Welcome to the February 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 low vitamin D levels and susceptibility to opioid addiction, (2) FODMAPS and IBS, (3) is fish oil a prebiotic? and (4) the effect of various types of alcohol on risk for COVID.

Thorne Mental Health Moment: More Good News for Vitamin D

Vitamin D is an important nutrient for a number of reasons. Many years ago, we believed vitamin D only played a role in early development and bone health. But in recent decades we have added regulation of inflammatory support, support for immune health, benefits for neurological and cardiovascular health, and support for mood and skin.

Growing research now indicates that an inadequate vitamin D level might play a role in vulnerability to addictive behavior. Research over the past two decades has confirmed that the skin makes beta-endorphin in response to exposure to ultraviolet light.1 Beta-endorphin is an opiate-like substance made naturally by the body that regulates processes such as pain, behavior, and mood. Beta-endorphin is, for example, one of the substances in the body that is attributed to “runner’s high.”2 (Endogenous cannabinoids are too.)

Because it can bind to opiate receptors, some research around beta-endorphin has focused on the positive and negative behaviors this might influence. Both humans and animals make vitamin D in their skin from exposure to UV light. The fact that sun exposure leads to more endorphins means the experience of being in the sun is often perceived with positive emotions. These positive feelings reinforce a behavior (getting adequate sun exposure) we need for good health. The negative side can be the development of an addictive behavior that drives some individuals to spend excessive time in the sun or in tanning beds. Although uncommon, this addictive behavior can increase the incidence of skin cancer3 and is thus a cause for concern. The positive outcome of being in the sun is that it stimulates vitamin D synthesis.

Recent research has looked at whether a low vitamin D level could be a driver, not only for healthy levels of UV exposure, but also for unhealthy or addictive behaviors. A new study indicates there might be a relationship.4 Researchers found that individuals with modest-to-severe vitamin D deficiency were significantly more likely to be diagnosed with opioid-use disorder or self-report opioid use. Although it is unknown whether this could be part of a preventive or therapeutic strategy, vitamin D plays such an important role in health that understanding vitamin D status is a valuable part of a strategy for overall health and healthy aging.

Thorne has several vitamin D products to support individual needs. Want to check your vitamin D level at home?

Contributed by Jacqueline Jacques, ND


  1. Slominski AT, Zmijewski MA, Plonka PM, et al. How UV light touches the brain and endocrine system through skin, and why. Endocrinology 2018;159(5):1992-2007. doi:10.1210/en.2017-03230
  2. Boecker H, Sprenger T, Spilker ME, et al. The runner’s high: opioidergic mechanisms in the human brain. Cereb Cortex 2008;18(11):2523-2531. doi:10.1093/cercor/bhn013
  3. Fell GL, Robinson KC, Mao J, et al. Skin β-endorphin mediates addiction to UV light. Cell 2014;157(7):1527-1534. doi:10.1016/j.cell.2014.04.032
  4. Kemény LV, Robinson KC, Hermann AL, et al. Vitamin D deficiency exacerbates UV/endorphin and opioid addiction. Sci Adv 2021;7(24):eabe4577. doi:10.1126/sciadv.abe4577

Do FODMAPs or Gluten Cause IBS Symptoms?

Approximately five percent of U.S. adults suffer from irritable bowel syndrome (IBS), a functional gastrointestinal disorder characterized by recurring abdominal pain with either constipation or diarrhea, or a mix of both. Treatment recommendations often include dietary changes, including avoidance of gluten and/or types of carbohydrates known as fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs). Previous research focused primarily on eliminating foods to relieve symptoms, rather than exploring how different foods might provoke symptoms.

In a recent crossover study, 110 adults with moderate-to-severe IBS maintained a low-impact, gluten-free diet with minimal FODMAP content beginning two weeks prior to any intervention and throughout the study – except for during the time they were doing the particular intervention. Participants were then divided into three groups and randomized to one of three interventions – FODMAPs (50 g/day), gluten (17.3 g/day), or placebo, each for one week, followed by a one-week washout before switching to another protocol until all groups received the interventions.

Throughout the study, participants reported stool habits and quality of life using the IBS-SSS questionnaire and a stool diary. The IBS-SSS score (high score = worse symptoms) was highest with the FODMAP intervention and was statistically significant compared to both gluten and placebo. There was no statistical difference between IBS-SSS scores for the gluten or placebo interventions. The results of the study indicate a possible exacerbation of IBS symptoms by FODMAPs but not gluten, compared to placebo. The authors note several limitations of the study and recommend that future studies investigate the differences between individual responses to better understand possible underlying mechanisms for IBS.

