diversity in preventing pathogenic bacteria from colonizing the gut. The researchers used both in vitro cultures and mice whose guts were free of bacteria (referred to as germ-free) to test multiple combinations of bacteria against two known pathogenic bacteria – Klebsiella pneumoniae and Salmonella enterica. First, they individually cultured 100 different human gut symbionts (bugs that live in harmony with humans for the mutual benefit of both) with Klebsiella and then Salmonella. These 100 were then ranked according to their ability to limit pathogen colonization. They next performed the same experiments with germ-free mice.

They found that when one beneficial bacterial species is paired with one pathogenic species, even the best-performing ones were only able to stop the spread of the pathogen on a limited basis. However, when diverse groups of up to 50 symbiotic bacteria were provided, the growth of the pathogenic bacteria was significantly halted. And, while diversity is important, so is the composition of the bacterial community. Certain bacteria are needed in the mix to impact pathogenic colony formation. Although no specific bacteria alone significantly halted progression, when combined with other species they “ganged up” on the Klebsiella or Salmonella by competing for the same nutrients. Thus, diversity, as well as composition of that diverse community, were both found to be important for immune support in the gut.

Note: How diverse is the microbial makeup of your gut? Among other factors, Thorne’s Gut Health Test provides you with a diversity score, dysbiosis score (based on the ratio of beneficial to neutral to pathogenic bacteria in your sample), and a list of specific bacterial species present. Learn more about what this test offers here.

Contributed by Kathi Head, ND

Reference