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L-Carnitine Guide: What Is It and Who Should Use It

Amino acids build proteins which build cellsOein other words they make up our very foundation. Every part of us starts with a cell; that means skin, hair, finger and toe nails, major organs, blood, and muscles to name a few of our components. The chemistry of amino acids gets tricky and some of them are synthesized or made from others. L-carnitine, an example of one of these, results from lysine and methionine combining in our bodies. We can also get it from red meats, avocados, and dairy as well as supplements.

Knowing where it comes from means nothing if you don’t know what it does for you. Actually it serves many important functions including helping muscles fight off the fatigue and soreness brought on by a heavy workout. It also burns fat, promotes energy, and helps dieters remain strong and not feel hungry.

L-carnitine works by carrying chains of fatty acids to the mitochondria (energy production centers) of cells where it turns into energy crucial for muscle function. Another way of saying it is that it metabolizes fat and converts it into energy. Our bodies make l-carnitine in the liver and kidneys and then store it in the sperm, muscles, brain, and heart. Although some people lack enough lysine and methionine to make l-carnitine or can’t absorb enough from their diets, it doesn’t happen very often. People tend to supplement their diets when they have certain medical conditions, which we’ll discuss later in this article and when they practice bodybuilding or other extreme athletics.

L-carnitine most notably benefits the human cardiovascular system by increasing heart energy and function. All these pluses make it extremely popular in the world of supplementation.

Some other conditions that may lead to L-carnitine deficiency are diets too high in fat, medications, liver and/ or kidney dysfunction, and an inherited inability to absorb it. If you experience symptoms such as chest or muscle pain, low blood pressure, mental confusion, or extreme fatigue, tell your doctor or trainer. It could be that using an L-carnitine supplement will eliminate these problems.

Researchers have studied L-carnitine for over 70 years. Some skeptics downplay the results, but generally speaking supplementing with this amino acid shows positive results. It promotes blood flow which increases energy, metabolizes fat rather than storing it up to add pounds, stimulates the memory and mental focus, builds strong muscles and helps keep them from breaking down too much in the catabolic state after working out, and helps dieters keep up their strength.

Different Forms

L-Carnitine comes in a number of easy-to-take forms, such as tablets, capsules, liquid, powder, and serum. The choice as to how best to ingest it is of course up to you. Liquid and serum enter the bloodstream more quickly and are more concentrated forms. When you apply the serum under your tongue it bypasses the digestive system, thus avoiding any stomach or intestinal upsets. This happens because the membranes in the mouth absorb it directly. Capsules digest a bit more quickly than tablets. Most products are vegetable rather than animal based.In most cases the L-carnitine combines with other amino acids and supplements. For instance a high quality protein powder usually contains a number of ingredients essential to building and preserving strong, lean muscle mass. You’d be wise to talk with your trainer, nutritionist, or healthcare professional to find which ingredients will best meet your needs.

Different Types

You’ll find that there are different types of L-carnitine. Because the chemical make-ups vary slightly some work better for specific functions than others:

  • Acetyl-L-Carnitine- the acetyl group basically means a collection of acetyl acid. To put it simply the addition of it to the carnitine aids in good memory function and mental focus. As with other forms of L-carnitine it also increases energy
  • L-Carnitine-L-Tartrate- tartrate, found in nature in some fruits, helps stabilize the L-carnitine. It’s also and effective antioxidant and some studies have shown it aids in more rapid muscle recovery after heavy stress
  • L-Carnitine fumarate- especially good for both metabolizing fat and sending plenty of oxygen to the heart, both valuable properties for athletes
  • D-Carnitine, D-L-Carnitine- only available synthetically and the FDA labels it as an illegal food additive
  • Glycine Propionyl-L-Carnitine (GPLC) – especially good for muscles as it promotes strong blood flow to them and makes up for oxygen lost during workout. Enhances fat metabolism and waste removal from cells


In addition to helping those with carnitine deficiencies, L-carnitine supplementation may benefit individuals with the following conditions or goals:


The research and studies sometimes conflict, but some believe that acetyl-l-carnitine may slow the effects of dementia occurring in early Alzheimer’s. This form of carnitine has proven effective in sharpening mental focus.


