Read the label on a ketone salt and you may see D-BHB, D,L-BHB or racemic BHB. They sound alike, but they describe different mixes of the same molecule. Here is what the letters mean.
Why we write about this
Our founder, Dr. Csilla Ari, has studied D,L-BHB in the lab, and our KETOSTART line contains D,L-BHB. We want you to know what that means.
Mirror-image molecules
Some molecules come in two versions that are mirror images of each other, like your left and right hands. Chemists call them enantiomers and label them D and L. Beta-hydroxybutyrate (BHB) is one of these molecules.
- D-BHB: the form your liver mainly makes during fasting or a ketogenic diet, and the form most quickly used for energy.
- L-BHB: present in much smaller amounts in the body. It is processed more slowly, so it stays in the bloodstream longer
- D,L-BHB: a roughly equal mix of both, common in ketone salt supplements. Also referred to as racemic.
New to BHB? Start with What Is BHB?
Why the form matters in research
When you read a study, check which form was used, because results with one form may not apply to the other.
- In Dr. Ari's 2024 lab study, researchers used sodium D,L-BHB at 2 mM on scratched rat neurons to simulate nervous system injury. After 24 hours, 49% of the injured gap areas had narrowed, compared with 1.5% in untreated dishes.
- In a 2020 rat study of spinal cord injury, researchers used a calcium/sodium BHB salt together with a ketogenic diet. You can read about it in our post on spinal cord injury and nutrition research.
Both are animal or lab studies. They do not show that any form of BHB helps people recover from an injury.
What we still do not know
- How D-BHB and L-BHB compare head to head for brain-related outcomes.
- Whether L-BHB has distinct effects in people.
- The best form and amount, if any, for specific situations.
How to read a ketone label
- Look for the form: D-BHB, D,L-BHB or racemic BHB.
- Check grams of BHB per serving, not just the total salt weight.
- Note the minerals (sodium, potassium, calcium, magnesium) and their amounts, especially if you watch your sodium.
The bottom line
D-BHB and L-BHB are mirror-image forms of the same ketone. Many supplements, and some research, use a D,L mix. Knowing the form helps you read both labels and studies. KETOSTART provides 6 g of D,L-BHB per serving to help you reach and maintain ketosis.
This article is for education only and is not medical advice. These statements have not been evaluated by the FDA. Our products are not intended to diagnose, treat, cure or prevent any disease. Talk to your doctor before changing your diet or supplements.
Disclosure: Dr. Csilla Ari, an author of the 2024 study, is the founder of Audacious.