Understanding L-carnitine deficiency and its side effects

Are you feeling tired, lethargic and irritable? You might be missing one of these essential micronutrients in your body. 

L-carnitine is a compound made up of the amino acids lysine and methionine. A deficiency of this vitamin can lead to symptoms of muscle weakness, tiredness and lethargy. Derived from the Latin word carnus or flesh, L-carnitine is crucial in metabolizing fats to form adenosine triphosphate, the cell’s energy currency [1]. 

Organs in the body that are rich in L-carnitine include skeletal muscles, cardiac muscles and the liver. L-carnitine is needed to transport long-chain fatty acids into the mitochondria. The mitochondria are tiny cell organelles that metabolize fats and carbohydrates to form ATPs.

L-carnitine is also responsible for transporting toxic compounds released during the metabolism of organic compounds out of the mitochondria. These toxic compounds are then neutralized in the cell’s cytoplasm.

Hence, L-carnitine does not only play a critical role in lipid metabolism, but it also clears the mitochondria of toxic compounds. 

Although the body produces L-carnitine naturally, some individuals cannot make this critical nutrient naturally. L-carnitine deficient individuals include those who inherit genes that prevent the body from producing L-carnitine.

Others with medical conditions, such as Crohn’s disease, who have trouble absorbing nutrients could also be L-carnitine deficient. 

Since L-carnitine is a critical nutrient, individuals who lack this nutrient should receive supplementation to correct the deficiency. For example, as one ages, studies have shown that L-carnitine production also reduces. Hence, for older adults, supplementation with L-carnitine is necessary. 

L-carnitine supplementation for deficiency

L-carnitine and its benefits 

L-carnitine has many benefits for the body. Here are some benefits of this vital nutrient: 

  • Prevent cardiovascular diseases 
  • Prevent muscle wasting 
  • Delay progression of dementia 
  • Manage chronic heart failure symptoms 
  • Improve brain function 
  • Delay cognitive decline in older adults with dementia 
  • Improve exercise performance 
  • Improve recovery after exercise 
  • Manage type 2 diabetes and prevent complications 

Deficiency in L-carnitine 

When the level of L-carnitine is not sufficient or available to all cells in the body, this can lead to symptoms of L-carnitine deficiency, such as heart or liver problems and muscle weakness. 

Skeletal and cardiac muscles with low L-carnitine levels may start to work poorly. Although those with certain medical conditions and genetic factors are at increased risk of being L-carnitine deficient, low levels of this nutrient can happen in children and adults. 

There are two types of deficiency associated with L-carnitine. These include primary and secondary carnitine deficiency [2]. Those with primary muscle carnitine deficiency inherit a genetic disorder where a gene that instructs the formation of proteins that carry L-carnitine from the blood to the cells is defective.

In this case, an individual may have low levels of L-carnitine. However, if the liver and heart are also affected, this leads to systemic L-carnitine deficiency. 

Meanwhile, secondary carnitine deficiency is more common compared to primary carnitine deficiency. This condition results from a problem of having insufficient L-carnitine levels in the blood.

In contrast, primary carnitine deficiency results from a problem in getting carnitine into the cells. Several health problems cause secondary carnitine deficiency. 

What are the factors or health conditions that lead to carnitine deficiency? 

These conditions limit the amount of L-carnitine absorbed in the body: 

  • Liver disease 
  • Digestive diseases that result in poor L-carnitine absorption 
  • Kidney disease, especially those who are in dialysis 
  • Certain metabolic disorders 
  • Malnutrition 
  • Mitochondrial diseases 
  • Certain medicines

Who is at risk of primary and secondary L-carnitine deficiency? 

Primary: A child or infant who gets an abnormal copy of the gene that causes poor uptake of L-carnitine from the blood to the cells has a primary deficiency. The infant or child should inherit the abnormal copy of the gene from the mother and father. 

Secondary: Individuals at risk of secondary L-carnitine deficiency include those with certain health conditions such as liver and kidney diseases. 

L-carnitine deficiency symptoms

Secondary L-carnitine deficiency leads to minor symptoms. In contrast, primary L-carnitine deficiency leads to more severe symptoms. Children who inherit the abnormal copy of the gene from both parents can exhibit the symptoms of carnitine deficiency.

However, some individuals could only develop the symptoms later in adulthood. Here are some of its symptoms: 

  • Muscle weakness exhibited by floppy or decreased muscle tone 
  • Irritability 
  • Fatigue or constant tiredness 
  • Lack of energy 
  • Delayed motor development 
  • Poor feeding in infants 
  • If the liver is affected, individuals could exhibit symptoms of hypoglycemia or low blood sugar levels. 
  • Individuals could exhibit shortness of breath, edema or swelling if the kidney is affected. 