Contributed by Jennifer L. Greer, ND, MEd

Fish Oil as a Prebiotic – Microbiome Changes, Cardiometabolic Improvements, SCFA Increases

Prebiotics are nutrients in foods or supplements that “feed” bacteria in the gut, support a healthy microbiome, and improve the health of the host. We typically think of various types of fiber as prebiotics. But more recently, other food constituents, such as polyphenols from berries and other fruits, have exhibited prebiotic activity. Recent research finds that omega-3 fatty acids from fish oil appear to exert some of their benefits by positively modifying the gut microbiome.

In a 6-week study, 69 adults, ages 18 or older and with a chronically low fiber intake (less than 15 grams daily), were divided into two groups – once daily either 500 mg of fish oil (containing 165 mg EPA and 110 mg DHA) or 20 g of inulin, a well-established prebiotic. Stool samples, anthropometric measurements, and fasting blood samples were taken at baseline and at the study’s end.

Result highlights:

  • Omega-3 supplementation resulted in increased Coprococcus and Bacteroides.
  • Bifidobacterium and Ruminococcaceae UCG- 011 increased in the inulin group.
  • Both groups had increased short-chain fatty acids (SCFAs) – more so in the inulin group.
  • The increased abundance of Coprococcus in the omega-3 group is associated with increased SCFA iso-butyrate.
  • Increased Coprococcus is associated with decreased levels of the cardiovascular risk factors VLDL-cholesterol and triglycerides.
  • Increased Bifidobacterium in the inulin group also is associated with decreased VLDL.
  • Omega-3 supplementation is associated with a strongly significant decrease in Collinsella, which could benefit fatty liver. A previous study found a 3-fold increase in this bacterial genus in individuals who have non-alcoholic fatty liver disease.

This provides another mechanism by which fish oils can benefit cardiovascular health.

Looking for a prebiotic? In addition to fish oil products, Thorne has a non-fiber prebiotic, as well as fiber-based prebiotics.

Contributed by Amanda Frick, ND, LAc

The effect of various types of alcoholic beverages on COVID-19 risk

The health effects of alcohol have been widely researched and reported – both in terms of adverse effects as well as benefits; for example, the benefits of red wine for cardiovascular health. Numerous studies show a non-linear relationship between alcohol consumption and particular health risks, with lower intakes having a more protective effect than either no or heavy alcohol consumption.

The present study examined the effect of alcohol consumption on COVID-19 infection risk. Alcohol consumption habits were collected from 473,958 adults from 22 health centers in the United Kingdom. The incidence of testing positive for COVID was also assessed from the beginning of the pandemic through July 26, 2021. Of the participants, 77,217 were tested for COVID and 16, 559 tested positive.

The alcohol consumption questionnaire asked about alcohol consumption status – never drank, past drinker, current drinker. The current drinkers were assessed in terms of how often they drank, how many drinks they consumed per week, and the type and amount of alcohol consumed. Alcohol types included red wine, white wine/champagne, beer/hard cider, spirits (hard liquor), and fortified wine (wine mixed with alcohol, such as sherry or port).


  • Compared to non-drinkers, consumers of red wine had 10- to 17-percent lower COVID-19 risk – 1-2 glasses per week (12% lower), 3-4 glasses per week (10% lower), and 5 or more glasses per week (17% lower).
  • Consumption of 1-4 glasses of white wine or champagne per week conferred a 7- to 8-percent lower risk; no protection was afforded by higher amounts.
  • Low consumption of fortified wine (1-2 glasses per week) conferred a 12-percent decreased risk; there was no significant effect from 3-4 glasses and a 10-percent increased risk with 5 or more glasses.
  • Consumption of 1-4 drinks of hard liquor weekly had no effect on COVID risk; however, a higher amount resulted in a significant 9-percent increased risk.
  • Beer or hard cider increased risk, no matter the weekly amount consumed, compared to non-drinkers; increased risks were 7-, 18-, and 28-percent higher for 1-2 glasses, 3-4 glasses, and 5 or more glasses, respectively.
  • The researchers speculate that the polyphenol content – flavonoids found in particularly high amounts in grapes, berries and other fruits – rather than the alcohol content is responsible for the protective effect of red wine compared to other alcoholic beverages.

Contributed by Kathi Head, ND