Welcome to the first 2023 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.

This month’s issue focuses on women’s health. In this issue: (1) Mental Health Moment: walnuts’ effect on stress in women college students, (2) diet and bacterial vaginosis, (3) positive mood mid-cycle, and (4) caffeine during pregnancy.

Mental Health Moment: Walnuts Can Benefit Stress

Acute and chronic stress play roles in overall health and well-being, from cognition and mental health to metabolism and gut function. Stress influences the food choices we make, and in turn, our diet patterns also can help or hinder mental and physical wellness. Walnuts, in particular, have been studied abundantly across different health disciplines because walnuts are rich sources of omega-3 fatty acids, as well as other neuroprotective compounds like melatonin, polyphenols, folate, and vitamin E.

This randomized controlled trial examined the effects of walnut consumption on the stress levels and overall mental health of college-aged students, the majority of whom were female. Over 16 weeks, participants consumed one serving of walnuts daily (about 56 grams or ½ cup). Blood, saliva, and stool samples were collected before and after the study to examine differences in the stress hormone levels, microbiome diversity, and general blood markers related to mental health. Mental health, mood, general well-being, and sleep habits also were assessed with several questionnaires before and after the study to evaluate health through a holistic lens.

The results show that the participants who consumed walnuts reported improved levels of stress, depression, and anxiety symptoms, and had improved blood markers during times of elevated academic stress, such as during final exam period. Participants consuming walnuts also experienced improved ease of falling asleep, sleep quality, and decreased grogginess after waking, all of which contributes to overall general health and well-being.

In subgroup analysis, academic stress was associated with decreased gut microbiome diversity in women, which was improved by walnut consumption. Because of the low number of men in the study, a similar connection could not be established.

Contributed by Carly Duffy, MPh, RD

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Note: Wondering about your own gut microbial diversity? Thorne’s Gut Health Test measures that, as well as much more. Or explore Thorne’s suite of products for stress support.

How Dietary Factors Influence Risk for Vaginosis

A high-sugar diet has long been associated with an increased risk for vaginal yeast infections – from Candida, for example. Studies also show an association between a high-carb diet and vaginal bacterial infections.

In a recent study, 144 women with bacterial vaginosis were compared with 151 heathy women. Women in both groups completed food frequency questionnaires for the year prior to vaginosis or the previous year in healthy controls. The study found a diet high in sugary desserts, refined grains, sweet drinks, fried potatoes, and fatty/red meat was associated with more than three times the risk for bacterial vaginosis – when comparing women with the highest intakes of these foods to those with the lowest intakes. On the other hand, women who ate mostly an ovo-vegetarian diet – consisting predominantly of vegetables, legumes, eggs, and whole grains – were 87-percent less likely to develop bacterial vaginosis when compared to women in the group who ate the least amount of these foods

Contributed by Kathi Head, ND

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Note: In addition to eating a healthy diet, consider Women’s Daily Probiotic to help maintain a balanced vaginal microbiome.*

Positive Mood Increases Mid-Menstrual Cycle

The idea that mood changes coincide with hormonal changes of the menstrual cycle is not new. However, previous studies show mixed results when it comes to relating negative mood to phases of the menstrual cycle – 8.5 percent found a non-premenstrual increase in negative mood, 15 percent found a premenstrual increase, 38 percent found greater negative mood in premenstrual plus another phase, and 38 percent found no evidence of an association between negative mood and menstrual phases.

In the current study, 66 women ages 19-32 with regular menstrual cycles completed a mood-related questionnaire at three time points during their menstrual cycle – early follicular phase (between cycle days 2-5), late follicular phase (14-17 days before the next expected menstruation), and mid-luteal phase (5-8 days before the next menstruation). Participants then reported the actual start date of their subsequent menstruation. Six participants were excluded because the questionnaire timing ultimately did not match up with the actual next menstrual cycle.

Mood fluctuations, both positive and negative, occurred throughout the cycle with most mood changes taking place mid-cycle. Among participants, positive feelings – friendly, cheerful, focused, active – increased at mid-cycle, while negative feelings – anxious, depressed, fatigued, hostile – decreased at mid-cycle. There were no differences in positive or negative mood between early follicular and mid-luteal phases.

Contributed by Jennifer L. Greer, ND, MEd

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Note: Not feeling the positive mood as you approach your menses? Try Thorne’s Meta-Balance. Although Meta-Balance is often used to support hormone fluctuations associated with menopause, it can also support the hormonal ups-and-downs as you approach your menses.

Caffeine Intake Throughout Pregnancy

Enzymes in the maternal liver that metabolize 90 percent of caffeine consumed are absent in the fetal liver and placenta. Similarly, the half-life of caffeine nearly doubles in pregnancy, meaning it takes longer to be metabolized and clear the body. During pregnancy, regardless of trimester, it is recommended to consume no more than 200 mg caffeine per day because it is associated with miscarriage, stillbirth, low birth weight or small for gestational age, and overweight or obese offspring. This study evaluated the intake of caffeine before and throughout pregnancy, variations in caffeine consumption, and factors associated with the non-adherence to caffeine intake recommendations in pregnancy.

This prospective cohort study analyzed data from 428 healthy pregnant women in Spain who were less than 14 weeks gestation. A trained researcher conducted structured interviews at the end of each trimester to gather data on socio-demographics, anthropometrics, health habits, incidence of insomnia, physical activity, and adherence to a Mediterranean-style diet to compare to pre-pregnancy information (PRE). Caffeine intake was quantified from a validated food-frequency questionnaire.  

PRE caffeine intake was 100 mg/day (median) and 181.1 inter-quartile range (IQR; suggesting a large spread of intakes). The first trimester was 9.4 mg/day (IQR 66.2), second trimester was 12.1 mg/day (IQR 65.6), and third trimester was 14 mg/day (IQR 61.1). Caffeine intake was higher among active smokers pre-pregnancy and throughout pregnancy (p<0.001) and women who did not adhere to a Mediterranean style-diet and who did less exercise (p<0.001). Noncompliance with recommendations of caffeine intake before pregnancy (>300 mg/day) was 10.8 percent (n=50). During pregnancy, 6.2 percent of women (n=28) in the first trimester, 4.2 percent (n=19) in the second trimester, and 2.7 percent (n=12) in the third trimester exceeded the caffeine intake recommendations for pregnancy (>200 mg/day).

This study found that the prevalence of caffeine intake in these women was lower during pregnancy compared to PRE, although it increased throughout trimesters with the greatest sources being coffee, cola drinks, milk chocolate, and decaffeinated coffee. The researchers conclude that many women adhere to the recommendations and, although the intake might be considered low, the increases throughout pregnancy could have consequences on baby and maternal health. 

Contributed by Laura Kunces, PhD, RD

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Note: Looking for nutritional support for pregnancy or when trying to conceive? Consider Thorne’s prenatal multi (Basic Prenatal) and Prenatal DHA.