L-Carnitine is a nutrient that is needed by the body to transport fats into the mitochondria where they are utilized to create energy. L-Carnitine can be synthesized by the body in the liver and kidneys from the amino acids lycine and methionine but it is also found in the diet, particularly in red meat. Under certain conditions, the need for L-carnitine may exceed an individual’s capacity to synthesize it, making it a conditionally essential micronutrient. Vegetarians are likely to lack L-carnitine. Newborns may lack sufficient levels of L-carnitine and it is found in mother’s milk and it is now added to some soy baby formulas.(1)
L-Carnitine supports the heart muscle and significantly improves cardiac health in patients after a heart attack, according to a recent study. Their findings, based on analysis of key controlled trials, associated L-carnitine with a significant reduction in death from all causes and a highly significant reduction in ventricular arrhythmias and anginal attacks following a heart attack, compared with placebo or control. L-Carnitine has also been shown to help patients with congestive heart failure.(2,3)
L-Carnitine has also recently been shown to improve the physical capacity of patients on dialysis by increasing energy usage from fats. L-carnitine levels tend to be decreased in patients on kidney dialysis since dialysis removes L-carnitine instead of being reabsorbed and since there is impaired production in the liver and kidneys. This is why such patients often have muscle weakness, that can be partially alleviated with L-carnitine supplementation.(4)
L-Carnitine is also used to improve fat burning and improve exercise performance. By enabling your body to burn more fat, you spare your carbohydrates and that may improve athletic performance. A number of small studies have shown increases in maximal oxygen uptake and decreases in plasma lactate with taking 2-4 gm/day of L-carnitine. There have not been large, controlled trials that have shown carnitine to improve athletic performance. My experience has shown benefit in certain types of athletes, esp. basketball and soccer players and sprinters.(5,6) In conclusion, given that supplementation with even large dosages of L-carnitine has not been proven to cause any harm, it might be worth a trial of 1-4 gm/day depending upon your condition. Speak to Dr. Weitz about whether L-carnitine is recommended for you and how much.
***Of course, if you are suffering with heart failure or are on dialysis, check with your doctor before taking any nutritional supplements like L-carnitine.
References:
1. http://lpi.oregonstate.edu/infocenter/othernuts/carnitine/
2. Carnitine in the secondary prevention of cardiovascular disease: systematic review and meta-analysis. Mayo Clin Proc. 2013;nn(n):1-8 http://www.medpagetoday.com/upload/2013/4/12/jmcp_ft88_4_2.pdf.
3. Rizos I. Three-year survival of patients with heart failure caused by dilated cardiomyopathy and L-carnitine administration. Am Heart J. 2000;139(2 Pt 3):S120-123.
4. Kudoh Y, Aoyama S, Torii T, et al. The effects of oral L-Carnitine supplementation on physical capacity and lipid metabolism in chronic dialysis patients. Nephron Extra. 2014;4:33-41.
5. Vecchiet L, Di Lisa F, Pieralisi G, et al. Influence of L-carnitine administration on maximal physical exercise. Eur J Appl Physiol Occup Physiol. 1990;61(5-6):486-490.
6. Karahan M, Çoksevim B, ArtisS. The effect of L-carntine supplementation on 1500m running performance. Ovidius University Annals, Series Physical Education and Sport / SCIENCE, MOVEMENT AND HEALTH., Issue 2 suppl. 2010.