For many of you using L-carnitine for cardiovascular health, cognitive health (acetyl-L-carnitine), and even weight loss, don't be alarmed. This study is just an anomaly is a sea of positive studies. However, it does deserve some discussion, so let's break it down.
In this newly published study, researchers examined carnitine levels in 2,595 heart patients, and found high levels were associated with increased risk of heart disease, heart attack and stroke – but only when TMAO (trimethylamine-N-oxide) levels were also high. TMAO is a substance that has been linked to cardiovascular disease, and it's been shown that specific bacteria in the intestines biotransform (metabolize) L-carnitine into TMAO. Further, their population growth can be promoted by diets high in carnitine.
Since dietary carnitine is found only in meat, TMAO levels in vegetarian and vegan participants were significantly lower than in omnivores (since their diet does not promote the growth of the specific bacteria, so when they do ingest carnitine, they do not produce significant levels of TMAO).
However, there will always be positive and negative studies surrounding any therapy. The trick is not to look at the study of the day, but consider the totality of evidence, and for carnitine, the vast bulk of studies show amazing health benefits to many health conditions, including cardiovascular health.
Update: following this post, I covered 4 positive studies on L-carnitine...
In this situation, whole meat and even L-carnitine supplements are probably not the main issue here. Healthy diets can be rich in 'red' free-range, grass-fed, and ideally organic meat (in addition to fruits, vegetables, healthy fats, etc.) and still improve the gut flora and health risk factors. The systematic review that the researchers cite themselves concludes that "consumption of processed meats, but not red meats, is associated with higher incidence of [coronary heart disease] and diabetes mellitus."
Furthermore, L-carnitine has been shown the potential to prevent clogged arteries in other studies, and the mouse model used in the present study (an abnormal genetically-modified species) may not be the best transferable model to humans, and therefore, the results may not be relevant to humans (just like studies on soy phytoestrogens showed negative effects for breast cancer in animal studies, while human studies showed benefits to breast cancer patients). There are many uncertainties around this study, so don't get tied-up in a knot over these results.
Source:Intestinal microbiota metabolism of l-carnitine, a nutrient in red meat, promotes atherosclerosis
Looking to stay on top of the real story behind these negative studies? Click HERE to subscribe to Know Guff by email.
- Does L-Carnitine Help with Weight Loss?
- Carnitine Beneficial in Intermittent Claudication and Pregnancy
- Two More Carnitine Studies Show Benefits for Cardiovascular Health and ALS
- L-Carnitine Improves Behaviour in Autistic Kids
- L-Carnitine May Help Kids with Asthma
- L-Carnitine May Reduce Oxidative Damage
- L-Carnitine Helps Treat Autism Spectrum Disorders
- L-Carnitine May Protect Mitochondrial Function in Liver
- L-Carnitine Benefits Huntington's Disease
- L-Carnitine May Reduce Inflammation in Hemodialysis Patients
- Advantages of L-carnitine in Treating Hepatitis C