Carnitine

Table of Contents

What is Carnitine?

Carnitine is a naturally occurring compound found in the body, primarily in muscle tissue, where it plays a crucial role in the transportation of fatty acids into the mitochondria, the cellular organelles responsible for energy production. It is essential for the metabolism of fatty acids and the production of energy, particularly during periods of increased energy demand, such as exercise.

Carnitine exists in several forms, each with its own specific properties and functions. Some of the main types of carnitine include:

L-Carnitine: This is the most common and widely studied form of carnitine. It is synthesized in the body from the amino acids lysine and methionine and is primarily involved in the transport of long-chain fatty acids into the mitochondria for energy production. L-Carnitine is available as a dietary supplement and is commonly used for various purposes, including athletic performance, weight management, and cardiovascular health.
Acetyl-L-Carnitine (ALCAR): Acetyl-L-carnitine is a modified form of L-carnitine that has an acetyl group attached to it. It is better absorbed and crosses the blood-brain barrier more readily than L-carnitine, allowing it to exert effects on brain function. ALCAR is often used to support cognitive function, memory, and mood, and it may have neuroprotective effects.
Propionyl-L-Carnitine (PLC): Propionyl-L-carnitine is another modified form of L-carnitine that has a propionyl group attached to it. It is thought to have similar benefits to L-carnitine but may have specific effects on cardiovascular health, including improving blood flow and reducing symptoms of peripheral artery disease (PAD). PLC is sometimes used in combination with other nutrients for heart health support.
L-Carnitine L-Tartrate (LCLT): L-Carnitine L-tartrate is a salt form of L-carnitine that is commonly used in sports nutrition supplements. It is believed to enhance exercise performance, reduce muscle damage, and promote recovery after exercise. LCLT is often used by athletes and fitness enthusiasts to support endurance, muscle recovery, and overall exercise capacity.
D-Carnitine: D-Carnitine is a synthetic form of carnitine that is chemically similar to L-carnitine but has different biological effects. Unlike L-carnitine, D-carnitine has been shown to inhibit the activity of carnitine transporters in the body, potentially interfering with normal carnitine metabolism. D-Carnitine is not commonly used as a dietary supplement and may have adverse effects on health.

What are the Benefits of Carnitine?

Carnitine offers several potential health benefits due to its essential role in fatty acid metabolism and energy production. Some of the ways in which carnitine may benefit health include:

Energy production: Carnitine plays a crucial role in the transport of long-chain fatty acids into the mitochondria, where they are oxidized to produce energy. By facilitating the entry of fatty acids into the mitochondria, carnitine helps support cellular energy metabolism, particularly during periods of increased energy demand, such as exercise or fasting.
Athletic performance: Carnitine supplementation has been studied for its potential to enhance exercise performance, reduce fatigue, and improve recovery after exercise. It may help increase the utilization of fatty acids as a fuel source during exercise, sparing glycogen stores and delaying the onset of fatigue. Some research suggests that carnitine supplementation, particularly with forms like L-carnitine L-tartrate (LCLT), may improve endurance, muscle recovery, and overall exercise capacity.
Heart health: Carnitine has been investigated for its potential cardiovascular benefits, particularly in individuals with heart disease or risk factors for heart disease. It may help improve cardiac function, reduce symptoms of angina, and enhance exercise tolerance in people with heart failure or peripheral artery disease (PAD). Carnitine supplementation, especially with forms like propionyl-L-carnitine (PLC), has been shown to improve blood flow and reduce symptoms of PAD.
Weight management: Some studies suggest that carnitine supplementation may have beneficial effects on weight management and body composition. Carnitine is involved in the transport of fatty acids into the mitochondria for energy production, and it may help enhance fat metabolism and promote the use of fat as a fuel source, potentially leading to improved fat loss and weight maintenance.
Cognitive function: Acetyl-L-carnitine (ALCAR), a modified form of carnitine, has been studied for its potential cognitive-enhancing effects. It may help support brain function, memory, and mood by crossing the blood-brain barrier and exerting neuroprotective effects. ALCAR supplementation has been investigated for its potential to improve symptoms of age-related cognitive decline, Alzheimer’s disease, and other neurological disorders.
Male fertility: Carnitine plays a role in sperm metabolism and energy production, and it is concentrated in the epididymis, the structure in the male reproductive system where sperm mature. Some research suggests that carnitine supplementation may improve sperm quality, motility, and overall fertility in men with infertility issues.

What happens if I don’t get enough Carnitine (Deficiency)

Carnitine deficiency can lead to a range of symptoms and health complications due to its essential role in fatty acid metabolism and energy production. Some potential consequences of carnitine deficiency include:

