Welcome to the March 2020 edition 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 of the most interesting studies.

Research summaries in this issue include: (1) vitamin D in the diet, (2) microbiome and personality, (3) coffee preparation and diabetes risk, and (4) anti-aging effects of the Mediterranean Diet.

Vitamin D status is hard to maintain with food alone

One argument often used against nutritional supplements is that people can get all the nutrients they need from diet alone. Yet there is ample data to indicate this is not the case, given the limitations of modern diets and lifestyles. Case in point – we know many individuals struggle with getting sufficient vitamin D.

Although vitamin D can be obtained from food and made in the skin from sunlight exposure, there are not many good food sources, and individual ability to make this nutrient can be impaired under many circumstances. Age, skin tone, body weight, and lack of exposure to sun all have a negative impact on the ability to make vitamin D.

According to the American Academy of Clinical Endocrinologists, the average rate of vitamin D deficiency in U.S. adults is 41.6 percent,1 and can be as high as 82 percent in dark-skinned individuals.

Because one factor that greatly increases the likelihood of vitamin D deficiency is living very far north or very far south; i.e., where there is limited exposure to the sun for up to half the year, researchers studied how individuals living in a far-north community compensated for low natural vitamin D production by eating a vitamin-D rich diet.2

A second factor that increases risk of deficiency is body weight. Individuals with excess body weight have a greater risk of vitamin D deficiency because, as a fat-soluble vitamin, it tends to become stored in fat rather than going where it is needed.

Thus, 22 overweight individuals residing in a town in Norway ate salmon (a good source of vitamin D) for dinner five nights per week, totaling 750 grams (1.65 pounds) of salmon weekly. A second group of 22 individuals ate a comparable meal of cod, and a third control group did not consume fish.

For reference, 750 grams of salmon should provide about 4,000 IU of vitamin D, while 750 grams of cod should provide only 300 IU of vitamin D. The recommended daily intake of vitamin D for healthy adults is 600 IU.

By the end of the 8-week study, all groups had decreased vitamin D status. While the salmon group decreased the least, it was still concluded that this intake of vitamin D from food was not adequate to prevent deficiency in this population.

Obviously, most of you reading this are not overweight individuals living in such places as Anchorage, Alaska or Yellowknife, Northwest Territories – but with so many other factors making vitamin D deficiency common, this study does indicate that trying to compensate through diet alone is very hard.

If you want to know more about your vitamin D status, then you can easily take this at-home test to better understand your personal need for this important nutrient.

If you aren’t getting enough vitamin D in your diet, then explore Thorne’s suite of vitamin D supplements.

Contributed by Jacqueline Jacques, ND


  1. Vitamin_D_Deficiency_formatted.pdf. https://www.aace.com/sites/default/files/2019-02/Vitamin_D_Deficiency_formatted.pdf. [Accessed February 24, 202]
  2. Bratlie M, Hagen I, Helland A, et al. Five salmon dinners per week were not sufficient to prevent the reduction in serum vitamin D in autumn at 60° north latitude: a randomised trial. Br J Nutr 2020;123(4):419-427. doi:10.1017/S0007114519002964

Is the gut microbiome linked to personality?

Evidence already links the type and diversity of the gut microbiome to digestive and immune health, to development and metabolism, and even to mood. A recent study investigated the correlation between the gut microbiome and general, less transient features of personality in the general population.

In particular, researchers looked at the personality traits of sociability (a combination of extroversion, social skill, and communication) and neurotic tendency (a combination of neuroticism, stress, and anxiety).

Based on analysis for 23 genera from 261 individuals, sociability score was a positive predictor of Akkermansia, Lactococcus, and Oscillospira abundance, whereas it was a negative predictor for Desulfovibrio and Sutterella. The score for neurotic tendency negatively predicted the abundance of Corynebacterium and Streptococcus genera in the samples.

Participants with larger social networks tended to have higher microbiome diversity, while those with more stress and anxiety generally had less diverse gut microbiomes with different composition.

The authors note that Akkermansia and Oscillospira have previously been associated with good health, whereas Desulfovibrio has been previously associated with autism pathophysiology, although there is some conflicting evidence.

