If you're looking to put a little extra pep in your step, carnitine may be what you need. Carnitine is a naturally occurring amino acid derivative that plays a primary role in energy production. Scientific literature has documented many health benefits of carnitine supplementation, including enhanced metabolism and mitochondrial function, relief of nerve pain, antioxidation, and reduced risk of cardiovascular and neurodegenerative diseases (16). 

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What is Carnitine?

Carnitine is an amino acid derivative responsible for transporting long-chain fatty acids into the energy-producing cell units (the mitochondria). Carnitine is a conditionally essential nutrient, meaning it can be made by the body and obtained through food or dietary supplements. In certain scenarios, the body's requirements may exceed an individual's capacity to synthesize it. Endogenous carnitine is synthesized from the amino acids lysine and methionine in the kidneys, liver, and brain. (7, 15) 

Carnitine's primary function is to facilitate the conversion of fatty acids into cellular energy through beta-oxidation. Carnitine acts as a transport carrier, shuttling long-chain fatty acids across the mitochondrial membrane, enabling their utilization for energy production. Beta-oxidation is a vital biochemical process, especially in tissues with high energy demands, such as the heart and skeletal muscles. (15) 

Supplemental carnitine is available in several different forms. Each form has unique characteristics and potential benefits; determining which form is best will depend on the therapeutic goal of supplementation. L-carnitine, a derivative of the amino acid lysine, is the most widely available, least expensive, and best-studied form of carnitine. Acetyl-L-carnitine is the acetylated form of L-carnitine. Acetyl-L-carnitine is more easily absorbed in the gut and transported across the blood-brain barrier than L-carnitine. Acetyl-L-carnitine is commonly the preferred form in trials studying brain disorders. Propionyl-L-carnitine is an ester form of L-carnitine commonly used in studies for heart disease. The body can convert carnitine between its various forms and transport it between tissues as needed, depending on the cells' metabolic needs. (1, 5)

The Top 5 Therapeutic Uses of Carnitine

Supplemental carnitine has a diverse array of health benefits. In this section, we will discuss five areas in which the role of carnitine has been extensively studied. 

1. Energy Metabolism and Endurance

 Mitochondria play a central role in energy metabolism within cells, serving as the powerhouses responsible for generating adenosine triphosphate (ATP), the primary energy currency of cells. ATP is essential for various cellular functions and activities. Mitochondria are surrounded by an outer and inner membrane. The space enclosed by the inner membrane is known as the mitochondrial matrix. The key steps in energy metabolism occur in different parts of the mitochondria. Carnitine plays a pivotal role in energy production by facilitating the transport of fatty acids into the mitochondrial matrix, where they undergo oxidation to produce energy. (17) 

Because maximal exercise in trained athletes is associated with a decrease in plasma L-carnitine, restoring levels with supplementation is theorized to benefit athletic performance. Clinical studies have explored the impact of carnitine supplementation on athletic performance, with some suggesting that taking 2 grams of L-carnitine, either before exercise or daily for up to 24 weeks, improves exercise capacity, reduces the perception of effort, delays the onset of fatigue, and reduces post-exercise muscle pain. (14, 19, 33)

2. Weight Management

Carnitine has been explored for its therapeutic potential in weight loss and obesity management, with clinical studies providing insights into its effectiveness. L-carnitine's role in fatty acid oxidation enhances fat metabolism and, to some degree, affects the burning of carbohydrates, leading to a reduction in body weight and fat mass. L-carnitine may be useful for weight loss in conjunction with a low-calorie diet and exercise. (1)

Meta-analyses show that taking L-carnitine in doses of 250 mg to 4 grams daily reduces weight and body mass index by a small amount. Oral L-carnitine in doses of 2 grams daily taken for up to six months appears to offer the most benefit in expediting weight loss. Interestingly, follow-up subgroup analyses show that L-carnitine only reduces weight and BMI in overweight and obese patients. (2, 27, 32) 

The efficacy of L-carnitine has also been evaluated in combination with pharmaceutical weight-loss medications. Research shows that taking 2 grams of L-carnitine daily with 360 mg of orlistat or 10 mg of sibutramine for one year enhances weight loss outcomes compared to drug monotherapy in patients with type 2 diabetes. 

3. Cardiovascular Health

The heart cannot function properly without adequate levels of carnitine. Not only is carnitine required for oxygen utilization and energy metabolism within the heart's muscular tissue, but it also acts as an antioxidant. These antioxidant properties prevent the production of toxic fatty acid metabolites that disrupt cellular membranes and cause oxidative damage, which is implicated in cardiovascular disease. During ischemic events, carnitine prevents fatty acid ester accumulation, which can lead to fatal heart arrhythmias. These properties make carnitine beneficial in assisting recovery from heart attack and treating symptoms of angina, arrhythmia, and congestive heart failure. (17, 34) 

Additionally, evidence shows that carnitine improves cardiovascular risk factors, including high cholesterol and insulin resistance. Carnitine benefits lipid profiles by lowering triglycerides and total cholesterol levels and raising HDL cholesterol. One meta-analysis shows that taking 200 mg to 3 grams of L-carnitine daily effectively reduces plasma glucose, insulin, and HbA1c levels.  

