What is Carnitine?

Scientists discover the amino acid’s hidden power.

What Is Carnitine?

Many foods contain carnitine, though the best dietary sources are red meat and dairy products. We can also synthesize carnitine in the liver from the amino acids lysine and methionine.

In the body, carnitine has several useful functions, but the one of primary interest to most people is its role in transporting long-chain fatty acids into the powerhouse of cells (the mitochondria), where they are broken down to a form that can be used to create energy. In fact, this function alone spurred the creation of carnitine in supplemental form decades ago. And, in theory, it makes sense:

Supplement with carnitine => increased total carnitine in the body => more fat is transported into your cells and burned for energy, sparing carbohydrate use, making you leaner and enhancing endurance performance.

We also know that skeletal muscle carnitine concentration decreases during exercise, which made this theory even more convincing. If we exercise and our carnitine stores drop, supplemental carnitine will help our bodies continue using fat for energy instead of stored carbohydrates.

Unfortunately, we were all left wondering why this theory didn’t translate to real life. Supplemental carnitine never made its way into the muscle cells to increase total carnitine concentration. And, therefore, our bodies burned the same amount of fat and carbohydrates with or without using carnitine.

New Carnitine Supplements

So what’s different now? New research-backed forms of carnitine have hit the market, notably glycine propionyl-l-carnitine (GPLC) and carnitine tartrate. In one study, resistance-trained men given 4.5 g of GPLC 90 minutes prior to a cycling test increased peak power compared to those given a placebo. Studies on carnitine tartrate indicate that it can boost recovery.

The mechanical stress of exercise leads to structural damage to muscle cells. Carnitine tartrate may minimize some of this muscle damage by replacing carnitine depleted during exercise. A study from the University of Connecticut found that trained men who took 2 g carnitine tartrate per day for three weeks prior to a bout of squats experienced less muscle-tissue damage than the men taking a placebo. Carnitine works by promoting muscle-tissue oxygen consumption, which mitigates the biochemical cascade that results in muscle damage, soreness and decreased performance.

The Potential of Carnitine

• Enhanced recovery and decreased muscle damage in trained athletes
• Improved exercise performance in those with peripheral arterial disease (PAD)
• Increased exercise tolerance in those with congestive heart failure
• Increased strength and exercise tolerance in those with COPD (chronic obstructive pulmonary disease)

Carnitine: An Action Plan

A study from the University of Nottingham found that supplemental carnitine does indeed enter muscle cells, increasing total skeletal carnitine content if you take it when your circulating insulin levels are high. How can you do this? Take carnitine with food or a beverage that boosts your body’s production of insulin. The best way to do that is through sugary foods such as a sports drink, sports gel with water or another high-glycemic carbohydrate.