The authors acknowledge it is not possible to conclude cause and effect from the study’s design, especially given the bidirectional nature of the influence of the gut microbiome and the body on each other; but they suggest these are areas worthy of additional investigation. For instance, this provides added motivation to increase dietary fiber – which has been shown to support microbiome diversity and health-promoting microbial species – to support emotional health.

How is your gut microbial diversity? Find out this and much more with Onegevity’s at-home GutBio Test.

Contributed by Sheena Smith, MS MA


Filtered coffee decreases type 2 diabetes risk

Although observational studies show regular coffee consumption is associated with lower risk of developing type 2 diabetes (T2D), few studies have differentiated types of coffee brews and their effect on biomarkers. Coffee that is prepared by different brewing methods, particularly filtered and unfiltered, results in different chemical compositions.

Unfiltered coffee contains higher amounts of the diterpenes cafestol and kahweol than does filtered coffee. Cafestol was previously shown to increase total and low-density lipoprotein (LDL) cholesterol, triglycerides, and blood pressure. Therefore, it is likely relevant that the differences in terpene content in filtered versus unfiltered coffee might carry different potential implications for metabolic health.

Through a case-control study nested within an intervention program (Vasterbotten Intervention Programme), plasma samples from 421 case-control pairs, and samples from a subset of 149 pairs, were analyzed at a 10-year follow-up analysis. The baseline samples were used to identify biomarkers of coffee intake and to investigate associations between coffee intake and T2D risk.

Habitual intake of filtered coffee demonstrates a decreased risk for type 2 diabetes. 

Plasma metabolites specifically associated with unfiltered (boiled) coffee showed no observed effect on T2D markers. However, an inverse association was observed between the metabolite panel of filtered coffee drinkers and T2D risk.

The lack of association for unfiltered coffee might be due to the limited number of unfiltered coffee consumers in the study, or a lack of protective effect of boiled coffee intake, which warrants further investigation.

Contributed by Amanda Frick, ND, LAc


  • Shi L, Brunius C, Johansson I, et al. Plasma metabolite biomarkers of boiled and filtered coffee intake and their association with type 2 diabetes risk. J Intern Med doi:10.1111/joim.13009

Anti-aging effects of the Mediterranean Diet

This study indicates that adherence to the Mediterranean Diet might support healthy aging by decreasing the risk for frailty. The NU-AGE Project, a 1-year study on the effect of the Mediterranean Diet on 612 non-frail or pre-frail elderly Europeans, yielded interesting findings.

In general, the dietary changes involved increased consumption of fruits, vegetables, legumes, whole grains, and fatty acids from fish, coupled with decreased consumption of sugar, saturated fats, sodium, and alcohol. Overall, the dietary changes led to a more diverse diet. Adherence significantly altered the microbiome in ways that should help prevent frailty in the elderly. Some specific effects of the diet included:

  • Increased taxa (groups of bacterial organisms) that are associated with several markers of decreased frailty
  • Increased taxa associated with improved cognitive function
  • Increased taxa associated with decreased inflammation – including C-reactive protein and interleukin-17
  • Dietary changes associated with increased short-chain fatty acids that are important for the health of the GI tract
  • Dietary changes associated with increased branched-chain amino acids that are associated with improved muscle mass
  • Dietary changes associated with decreased ethanol, carbon dioxide, p-cresol (a phenol compound created by bacterial fermentation in the gut that is a possible carcinogen), and secondary bile acids

The researchers concluded that, “Increased adherence to the Mediterranean Diet modulates specific components of the gut microbiota associated with a reduction in risk of frailty, improved cognitive function, and reduced inflammatory status.”

Consider combining the Mediterranean Diet with supplements to support healthy aging. Get more information about the Mediterranean Diet.

Contributed by Kathi Head, ND


  • Gosh T, Rampelli S, Jeffery I, et al. Mediterranean diet intervention alters the gut microbiome in older people reducing frailty and improving health status: the NU-AGE 1-year dietary intervention across five European countries. Gut 2020;0:1-11. doi:10.1136/gutjnl-2019-319654