Welcome to the October 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.

In this issue you will find studies on (1) inadequate intake of immune nutrients in the U.S. population, (2) vitamin C and muscle mass later in life, (3) results of a U.S. supplement-use survey, and (4) a summary and link to a fascinating study on animals and COVID risk.


Do U.S. adults have an adequate intake of immune-supportive nutrients?

The immune system relies on micronutrients to function properly. The B vitamin complex, vitamins A, C, D, and E, and the minerals zinc, selenium, and iron all play a beneficial role in the immune response.* These essential nutrients should be obtained from food or supplementation to have adequate levels present in the body to provide immune support.*

The National Health and Nutrition Examination Survey (NHANES) assesses the health and nutritional status of adults and children in the United States and compiles specific dietary intake information provided by participants. In the current study, NHANES data from 2005-2016 were analyzed for nutrient intake and cross-referenced with Estimate Average Requirement (EAR), a value based on the estimated nutrient needs to prevent deficiency or disease in 50 percent of the population. The authors focused on vitamins A, C, D, and E, and zinc, because they are the most common immune-related nutrient inadequacies in U.S. adults.

In general, intake of immune-supportive nutrients was inadequate for a significant number of adults. Based on diet alone, the prevalence of inadequacy was 45 percent for vitamin A, 46 percent for vitamin C, 95 percent for vitamin D, 84 percent for vitamin E, and 15 percent for zinc. For individuals who reported taking supplements along with diet, nutrient inadequacies decreased to 35 percent for vitamin A, 33 percent for vitamin C, 65 percent for vitamin D, 60 percent for vitamin E, and 11 percent for zinc.

The researchers concluded that the combination of a healthy, nutrient-dense diet, along with a multi-vitamin/mineral supplement can help fill gaps and meet micronutrient intake needs for general health. Individuals at higher risk from nutrient deficiencies, such as older adults, can benefit from specific nutrient supplementation as well. Ultimately, future research is needed to better understand nutrient inadequacies among U.S. adults and determine public health guidelines for addressing these needs.

Explore Thorne’s immune-support products

Contributed by Jennifer L. Greer, ND, MEd

  • Reider C, Chung R, Devarshi P, et al. Inadequacy of immune health nutrients: intakes in U.S. adults, the 2005-2016 NHANES. Nutrients 2020;12(6):1735. doi:10.3390/nu12061735
  • Click to access full text of the study

Higher vitamin C intake is associated with greater muscle mass later in life 

Loss of muscle mass is commonly associated with aging. One of vitamin C’s well-known effects, supporting synthesis of carnitine and collagen, suggests it can be supportive for the growth of muscle tissue in general.* A large prospective study, including more than 13,000 adults ages 42-82, investigated the association between vitamin C and muscle mass.  

Participants were segmented into five groups (quintiles) by quantity of vitamin C intake and into two groups by plasma vitamin C levels (sufficient or insufficient) for analyses. Both markers (intake and plasma vitamin C) showed similar trends when associated with muscle mass for men and women.

Dietary vitamin C intake was similar between women and men. However, the highest vitamin C intake groups for both men and women consumed about 130 mg more each day than the lowest-intake groups. As might be expected, higher vitamin C intake was associated with higher plasma levels (0.5 μmol/L per 1 mg more vitamin C intake). Fruit contributed the greatest portion of dietary vitamin C (26.5% for men, 32% for women) with vegetables next (25.2% for both). More men than women (34.7% versus 16.8%) were identified as having insufficient (< 50 μmol/L) or deficient (< 11.4 μmol/L) (0.9% versus 0.2%) plasma vitamin C levels.

Fat-free mass (FFM), an easy-to-measure surrogate for skeletal muscle mass, was positively associated with plasma vitamin C levels in general. Participants in the highest vitamin C intake quintile had significantly higher FFM than those in the lowest vitamin C intake quintile. The significance remained when FFM was standardized to total body mass or to BMI. Vitamin C supplements also showed a positive correlation with FFM. When participants were divided by plasma vitamin C levels (sufficient or not), and when participants were divided by age (< 65 years versus ≥ 65 years), a similar significant difference in FFM was found.

