Alpha-ketoisocaproic acid

Amino-acidKeto acid

What is it

Alpha-ketoisocaproic acid (KIC) is the keto acid corresponding to the branched-chain amino acid leucine. It is sold in sports nutrition products as a metabolite of leucine intended to support muscle and reduce protein breakdown.

Evidence for 1 use

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Muscle protein synthesis support

Mixed Evidence

Small human studies suggest mTORC1 activation similar to leucine, but evidence that KIC adds meaningful benefit over leucine or whole protein is limited.

How it works

KIC sits at the transamination step between leucine and its catabolic metabolites. Supplementing KIC can in principle be transaminated back to leucine in the body. Animal and small human studies suggest KIC has mTORC1-activating and possibly anti-catabolic effects, but the evidence is not as strong as for leucine itself. Whether KIC supplementation offers any advantage over taking leucine or whole protein is unclear.

Dosage

DSLD does not list a single standardized dose. Commercial products commonly supply 1-3 g per serving as part of a BCAA or recovery blend. No RDA exists.

When and how to take it

Most often taken before or after training, with or without food.

1 commercial form

Compare the main delivery options and what they’re best suited for.

Calcium KIC

Common ingredient in older BCAA and recovery formulas.

Salt form used to stabilize the keto acid

Safety

Short-term use in studied amounts appears well tolerated. Higher long-term doses have not been extensively evaluated.

Who should be cautious

Avoid in pregnancy and breastfeeding. People with maple syrup urine disease or other branched-chain amino acid disorders must avoid KIC.

Interactions

No major drug interactions are documented at typical sports nutrition doses.

Frequently asked questions

Is KIC the same as leucine?⌄

No, but it can be converted to leucine in the body and has overlapping effects.

Is it banned?⌄

KIC is not currently a controlled or banned substance for general use. Athletes should check their sport's rules.

References

Alpha-ketoisocaproic acid on Wikidata — Wikidata link

Alpha-ketoisocaproic acid (ChEBI:48430) — ChEBI link

Alpha-ketoisocaproic acid (PubChem CID 70) — PubChem link

Alpha-ketoisocaproic acid on NIH DSLD (US supplement label database) — NIH Dietary Supplement Label Database link

Research on Alpha-ketoisocaproic acid (PubMed search) — PubMed link

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Evidence-based·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.