How does Carnitine Support Hashimoto’s?

If you're like many people, you may not have heard of carnitine, but this important nutrient is essential to our body's ability to optimally burn fat, which is needed for energy. 

Carnitine is an amino acid that comes in several forms, including acetyl-L-carnitine, L-carnitine, and propionyl-L-carnitine. The Latin word carnus means "meat". Eating meat is the most important way to get carnitine in our diet. Our body stores carnitine in skeletal and cardiac muscle tissue. 

In general, acetyl-L-carnitine (also known as ALCAR) is the form considered most beneficial to the brain; it crosses the blood-brain barrier and research has shown it to be potentially beneficial for people suffering from various neurodegenerative diseases.

L-carnitine is the form considered most beneficial for muscles. It has been shown in research to relieve muscle weakness and pain.  It is commonly used in dietary supplements designed to improve athletic performance, optimizes fat-burning, and aid muscle recovery. 

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Propionyl-L-carnitine has been studied for circulatory problems such as high blood pressure or peripheral vascular disease. Research has shown that carnitine supplementation helps reduce fatigue in hypothyroid patients and improves muscle weakness in hypo and hyperthyroid patients. 

Carnitine provides these health benefits by supporting the health of our mitochondria (powerful energy factories found in most of our cells) in several ways:

Carnitine transports long-chain fatty acids to the mitochondria where the fatty acids are burned to produce our body's energy (in the form of adenosine triphosphate - ATP). 

Carnitine carries the toxic byproducts of our body cells (produced during the energy production process mentioned above) so that toxins do not build up. 

Degradation of mitochondria can occur when too many toxins (also known as free radicals) accumulate; this causes delayed energy production and results in less energy.  It can also cause poor muscle metabolism and other negative health effects.

As a powerful antioxidant, carnitine neutralizes the accumulation of free radicals (oxidative stress).  Our mitochondria can also be affected by other types of free radical formation. Chronic stress, environmental toxins (like heavy metals), or a lack of protective antioxidants (like vitamin C) can compromise mitochondrial health.

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Carnitine helps minimize this buildup by scavenging free radicals and maintaining and protecting levels of key antioxidant enzymes like glutathione peroxidase. 

Because of the importance of mitochondria to our metabolic health, researchers have long studied carnitine levels in people with various metabolic disorders, including thyroid disease (Hashimoto's and Graves' disease).

Graves’ disease 

Most of the early research (from 1959 to early 2000) regarding carnitine and thyroid disease actually focused on Graves' disease. Scientists who examined the effects of L-carnitine on thyroid health suggested that carnitine was a peripheral antagonist of thyroid hormone activity in some tissues (meaning that L-carnitine could prevent T3 from entering and T4 in cells). In hyperthyroidism, with high levels of thyroid hormone, the body has been found to burn and run out of carnitine. Higher levels of thyroid hormone resulted in higher levels of carnitine excreted in the urine.

The researchers wanted to validate previous laboratory studies regarding the effects of carnitine on improving thyroid hormone levels. In a 6-month study published in 2001, fifty women received a fixed dose of TSH-suppressing L-T(4) therapy. 

The women were divided into five groups, with each group receiving a different set of carnitine supplements (2 or 4 g/d of oral L-carnitine) or a placebo. The researchers assessed changes in nine thyroid parameters and symptoms. When given either dose of L-carnitine, the women's thyroid symptoms improved and the symptoms of hyperthyroidism reversed.

That said, you may be wondering why carnitine would be good for people with hypothyroidism if carnitine is indeed an antagonist of thyroid hormone activity. 

More recent research has shown that carnitine may be beneficial for both hypothyroidism and hyperthyroidism, with a reduced concentration of carnitine in the skeletal muscle of people with both thyroid conditions. Carnitine appears to work differently depending on a particular individual's metabolic status and thyroid hormone levels.

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Hypothyroidism and fatigue

In research published in 2016, when hypothyroid patients were given levothyroxine, the extra thyroid hormone promoted the synthesis of carnitine. However, the scientists found that there was still a lack of carnitine in these patients. The researchers hypothesized that while the elevated thyroid hormone increased carnitine synthesis, it also accelerated the oxidation of mitochondrial fatty acids (similar to what is observed in a hyperthyroid state), lowering carnitine levels. So essentially more was produced, but even more was expelled, resulting in continued shortages. It turns out that this can cause a relative lack of carnitine, which can result in persistent fatigue.

In the 2016 study, 60 patients with hypothyroidism-related fatigue were given L-carnitine (990 mg of L-carnitine twice daily) or a placebo for 12 weeks. After 12 weeks, the researchers noted that the group that received L-carnitine actually showed improvements in fatigue, with the most significant improvements in "brain fatigue". 

The most significant findings were those under the age of 50, those over the age of 50 with high levels of free T3, and those who had hypothyroidism following a thyroidectomy (using relatively high doses of thyroid hormone). The researchers concluded that these populations were more metabolically active (hence a relative carnitine deficiency). Other case-based studies have also shown the benefit of L-carnitine on symptoms of hypothyroidism.

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Muscle weakness and pain are common in both hyperthyroidism and hypothyroidism. The researchers found that more than half of the patients with hypothyroidism had muscle disorders, with 54% having muscle weakness and 42% having cramps. Why is muscle weakness so common? 

The metabolic effect of insufficient thyroid hormone is partly responsible for this. T3 is a huge regulator of mitochondrial health. The decrease in triiodothyronine (T3) can cause a reduction in muscle energy metabolism, as well as affect the efficiency of normal muscle function. A deficiency of thyroxine (T4) also decreases the body's ability to produce energy. Research also showed that in patients with hypothyroidism, there was indeed a tendency for muscle carnitine levels to be lower than normal and for carnitine levels to improve with thyroid hormone treatment.

Carnitine has traditionally been used by individuals with hyperthyroidism to help with symptoms resulting from hyperthyroid-induced carnitine depletion (such as muscle breakdown), so scientists initially believed that carnitine acted as a receptor "antagonist" or blocker of thyroid hormone and warned against the use of carnitine in hypothyroidism. 

However, subsequent research has shown that carnitine modulates thyroid hormones in our cells so that it can act as an "agonist" (a substance that triggers a reaction in combination with a receptor) that aids the action of the thyroid hormone in cases of hypothyroidism, and as an "antagonist" (blocker) in cases of hyperthyroidism. Studies have shown benefits in both hypothyroidism and hyperthyroidism.

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Symptoms of Overmedication

Symptoms of overmedication include fast or irregular heartbeat, nervousness, irritability or mood swings, muscle weakness or tremors, diarrhea, menstrual irregularities, hair loss, weight loss, insomnia, pain chest pain, and excessive sweating. 

It is highly recommended that do not start, change, increase, decrease or stop your treatment without consulting your doctor.


Therefore, if symptoms such as fatigue, brain fog, constipation, muscle weakness and pain, and digestive problems occur, even after starting thyroid hormone treatment, it could be due to a single cause, such as lack of carnitine. The good news is that addressing this single root cause can help resolve some of your bothersome and persistent symptoms. So, consult your doctor and find the root cause of your disease for a better life.



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