The role of Beta-Hydroxybutyrate (BHB)
At the heart of most artificial ketone supplements is the molecule Beta-Hydroxybutyrate (BHB). BHB is one of the three main ketone bodies that the body produces naturally during ketosis, along with acetoacetate and acetone. However, BHB is the most stable and widely used in supplements. The body preferentially uses the D-BHB enantiomer for energy, while the L-BHB isomer is metabolized more slowly. Most readily available supplements contain a racemic mixture of both, meaning you get a less potent product than those containing only the D-BHB form.
Ketone salts: The most common form
Ketone salts are a popular and affordable type of exogenous ketone, typically found in powder form. Their composition is straightforward: a ketone body, almost always BHB, is bonded to a mineral ion to create a salt.
Commonly used mineral salts include:
- Sodium
- Potassium
- Calcium
- Magnesium
This bonding process helps to stabilize the BHB and allows for easier ingestion. The mineral salts also help to replenish electrolytes that are often depleted during the early stages of a low-carb, high-fat diet, a period often referred to as the 'keto flu'. However, this also means that high doses can deliver a significant salt load, potentially causing gastrointestinal issues for some users.
Ketone esters: The potent, fast-acting option
Ketone esters are a more advanced and potent form of exogenous ketones, commonly available in liquid form. The defining feature of a ketone ester is an ester bond, which links a ketone body (BHB or acetoacetate) to a precursor compound, such as 1,3-butanediol. When consumed, the body breaks the ester bond to release the free ketone body for energy.
Types of ketone esters include:
- (R)-3-hydroxybutyl (R)-3-hydroxybutyrate (KME): A monoester linking D-BHB to 1,3-butanediol.
- (R,S)-1,3-butanediol acetoacetate (KDE): A diester of acetoacetate and 1,3-butanediol.
Ketone esters typically raise blood ketone levels higher and faster than ketone salts, but they are also more expensive to produce and have a notoriously unpleasant taste.
Ketone precursors: Stimulating natural production
Instead of providing pre-formed ketone bodies, some supplements use precursors that the body converts into ketones. The most well-known are Medium-Chain Triglycerides (MCTs), which are fats that are rapidly metabolized into ketones in the liver.
Common MCTs used include:
- Caprylic acid (C8)
- Capric acid (C10)
- Lauric acid (C12)
Another precursor is 1,3-butanediol, a molecule that is metabolized in the liver to produce BHB. It is often used as the precursor compound in ketone esters but is also available on its own. Unlike direct ketones, precursors require the liver to do some work, resulting in a more gradual and sustained rise in blood ketone levels.
Comparison of artificial ketone types
Understanding the differences between the main types of exogenous ketone supplements is key to choosing the right product for your needs.
| Feature | Ketone Salts | Ketone Esters | Ketone Precursors (MCTs) |
|---|---|---|---|
| Composition | BHB bonded to mineral salts (Na, K, Ca, Mg) | BHB or AcAc bonded to an alcohol compound (e.g., 1,3-butanediol) | Medium-chain fatty acids (C8, C10) |
| Effect on Ketones | Moderately elevates blood ketone levels | Rapidly and significantly elevates blood ketone levels | Gradually and moderately elevates blood ketone levels |
| Typical Form | Powder | Liquid | Oil or Powder |
| Cost | Generally more affordable | More expensive due to complex manufacturing | Variable, often a mid-range option |
| Taste | Often flavored to mask mineral taste | Poor palatability is a common complaint | Generally palatable; some oils can have a distinct flavor |
| Side Effects | Potential for high mineral load and GI distress | Can cause nausea at high doses | GI distress (diarrhea) can occur with high doses |
For a more in-depth look at the science behind ketone supplements, you can review the extensive research on the topic see this article on the National Institutes of Health (NIH) website for one example.
Conclusion
Artificial ketones are not a single substance but a category of supplements with distinct formulations, each made from different core components. Ketone salts provide BHB bonded to minerals, offering a cost-effective and accessible way to increase ketones. Ketone esters provide a more potent and rapid increase by bonding BHB to a precursor like butanediol. Finally, ketone precursors such as MCTs provide the raw material for your body to produce its own ketones. Your choice depends on your specific goals regarding efficacy, speed of effect, taste, and budget.
