Welcome to the March 2022 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. 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: (1) this month’s Mental Health Moment – a study on vitamin B6, oral contraceptives, and mood, (2) how diet patterns affect resting metabolic rate, (3) how diet patterns affect life expectancy, and (4) the effect of exercise on the microbiome and, in turn, its effect on type 2 diabetes.

Thorne Mental Health Moment: Vitamin B6 Helps Mood in Women Using Oral Contraceptives

Although vitamin B6 might not get the attention that vitamin B12 and folate do, it is very significant for regulating mood. This is because vitamin B6 is needed to make many important neurotransmitters, including serotonin, dopamine, and gamma-aminobutyric acid (GABA). Thus, altered levels of these important neurotransmitters can occur when there isn’t an adequate amount of B6 available to support their synthesis. In particular, the level of serotonin is tied to mood and can be negatively impacted by a low B6 level.1

About 14 percent of U.S. women ages 15-49 use oral contraceptives,2 which can potentially impact the health of millions of women. It has been well established since the 1970s that oral contraceptives for birth control can lower B6 levels.3 In addition, low B64 and use of oral contraceptives are both associated with mood changes – although studies appear to support both positive and negative changes depending on the kind of contraception and the individual.5

Despite years – decades really – of research in both areas, little available science connects the dots to answer the question of whether B6 supplements positively impact mood in women taking oral contraceptives. A group of University of Arizona researchers sought to answer this question. They conducted a small, double-blind, placebo-controlled crossover study in eight young women who were taking a combined estrogen-progestin contraceptive pill.6 The study used a dose of 100 mg of vitamin B6 compared to a placebo, and evaluated mood using two validated questionnaires (Beck Depression Inventory-II (BDI-II) and Profile of Mood States (POMS)). Although POMS scores were not affected, B6 supplementation significantly changed BDI-II scores (decreased by 20 percent). In addition, BDI-II scores increased in the placebo group.

This was obviously a very small study, but it does suggest that vitamin B6 might benefit mood in women who use this form of birth control. Larger studies are needed to validate this in the future.

Contributed by Jacqueline Jacques, ND


  1. Stach K, Stach W, Augoff K. Vitamin B6 in health and disease. Nutrients 2021;13(9):3229. doi:10.3390/nu13093229
  2. FastStats. Published November 10, 2020. https://www.cdc.gov/nchs/fastats/contraceptive.htm [Accessed February 28, 2022]
  3. Aly HE, Donald EA, Simpson MHW. Oral contraceptives and vitamin B6 metabolism. Am J Clin Nutr 1971;24(3):297-303. doi:10.1093/ajcn/24.3.297
  4. Merete C, Falcon LM, Tucker KL. Vitamin B6 is associated with depressive symptomatology in Massachusetts elders. J Am Coll Nutr 2008;27(3):421-427. doi:10.1080/07315724.2008.10719720
  5. Robakis T, Williams KE, Nutkiewicz L, Rasgon NL. Hormonal contraceptives and mood: review of the literature and implications for future research. Curr Psychiatry Rep 2019;21(7):57. doi:10.1007/s11920-019-1034-z
  6. Curtin AC, Johnston CS. Vitamin B6 supplementation reduces symptoms of depression in college women taking oral contraceptives: a randomized, double-blind crossover trial. J Diet Suppl 2022 Feb 2:1-13. doi: 10.1080/19390211.2022.2030843.

Do Healthy and Unhealthy Dietary Patterns Affect Resting Metabolic Rate?

The human body requires energy to function, even while at rest, which is known as resting metabolic rate (RMR). Some dietary patterns are associated with RMR, although with limited data. It is also well-known that eating habits play a role in obesity rates, and it is hypothesized that a dietary pattern of high energy intake, such as with an unhealthy dietary pattern, can reduce RMR and lead to body fat accumulation.

A recent study of 360 Iranian women ages 18-50 with a body mass index of at least 25 (overweight/obese), examined the association between dietary pattern and altered RMR. Participants completed a food frequency questionnaire to assess dietary intake. RMR, body composition, daily physical activity level, and biochemical measures (fasting glucose, lipids, liver enzymes, C-reactive protein) were assessed.

Participants were categorized into healthy versus unhealthy dietary patterns with low, medium, or high adherence to each. A healthy dietary pattern included high intakes of vegetables, fruits, nuts, low-fat dairy, seasonings, animal proteins, legumes, and olive oil. Unhealthy dietary patterns were characterized primarily by processed foods, desserts, high-fat dairy products, solid oils, junk food, and energy drinks.

Participants with the highest adherence to the unhealthy dietary pattern had higher waist circumference, visceral fat, fasting blood sugar, and C-reactive protein. Conversely, the women with the highest adherence to the healthy dietary pattern were least likely to experience an RMR decrease. The authors conclude there are significant associations between different dietary patterns and RMR, and that further research would create a better understanding of obesity’s etiology.

