Trial reportNutrients2019
Protein Intake at Twice the RDA in Older Men Increases Circulatory Concentrations of the Microbiome Metabolite Trimethylamine-N-Oxide (TMAO).
Trial report in Nutrients, 2019. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 26 papers, 6 of them syntheses that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
26 citing papers in PubMed, 6 syntheses or guidelines pooled it, 39 citations in OpenAlex.
- The Association Between Lifestyle Interventions and Trimethylamine N-Oxide: A Systematic-Narrative Hybrid Literature Review.Nutrients · 2025Pooled it
- Terrestrial Animal Source Foods and Health Outcomes for Those with Special Nutrient Needs in the Life Course.Nutrients · 2024Pooled it
- Gut microbiota-derived trimethylamine N-oxide is associated with the risk of all-cause and cardiovascular mortality in patients with chronic kidney disease: a systematic review and dose-response meta-analysis.Annals of medicine · 2023Pooled it
- Red meat consumption and risk factors for type 2 diabetes: a systematic review and meta-analysis of randomized controlled trials.European journal of clinical nutrition · 2023Pooled it
- Effects of Microbiota-Driven Therapy on Circulating Trimethylamine-N-Oxide Metabolism: A Systematic Review and Meta-Analysis.Frontiers in cardiovascular medicine · 2021Pooled it
- At the Intersection of Gut Microbiome and Stroke: A Systematic Review of the Literature.Frontiers in neurology · 2021Pooled it
- A red wine intervention does not modify plasma trimethylamine N-oxide but is associated with broad shifts in the plasma metabolome and gut microbiota composition.The American journal of clinical nutrition · 2022Trial
- A period of 10 weeks of increased protein consumption does not alter faecal microbiota or volatile metabolites in healthy older men: a randomised controlled trial.Journal of nutritional science · 2020Trial
- The Application of Metabolomics in Frailty: Trends, Challenges, and Future Directions.Metabolites · 2026Review
- Associations between High Protein Intake and Cardiovascular Diseases by Age Groups: A Cohort Study.The journal of nutrition, health & aging · 2026Article
- Aging immunity: unraveling the complex nexus of diet, gut microbiome, and immune function.Immunometabolism (Cobham, Surrey) · 2025Review
- The impact of a high-protein diet with strength training on the gastrointestinal microbiota in community-dwelling older adults: subanalysis of a randomized controlled trial.Frontiers in nutrition · 2025Article
- Gut Microbiota in Patients Receiving Dialysis: A Review.Pathogens (Basel, Switzerland) · 2024Review
- The association of dietary nitrates/nitrites intake and the gut microbial metabolite trimethylamine N-oxide and kynurenine in adults: a population-based study.Frontiers in nutrition · 2024Article
- Gut microbiome in healthy aging versus those associated with frailty.Gut microbes · 2023Review
- The role of gut-dependent molecule trimethylamine N-oxide as a novel target for the treatment of chronic kidney disease.International urology and nephrology · 2023Review
- The Influence of Animal- or Plant-Based Diets on Blood and Urine Trimethylamine-N-Oxide (TMAO) Levels in Humans.Current nutrition reports · 2022Review
- Gut Metabolite Trimethylamine N-Oxide Protects INS-1 β-Cell and Rat Islet Function under Diabetic Glucolipotoxic Conditions.Biomolecules · 2021Article
- Can diet modulate trimethylamine N-oxide (TMAO) production? What do we know so far?European journal of nutrition · 2021Review
- Chemical rescue of mutant proteins in living Saccharomyces cerevisiae cells by naturally occurring small molecules.G3 (Bethesda, Md.) · 2021Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
14 authors at 7 institutions in 6 countries.
Funding
Abstract
Higher dietary protein intake is increasingly recommended for the elderly; however, high protein diets have also been linked to increased cardiovascular disease (CVD) risk. Trimethylamine-N-oxide (TMAO) is a bacterial metabolite derived from choline and carnitine abundant from animal protein-rich foods. TMAO may be a novel biomarker for heightened CVD risk. The purpose of this study was to assess the impact of a high protein diet on TMAO. Healthy men (74.2 ± 3.6 years, n = 29) were randomised to consume the recommended dietary allowance of protein (RDA: 0.8 g protein/kg bodyweight/day) or twice the RDA (2RDA) as part of a supplied diet for 10 weeks. Fasting blood samples were collected pre- and post-intervention for measurement of TMAO, blood lipids, glucose tolerance, insulin sensitivity, and inflammatory biomarkers. An oral glucose tolerance test was also performed. In comparison with RDA, the 2RDA diet increased circulatory TMAO (
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.