Impaired fatty acid metabolism: Carnitine is necessary for the transport of long-chain fatty acids into the mitochondria, where they are oxidized to produce energy. Without sufficient carnitine, the transport of fatty acids into the mitochondria may be impaired, leading to reduced energy production and increased reliance on glucose metabolism.
Muscle weakness and fatigue: Carnitine deficiency can impair energy production in muscle cells, leading to muscle weakness, fatigue, and exercise intolerance. Individuals with carnitine deficiency may experience decreased stamina and endurance during physical activity.
Cardiovascular complications: Carnitine deficiency may increase the risk of cardiovascular complications due to impaired energy metabolism in cardiac muscle cells. Symptoms may include chest pain (angina), palpitations, and reduced exercise tolerance. Severe carnitine deficiency can lead to cardiomyopathy, a condition characterized by weakened heart muscle and impaired heart function.
Hepatic encephalopathy: In severe cases of carnitine deficiency, particularly in infants and young children, hepatic encephalopathy may occur. This condition is characterized by impaired brain function due to liver dysfunction and elevated levels of ammonia in the blood. Symptoms may include confusion, lethargy, seizures, and coma.
Hypoglycemia: Carnitine deficiency may impair fatty acid oxidation and energy production in the liver, leading to decreased glucose production and hypoglycemia (low blood sugar levels). Hypoglycemia can cause symptoms such as weakness, dizziness, confusion, and loss of consciousness.
Developmental delay: Carnitine deficiency in infants and young children can affect growth and development, leading to developmental delay, failure to thrive, and neurological abnormalities. Early detection and treatment of carnitine deficiency are crucial to prevent long-term complications.

Carnitine deficiency can be caused by various factors, including genetic disorders that affect carnitine synthesis or transport, certain medications that interfere with carnitine metabolism, inadequate dietary intake of carnitine, and conditions that increase carnitine excretion, such as kidney disease or dialysis.

Recommended Dietary Allowances (RDAs) for Carnitine

There are no established recommended dietary allowances (RDAs) or dietary reference intakes (DRIs) for carnitine by authoritative health organizations such as the Institute of Medicine (IOM) or the National Institutes of Health (NIH). Carnitine is not considered an essential nutrient because the body can synthesize it from the amino acids lysine and methionine and obtain it from dietary sources.

Best Food Sources for Carnitine

Carnitine is found primarily in animal-derived foods, particularly meat and dairy products, although smaller amounts can also be found in some plant-based foods. Here are some of the best food sources of carnitine:

Beef: Beef is one of the richest sources of carnitine, particularly in lean cuts such as sirloin, tenderloin, and ground beef.
Pork: Pork, including cuts like pork loin and pork chops, contains significant amounts of carnitine.
Lamb: Lamb is another meat source rich in carnitine, with higher levels found in lean cuts.
Poultry: Chicken and turkey are good sources of carnitine, especially in breast meat.
Fish: Fish and seafood, such as cod, salmon, tuna, and shrimp, contain carnitine, although levels may vary depending on the type of fish and how it’s prepared.
Dairy products: Milk, cheese, and yogurt contain small amounts of carnitine, with higher levels found in whole milk and dairy products made from whole milk.
Eggs: Eggs are a good source of carnitine, with higher levels found in the egg yolk compared to the egg white.
Tempeh: Tempeh, a fermented soybean product, contains small amounts of carnitine and can be a source of carnitine for vegetarians and vegans.
Avocado: Avocado contains small amounts of carnitine, along with other beneficial nutrients such as healthy fats, fiber, and vitamins.
Asparagus: Asparagus contains a moderate amount of carnitine and is a good source of other nutrients like folate, vitamin K, and fiber.

While animal-derived foods are the richest sources of carnitine, plant-based foods can also contribute to carnitine intake, albeit in smaller amounts.

Carnitine Interaction with Medication/Overconsumption

Taking excess carnitine supplements may lead to potential adverse effects, although they are generally rare and occur more frequently with high doses. Some possible effects of excessive carnitine intake include:

Gastrointestinal issues: High doses of carnitine supplements may cause gastrointestinal discomfort, including nausea, vomiting, diarrhea, and abdominal cramps, in some individuals.
Odor: Some people may notice a fishy or “body odor” smell when taking high doses of carnitine supplements, as excess carnitine can be converted into trimethylamine (TMA) by bacteria in the gut. TMA has a strong odor reminiscent of fish or body odor.
Increased risk of cardiovascular events: There is some concern that high doses of carnitine supplements may increase the risk of cardiovascular events, particularly in individuals with existing heart disease or risk factors for heart disease. This is based on studies suggesting that carnitine can be converted into trimethylamine-N-oxide (TMAO), a compound associated with increased cardiovascular risk. However, more research is needed to fully understand the relationship between carnitine supplementation and cardiovascular health.
Acylcarnitine accumulation: Excessive carnitine supplementation may lead to the accumulation of acylcarnitines, which are intermediate compounds in fatty acid metabolism. Elevated levels of acylcarnitines in the blood have been associated with metabolic disturbances and mitochondrial dysfunction.
Interactions with medications: Carnitine supplements may interact with certain medications, particularly those that affect carnitine metabolism or renal function. Some potential interactions include:
- Thyroid hormone medications: Carnitine supplements may interfere with the action of thyroid hormone medications, potentially reducing their effectiveness.
- Anticoagulant medications: Carnitine supplements may enhance the effects of anticoagulant or antiplatelet medications, increasing the risk of bleeding.
- Valproic acid: Valproic acid, a medication used to treat epilepsy and bipolar disorder, can decrease carnitine levels in the body. Carnitine supplementation may be recommended for individuals taking valproic acid to prevent carnitine deficiency.
- Renal function: Carnitine is primarily excreted by the kidneys, so individuals with impaired renal function may be at increased risk of carnitine accumulation and toxicity when taking carnitine supplements.