Welcome to the July 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 and wellness. Our medical team, which includes 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: the Mediterranean diet improves well-being in pregnancy, (2) breathing exercises increase the body’s glutathione level, (3) blueberries support bone health, and (4) low vitamin D can contribute to infertility and miscarriage risk.

Mental Health Moment: Mediterranean Diet and Well-Being, Stress, and Sleep During Pregnancy

The Mediterranean diet has been widely studied for its positive association with a variety of health conditions and overall well-being. This study evaluated the influence of a Mediterranean diet intervention on pregnancy, specifically a pregnant woman’s stress level, state of mind, and sleep.

The participants were women in their second trimester of pregnancy who were at risk for small-for-gestational-age newborns. The women were randomly assigned to one of three groups: (1) a “usual care” control group, (2) a Mediterranean diet with supplemental omega fatty acid-rich foods group, or (3) a stress intervention program. The Mediterranean diet group received nutrition education and counseling with dietitians at the start of the study and monthly until they reached 34-36 weeks of gestation.

Participants completed self-reported lifestyle assessments to measure stress, sleep, and mindfulness at baseline and at the end of the study. A participant subgroup also provided urine samples to measure cortisone and cortisol metabolites as stress markers at the beginning and end of the study.

The researchers found the Mediterranean diet group had significantly lower stress scores based on reported surveys, as well as improved sleep quality compared to the control and stress intervention groups. These findings were reinforced with urine lab markers, which showed an increase in metabolites that down-regulate cortisol in the body, with an overall improvement of stress levels and well-being. 

Note: Whether you are pregnant or not, stress can have a detrimental effect on your body. How are your stress hormones? You can find out with Thorne’s at-home Stress Test for a 24-hour snapshot of your cortisol fluctuations along with DHEA. Or, if sleep is an issue, you can check your 24-hour rhythm of both cortisol and melatonin with Thorne’s at-home Sleep Test.

Contributed by Carly Duffy, MPH, RD

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Breathing Exercises Increase Glutathione and Decrease Oxidative Stress

Oxidative stress occurs when there are inadequate antioxidants available to neutralize the reactive oxygen species (ROS) the body naturally produces or is exposed to from the environment. Although a certain amount of oxidative stress is normal, an imbalance can lead to excess inflammation and premature aging. Although deep breathing is often recommended for stress relief, a recent systematic review and meta-analysis of clinical trials found that deep breathing techniques can also benefit markers of oxidative stress.

The meta-analysis included 10 randomized controlled trials from five countries (lasting from 20 days to 3 months), 519 participants (267 in treatment groups; 252 in control groups), and a mix of healthy adults and individuals with a previous medical diagnosis of chronic obstructive pulmonary disease (COPD), high blood pressure, or diabetes. The studies utilized various breathing techniques, including deep breathing, pranayama yogic breathing, inspiratory muscle training (IMT), and diaphragmatic breathing. 

The most significant results of the meta-analysis were decreases in the oxidation product malondialdehyde (MDA) and increases in glutathione (GSH), the latter being an important antioxidant produced by the body.

MDA, the primary outcome measure in eight of the 10 studies (443 participants), was significantly decreased in the breathing intervention group compared to controls. Seven of 10 studies (383 participants) measuring GSH reported significant increases, except for one study in COPD patients that showed no change. Other markers analyzed, including superoxide dismutase (SOD) and nitric oxide (NO), had inconsistent results among studies but warrant further research.

Overall, the authors conclude that breathing exercises can be a helpful tool to increase levels of antioxidants in the body and reduce markers of oxidative stress.

Note: In addition to breathing exercises, antioxidant supplements can mitigate oxidative stress.* Thorne offers a sustained-release glutathione supplement in addition to a wide array of other antioxidant supplements.

Contributed by Carina Toledo, MS Clinical Nutrition, MHI

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Moderate Blueberry Consumption Can Reduce Bone Loss in Postmenopausal Women

Bone loss is a common concern of postmenopausal women, and, in previous studies, antioxidant intake has been associated with higher bone density. Blueberries have a high level of a class of antioxidants called flavonoids, which seem particularly beneficial for health. In a crossover study design, the effect of blueberries on bone health was examined in animals and humans.

In the preclinical animal portion of the study, 20 female rats were fed a polyphenol-free diet for 10 days, after which baseline calcium excretion was measured. The rats were then cycled through four 10-day dietary interventions, each followed by a washout period of 10 days. Each diet included a specific percentage of freeze-dried blueberries: 2.5, 5, 10, and 15. Net calcium retention, which represents bone balance, was significantly increased with the 2.5- and 5-percent blueberry diets. Higher dosages of blueberries did not correspond to a significant increase in net calcium retention.

The clinical portion of the study was completed by 13 healthy women ages 45-70 who were at least four years post menopause onset and who had not taken a medication for osteoporosis in the previous six months to two years. The cross-over design included three 6-week intervention periods divided into low (17.5 g/day), medium (35 g/day), and high (70 g/day) freeze-dried blueberry powder consumption. Each intervention period was followed by a 6-week washout period.

Low- and medium-blueberry consumption corresponded to higher calcium retention compared to no blueberry consumption. Medium blueberry consumption was also associated with a significant decrease in the bone resorption serum marker RANKL. In both arms of the study, blueberry consumption at moderate doses equivalent to less than 1 cup per day of fresh blueberries reduced bone loss.

Note: Looking for a supplement to augment that wonderful bowl of fresh blueberries? Check out Thorne’s Advanced Bone Support*.

Contributed by Jennifer L. Greer, ND, MEd

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Vitamin D Status, Fertility, and Fecundability

There is significant research connecting vitamin D status with fertility. This recent study looked at the effect of vitamin D status on both infertility (history of inability to conceive) and decreased fecundability (taking longer to become pregnant). In a prospective, population-based study, 3,115 Finnish women (age 31) completed fertility questionnaires and measured blood levels of 25-hydroxyvitamin D (25(OH)D). Women (n=375) were in the infertility group if they answered “yes” to whether they had been examined or treated for infertility. The decreased fecundability group (n=338) took 12 months or more to become pregnant after discontinuing contraceptives and actively trying to conceive; 198 women were in both groups. Women who experienced neither infertility nor decreased fecundability were in the control group (n=2,051). Women who had not tried to become pregnant (n=754) or whose partner (n=38) was the cause of the fertility issues were excluded from the study.

Evaluation of vitamin D status yielded these results:

  • Low vitamin D and history of infertility
  • Low vitamin D status seen in women with a history of two or more miscarriages
  • Multiple miscarriages seen more often in women with vitamin D levels <30 nmol/L (< 12 ng/mL, which is very low) and less prevalent in women with vitamin D levels >75 nmol/L (>30 ng/mL, which is the lower range of adequate)
  • A history of both infertility and decreased fecundability associated with low vitamin D status

Note: If you are planning a pregnancy or have patients who are, be sure to check their vitamin D status. And you can check it easily at home and monitor progress with Thorne’s at-home Vitamin D Test.

Contributed by Kathi Head, ND

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