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Pets Thrive on Nutrtional Supplementation |
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by Kevin Owen, Ph.D.
L-carnitine—its advantages in companion animal nutrition—most people don’t realize that the heart obtains 70–80 percent
of its energy from fat breakdown. The fundamental role that L-carnitine
plays in energy metabolism, together with the dependence of theheart
on fatty acid breakdown for energy production, make L-carnitine
a crucial component in maintaining a healthy heart.
Over the last decade consumers
have become
increasingly attracted to
taking better care not
only of themselves but
also their pets. In fact,
pet owners are focusing
as much time on their pet’s nutritional programs
as on their own families. The main goal in mind
being an improvement in the overall health of
their pets, resulting in an extension and quality
of life. In knowing this, pet food manufacturers
are constantly examining new novel ingredients
to improve the overall health of pets. One such
ingredient that has received much attention of
the last 5 years is L-carnitine.
L-carnitine is a vitamin-like compound that is
widely utilized in both the human and animal
nutrition fields. Its primary function is to transport
long chain fatty acids across the mitochondrial
membrane into the mitochondria so they
can be broken down through a process called
â-oxidation. L-carnitine appears to be particularly
important when the production of energy
relies to a large extent on â-oxidation of fatty
acids. With this in mind, clinical studies support
the need for supplemental L-carnitine in pet food
diets targeted for the following applications.
Weight Management:
Overweight and obesity are increasing at an
alarming rate in both human adults and their
pets. It has been estimated that more than 50
percent of U.S. adults and 40 percent of dogs
and cats are currently overweight. This is
where L-carnitine comes as good news as it
helps promote a healthier body weight and
favors muscle (lean tissue) deposition and
reduced body fat content.
Clinical studies evaluating the effect of supplementing
high (300 to 500 ppm) levels of Lcarnitine
in dogs and cats respectively confirm
L-carnitine helps pets lose fat mass quicker
while helping the animal maintain lean muscle
mass. Thus at the conclusion of these studies,
all pets had more lean muscle mass. Because
lean muscle uses more calories than fat, investigators
conclude that increased lean mass is
desirable for long-term prevention of recurrence
of obesity. Based on these studies,
researchers proposed L-carnitine apparently
directs metabolism toward more protein and
less fat accretion.
Heart Function:
As a natural component of the heart, L-carnitine
supports healthy cardiac function. Most
people don’t realize that the heart obtains
70–80 percent of its energy from fat breakdown.
The fundamental role that
L-carnitine plays in energy metabolism,
together with the dependence of the heart on
fatty acid breakdown for energy production,
make L-carnitine a crucial component in
maintaining a healthy heart.
In dogs there is an association between idiopathic
carnitine deficiency and myocardial disease;
50–90 percent of dogs with
cardiomyopathy may have myocardial carnitine
deficiency, which results in impaired heart
muscle contraction. Other diseases, such as congestive
heart failure and myocardial ischemia, can
produce myocardial carnitine deficiency. On the
other hand, clinical reports show that L-carnitine
supplementation can improve heart function.
Liver Function:
As a normal structural component of the liver,
L-carnitine supports healthy hepatic function.
In healthy animals the liver maintains a balance
between lipids entering the liver through
diet and metabolic processes and lipids
removed from the liver by â-oxidation or
exportation to other tissues. L-carnitine is
required for these metabolic processes. In
many disease states, as well as in pregnancy
and lactation and during food deprivation, the quantity of fatty acids reaching the liver
increases due to the increased breakdown of
body fat. If there is a deficiency of L-carnitine,
these fatty acids cannot be efficiently processed
and consequently lipid accumulates in the
liver cells (hepatic lipidosis). In humans this
can result in severe hepatic failure.
 Growing Animals:
The ability to synthesize L-carnitine is under
developed in young puppies and kittens and
therefore, the maternal milk contains large
amounts of L-carnitine in the first days of life. In
addition, L-carnitine supplementation has been
shown to increase muscle and bone mass as well
as bone density in growing large breed puppies.
Performance Animals:
Fat and carbohydrates are the primary fuels
used to meet the energy demands on physical
exercise. In addition to supporting the cardiovascular
system and promoting a healthier
weight, L-carnitine’s fundamental role in fat metabolism may result in multiple benefits for
animals used for work and sporting purposes
- optimization of performance
- delayed onset of fatigue
- enhancement of recovery process
Sources of L-carnitine:
L-carnitine is supplied to the pet’s body
through both endogenous synthesis and food
intake. Although healthy dogs and cats
have some ability to endogenously synthesize
L-carnitine, and small amounts are supplied
by dietary means, supplementation is required
to help optimize L-carnitine’s health benefits.
Natural Levels of L-carnitine in Pet Foods:
Most pet foods are relatively low in L-carnitine
due to the types of ingredients used. L-carnitine
occurs naturally in both plant and animal
origin foods with animal foods containing
greater amounts of L-carnitine than those of
plant origin. However, there is a common concern
that compared to uncooked “natural”
foods, such as raw ground beef or mouse carcass,
many pet foods have a low content of
L-carnitine due to losses in washing, freezing
and cooking of raw ingredients. Because
L-carnitine is water soluble, a significant
amount of the total L-carnitine is leached from
tissues and lost in ingredient processing. A
recent survey of U.S. grocery brands showed
that L-carnitine levels in almost all dry and
canned dog and cat food was 1–7 percent of
the level in raw ground beef. To overcome this
potential deficiency, supplemental L-carnitine
can be incorporated in food formulation treats
or as a stand alone powder that can be added
to food.
L-form vs. D-form:
Carnitine can be obtained chemically in the
D- or L-form. Only the L-form is metabolically
active and of nutritional value. The
D-form can actually be harmful. D-carnitine
competitively inhibits the transport of
L-carnitine in the cell. D-carnitine is responsible
for muscle weakness and cardiac arrhythmias
in some patients given racemic D,
L-carnitine. D-carnitine is not just an inert
substance but a potentially toxic impurity.
In summary, extensive clinical and animal
research has discovered L-carnitine has a beneficial
role to play in a broad array of applications
including weight management, heart health,
liver function and sporting performance. All
benefits are obtained due to L-carnitine’s
activity in fatty acid metabolism.
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