When we say ketones, our company is discussing the primary circulating fatty acid metabolites beta-hydroxybutyrate (OHB) and acetoacetate (AcAc). Much more on ketone basics here. Exogenous ketones (also called ketone supplements) and well-formulated ketogenic diets share at least one thing in common. Both lead to increased circulating concentrations of beta-hydroxybutyrate (BOHB), but ultimately are associated with very different patterns of ketosis, as well as differing metabolic and physiologic outcomes. To put it briefly, they really should not be assumed to have equivalent effects since they achieve similar BOHB blood levels. With that in mind, there are many reasons we need to continue to study the various forms and potential applications of recommended keto supplements.
For the past few million years, the only way for humans to make use of ketones for fuel ended up being to restrict carbohydrates low enough and for enough time to induce the liver to make them. This is admittedly hard for most people to accomplish in a world that still believes that dietary carbs are great and fats are bad. An emerging alternative is always to consume ketones as a dietary supplement. The study into how these function within the body and what benefits they are able to confer remains early stage, but there are already several such products available for sale. In this particular section, we are going to discuss how exogenous ketones affect blood ketone levels, and how they could influence health insurance and disease compared to ketones produced within the body.
The 2 predominant ketones produced by the liver are beta-hydroxybutyrate (BOHB) and acetoacetate (AcAc). Here’s a short breakdown of basic info on these ketones:
It is actually estimated that the keto-adapted adult can make 150 or even more grams of ketones daily after adjusting to a total fast (Fery 1985), and perhaps 50-100 grams per day on the well-formulated ketogenic diet.
Some AcAc naturally stops working to form acetone, which will come out with the lungs and kidneys, giving a chemical odor for the breath when ketones are high.
Most of the AcAc made in the liver is picked up by muscle and transformed into BOHB.
Included in the keto-adaptation process, how muscles and kidneys handle BOHB and AcAc changes over the first few weeks and months, and so the ratio of AcAc to BOHB within the blood changes considerably within the first couple of weeks.
Whilst the ultimate fate of the majority of ketones in the blood will be burned for fuel, BOHB and AcAc appear to have differing roles in regulating genes and cellular functions.
Particularly with gene regulation, BOHB seems to play a more significant regulatory role than AcAc, but AcAc could have a particular role in signaling muscle regeneration .
Sources and Formulations of Exogenous Ketones – The two compounds typically called ‘ketone bodies’ (BOHB and AcAc) are made and utilized for multiple purposes across nature from algae to mammals, but seldom in concentrations ideal for extraction as human food. For that reason, the source of many exogenous ketones is chemical synthesis. Furthermore, most current research and utilize of ketone supplements targets BOHB. This is because AcAc is chemically unstable – it slowly stops working to make acetone by releasing loejbp one molecule of CO2.
In a keto-adapted individual where ketone metabolism is brisk with up to 100 grams or maybe more being oxidized (i.e., ‘burned for energy’) daily, the small amount lost in breath and urine as acetone is minor. But as this breakdown occurs spontaneously without the need for the help of enzymes, additionally, it happens to AcAc in a stored beverage or food (even just in an air-tight container), making the shelf-lifetime of AcAc-containing products problematic. Thus all current ketone supplements include BOHB in certain form as opposed to the natural mixture of BOHB and AcAc created by the liver.
Another essential distinction between endogenous and exogenous BOHB is the fact that most synthetic BOHB utilized in dietary supplements is a mixture of the two ‘D’ and ‘L’ isomers, whereas endogenously produced BOHB includes only the D-isomer. Metabolically, the two isomers are very different, and current published information shows that a lot of the energy and signaling benefits associated with BOHB derive from your D-form. This really is potentially problematic as the L-isomers are not metabolized via the same chemical pathways as the D-forms (Lincoln 1987, Stubbs 2017), plus it remains unclear whether humans can convert the L-form to the D-form.
Thus, whilst the L-isomers tend not to appear to be toxic, they are not likely to impart exactly the same benefits because the D-forms. Additionally, the current assays for blood ketones are specific to the D-isomer, so it is hard to track blood levels and clearance for any L-isomer taken in a supplement.