Downloaded from https://academic.oup.com/eurheartj/article-abstract/40/42/3498/5583781 by DeepDyve user on 06 December 2019 DISCUSSION FORUM European Heart Journal (2019) 40, 3498 doi:10.1093/eurheartj/ehz615 Trimethylamine N-oxide: not just red meat—egg yolk and renal function are also important J. David Spence * Stroke Prevention & Atherosclerosis Research Centre, Robarts Research Institute, Western University, 1400 Western Road, London, ON N6G 2V4, Canada Online publish-ahead-of-print 8 October 2019 This commentary refers to ‘The red and the white, and This suggests that approaches such as repopulation of the intestinal the difference it makes’, by A. Davies and T.F. Lu¨scher, microbiome may be a way to treat atherosclerosis. 2019;40:595–597. High levels of TMAO accelerate decline in renal function, and in- crease mortality in patients with severe renal disease. However, we In their editorial about trimethylamine N-oxide (TMAO), Davies and . found that plasma levels of TMAO and six other intestinal metabo- 1 . Lu¨scher said that the study referred to ‘proves that red meat, . lites were significantly elevated by even mild renal impairment; an . 2 4 through L-carnitine, is the major source of elevated TMAO plasma . estimated glomerular filtration rate (eGFR) <66 mL/min/1.73 m . levels in a healthy Western population’. That statement ignores the . Renal function declines with age; above age 80 the mean eGFR major contribution of egg yolk to TMAO production, from phosphat- . among patients referred to our stroke prevention clinics was . 2 idylcholine. The yolks of two large (65 g) eggs contain 474 mg of chol- . <60 mL/min/1.73 m . esterol and 320 mg of phosphatidylcholine, i.e., more cholesterol and Thus, patients with impaired renal function, including the elderly, as much TMAO precursor as a Hardee’s Monster Thickburger, a 12- should not only limit intake of red meat, but should also avoid egg ounce beef burger. There is a linear dose response of plasma TMAO yolk. Egg whites and egg white-based substitutes can be used instead with egg consumption; two eggs more than double levels of TMAO. to make delicious omelettes, frittatas, and egg salad sandwiches. In patients referred for coronary angiography, Tang et al. meas- Conflict of interest: none declared. ured plasma TMAO after a test dose of two hard-boiled eggs, and found that patients in the highest quartile of TMAO had a 2.5-fold in- crease in the 3-year risk of stroke, myocardial infarction, or vascular References death. 1. Davies A, Luscher TF. The red and the white, and the difference it makes. Eur . Heart J 2019;40:595–597. Patients with severe atherosclerosis not explained by traditional . 2. Tang WHW, Wang Z, Levison BS, Koeth RA, Britt EB, Fu X, Wu Y, Hazen SL. risk factors (unexplained atherosclerosis) had significantly higher lev- Intestinal microbiota metabolism of phosphatidylcholine and cardiovascular risk. N els of TMAO, P-cresylsulfate, p-cresyl glucuronide, and phenylacetyl- Engl J Med 2013;368:1575–1584. . 3. Bogiatzi C, Gloor G, Allen-Vercoe E, Reid G, Wong RG, Urquhart BL, Dinculescu glutamine than patients with high levels of risk factors and little/no V, Ruetz KN, Velenosi TJ, Pignanelli M, Spence JD. Metabolic products of the in- carotid plaque (protected phenotype), despite no differences in diet- testinal microbiome and extremes of atherosclerosis. Atherosclerosis 2018;273: ary intake of TMAO precursors and no difference in renal function. 91–97. . 4. Pignanelli M, Bogiatzi C, Gloor G, Allen-Vercoe E, Reid G, Urquhart BL, Ruetz In backward linear regression, both TMAO and p-cresylsulfate were KN, Velenosi TJ, Spence JD. Moderate renal impairment and toxic metabolites significant predictors of carotid plaque, and more significant than sex, . produced by the intestinal microbiome: dietary implications. J Ren Nutr 2019;29: 3 . diastolic blood pressure, total cholesterol, and diabetes mellitus. . 55–64. * Corresponding author. Tel: 1-519-931-5731, Fax: 1-519-931-5737, Email: email@example.com Published on behalf of the European Society of Cardiology. All rights reserved. V The Author(s) 2019. For permissions, please email: firstname.lastname@example.org.
European Heart Journal – Oxford University Press
Published: Nov 1, 2019