Little-Known Nutrient Sets Metabolism in Motion:New Research Focuses on a ‘Conditionally Essential’ Nutrient Called L-Carnitine

FAIR LAWN, NJ – Beyond vitamins and minerals, researchers are now focusing attention on a sub-category of nutrients, called “conditionally essential” – that is, essential under certain conditions. A conditionally essential nutrient that is now generating keen interest among researchers is L-Carnitine (ehl-car-nih-teen).

This trend in research follows a path paved by essential vitamins E and K and the nutrient choline over the years: presence of deficiency symptoms commands research; research finds a relationship between deficiency and nutrient under certain circumstances; the relationship is applied to other conditions; and additional functions are identified. L-Carnitine is a vitamin-like nutrient needed in all human and animal cells. L-Carnitine was initially identified as an essential nutrient in newborns and in people with an inherited metabolic defect. In both cases, scientists discovered that the body generates only small quantities of L-Carnitine naturally and that the majority of the cell’s supply comes from dietary sources. Deficiency symptoms include muscle weakness, fat accumulation in muscle tissue and heart conditions.

These discoveries led to the description of L-Carnitine’s critical function in fat metabolism. Subsequent research has demonstrated that L-Carnitine is a key factor in weight management and cardiovascular health.

L-Carnitine, like many of the B vitamins, is a co-factor in metabolism and assists in the process of converting protein, fat and carbohydrates from food into fuel for the body. Some of this fuel is used immediately for energy, and some is stored for use later on as, for example, fatty acids. The immediate energy is burned easily, but stored energy requires transport nutrients like L-Carnitine and elements like oxygen to set the metabolic process in motion.

Like a little shuttle bus, L-Carnitine is responsible for transporting fatty acids from stored spaces in the liver and muscle tissue into the “powerhouses” of cells, known as the mitochondria. This gives energy to the muscles, allowing them to pump stronger, which in turn stimulates oxygen to circulate more efficiently throughout the body. The increased supply of oxygen continues the cycle – more oxygen leads to more fatty acid being burned for fuel. Instances when oxygen is in limited supply include quick bursting activities and heart failure, when the heart pump is weak and circulation of nutrients is poor.

High levels of L-Carnitine increase the speed of burning fatty acids into energy, while low
L- Carnitine levels reduce the rate.1 With the ability to use immediate as well as stored energy, muscles in the body work better, stronger and more efficiently. For the population at large, the amount of L-Carnitine in the body is the most important factor governing the rate of fat metabolism.1

Exercise
Researchers are homing in on the role conditionally essential nutrients play in exercise as well. Since L-Carnitine increases the speed at which energy can be generated, use of L-Carnitine logically applies to optimizing performance in exercise.

In fact, sports enthusiasts have used L-Carnitine since the early 1980s to enhance their metabolism. Research shows that additional L-Carnitine in the system enables the body to tap into its secondary energy source – body fat – for energy. It also increases blood flow, which ultimately allows the athlete to exercise longer and feel less pain and soreness during and after the activity.2 3

Weight Management
Scientists have presented hundreds of theories about weight loss, but conditionally essential nutrients may be a key factor that has been overlooked in their attempts to jump-start weight loss. The ability of L-Carnitine to convert fatty acids into energy can also help people maintain a realistic weight. Research has shown by taking supplemental L-Carnitine, people can burn their fat stores more efficiently while maintaining lean muscle mass. In addition, the nutrient has been shown to affect other key factors in weight management by increasing tolerance to exercise with improved energy and decreased soreness.

Cardiovascular Health
Considerable attention has been devoted to the role of nutrition in cardiovascular health, but conditionally essential nutrients like L-Carnitine have shared little of the spotlight, until now. Research shows that L-Carnitine levels are depleted in the heart muscle of heart failure patients. One researcher showed that supplementation with L-Carnitine in heart failure patients improved energy metabolism and the actual performance of the heart muscle.4

In addition, research shows that L-Carnitine may be valuable in protecting against other heart problems related to insufficient pumping of the blood. It has been shown to reduce common heart pain called angina pectoris, reduce myocardial ischemia, which can lead to a heart attack, and reduce the extent or severity of a heart attack. 5 6 7

Where Can You Find L-Carnitine?
Healthy individuals can generate approximately 20 milligrams of L-Carnitine within the body, which represents approximately 10 percent of the nutrient used each day by the average person. Under certain conditions however, the body cannot synthesize and store adequate amounts. This is seen frequently in newborns, especially when premature.

Conditional essentiality is also seen with physical stress due to intense exercise or medical conditions. Under these conditions, the endogenous supply is extended with L-Carnitine in the diet or supplemental form. A balanced diet including foods such as enriched infant formula, lamb, beef, pork and poultry can provide approximately 10-30 milligrams of L-Carnitine to the body daily.1 8

Supplemental L-Carnitine is usually seen as a single nutrient or in formulations marketed for enhancement of exercise and metabolism. Supplement manufacturers generally follow research levels associated with health benefit, offering products that range between 50-250 milligrams
of L-Carnitine.

Future Potential for L-Carnitine
Malfunctions in metabolism can result in problems linked with many public health issues including overweight, obesity and heart disease. Conditionally essential nutrients may become the next clues to promoting health and preventing these health concerns. As researchers continue to reveal the capabilities and health functions of L-Carnitine, they will also explore the role of L-Carnitine in infant nutrition and cognitive health. Beyond vitamins and minerals, conditionally essential nutrients may soon emerge as missing links in the nutrition story.


The L-Carnitine InfoCenter was founded by Lonza, Inc. in 2001 to provide credible and reliable information on L-Carnitine for health professionals, educators and communicators. Additional information on L-Carnitine can be found on http://www.carnitine.com.

REFERENCES:

  1. Leibovitz, 1998. L-Carnitine: The energy nutrient. Keats Publishing, Los Angeles, CA. Pp 12-17.
  2. Burke, 1999. What Causes Muscle Fatigue (Ch. 3)? In: Muscle Recovery. Avery Publishing Group, Garden City Park, NY. Pp 33-36.
  3. Giamberardino, et al., Effects of prolonged L-Carnitine administration on delayed muscle pain and CK release after eccentric effort. International Journal of Sports Medicine 17(1996)
    Pp 320-324.

  4. Masumura, et al., Myocardial Free Carnitine And Fatty Acylcarnitine Levels In Patients With Chronic Heart Failure. Japanese Circulation Journal 54(1990) 1471-1476.
  5. Ferrari, et al., The Metabolical Effects Of L-Carnitine In Angina Pectoris. International Journal of Cardiology 5(1984) 213-216.
  6. Paulson, et al., 1995. Experimental Evidence of the Anti-ischemic Effect of L-Carnitine (Ch. 13) In: The Carnitine System: A New Therapeutical Approach to Cardiovascular Diseases. Kluwer Academic Publishers, The Netherlands. Pp 183-197.
  7. Singh, et al., A Randomized, Double Blind, Placebo-Controlled Trial Of L-Carnitine In Suspected Acute Myocardial Infarction. Postgrad Med J 72(1996) 45-50.
  8. Di Palma. L-Carnitine: Its Therapeutic Potential. American Family Physician 34(1986) 127-130.
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