Since the symptoms may be similar to other health conditions, it is best to consult your doctor when you show the signs and symptoms mentioned earlier. Your doctor can diagnose you if you have L-carnitine deficiency. 

L-carnitine deficiency symptoms

Diagnosis of L-carnitine deficiency 

Infants with L-carnitine deficiency may be diagnosed during standard newborn screening tests. A geneticist or neurologist can determine if an adult individual has L-carnitine deficiency. 

Here is some vital information that should be taken down to support a diagnosis: 

  • Health history 
  • Physical exam 
  • Symptoms of past health conditions 
  • Family’s health history 
  • Results of the neurological exam 

If you suspect that you have L-carnitine deficiency, there are some tests that you can undergo to confirm if you have this nutrient deficiency. Consult with your doctor on potential tests that you can undergo to diagnose the deficiency.

Some of these tests can include blood tests to check your carnitine level in the blood; urine tests; exercise and heart tests; and genetic tests. 

Treatment of L-carnitine deficiency 

The primary treatment and management of this nutrient deficit involve taking L-carnitine supplements. These supplements are available in pill form and increase the amount of L-carnitine inside the cells and in the blood. 

If you have primary L-carnitine deficiency, you must take L-carnitine supplementation for the rest of your life. 

Side-effects of L-carnitine deficiency 

L-carnitine deficiency can lead to complications or side effects. One of the most severe complications includes heart weakness. Once the heart is affected, this can lead to symptoms of shortness of breath and edema or swelling in the legs and hands. Heart weakness leads to poor blood pumping to different parts of the body.

As a result, you do not get enough oxygen in your body, which explains the shortness of breath. The swelling in your feet is due to the pooling of blood in the lower extremities due to poor circulation and blood pumping by the heart. 

Notably, heart weakness can resolve with sufficient supplementation with L-carnitine. Your doctor will examine your heart’s function by performing an electrocardiogram (ECG). Heart weakness is one of the earliest signs of L-carnitine deficiency. 

A severe second complication of L-carnitine deficiency involves liver problems. The liver stores L-carnitine, necessary for metabolizing fats and preventing fatty liver. A lack of L-carnitine results in fatty liver and enlargement of the liver. 

Liver problems develop early in those with primary L-carnitine deficiency, including infants who lack the enzymes that transport L-carnitine from the blood to the cells in the body. Infants with liver problems exhibit irritability and poor feeding.

When not corrected, severe liver problems can lead to hypoglycemia. Severe hypoglycemia is a medical emergency since this can lead to coma and even death when not treated immediately with the sugar dextrose. 

Prevention of L-carnitine deficiency

Always consult your doctor or geneticist to determine your risk of passing the abnormal gene to your future children if you have family members who are L-carnitine deficient. 

However, if you have secondary L-carnitine deficiency, you can correct this by taking L-carnitine supplementation. Always consult your doctor before taking L-carnitine supplements to ensure your safety. 

You can also eat food rich in L-carnitine, such as the following: 

  • Red meat 
  • Chicken meat 
  • Codfish 
  • Milk 
Prevention of L-carnitine deficiency through proper diet

Take home message 

L-carnitine is an essential nutrient that can be produced naturally in the body. However, some are L-carnitine deficient and fall in the category of primary L-carnitine deficient or secondary L-carnitine deficient. 

Those with primary L-carnitine deficiency inherit a defective gene, making it challenging to transport L-carnitine from the blood to the cells. Signs and symptoms often appear during childhood and can be corrected through supplementation with the nutrient. 

Individuals with secondary L-carnitine deficiency can address the deficiency through supplementation with L-carnitine or eating food rich in this nutrient. 

L-carnitine is an essential nutrient since this metabolizes fats to energy in the mitochondria. It benefits the body by promoting brain health in managing conditions such as type 2 diabetes

Some signs and symptoms of L-carnitine deficiency include muscle weakness, tiredness and irritability. When left untreated, lack of this nutrient leads to heart weakness and liver problems. Treatment of the deficiency involves L-carnitine supplementation or intake of nutrients from food sources. 

[1] https://jissn.biomedcentral.com/articles/10.1186/s12970-020-00377-2 
[2] https://ods.od.nih.gov/factsheets/Carnitine-HealthProfessional/ 

Photograph: Anna_Ostanina/Envato
The information included in this article is for informational purposes only. The purpose of this webpage is to promote broad consumer understanding and knowledge of various health topics. It is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified health care provider with any questions you may have regarding a medical condition or treatment and before undertaking a new health care regimen, and never disregard professional medical advice or delay in seeking it because of something you have read on this website.