L-carnitine, also called carnitine, and conjugated linoleic acid (CLA) are naturally occurring compounds. They’ve become popular for their potential to reduce body fat and enhance athletic performance. But it’s important to understand the limitations of their effectiveness before working them into your routine.
What Is Carnitine?
Carnitine is a compound derived from amino acids, the building blocks of protein. Carnitine is essential for energy production in your body. It carries long–chain fatty acids to energy-producing mitochondria in your cells, and helps remove toxins to prevent them from building up, according to the National Institutes of Health (NIH) Office of Dietary Supplements (ODS).
Your liver and kidneys typically make all the carnitine you need from the amino acids lysine and methionine. But this compound also occurs naturally in some foods, particularly animal products.
Most people’s bodies can make enough carnitine. But people with certain conditions, like kidney dysfunction, may need to get carnitine from food or supplements.
Carnitine and Weight Loss
Because of its role in converting fatty acids into energy, carnitine has been marketed as a dietary supplement. But according to the ODS, research has found only a “possible modest reduction in body weight” from taking carnitine.
Carnitine and Athletic Performance
Carnitine supplements may help improve athletic performance.
In a review published in the journal Nutrients, researchers found that taking 3 to 4 grams (g) of L-carnitine 60 to 90 minutes before exercise could increase strength and endurance. However, this effect was only seen in high-intensity exercises.
Food Sources of Carnitine
Carnitine is found mostly in animal products and in smaller amounts in some plant-based sources. According to the ODS, foods high in carnitine include:
- Cooked ground beef, 3-ounce (oz) serving: 65 to 74 milligrams (mg)
- Whole milk, 1 cup: 8 mg
- Codfish, 3-oz serving: 3 to 5 mg
- Chicken breast, 3-oz serving: 2 to 4 mg
Experts haven’t set an upper-limit for carnitine intake. But consuming more than 4 g per day may cause nausea, vomiting, diarrhea, abdominal cramps, and a fishy body odor.
What Is Conjugated Linoleic Acid (CLA)?
CLA is a fatty acid found in dairy, beef, and lamb products. It may have benefits such as aiding weight loss, increasing exercise performance, and reducing inflammation, according to a review published in the journal Nutrition & Metabolism.
CLA and Weight Loss
Like carnitine, CLA is available in the form of supplements aimed at enhancing weight loss.
According to the ODS, research suggests that CLA may play a role in converting fat for energy, reducing fat storage, and promoting fat-cell turnover.
A randomized controlled trial published in the journal Nutrients found that women who were overweight or obese and took 3 g of CLA per day had significant reductions in total body fat after 12 weeks.
But in a review published in the journal Food Research International, researchers noted that the weight loss effects of CLA may be small, and that more studies are needed on people in the general population.
CLA Safety
CLA tends to be well-tolerated, according to the ODS. Although, like carnitine, CLA may cause minor side effects, such as abdominal discomfort, constipation, and diarrhea.
Best Supplements for Athletic Performance
According to ODS, most studies on the potential of supplements to enhance athletic performance do not include carnitine and CLA. Instead, they focus on more-common ingredients, like amino acids, protein, creatine, and caffeine.
While some supplements, particularly caffeine and creatine, may help improve endurance or strength, others show little evidence for their effectiveness.
Organizations like the American College of Sports Medicine recommend focusing on good nutrition through a well-rounded diet to improve performance instead of relying on supplements, according to the ODS.
For most adults, including athletes, the Dietary Guidelines for Americans describes a healthy dietary pattern as one that includes:
- A variety of fruits, vegetables, and whole grains
- Protein sources like lean meats, poultry, eggs, and legumes
- Low–fat dairy products like low-fat milk, yogurt, and cheese
