This rare condition can lead to :. To treat it, the physician will prescribe pharmacological doses of carnitine, to correct the problems of cardiomyopathy and muscle weakness. If it happens as a result of other metabolic diseases, this is secondary carnitine deficiency.
Cancer and aging reduce carnitine levels. Foods that provide carnitine are mainly animal products, dairy, poultry, and meat. Red meat has one of the highest concentrations.
Adults whose diets are rich in red meat consume on average around 60 to mg of carnitine per day. A vegan diet normally provides between 10 and 12mg per day. Studies suggest that the body absorbs 54 to 86 per cent of dietary carnitine into the bloodstream, but only 14 to 18 percent when it is taken as a supplement. Carnitine is said to have many therapeutic properties that may be useful in treating a range of conditions and illnesses. As an antioxidant , carnitine fights off harmful free radicals, which cause severe damage to cells.
Health conditions that carnitine may be used to treat include heart failure or heart attack , angina , and diabetic neuropathy. One review study has stated that acetyl-L-carnitine ALC had a moderate effect on reducing pain, but the evidence is still conflicting , and more research is needed. One study found that ALC is as effective as a conventional treatment, methylcobalamin MC , in treating diabetic peripheral neuropathy.
Another investigation , involving 19 patients, found that ALC did not change the frequency or severity of the condition. For some time, studies have suggested that carnitine may help treat the symptoms of angina if used alongside conventional treatment. In , a review and meta-analysis linked L-carnitine with a 27 percent reduction in all-cause mortality, and notably, a 65 percent drop in ventricular arrhythmias and a 40 percent fall in the development of angina.
However, it did not lead to a fall in the development of heart failure or a repeat myocardial infarction MI. Carnitine may also normalize the type of blood vessel dysfunction that happens with congenital heart defects , according to Dr. Stephen M. Most chronic diseases lead to a loss of mitochondrial function that can result in fatigue and other symptoms.
Research published in Alternative Therapies In Health And Medicine suggests that combinations of supplements, including carnitine, might help improve mitochondrial function. Findings published in the journal Thrombosis Research looked at the efficacy, safety and tolerability of propionyl-L-carnitine PLC given to patients with a condition known as intermittent claudication. Intermittent claudication can lead to pain when walking or running, because damage or narrowing of an artery leads to poor blood supply.
The pain usually occurs in the feet, calves, thighs, hips or buttocks, depending on where the artery damage or narrowing occurs. The authors found that patients with peripheral arterial disease were able to walk comfortably for longer times and distances after using PLC. Studies on men with infertility have suggested that 2 to 3 grams a day for 3 to 4 months can increase sperm quality, and that 2 grams for 2 months may increase sperm motility.
But the researchers also found that frequent meat eaters produced significantly more TMAO than vegetarians after consuming the same amount of L-carnitine. For instance, L-carnitine supplements mg were given to 80 healthy volunteers, including 24 who were long-term vegetarians or vegans. Several of the meat eaters and 1 committed vegan were also given an 8-ounce steak, containing mg of L-carnitine. Fecal studies also showed that meat eaters and vegetarians had different types of bacteria in their guts, and the meat eaters had more of the bacteria involved in breaking down L-carnitine into TMAO.
This was confirmed by giving the volunteers antibiotics for one week to suppress the gut bacteria, then repeating the L-carnitine supplement experiment. With suppressed levels of gut bacteria, the volunteers produced very little TMAO. Stanley Hazen in a press release. The main food sources for carnitine are red meat and full-fat dairy products. It is also found in fish, poultry, tempeh, wheat, asparagus, avocados and peanut butter.
L-carnitine is also commonly available as a dietary supplement, which is advertised as a weight loss and body building tool despite a lack of supporting scientific evidence. Plus L-carnitine is added to many energy drinks. Carnitine plays a vital and complex role in cardiac metabolism. Some people have diseases that cause a carnitine deficiency, so they need to take carnitine supplements. Studies have also shown that carnitine may help treat some heart conditions, such as angina, arrhythmias, heart attacks and heart failure.
