Welcome to the July 2021 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. THORNE's 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 new studies on: (1) measurable anti-aging effects of a diet and lifestyle intervention, (2) protein equivalents – vegan versus animal-sourced, (3) a ketogenic diet that supports immunity, and (4) tai chi versus conventional exercise for central obesity.
Anti-aging Effect of Diet and Lifestyle Intervention
Assessment of DNA methylation patterns is becoming an accepted means of determining the biological age of various tissues in the body. DNA methylation occurs when a methyl group attaches to a cytosine residue (a chromosome building block) of a chromosome. Of the more than 20 million methylation sites on the human genome, several thousand correlate with aging. Specific patterns emerge during the aging process, with some areas becoming hyper- (over)methylated, while other areas on the chromosome are hypo- (under) methylated.
A recent fascinating trial looked at the effect of lifestyle modification on DNA methylation patterns assessed using the Horvath DNAmAge clock. In this randomized, controlled 8-week trial, 42 (38 completed the study) men (ages 50-72) were assigned to either a total lifestyle intervention (n=18) or no intervention (n=20). DNA methylation analysis was conducted genome-wide on saliva samples using the Illumina Methylation Epic Array, and DNAmAge was calculated using the online DNAmAge clock. Lifestyle modifications included diet, sleep, exercise, stress reduction/relaxation, and probiotic and fruit/vegetable powder supplements.
After eight weeks, the men in the diet and lifestyle group exhibited a 3.23-year decrease in biological age as measured by DNAmAge clock (statistically significant at p=0.018). The difference within the same person between the beginning and end of the study was a decrease of 1.96 years – trending toward significance (p=0.066). Blood markers that changed significantly in the treatment group were a 25-percent decrease in triglyceride levels and a 15-percent increase in serum 5-methyltetrahydrofolate (5-MTHF) levels. It should be noted that part of the diet included two cups daily of green leafy vegetables (kale, spinach, etc. – all high in folate).
The authors conclude that this is the first randomized, controlled trial to suggest that diet and lifestyle interventions can impact the DNAmAge clock. Full text available here (including details of the intervention).
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Contributed by Kathi Head, ND
- Fitzgerald K, Hodges R, Hanes D, et al. Potential reversal of epigenetic age using a diet and lifestyle intervention: a pilot randomized clinical trial. Aging (Albany NY). 2021 Apr 12;13(7):9419-9432. doi: 10.18632/aging.202913.
Is Consumption of Plant-Based Proteins Equivalent to Animal-Based Proteins in Young Adults?
Does the human body respond to all protein sources the same? A research team recently investigated the hypothesis that the body’s anabolic response to equivalent amounts of various protein sources is affected by the protein’s digestibility – that is, the essential amino acid content of each food. Animal proteins are generally considered to have higher digestibility than plant sources.
The study included 56 healthy adults between the ages of 18 and 40. Participants completed body composition testing and were randomly assigned to treatment groups. Each group received an ounce-equivalent amount of a protein source (beef, pork, egg, red kidney beans, peanut butter, tofu, mixed nuts). Blood samples were collected before and after consumption of the protein meals.
In general, animal-based protein sources led to greater whole-body anabolic responses than ounce-equivalent plant-based proteins. However, when protein sources were normalized to essential amino acid content, the response differences were minimal. The authors note that normalizing protein sources to essential amino acid content could lead to vast discrepancies in calories consumed. For example, it would take 525 kcal of mixed nuts to equal the essential amino acid content of 2 eggs (155 kcal), for example. In general, the authors recommended that development of any new dietary guidelines should consider the anabolic response to different protein sources.
Contributed by Jennifer Greer, ND, MEd
- Park S, Church D, Schutzler S, et al. Metabolic evaluation of the dietary guidelines' ounce-equivalents of protein food sources in young adults: a randomized controlled trial. J Nutr 2021;151(5):1190-1196. doi:10.1093/jn/nxaa401
- Full text available here
Ketogenic Diet Appears to Support Robust Immune Function
Ketogenic diets, which largely replace calories from carbohydrates with those from fats, cause the liver to produce ketones, creating a body state called ketosis, with higher levels of ketones circulating through the body than normal. These ketones are used to make energy through a similar pathway to glucose (blood sugar). Of the three types of ketone molecules, beta-hydroxybutyrate (BHB) is the form used by the body for transport. Despite its growing popularity and a history of use treating certain forms of epilepsy, the effects of a ketogenic diet and higher levels of BHB in the population are not well understood. To better understand how the body responds to a ketogenic diet, researchers conducted laboratory and human studies focused on the immune system’s T cells. Different types of T cells are involved in regulating immune responses or carrying out aspects of an immune response, making their function central to a healthy immune system.
In the laboratory studies, human T cells were exposed to BHB at a quantity similar to the body during ketosis and compared to T cells not exposed to BHB. The cells exposed to BHB produced more signals that generated a stronger immune response than unexposed cells. These cells also demonstrated higher energy production without a reduction in energy produced from glucose, making them more efficient. Interestingly, more reactive oxygen species (ROS), which are often thought of as harmful, but which can strengthen an immune response when present in low quantities, were produced in BHB-exposed T cells, enhancing their responsiveness. These changes occurred without detectable harm to the cellular machinery. Moreover, a significant increase in memory cells, responsible for long-term immunity, was seen in the BHB-treated group.
In addition to the laboratory studies, 44 healthy human participants followed a ketogenic diet for three weeks and provided weight data and blood samples before and after. As might have been expected based on common claims surrounding ketogenic diets, the overweight participants had significant reductions in body mass index; normal weight participants experienced only small changes. When their T cells were studied, similar results were found to the cells in the laboratory study, with increases in immune responsiveness, memory formation, and energy efficiency. Participant blood sugar levels did not change during the study. Overall, the authors conclude that a ketogenic diet is immune-supportive.
Contributed by Sheena Smith, MS MA
- Hirschberger S, Strauss G, Effinger D, et al. Very-low-carbohydrate diet enhances human T-cell immunity through immune-metabolic reprogramming. EMBO Mol Med 2021 Jun 21:e14323. doi: 10.15252/emmm.202114323.
- Full text available here
Tai Chi Versus Conventional Exercise for Central Obesity
Central obesity measured by waist circumference is one of the five signs of metabolic syndrome, which has become increasingly common in aging adults. This study sought to determine whether tai chi is as effective as a conventional exercise program for reducing waist circumference.
Participants (n=543) ages 50 and older were assigned to one of three groups (181 in each group): tai chi, regular exercise (aerobic and strength training), or no exercise – for 12 weeks. The primary outcome was waist circumference, with body weight and other metabolic parameters assessed as secondary outcomes – measured at baseline, week 12, and week 38 (six months after the study end, to evaluate whether improvements were maintained).
At 12 weeks, the tai chi group had an average 1.8-cm decrease in waist circumference and the conventional exercise group an average 1.3-cm decrease, both relative to the control no-exercise group – both statistically significant (p<0.001). And both exercise groups experienced statistically significant weight loss compared to the no-exercise group (p<0.05). Improvements in waist circumference and body weight were maintained six months after the study ended.
The researchers conclude: “Tai chi is an effective approach to reduce waist circumference in adults with central obesity aged 50 years or older.” July 26, 2021 • Kathi Head, ND (THORNE)
Contributed by Amanda Frick, ND, LAc
- Siu P, Yu A, Chin E, et al. Effects of tai chi or conventional exercise on central obesity in middle-aged and older adults: a three-group randomized controlled trial. Ann Intern Med 2021 Jun 1. doi: 10.7326/M20-7014.