Protein - Carnitine

Question 1

Carnitine

Answer 1

• Carnitine is an amino acid derivative that can be obtained from the diet or synthesised in the body from methionine and lysine. This production requires iron, vitamin C, B3, B6.

Question 2

Deficiency

Answer 2

• Deficiency of carnitine (rare) results primarily from errors of metabolism, and not from insufficient dietary intake, as the body is usually able to synthesise adequate quantities.

Question 3

Mutations & conditionally essential

Answer 3

• Mutations of the ‘SLC22A5’gene can make it a conditionally essential AA.

Question 4

Food Sources

Answer 4

• Direct food sources: nuts, seeds, avocado, asparagus, spinach, red meats, dairy

Question 5

Function: Thyroid

Answer 5

• Carnitine acts as a peripheral thyroid hormone antagonist, so it can be used therapeutically in cases of hyperthyroidism.
  antagonist = inhibits the physiological action

Question 6

Function:
Assist ATP synthesis from fatty acids

Answer 6

Function:
* Carnitine facilitates the transport of long-chain fatty acids across the mitochondrial membrane so they can be oxidised (‘burnt’) to create ATP. For example, in myocardial cells
* It also removes potentially toxic metabolites out of mitochondria, and acts as an antioxidant
Therapeutic Uses:
* Weight loss
* Heart failure
* Infertility – improves sperm count, motility; also reduces oxidative damage (highly concentrated in the testes)
* Fatigue and concentration
* Athletic performance
* ADHD (also shown to increase dopamine and acetylcholine production)

Question 7

Carnitine Supplementation: Dosage

Answer 7

• 1-2g twice a day
• Consider capsule / tablet rather than powder due to its unfavourable smell.

Question 8

Drug Interactions:

Answer 8

• Supplementing carnitine alongside anticoagulants (e.g. warfarin) increases the blood-thinning effects.
• Thyroid-hormones due to carnitine’s effects as a peripheral thyroid hormone antagonist, and thus high dose carnitine is contraindicated with hypothyroidism.

Question 9

Caution:

Answer 9

• L-carnitine use has been associated with nausea, vomiting, abdominal cramps, heartburn, gastritis, diarrhoea, body odour and seizures, but only at high doses.
• One of its metabolites can cause the urine, breath and sweat to have a fishy odour.