Welcome to the June 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: (1) this month’s Mental Health Moment – berries and dementia risk, (2) green space and cognitive function, (3) gut fungi and gestational diabetes, and (4) egg consumption and cardiovascular health.


Mental Health Moment: Berry consumption and dementia risk

This month’s Mental Health Moment looks at cognition and dementia risk. Six million older U.S. adults live with some form of dementia, of which 80 percent have an Alzheimer’s diagnosis.1 Age is a primary risk factor for neurodegenerative diseases that impact quality of life. In the aging population, it is predicted that every 20 years the worldwide cases of dementia will double.2 This puts an added burden on the already limited medical care and disease management strategies for this population. Because truly effective treatments are still being developed, shifting the focus to preventative methods is key.

Modifiable lifestyle factors – such as diet, exercise, and smoking status – impact the risk of cognitive decline. Berries with their high antioxidant content have been shown to promote healthy metabolism and inflammatory responses, while reducing oxidative stress and positively impacting neurological signaling and blood vessel function. Polyphenols are antioxidant compounds found in many plants, including red, blue, and purple fruits and vegetables, that have been shown to improve cognitive function.

A study exploring the effects of blueberry supplementation examined 33 participants (ages 50-65) who were overweight, pre-diabetic, and had reported mild memory loss. They were divided into an experimental group and a control group. The experimental group consumed a blueberry powder twice daily for 12 weeks, with each serving being the equivalent of one-half cup of whole blueberries.1 Cognitive tests were given before and after the intervention to assess changes in the level of cognitive decline. These tests targeted executive functioning, such as working memory, mental flexibility, and self-control. The blueberry supplementation group had improvement in cognitive tasks, lower fasting insulin levels that reflect improved metabolism, and reduced oxidative stress. 

In a similar study of cranberry supplementation, 60 participants (ages 50-80) with no subjective memory complaints were randomized to a control or a treatment group.2 The treatment group received two sachets daily of 4.5 grams of freeze-dried cranberry powder, equal to consuming one cup of fresh cranberries – providing 281 mg proanthocyanins, 20 mg flavanols, and 59 mg anthocyanins. Biometric and anthropometric measurements, cognitive performance tests, and MRIs were conducted before and after the intervention period.

At the end of the study, the cranberry group had increased total plasma polyphenol metabolites, increased neural blood flow, and improvements in episodic memory. In addition, participants in the cranberry-supplemented group had improvements in metabolic markers, including fasting blood glucose, LDL cholesterol, and blood pressure.

Contributed by Carly Duffy, MPH, RD

References

  1. Krikorian R, Skelton MR, Summer SS, et al. Blueberry supplementation in midlife for dementia risk reduction. Nutrients 2022;14(8):1619. doi: 10.3390/nu14081619. 
  2. Flanagan E, Cameron D, Sobhan R, et al. chronic consumption of cranberries (Vaccinium macrocarpon) for 12 weeks improves episodic memory and regional brain perfusion in healthy older adults: A randomised, placebo-controlled, parallel-groups feasibility study. Front Nutr 2022;9:849902. doi: 10.3389/fnut.2022.849902.

It appears the bilberry (containing a similar polyphenol profile) in Advanced Nutrients might benefit more than the eyes. Check out Thorne’s other products that offer cognitive support.


Access to green space benefits cognitive function in middle-aged women

Does access to green space promote cognitive function throughout middle age? That was the question asked by a group of researchers in a recent longitudinal health study. Green space has previously been associated with factors that could impact cognitive function, including decreased levels of air pollution, lower risk of depression, and increased physical activity.

The Nurses’ Health Study II included 116,429 female nurses (ages 25-42) with data collection beginning in 1989. From 2014-2016, more than 40,000 participants were asked to complete an online cognitive assessment that measured psychomotor speed, attention, learning, and working memory. Approximately 14,000 completed assessments were submitted for review. Exposure to green space was estimated using the Normalized Difference Vegetation Index (NDVI), which is based on satellite imagery. Additional measures included exposure to particulate matter, depressive symptoms, and time spent per week in physical activity.

The study found that exposure to residential green space was associated with higher processing speed, attention, and overall cognition. For processing speed and attention, exposure to green space was estimated as being the equivalent of 1.2 years younger. However, learning and working memory were not associated with green space access.

In this study, although the association between exposure to green space and cognitive function could not be explained by air pollution or physical activity, the evidence suggests that depression might have been a factor. The authors note this finding is similar to previous research that consistently links access to green space with lower levels of depression, which has also been found in previous research to be a risk factor for dementia.