Because levels of carnitine are low in the failing heart muscle, supplemental amounts might counteract the toxic effects of free fatty acids and improve carbohydrate metabolism [ 17 ]. In short-term studies, carnitine has had anti-ischemic properties when given orally and by injection.
Treatment with L-carnitine significantly reduced mortality 5 days after randomization but did not significantly affect the risk of heart failure or death at 6 months. The authors of a meta-analysis combined the results from this trial with those from 12 smaller trials [ 20 ]. Claudication results from an inadequate supply of oxygen-rich blood to the legs and leads to an accumulation of acetylcarnitine in muscle due to its incomplete utilization.
Patients with peripheral arterial disease who develop claudication have significant impairments in exercise performance and have difficulty walking even short distances at a slow speed [ 18 ]. Research indicates that carnitine might improve the performance of skeletal muscles in the leg. A similar multicenter trial in the United States and Russia found that the same daily dose and form of carnitine administered for 6 months in patients with disabling claudication significantly improved walking distance and speed, reduced bodily pain, enhanced physical function, and improved perceived health state compared to patients in the control group [ 22 ].
The authors of a systematic review and meta-analysis that included these and 12 other randomized clinical trials concluded that propionyl-L-carnitine significantly increases peak walking distance in patients with claudication [ 23 ]. These findings suggest that L-carnitine, when administered for up to 1 year, might have beneficial effects on the cardiovascular system in certain settings. Other research, however, has raised concerns about the cardiovascular effects of chronic exposure to carnitine.
A study that included both rodents and 2, humans undergoing elective cardiac evaluation found that L-carnitine is metabolized by intestinal microbiotia to trimethylamine-N-oxide TMAO , a proatherogenic substance that is associated with cardiovascular disease risk [ 24 ].
Due to differences in intestinal bacteria composition, omnivorous study participants produced more TMAO than vegans or vegetarians following consumption of L-cartinine. The study also found dose-dependent associations between fasting plasma L-carnitine concentration and risk of coronary artery disease, peripheral artery disease, and overall cardiovascular disease, but only among participants with concurrently high TMAO levels.
The researchers noted that these findings could partly explain the link between high levels of consumption of red meat a rich source of carnitine and increased cardiovascular disease risk. More research is needed to fully understand the effects of carnitine on cardiovascular health. Cancer Fatigue resulting from chemotherapy, radiation treatment, and poor nutritional status is common in cancer patients [ 25 ].
They may also be deficient in carnitine [ 25 ]. In both studies, most subjects were carnitine deficient before taking the supplements. Type 2 diabetes Insulin resistance, which plays an important role in the development of type 2 diabetes, may be associated with a defect in fatty-acid oxidation in muscle [ 27 ].
This raises the question of whether mitochondrial dysfunction might be a factor in the development of the disease. Increased storage of fat in lean tissues has become a marker for insulin resistance [ 27 ]. Early research suggests that supplementation with L-carnitine intravenously may improve insulin sensitivity in diabetics by decreasing fat levels in muscle and may lower glucose levels in the blood by more promptly increasing its oxidation in cells [ ]. The treatment was most effective in subjects with type 2 diabetes of short duration [ 30 ].
HIV-infected individuals often accumulate fat in some areas of the body and lose fat in others and develop high levels of blood fats hyperlipidemia and insulin resistance, which together constitute the lipodystrophy syndrome. This syndrome may represent mitochondrial toxicity brought about by the HIV infection and the antiretroviral drugs used to treat it, and can induce a carnitine deficiency that limits mitochondrial fat metabolism [ 31 ].
The molecular mechanisms by which this occurs are poorly understood. End-stage renal disease and hemodialysis Carnitine homeostasis balance within the body among individuals with renal diseases can be substantially impaired by several factors, particularly reduced synthesis and increased elimination of the compound by the kidneys as well as reduced intake from food due to poor appetite and consumption of fewer animal products [ 41 ].