Peripheral artery disease (PAD) is a condition in which narrowed arteries, caused by atherosclerosis, reduce blood flow to the arms and/or legs. It often presents with intermittent claudication, lower extremity muscle pain that occurs during movement and exercise. Clinical studies have demonstrated that propionyl-L-carnitine improves walking capacity and quality of life in patients with PAD and intermittent claudication.

4. Diabetic Neuropathy

Diabetic patients commonly exhibit diminished serum carnitine levels (15). Diabetes also increases the risk of atherosclerotic cardiovascular disease and compromised kidney and liver function. Carnitine, especially L-propionyl carnitine, also demonstrates significant enhancements in both peripheral vascular and nerve function in diabetic patients. In light of these factors, managing neuropathy with carnitine seems justified for individuals with diabetes. (3) 

Peripheral nerve dysfunction, called diabetic neuropathy, occurs in about 50% of people with diabetes mellitus and causes chronic nerve pain in one-third of this population subset (17). A 2019 Cochrane review concluded that acetyl-L-carnitine increases nerve fibers, regenerates nerve fiber clusters, and improves vibratory sensations. Studies included in this analysis suggest that taking acetyl-L-carnitine in doses of 2-3 grams daily for up to one year modestly reduces neuropathy-associated pain scores by about 15 points on a 100-point visual analog scale. (29) 

5. Cognitive Function

Alzheimer's disease is characterized by the accumulation of plaques and neuronal degeneration, particularly affecting cholinergic neurons involved in memory functions. These neurons use acetylcholine, and Alzheimer's treatment often involves increasing acetylcholine levels. Carnitine may be conditionally essential for individuals with Alzheimer's, as it supports acetylcholine synthesis and helps remove toxic compounds, potentially alleviating mitochondrial dysfunction associated with extensive brain degeneration. A 2003 meta-analysis, including 21 clinical trials and over 1,000 adults with mild cognitive impairment or mild Alzheimer's disease, found that those taking acetyl-L-carnitine showed better clinical and psychometric scores compared to the placebo groups, suggesting the potential cognitive benefits of acetyl-L-carnitine. (6)

Clinical research also shows that acetyl-L-carnitine improves measures of cognitive function and memory in elderly individuals with age-related cognitive decline. The mechanisms underlying these neuroprotective effects to support breath health are believed to include enhanced mitochondrial function, neuroprotection against oxidative stress, and potential modulation of neurotransmitter systems. (31)  

Dietary Sources of Carnitine

Meat and dairy products are the major natural dietary sources of carnitine. Red meat, such as beef and lamb, stands out as a particularly rich source of carnitine, providing substantial amounts per serving. Plant-based foods, such as grains, fruits, and vegetables, contain very little to no carnitine. The table below lists carnitine-rich foods and their approximate carnitine content per serving. Studies indicate that a typical omnivorous diet provides 24-145 mg of carnitine daily, whereas vegan diets only provide about 1.2 mg. (6, 23) 

The bioavailability of dietary carnitine ranges from 63-75%. This is much greater than the absorption rates of supplemental L-carnitine, which vary from 14-18%. (6) 

Supplementation: Dosage and Safety

Following established guidelines is important to ensure safety and efficacy when considering carnitine supplementation. Recommended dosages may vary based on specific health goals. Because individual requirements can differ, it's advisable to consult with a healthcare professional to determine an appropriate dosage tailored to your specific needs. (23)

Common doses of the various forms of carnitine are as follows:

• L-carnitine: 2 grams daily
• Acetyl-L-carnitine: 1.5-3 grams daily
• Propionyl-L-carnitine: 1.5-2 grams daily 

While carnitine supplements are generally well-tolerated, potential side effects can include gastrointestinal discomfort, nausea, diarrhea, and a fishy body odor. To minimize these risks, starting with lower doses and gradually increasing while monitoring your body's response is recommended. (23) 

Individuals with certain medical conditions or those taking specific medications should exercise caution. Carnitine supplements might not be suitable for people with seizure or thyroid disorders, and those on anticoagulant medications should consult with a healthcare provider before supplementation. (20) 

Choosing reputable sources for carnitine supplements is essential to ensure product quality and purity. Regular health check-ups and open communication with healthcare professionals can help manage potential risks and ensure that carnitine supplementation aligns with overall health objectives. Always prioritize safety and be attentive to unexpected reactions, discontinuing use if adverse effects occur.

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Summary

The therapeutic potential of carnitine spans various health domains, showcasing its significance in energy metabolism, cardiovascular health, cognitive function, and more. Carnitine, a naturally occurring compound, has been studied for its positive impact on conditions like cardiovascular disease, diabetic neuropathy, and age-related cognitive decline. Adopting a balanced approach is crucial to maximize carnitine's health benefits. This involves incorporating carnitine-rich foods into one's diet, such as meats and dairy, alongside considering responsible supplementation when necessary. Striking a balance between dietary sources and supplements ensures optimal carnitine intake, promoting overall well-being. As with any health strategy, consulting healthcare professionals is recommended to tailor approaches to individual needs and health goals, fostering a comprehensive and personalized approach to maximizing the benefits of carnitine.