Overview
What Are Carnitine Supplements?
Carnitine, primarily L-carnitine, is a supplement derived from an amino acid that plays a crucial role in energy production by transporting fatty acids into your cells' mitochondria.
The mitochondria act as engines within your cells, burning these fats to create usable energy.
Your body can produce L-carnitine out of the amino acids lysine and methionine. [ref]
However, for certain individuals like vegans or people with specific genetic issues, dietary supplementation might be beneficial.
Carnitine supplements are popular among athletes and individuals looking to support their exercise performance and weight loss.
They come in various forms, including L-Carnitine, L-Tartrate, Acetyl-L-Carnitine, and Propionyl-L-Carnitine, each having slightly different effects.
When is the Best Time to Take L-Carnitine Supplement?
The optimal time to take L-carnitine supplements largely depends on your fitness goals and daily routine.
For individuals aiming to enhance exercise performance, taking L-carnitine 30 to 60 minutes before a workout is recommended. [ref]
This timing allows the body to digest and absorb the supplement, potentially improving endurance and reducing muscle soreness post-exercise.
However, if you're using L-carnitine for weight loss or general health purposes, you might not need to time it around your workouts.
In such cases, taking it with meals throughout the day could be effective, as the presence of food can help increase its absorption.
What is the Best L-Carnitine Supplement?
The "best" L-carnitine supplement can vary based on individual needs and goals.
For athletes and those focused on physical performance, L-carnitine L-tartrate is a popular choice due to its rapid absorption and effectiveness in reducing muscle soreness and aiding in recovery.
Acetyl-l-carnitine is often favored for cognitive benefits, as it's known to cross the blood-brain barrier and may improve brain function.
Propionyl-L-carnitine is typically used for blood flow issues and related conditions due to its vascular health benefits.
The quality and purity of the supplement are paramount, so it's important to choose products from reputable manufacturers that provide transparent information about their sourcing and manufacturing processes.
Are L-Carnitine Supplements Safe?
L-carnitine supplements are generally considered safe when used in moderation and as directed.
The standard L-carnitine dose is 500–2000 milligrams per day (mg/day). [ref]
They are well-tolerated, but some may experience mild side effects like nausea, abdominal cramps, or diarrhea.
There are concerns about the safety of L-carnitine in large doses or for long-term use, as some studies suggest it might contribute to cardiovascular issues by increasing the concentration of TMAO, a metabolite linked to heart disease.
However, these findings are not conclusive, and more research is needed.
It's always advisable to consult with a healthcare provider before starting any new supplement, especially for individuals with pre-existing health conditions or those taking medications.
Are L-Carnitine Supplements Vegan?
Not all L-carnitine supplements are vegan, as the source of carnitine can vary.
Traditionally, carnitine is derived from animal sources, particularly meat.
However, vegan L-carnitine supplements are available, synthesized in a laboratory without animal products.
When choosing a vegan L-carnitine supplement, it's essential to look for labels that specifically state the product is vegan or plant-based.
Additionally, checking for certifications from recognized vegan organizations can provide further assurance.
As the demand for plant-based supplements grows, more manufacturers offer vegan-friendly versions of popular supplements, including L-carnitine.