Explore Thorne’s vitamin C products

Contributed by Sheena Smith, MS MA 

  • Lewis L, Hayhoe R, Mulligan A, et al. Lower dietary and circulating vitamin C in middle- and older-aged men and women are associated with lower estimated skeletal muscle mass. J Nutr Published online August 27, 2020:nxaa221. doi:10.1093/jn/nxaa221
  • Click to access full text of the study

General wellness and immune support cited as top reasons U.S. consumers take supplements

Every year since 2000, the Council for Responsible Nutrition conducts a survey to determine supplement use among U.S. adults. This year’s survey was conducted August 27-31 and included 2,006 participants age 18 or over; 1,471 identified themselves as supplement users.

The number one reason participants across all age groups cited for taking a supplement was for general health and wellness (40%), with immune support being cited as the number two reason (32%; although it was the number one reason for the 18-34 age group (38%)). Rounding out the top five reasons were: to fill nutritional gaps (25%); for cardiovascular health (23%); and for skin, hair, and nails (22%).

Looking at specific supplement categories, vitamins and minerals were number one (as they typically are), with 98 percent of respondents saying they had taken vitamins and/or minerals in the past year. Vitamins and minerals were followed distantly by specialty formulas/niche items (46%), “herbs/botanicals” (44%), sports nutrition (30%), and weight management (19%).

In looking at specific supplement nutrients, the top three supplements that participants noted using for immune support were vitamin C (61%), a “multivitamin” (57%), and vitamin D (47%). The remaining top 10 immune-supportive ingredients in descending order were zinc, B complex, probiotics, turmeric, elderberry, garlic, and Echinacea. For sleep and mental health support, the top three nutrients were magnesium, melatonin, and CBD.

Explore Thorne’s multi-vitamin/mineral formulas along with some single-ingredient vitamins

Contributed by Kathi Head, ND


Which animals have the highest risk of COVID-19 infection?

This study set out to develop a method for analyzing which animal species might be at the highest risk for acquiring COVID-19. It has been determined that the virus enters the body by binding, at least in part, to certain receptors called ACE2 receptors. The amino acid sequences in these receptors vary among species, and the scientists identified a certain sequence of 25 amino acids necessary for the SARS-CoV-2 (the virus that causes COVID-19) protein spike to bind to the ACE2 receptor. They then analyzed the ACE2 receptors of 410 vertebrate species, including 252 mammals, to see which ones had this susceptibility sequence, with the hypothesis being that having this sequence increases the risk for COVID-19.

The very high-risk category consisted of humans and 18 other primate species, including gorillas, baboons, chimpanzees, orangutans, macaque, and other monkeys. Among the 28 species in the high-risk group were whales and porpoises, Chinese hamster, bottle-nosed dolphin, white-tailed deer, reindeer, muskrat, and blue-eyed black lemur. Cows, goats, sheep, domestic cats, and several big-cat species were in the medium-risk category, while dogs and pigs were in the low-risk category. And despite all the bad press about bats and pangolins, several species of both were in the very low-risk category – along with guinea pigs and gerbils. No non-mammal vertebrates tested (birds, reptiles, fish, or amphibian) appear to be good candidates for virus transmission.

Why is this research important? It can have an impact on endangered species, possible animal models for COVID study, how we interact with our pets and livestock, and our knowledge of which animals might harbor the virus. The researchers noted that additional direct research with various species is needed to confirm their hypotheses.

We wrote about pets and COVID here on Take 5 Daily last May. Get the latest from the CDC on animals and COVID-19. Looking for a high-quality nutritional supplement for your pet? Explore thornevet.com.

Contributed by Kathi Head, ND

  • You can explore this fascinating study in more detail here.
  • Damas J, Hughes G, Keough KC, et al. Broad host range of SARS-CoV-2 predicted by comparative and structural analysis of ACE2 in vertebrates. Proc Natl Acad Sci U S A 2020 Sep 8;117(36):22311-22322. doi: 10.1073/pnas.2010146117.