L-Carnitine
The Science Behind an Important
Functional Nutrient for People and Pets
Johnny Lopez, PhD
Outline
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Introduction and history
Food Science and Chemistry
Roles of L-Carnitine in the body
Thinking outside the box
Summary
Introduction and history
• L-Carnitine first discovered in 1905
– 1927 structure became more defined
– 1948 thought to be a B vitamin (Vitamin BT)
• its role in B oxidation became more understood
– 1962 established it to be “L- Carnitine”
– Years later much more learned
Historical review of progress…
Item
Timeframe
On Mitochondria
1960’s
Inflammation and connective tissue
Late 60’s-70’s
Tumor and cancer cells
Early 70’s to date
Myopathies, cardiac failure
90’s thru today
infants and feeding formulas
Mid 90’s
Aging, type 2 diabetes, chronic fatigue,
Alzheimer's, performance
Late 90’s thru today
Food Science and Chemistry
O-
O
C
H C H
H
O C H
H C H
+
N
CH
CH
3
3 CH
3
L-Carnitine
Synonym:
Vitamin BT
Reactive properties:
• Molecular weight 161
• Hygroscopic
Stability: Thermostable (up to 395°F)
Toxicity: Small, LD50 (rats) >5 g/kg BW
Approved: AAFCO and FDA approved
Food Science and Chemistry
Naturally synthesized
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Manufactured in liver & kidneys but varies by species
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In dogs, liver is the only active organ
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In cats, both liver and kidney are active
Starts with protein-bound Lysine and Sadenosylmethionine
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A 5-step process, typically last step is rate limiting

to manufacture 1 g of LC requires 30 g of muscle protein

requires vitamin C, niacin, vitamin B6 and iron
In humans, 25% of L-carnitine needs met by synthesis.
Metabolic demands for L-Carnitine
• Can be divided into 3 categories
– Primary
– Secondary
– Functional shortage
• age dependent
• condition dependent
Carnitine content of foods (mg/g)
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Muscle (lamb) Muscle (beef) Muscle (pig) Heart (cattle) Muscle (poultry)Milk (cow)
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2.03
0.61
0.27
0.23
0.09
0.026
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Liver (lamb) - 0.022
Salmon 0.0006
Rice
0.018
Eggs and peas - 0.008
Potatoes
- 0.0003
Carrots/spinach - 0.000
adopted Heinz Loster 2003/Rigault 2007
Total Carnitine, humans (umol/ml)
Infants (3 kg)
• Skeletal muscle 1.98
• Liver
0.55
• Heart
0.77
• Plasma
– males
– females
0.026
0.023
Adults (70 kg)
• Skeletal muscle
• Liver
• Heart
• Brain
3.96
2.90
4.80
0.30
L-Carnitine in Pet Food
• Varies by type of ingredients
– foods of animal origin blended with other ingredients
– processing such boiling, soaked, washing
– freezing and/or drying
• Not understood is bioavailability of natural forms
of L-Carnitine
• It matters: bound vs free L-Carnitine
L-Carnitine physiology and its role
in energy production
Cell
+
CoA
L-Carnitine
L-Carnitine
ß-
+
CoA Oxidation
CoA
Krebs-Cycle
Respiration
Fatty
acid
CoA
+
Cytosol
L-Carnitine
L-Carnitine
+
CoA
Mitochondria
CoA
+
Energy
(ATP)
L-Carnitine supplementation
can influence total metabolism
Glucose
Glycogen
Pyruvate
Carboxylase
Pyruvate
↑ β-oxidation
Acetyl CoA
OAA
TCA
Protein
Amino Acids
α-kg
↓ BCAADH
(leucine, iso,)
Citrate
Fat +
L-Carnitine
Roles of L-Carnitine in the body
• Convert fat into energy.
– Helps manage weight loss in dogs and cats
• Cardio-vascular system
– Heart energy comes mostly from fat and L-Carnitine
• Antioxidant support
– Serves as an antioxidant
• Cognitive function
– cerebral absorption of Fat soluble vitamins; protect from oxidative decay
• Maintaining muscle integrity
– provide blood flow to smooth muscles
Human usage of L-Carnitine
• Large number of products entering the market
– Examples
• The amount of publications out per year
– Table
Thinking outside the box
• Weight management
• other applications
Thank You!
Johnny Lopez, PhD
Business & Technical Manager
Tel: 817-995-2484
Fax: 201-669-3576
Email: johnny.lopez@lonza.com