People with this condition often experience depletion of their amino acid levels and this could cause muscle deterioration. If you suffer from anorexia nervosa L-carnitine may help you get your strength back.

Better Workouts

Thanks to its fat metabolizing and energy production properties, many bodybuilders and others that exercise hard, find that supplementing with L-carnitine helps them get more bang for their buck when they work out.

Congestive Heart Failure

Congestive heart failure results when the heart becomes unable to pump enough blood to the lungs and other organs. L-carnitine improves heart health in many people that supplement with it. The extra energy it provides also allows them to get more exercise, thus stimulating the heart.

Chronic Fatigue Syndrome (CFS)

CFS remains a mystery, but some patients enjoy a better quality of life thanks to more energy when they supplement with L-carnitine.

Down’s Syndrome

L-carnitine, especially acetyl-l-carnitine aids memory and ability to focus. It has helped some people with Down’s syndrome improve in these areas.

Fat Burning

L-carnitine carries long-chain fatty acids to the mitochondria centers of the cells. These areas are where fat becomes energy so that muscles can burn it off rather than just storing it to add unhealthy weight to the body.

Heart Disease

Heart disease studies show impressive results when patients use L-carnitine. They seem less likely to experience chest pain, atypical heartbeats, or experience a second heart attack if they’d already had one. Additionally they often can exercise for longer periods.

High Cholesterol

Keeping cholesterol low is crucial to good heart health. L-carnitine helps raise good cholesterol levels and lower the bad.


This condition results when the thyroid gland works overtime, causing a number of uncomfortable symptoms. Regulating this gland is difficult, but L-carnitine has helped some people return to normal levels.


L-carnitine may help boost sperm count in males.

Kidney Disease

L-carnitine is made in the kidneys and liver, so it stands to reason that someone suffering from a kidney disease or disorder will benefit from ingesting more of it.

Leg Cramps

Some people suffer from peripheral vascular disease which means blood isn’t flowing properly to the legs. Because L-carnitine improves energy and stimulates the muscles, supplementing with it may allow them to exercise more and get that blood moving.

Liver Disease

Alcohol abuse leads to a build up of fat in the liver. L-carnitine may help minimize and possibly reverse this damage.


People generally go into shock after an injury, experiencing a heart attack, or losing too much blood. One function of L-carnitine is improved blood flow to the heart and other organs, so it may decrease the effects of shock.

Weight Loss

Opinions vary as to how well L-carnitine works when it comes to making it easier to lose weight. We’ve seen enough studies and heard enough testimonials to believe that it definitely proves beneficial. The fact that it helps metabolize fat makes it advantageous to dieters.

Amino acids such as L-carnitine help vegans, vegetarians, lactating women, and others deficient in them to receive more complete nutrition.

Disclaimer: These uses are suggestions resulting from various studies. They are not to be considered medical advice. If you experience symptoms related to these conditions or wish to improve any functions, don’t do so without consulting a healthcare professional.


A number of foods contain L-carnitine, especially lamb and dairy products. Other meats such as beef also contain it, but in lower quantities. Poultry, fish, peanut butter, asparagus, avocados, nuts, seeds, legumes, and wheat also contain some amounts.

Side Effects

Each person has a unique chemical make-up and reacts differently to substances. L-carnitine may cause rashes, unpleasant body odor, increased appetite, or diarrhea, but is generally well tolerated. As with any supplement, be sure to follow label directions. Always remember that more isn’t necessarily better. It’s best to talk with your doctor, trainer, nutritionist, or pharmacist before starting any supplementation program. If you take any medications learn about any possible interactions before trying L-carnitine. Research all products carefully to ensure that you purchase only those with high quality ingredients. Too many supplements add excess sugar for taste and fillers for bulk.


Whether you’re a bodybuilder, runner, team-sport player, or just want to be fit and healthy, L-carnitine may prove beneficial to you. Although many questions about protein, amino acids, and supplements in general still exist, most research in these areas finds positive results. The study of how to achieve maximum health is alive and well. We encourage you to pursue your own personal best!

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