Contributed by Jennifer L. Greer, ND, MEd

Reference

  1. Jimenez MP, Elliott EG, DeVille NV, et al. Residential green space and cognitive function in a large cohort of middle-aged women. JAMA Netw Open 2022;5(4):e229306. doi:10.1001/jamanetworkopen.2022.9306

Mycobiota composition in patients with gestational diabetes mellitus (GDM)

The human mycobiota includes the different fungal species living in a human and can encompass more than 300 species. Although a healthy adult gut has been characterized as having a low fungal abundance, a higher gut fungal abundance has been reported to favorably influence childhood growth. Although there is still much to learn, evidence supports a relationship between specific gut fungal genera and chronic diseases, such as Alzheimer’s disease, IBS, IBD, alcoholic liver disease, colorectal cancer, pancreatic cancer, mold-induced asthma, bronchiectasis, carotid atherosclerosis, diabetes mellitus, and obesity.

This observational study analyzed the fecal mycobiota of pregnant patients with gestational diabetes (GDM) in the second and third trimesters and compared it with pregnant women with normal blood sugar levels.

Forty-one GDM patients and 121 normo-glycemic women were analyzed. Most GDM patients were overweight, with excessive fat intake (> 40% total daily energy) and low fiber consumption (< 15 g/day).

The mycobiota of women with gestational diabetes was composed almost exclusively of the Ascomycota phylum (shown to be predominant in obese individuals). Basidiomicota (shown to be negatively correlated with obesity) accounted for 43 percent of the relative frequency of the controls. Kluyveromyces (p < 0.001; found to enable IBD), Metschnikowia (p < 0.001; related to skin pathologies), and Pichia (p < 0.001; inflammatory fungi associated with increased C. difficile infections) showed significantly higher frequencies in GDM patients, while Saccharomyces (p = 0.019; shown to be inversely correlated with IBD and obesity) was more prevalent in controls. Metabolic and inflammatory patterns of participants worsened, as usually occurs during the third trimester of pregnancy, and showed a reduction in fungal alpha diversity in GDM patients, with an increase in the relative frequency of Candida and a reduction of some pro-inflammatory taxa. Many associations between fungi and foods/nutrients were detected.

The transfer of fungi from mother to baby has been reported, and early fungal colonization has been hypothesized to impact the development of diseases later in life. Increased fungal abundance in children was associated with increased growth in height and reduced BMI, and the mycobiome characteristics have been implicated in obesity and many inflammatory and allergic diseases during childhood. Promoting a beneficial mycobiota in pregnancy might be a way to improve the inflammatory status and insulin resistance of the mother and the future health of the baby.

Contributed by Laura Kunces, PhD, RD

Reference

  1. Ferrocino I, Ponzo V, Pellegrini M, et al. Mycobiota composition and changes across pregnancy in patients with gestational diabetes mellitus (GDM). Sci Rep 2022;12(1):9192. doi: 10.1038/s41598-022-13438-0.

Thorne’s at-home Gut Health Test provides a full microbe download of the microorganisms found in a sample, including fungi. In addition to fungi, you will also learn which bacteria, parasites, archaea, and viruses are present in the gut’s ecosystem. 


Egg consumption and cardiometabolic risk factors

Eggs have historically received a bad rap because they contain cholesterol, which was assumed to increase blood levels of “bad” cholesterol. In recent years, however, eggs have begun to emerge from under the cloud. This latest study will help reinstate the noble egg to its rightful place as an excellent source of protein – assuming you aren’t allergic to eggs. 

This Chinese population-based study assessed 4,778 participants (ages 30-79) – 3,401 with cardiovascular disease (CVD) and 1,377 controls. Plasma levels of 225 biomarkers were assessed. Subjects were questioned about egg consumption and 11 other food groups. Egg consumption was correlated with metabolic markers and CVD risk and was found to correlate with 24 of 225 biomarkers tested, including several related to CVD risk. Higher egg consumption was associated with increased levels of large and very large (diameter) HDL (the “good” cholesterol), apolipoprotein A1 (associated with HDL), and acetate (related to lower blood pressure and heart rate). On the flipside, egg consumption was associated with lower levels of total cholesterol and VLDL. These findings support previous research that egg consumption does not contribute to CVD.

Contributed by Kathi Head, ND

Reference

  1. Pan L, Chen L, Lv J, et al. Association of egg consumption, metabolic markers, and risk of cardiovascular diseases: A nested case-control study. Elife 2022;11:e72909. doi: 10.7554/eLife.72909.