L-Carnitine

Key points

• L-carnitine helps move fatty acids into the mitochondria, the part of the cell that produces energy.
• The body makes its own and it is found in red meat and dairy, so true deficiency is uncommon.
• It is sold as a food supplement and offered as an injection or IV drip at some clinics.
• It is marketed for fat loss, energy and exercise, but the evidence for these is limited.

Quick facts

What it is

Amino acid derivative that carries fat into cells

Marketed for

Fat loss, energy and exercise

Forms

Food supplement; injection and IV drip

UK status

Not a licensed weight loss medicine

Evidence

Modest; small effect in people who are not deficient

How it works

To be burned for energy, fats have to be carried into the mitochondria, and L-carnitine is the shuttle that does this. The thinking behind the supplements and drips is that more carnitine could help the body use fat for fuel. In practice the body usually has enough, so adding more makes less difference than the marketing suggests.

What the evidence shows

L-carnitine has a genuine role in energy metabolism, and it is used medically for the rare condition of carnitine deficiency. For fat loss, sports performance and energy in people who are not deficient, the evidence is modest and mixed. Any effect on weight is small at best.

What it does not settle

• Benefits for fat loss or performance in healthy people are small and inconsistent.
• The value of IV drips over simply eating a normal diet is unclear.
• Long term effects of high dose supplements are still debated.

Side effects

Common

• At high oral doses it can cause nausea, stomach upset and a fishy body odour.
• Injections or drips can cause reactions at the site.

Less common but serious

• A drip is a medical procedure with its own risks and should be given by a suitable professional at a registered clinic.
• Material of unverified quality bought online carries the usual risks of an unknown dose and contamination.

Report any suspected side effect through the MHRA Yellow Card scheme.

UK legal status and access

L-carnitine is widely sold as a food supplement, and offered as an injection or IV drip at some private clinics. It is not a licensed weight loss medicine in the UK. If you are considering a drip, check that the clinic is registered and the person giving it is qualified.

Common questions