Metabolite in Red Meat Increases Kidney Disease Risk

TOPLINE:

Trimethylamine N-oxide (TMAO) is a gut microbiota-derived metabolite generated by metabolism of dietary L-carnitine, primarily from red meat, and choline, from a variety of animal source foods. TMAO has been shown to cause kidney injury and tubulointerstitial fibrosis in experimental models.

In this study, TMAO was independently associated with higher risks for incident chronic kidney disease (CKD) and faster kidney function decline in humans.

The findings suggest that TMAO may be a novel risk factor and intervention target for CKD prevention and treatment.

METHODOLOGY:

• Study population was 10,564 participants from two community-based, prospective cohorts without baseline CKD (estimated glomerular filtration rate [eGFR] ≥ 60 mL/min/1.73 m²).
• Incident CKD was defined as eGFR decline ≥ 30% from baseline, resulting in eGFR < 60 mL/min/1.73 m².

TAKEAWAY:

• During a median 9.4 years, 979 incident CKD events occurred.
• Correlation between baseline TMAO and total meat intake was small but statistically significant (P = .08).
• After adjustments for sociodemographic, lifestyle, diet, and cardiovascular risk factors, higher plasma TMAO was associated with more than doubled CKD incidence (hazard ratio, 2.24 for top vs bottom quintile).
• Higher TMAO levels were also associated with greater annual eGFR decline (top vs bottom quintile eGFR change = −0.43 mL/min/1.73 m² per year.
• Compared with other major CKD risk factors, the association for the top vs bottom TMAO quintile (−0.43 mL/min/1.73 m² per year) was similar to that seen per 10 years of older age (−0.43) and presence of diabetes (−0.51), and larger than that seen comparing Black vs non-Black race (−0.28) and per 10 mm Hg systolic blood pressure (−0.16).

IN PRACTICE:

“TMAO levels are highly modifiable by both lifestyle-like diet and pharmacologic interventions. Besides using novel drugs to lower TMAO in patients, using dietary interventions to lower TMAO in the general population could be a cost-efficient and low-risk preventive strategy for chronic kidney disease development. ... These findings support future studies to investigate whether lifestyle and pharmacologic interventions to lower TMAO may prevent CKD development and progression.”

SOURCE:

The study was conducted by Meng Wang, PhD, of Tufts University, Boston, and colleagues and published online in the Journal of the American Society of Nephrology.

LIMITATIONS:

Observational design, can’t exclude residual confounding.

Inter-assay variability.

Use of International Classification of Diseases codes for hospitalization-based CKD, subject to reporting errors.

DISCLOSURES:

The study was supported by grants from the National Institutes of Health and an American Heart Association Postdoctoral Fellowship. Dr. Wang had no disclosures but several coauthors have patents on various diagnostics and/or industry disclosures.

A version of this article appeared on Medscape.com.