Welcome to the August edition of Thorne’s Research Extracts. This is Thorne’s monthly research update on diet, nutrient, botanical, and lifestyle approaches to good health. Knowing that busy practitioners can’t always focus on the latest research, our medical team of NDs, MDs, PhDs, RDs, and MS (Biol) has summarized the essence of the very most interesting studies.

In this issue: (1) vitamin D and toxicity, (2) omega-3s, behavior, and family dynamics, (3) chicken soup and cognitive performance, and (4) black tea aroma and stress reduction.

Vitamin D and toxicity  NOT.

Knowledge about the safety of vitamin D has evolved greatly over the past few decades. It was once thought, because it’s an oil-soluble vitamin, that vitamin D would store in fat cells and build up to toxic levels. That is no longer the conventional wisdom, and studies such as the recent paper by John Lee, DO, and his research colleagues at the University of Iowa are greatly expanding the safety data on this essential nutrient.

Although the most responsible way to supplement vitamin D is to first obtain a baseline blood level, then supplementing to bring the level into an optimal range, and then retesting to be sure the blood level is in the desired range, some individuals just supplement with high doses without doing any blood testing.

The primary concern over this approach is that high blood levels of 25-OH vitamin D could result in too much calcium entering the bloodstream and thus, hypercalcemia, which can result in fatigue, muscle weakness, abdominal pain, kidney stones, cardiac arrhythmias, vomiting, pancreatitis, and coma.

Lee and his team of researchers performed a retrospective evaluation of patients who had elevated 25-OH vitamin D levels over a 16-year period, totaling 128,000 separate blood tests. Of these, only one percent were above 89 ng/mL, and only 0.12-percent were above 120 ng/mL.

A serum level above 80 is considered to be elevated, and a level of 120 or above is thought to be toxic. However, their study found that, of the 89 patients with a 25-OH vitamin D level above 120ng/mL, only three were symptomatic.

So, out of 128,000 tests, only three individuals demonstrated symptoms of vitamin D toxicity.

It is reassuring, for those individuals striving for a vitamin D level in an optimal range of 50-80 ng/mL, that this is a very safe blood level of this essential nutrient.

Contributed by Alan Miller, ND


Do omega-3s improve family dynamics?

In a trial studying the intersection of nutrition, behavioral changes, and family dynamics, children were given either 1 gram of an omega-3 supplement (300 mg DHA, 200 mg EPA, 400 mg of ALA, 100 mg DPA) in a fruit drink (n=100) or placebo of a fruit drink with no omega-3s (n=100). The 6-month trial was immediately followed by an evaluation and then a second evaluation six months later.

The trial utilized numerous behavioral questionnaires that evaluated behavioral changes in both groups of children, as well as the interpersonal relationships between caregiver partners.

The study concluded that there were significant behavioral improvements in the omega-3 supplemented children, correlating with reductions in both physical and psychological aggression indices between the childrens’ caregivers that resulted in improved overall family dynamics. 

Although the researchers noted the study’s limitations and need for follow-up, it does pose an interesting discussion around behavioral and nutritional interplay and how we frame the nature versus nurture debate.

Contributed by Stephen Phipps, ND, PhD


Essence of chicken – the secret behind the magic of chicken soup? 

Essence of chicken (EC) – a water extraction from whole chicken utilizing high temperature and pressure – is a common nutritional supplement in Southeast Asia characterized by high amino acid and dipeptide content and low sugar and fat content.

This Thailand study evaluated the effect of EC on cognitive function, as measured by assessments for short-term and working memory, as well as selective and sustained attention. Secondarily, stress levels were assessed:  no stress, mild stress, moderate stress, or severe stress.

During the 2-week study, the test group (n=117) consumed two daily servings of a commercial EC preparation. The control group (n=118) consumed two daily servings of a flavor-, appearance-, and macronutrient-matched placebo. Data was collected at days 0, 7, and 14.

Statistically significant effects of EC on working memory performance were observed across all stress groups.

The effects on short-term memory were statistically significant only in the moderate stress group, and fell just short of significance in the severe stress group. The authors hypothesize this differential effect relative to baseline stress could account for the varied results seen in previous studies.

Contributed by Sheena Smith, MS (Biol)


  • Suttiwan P, Yuktanandana P, Ngamake S. Effectiveness of essence of chicken on cognitive function improvement: a randomized controlled clinical trial. Nutrients 2018;10(7):845.
  • http://www.mdpi.com/2072-6643/10/7/845

Does inhaling the aroma of black tea actually reduce stress?

In a small crossover study, 18 healthy individuals participated in three experimental treatments in a three-day period. The trials consisted of saliva tests for the stress hormone chromogranin A (which increases during stress), a subjective profile of mood questionnaire and visual analog scale, and a baseline aroma smell test.

This was followed by three 15-minute stress-load periods consisting of math tests, followed by breathing in a designated aroma for one minute, followed by saliva tests and subjective profile questionnaires. The three aromas were Darjeeling tea, Assam tea, or hot water – each separated by 24 hours.

Inhaling the two tea aromas resulted in significantly lower salivary chromogranin A levels compared to inhaling the aroma of water.

No significant differences were noted between the two tea aromas, even though the Darjeeling tea was more concentrated and produced a stronger aroma than the Assam tea. In addition, the Darjeeling tea aroma trended toward a lower tension/anxiety score compared to water or Assam tea.

Contributed by Kathi Head, ND