Clinical Significance
Effect On Weight Loss
A 2013, 4-week, double-blind, randomized, placebo-controlled trial examined the effects of low dosage (500 mg/day) L-carnitine supplementation combined with motivation training on overweight Japanese males. The results showed that the group receiving L-carnitine and motivation training experienced significant weight loss and decreased serum triglyceride levels compared to the placebo group that did not. [ref]
A 2020 randomized controlled clinical trial showed that L-carnitine supplementation has a modest but significant impact on reducing body weight, BMI, and fat mass. [ref]
This was confirmed in another 2020 meta-analysis. The results showed that the effects of L-carnitine on weight and BMI were observed to vary in a non-linear manner based on the dosage of carnitine and the BMI of subjects throughout the trials. [ref]
Effect On Physical Performance
L-carnitine supplementation significantly alters maximal oxygen consumption (VO2) at rest and serum-free and total carnitine levels at rest and after exercise, according to a 2021 meta-analysis. [ref]
A 2014 research study investigated the effects of acute L-carnitine supplementation on the endurance performance of footballers. The results indicated that both dosages of L-carnitine (3g and 4g) enhanced the athletes’ endurance. A significant reduction in heart rate was also noted in the 4g L-carnitine and placebo groups. [ref]
A 2018 double-blind, randomized, and placebo-controlled study was conducted to evaluate the effects of L-carnitine supplementation on exercise performance, anaerobic capacity, and exercise-induced oxidative stress in resistance-trained males. The results showed that L-carnitine supplementation can significantly enhance exercise performance in resistance-trained males while also reducing blood lactate levels and oxidative stress, which are beneficial for recovery. [ref]
A 2019 review study highlighted that oral L-carnitine supplementation can increase human skeletal muscle carnitine content. [ref]
Other Studies
A 2010 study aimed to assess whether L-carnitine, known for its ability to modulate lipid profiles, glucose metabolism, oxidative stress, and inflammatory responses, could help regress NASH symptoms. The results showed that supplementing a diet with L-carnitine is beneficial in reducing inflammation markers (TNF-α, CRP) and improving liver function, blood glucose levels, lipid profile, insulin resistance (HOMA-IR), and the histological features of NASH. [ref]
A 2020 systematic review evaluated the effects of prolonged L-carnitine supplementation on metabolism and metabolic modifications, particularly in recreationally active, competitive, and highly trained athletes. Results showed that prolonged L-carnitine supplementation can affect physical performance under specific conditions. However, the elevation of fasting plasma trimethylamine-N-oxide levels raises concerns about potential pro-atherogenic effects. [ref]
A pilot phase 2 randomized, double-blind, placebo-controlled trial investigated the effects of L-carnitine supplementation on individuals in the context of SARS-CoV-2 infection. The results indicated that LC was well-tolerated by participants. [ref]
In 2023 a prospective, double-blind, randomized controlled trial that investigated the effects of L-carnitine adjunctive therapy on various monitoring variables in critically ill patients. Out of the 54 initial enrolled patients, 51 completed the trial. The results showed that, compared to the control group, the group receiving L-carnitine supplementation significantly increased serum albumin, total protein, and calcium levels. [ref]
Another 2023 clinical trial aimed to assess the impact of L-carnitine supplementation on patients with COVID-19 in an intensive care unit (ICU). The results showed that L-carnitine can potentially lessen inflammation and oxidative stress, as well as to enhance respiratory function. Yet, its impact on COVID-19 patients who are critically ill and reliant on ventilators remains unexplored. [ref]
Food Sources Of L-Carnitine
L-Carnitine is primarily found in animal products. Here are some common food sources:
- Red Meat: Beef and lamb, in particular, are rich sources of L-carnitine. The redder the meat, generally, the higher its L-carnitine content.
- Pork: Contains a good amount of L-carnitine, though typically less than beef and lamb.
- Poultry: Chicken and other poultry have lower L-carnitine levels than red meat but are still a good source.
- Fish: Various types of fish, such as cod and salmon, contain L-carnitine but in lower quantities than red meats.
- Dairy Products: Milk and cheese provide L-carnitine, primarily due to the cows' muscle tissue content. The L-carnitine content in dairy is less than in meats but can still contribute to dietary intake.
- Eggs: While lower in L-carnitine than meats, eggs are a good source of many nutrients, including L-carnitine.
For Vegetarians And Vegans
For vegetarians or those who have limited meat consumption, L-carnitine can be more challenging to obtain from the diet alone.
In such cases, dietary supplements might be considered, though it's advisable to consult with a healthcare provider before beginning any new supplement regimen.
It's also worth noting that the body can synthesize L-carnitine from the amino acids lysine and methionine. Ensure that your diet includes sufficient amounts of these amino acids, along with adequate levels of vitamin C, B6, niacin, and iron, which are necessary for the biosynthesis of L-carnitine.