In the meantime, you might burn more calories at rest by eating a healthy diet.

Contributed by Jennifer L. Greer, ND, MEd


Sustained dietary patterns can significantly affect life expectancy

Norwegian researchers conducted an extensive review of the effect of sustained dietary patterns on the life expectancy of U.S. adults. They used meta-analyses and data from the 2019 Global Burden of Disease Study. The consumption and frequency of the following categories of foods were assessed: fruits, vegetables, whole grains, refined grains, nuts, legumes, fish, eggs, milk/dairy, white meat, added oils, red meat, processed meat, and sugar-sweetened beverages. Three dietary patterns were assessed – from worst to best – standard Western diet, feasible diet, and optimal diet. Optimal diet focused on vegetables, fruits, whole grains, legumes, fish, and a handful of nuts, while reducing red meat, processed meats, sugar-sweetened beverages, and refined sugar. The typical Western diet was the reverse, higher in processed meats, red meat, sweetened beverages, and refined sugar, while lower in fruits, veggies, whole grains, and legumes. The feasibility diet was midpoint between a typical Western diet and an optimal diet.

 Although it is logical an optimal diet versus a Western diet could improve lifespan, the extent to which it increased life expectancy in the analysis was startling. The earlier the diet is optimized, the greater the impact. For example, an optimized diet compared to a Western diet starting at age 20 could increase life expectancy in U.S. women by 10.7 years and in U.S. men by 13 years! The greatest dietary impacts in this order for both women and men were legumes > whole grains > nuts > decreased red meat/processed meat. And if you’re well past age 20, don’t worry – you can still impact your life expectancy. For example, switching from a typical Western diet to an optimal diet at age 60 would increase life expectancy in U.S. women by eight years and in U.S. men by almost nine years. Changing from a typical diet to a feasible diet resulted in half as much increase in life expectancy as an optimal diet. The effects of white meat, eggs, and added oils were unclear.

Looking for other ways to support healthy aging? Explore Thorne’s healthy aging supplements. Or take a quiz to see which healthy aging supplement might be right for you. Want to find out your biological age – versus your chronological age? Take Thorne’s Biological Age Test.

 Contributed by Kathi Head, ND


Exercise for the Diabetic Gut – Potential Health Effects and Underlying Mechanisms

Research shows reduced microbiome bacteria diversity in diabetic patients that results in decreased abundance of short-chain fatty acid (SCFA) producers, notably butyrate-producing bacteria (primarily Roseburia intestinalis and Faecalibacterium prausnitzii), in addition to increased intestinal permeability. Similarly, Akkermansia muciniphila is noted as a bacterium that positively affects glucose homeostasis. This review analyzed the effects of exercise on gut microbiota composition and intestinal barrier function in individuals with type 2 diabetes mellitus (T2DM). Below is a summary of several microbiome changes observed from articles in the review.

In mice studies, moderate-to-high-intensity treadmill running (5 days/week for 6 weeks) showed exercise affects both abundance and composition of gut microbes. Exercising diabetic mice increased Firmicutes Clostridium cluster C-I, decreased the ratio of Bacteroides/Prevotella, and decreased species of Methanobrevibacter and Bifidobacterium. Other mice studies show regular physical exercise (swimming 5 days/week for 8 weeks) positively influences SCFA synthesis and decreases insulin resistance.

In human studies, sprint interval training or moderate-intensity continuous training (3 times/week for 2 weeks) increased Bacteroidetes phylum, decreased the Firmicutes/Bacteroidetes ratio, and decreased species of Clostridium and Blautia – the two most abundant genera in pre-diabetics and T2DM. Exercise also reduced systemic pro-inflammatory tumor necrosis factor-alpha, C-reactive protein, and intestinal inflammatory lipopolysaccharide binding protein. The changes in some of these specific microbes that contribute to inflammation and insulin resistance can ameliorate endotoxemia, increase insulin sensitivity, and improve glycemic control.

Although the research on exercise and gut microbiome changes in T2DM is limited, regular exercise can promote improved gut composition and function. The authors note that training regimens play a role in changes observed. For example, sprint interval training can lead to a higher abundance of Lachnospira genus; whereas, moderate-intensity continuous training can increase Veillonella genus and Faecalibacterium prausnitzii. Some studies have also found that changes in body composition can contribute to different microbiome compositions. Researchers believe targeting the gut microbiota could help predict the benefits of exercise on specific individuals. The article also provides insight as to possible mechanisms whereby exercise contributes to the alleviation of T2DM, including exercise training-induced production of SCFAs and improvements in gut barrier function and intestinal transit time.

Looking for insights into the make-up of your gut microbiome? Consider Thorne’s easy, at-home Gut Health Test.

Contributed by Laura Kunces, PhD, RD