Many patients with end-stage renal disease, particularly those on hemodialysis, become carnitine insufficient. Carnitine blood levels and muscle stores are low, which may contribute to anemia, muscle weakness, fatigue, altered levels of blood fats, and heart disorders.
Numerous studies suggest that high doses of supplemental carnitine often injected in patients on maintenance hemodialysis can correct some or all of these symptoms, though most involve small numbers of patients and are not double-blinded trials.
A recent meta-analysis of these studies concludes that carnitine supplements may aid anemia management but not blood-lipid profiles, and that their effects on exercise capacity or heart stability are inconclusive [ 42 ]. Male infertility The carnitine content of seminal fluid is directly related to sperm count and motility [ 43 , 44 ], suggesting that the compound might be of value in treating male infertility. The reported benefits may relate to increased mitochondrial fatty-acid oxidation providing more energy for sperm and reduced cell death in the testes [ 49 ].
Larger and more carefully designed studies are needed to evaluate carnitine's potential value as an infertility therapy. Rarer side effects include muscle weakness in uremic patients and seizures in those with seizure disorders. Some research indicates that intestinal bacteria metabolize carnitine to form a substance called TMAO that might increase the risk of cardiovascular disease [ 24 ]. This effect appears to be more pronounced in people who consume meat than in vegans or vegetarians.
The implications of these findings are not well understood and require more research. Carnitine interacts with pivalate-conjugated antibiotics such as pivampicillin that are used in the long-term prevention of urinary-tract infections [ 51 ]. Chronic administration of these antibiotics increases the excretion of pivaloyl-carnitine, which can lead to carnitine depletion.
However, while tissue carnitine levels may become low enough to limit fatty acid oxidation, no cases of illness due to deficiency have been described [ 1 , 6 ].
Treatment with the anticonvulsants valproic acid, phenobarbital, phenytoin, or carbamazepine has been shown to significantly reduce blood levels of carnitine [ ]. In addition, the use of valproic acid with or without other anticonvulsants may cause hepatotoxicity and increase plasma ammonia concentrations, leading to encephalopathy [ 54 , 55 ].
This toxicity may also occur following acute valproic acid overdose. L-carnitine administration may help treat valproic acid toxicity in children and adults, though the optimal regimen has not been identified [ ]. L-carnitine, acetyl-L-carnitine, and propionyl-L-carnitine are available over-the-counter as dietary supplements. Carnitine is often promoted as an aid for weight loss, to improve exercise performance, and to enhance a sense of well-being [ 2 ].
It is also a drug approved by the Food and Drug Administration to treat primary and certain secondary carnitine-deficiency syndromes. The federal government's — Dietary Guidelines for Americans notes that "Because foods provide an array of nutrients and other components that have benefits for health, nutritional needs should be met primarily through foods. In some cases, fortified foods and dietary supplements are useful when it is not possible otherwise to meet needs for one or more nutrients e.
For more information about building a healthy dietary pattern, refer to the Dietary Guidelines for Americans and the U. Department of Agriculture's MyPlate. This fact sheet by the Office of Dietary Supplements ODS provides information that should not take the place of medical advice.
We encourage you to talk to your healthcare providers doctor, registered dietitian, pharmacist, etc. Any mention in this publication of a specific product or service, or recommendation from an organization or professional society, does not represent an endorsement by ODS of that product, service, or expert advice.
Updated: March 29, History of changes to this fact sheet. Find ODS on:. Strengthening Knowledge and Understanding of Dietary Supplements. Health Information Health Information. Carnitine Fact Sheet for Health Professionals. Carnitine Health Professional Other Resources. Table of Contents Carnitine: What is it?
What are recommended intakes for carnitine? What foods provide carnitine? Absorption and metabolism of carnitine When can a carnitine deficiency occur? What are some current issues and controversies about carnitine?
Are there health risks from too much carnitine? Carnitine and medication interactions Supplemental sources of carnitine Carnitine and healthful diets References Disclaimer.
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