Carnitine and I go way back—I wrote about the health benefits of L-carnitine in the very first issue of my newsletter in August 1991. Back then all we really knew about this supplement was that it improved angina, heart function, and exercise tolerance in patients with coronary artery disease and heart failure.
But today, there are many reasons to take L-carnitine. For instance, research shows that, when older people take this safe, inexpensive nutritional supplement, it boosts physical and mental energy and endurance, reduces fatigue and muscle loss, and enhances cognitive function.
Two Key Benefits: Energy and Healthy Aging
Carnitine is an amino acid that is synthesized in the liver and kidneys—and concentrated in the body’s most metabolically active organs: the brain, heart, and muscles. Its primary job is to transport fatty acids into the mitochondria, where they’re burned for energy.
Young, healthy people produce all the carnitine they need. However, levels may be depleted by kidney disease, liver disease, genetic defects, valproic acid (an epilepsy drug), cancer—and advancing age. Declines in mitochondrial function are a significant underlying cause of the energy drain associated with aging, and carnitine plays an essential role in increasing energy production. Therefore, it’s not surprising that deficiencies in this amino acid are associated with fatigue, loss of muscle mass and increase in body fat, mental and physical slowdown, and frailty.
This leads to an obvious question. Could replenishing carnitine stores with nutritional supplements delay or reverse some of the adverse effects of aging?
L-Carnitine Puts Pep in Your Step
Clinical trials of supplemental L-carnitine have yielded consistently positive results in terms of self-reported physical and mental fatigue, ability to exercise, and improvements in body composition—particularly when the study subjects are older and/or have documented carnitine deficiencies.
Here’s an example. Italian researchers enrolled centenarians, who fatigued easily and had impaired strength and mobility, and gave them either 2 g of L-carnitine or placebo capsules daily. After six months, no significant changes were noted in the placebo group. Those who took L-carnitine, however, gained an average of 8.4 pounds of muscle mass and lost four pounds of fat. Mental and physical endurance improved, and they gained an average of four points on the 0–30 scale of the Mini-Mental State Examination, a common test of memory function.
Now you can see why I’m so enthusiastic about the health benefits of L-carnitine. If 100-year-olds can have such remarkable turnarounds, just imagine what it could do if you started taking L-carnitine in your 60s or 70s, when carnitine concentrations begin to plummet?
L-carnitine's efficacy in heart disease was confirmed by a meta-analysis published recently in the Mayo Clinic Proceedings. Researchers analyzed 13 placebo-controlled studies involving 3,629 patients with a history of heart attack. Compared with placebo, L-carnitine reduced angina by 40 percent, dangerous ventricular arrhythmias by 65 percent, and death by 27 percent.
Additional Benefits of L-Carnitine
L-carnitine is often positioned as a weight loss aid. Although it definitely improves body composition in older people, many of the studies in younger people aren’t so positive, probably because they already have optimal carnitine stores. It can, however, enhance exercise endurance and capacity in all age groups by increasing muscle carnitine levels and improving energy metabolism. L-carnitine is by no means a magic bullet, but if you’re willing to exercise regularly—especially if you do intermittent fasting—it may help.
Other health benefits of L-carnitine, especially acetyl-L-carnitine, include improved memory in older people and slowing of Alzheimer’s progression. The acetyl group in this type of L-carnitine can be used to form acetylcholine, an important neurotransmitter that markedly declines as dementia advances. Both forms, however, increase mitochondrial energy production and power up energy-starved brain cells.
Patients with cancer will likely benefit from L-carnitine as well. Most people who undergo chemotherapy and/or radiation report significant fatigue. In addition, advanced disease is associated with cachexia, or muscle wasting and weight loss, and low carnitine levels may well contribute to this. L-carnitine is not a cancer therapy, but it has been reported to improve fatigue and quality of life—and that’s reason enough to use it.
More benefits of L-carnitine include relief from chronic fatigue syndrome, diabetic neuropathy, peripheral vascular disease and intermittent claudication, insulin resistance and type 2 diabetes, kidney disease and dialysis, and male infertility and erectile dysfunction.
Start Reaping the Benefits of L-Carnitine
You can get carnitine from dietary sources including poultry, fish, dairy, and red meat, but for therapeutic purposes I recommend supplements. If memory is your main concern, you may want to go with acetyl-L-carnitine; otherwise, stick with less expensive L-carnitine. The suggested dose is 2–4 g per day, taken in divided doses (1–2 g twice a day) between meals.