Ketosis Part V: Medium-Chain Triglycerides

We have covered a lot of ground so far in looking over the literature on ketosis and ketogenesis.  We have seen what ketone bodies our body actually uses, and how they are regulated on many levels.

We already know that a high-fat diet is a great way to induce ketogenesis.  However a question many of you may be asking is “Do all fats have the same ketogenic potential?”  Well, the answer to that is no, some fats are better at inducing ketogenesis than others.  The most ketogenic fats we have are the medium-chain fats.

We consume many different kinds of fats, and all these fats vary in two different ways, chain length and saturation.  Saturation refers to the number of double bonds a fatty acid chain has, with no double bonds being a saturated fat, and one or more double bonds being an unsaturated fat.  The medium-chain fatty acids we will talk about here are all saturated fatty acids.  They are called medium-chain because they have between 6 and 12 carbons in their chain (1).  Here are a couple of diagrams of some of these medium-chain fats.

Caproic/Hexanoic Acid

Ketosis Part II: Regulation

Now that we have a good idea of what ketone bodies are, and how they start to get formed and where I think it is time to loot at the regulation of the process.  I think what has been really interesting to me in researching this topic is that I expected to find some sort of “master switch” for ketosis.  What I mean by that is I figured that something would happen that would turn on ketosis, and as such you are either in ketosis or out of ketosis.  However, as we saw in the last article everyone produces small amounts of ketones at rest, and ketosis is physiologic process that just happens when the substrates are available and are not being used for other processes. 

There are two main types of regulators for ketogenesis, and while they may seem very different to some people, I think they are rather similar.  It all depends on what energy our body is using, and in what amounts.  Ketogenesis can be controlled either through physiologic processes or through enzymatic processes.  We will start with the physiologic ways that ketosis is controlled, and then go to the enzymatic/hormonal ways, since those are probably a bit more complicated.

When we talk about physiologic processes that induce ketosis we are talking about what is going on in our body to make it start naturally producing ketone bodies.  There are three main ways this happens, and a fourth little trick people use to jump start the process (any guesses now what that is?).  The three ways are: starvation/fasting, prolonged exercise, and a low carb/high fat diet.  Let’s take a look at each of these in turn.

Ketosis Part I

Everyone has heard of it, some of you may love it, some of you may hate it.  While most people know the general facts about ketosis, I have been hearing a lot about it lately, and it seems like every time you talk to someone different about it they have a different opinion on it.  Some people think it is the ideal state for our bodies to be in, while some think of it like the plague, and something to be avoided at all costs. Well, I am going to try and clear up some of the confusion on the matter.  This won’t be an easy, or small task, so bear with me as I try and go through all the facts to make sure I get everything right.   As a general game plan I think a good place to start will be what are ketone bodies, how are they made, how are they transported and what tissues can use them.  Then we can move into their metabolism, uses, and long term ketosis.  Other topics will come up along the way, but that is what the information I hope to synthesize here for you.  In order to transmit all of this information we will have to get fairly technical, and I will have some pretty complicated figures presented, but hopefully I can pull out the main points of them for everyone.  Well, let’s get started.

Brain Fuels

If you ask many people what the primary fuel for your brain is they will most likely tell you that it is glucose.  In fact many sources used to say that the brain could ONLY use glucose as a fuel.  However, it has been known for some time that ketones are more efficient fuel source for our brains.  In fact this article says that ketogenic diets have been used as a treatment for epilepsy since the 1920’s!  And now, an even more efficient fuel is being talked about: Lactate.  Peter from Hyperlipid has a good write up about a paper that talks about the brain using lactate, and why he thinks it is such a good fuel.

This is all well and good, I am all for feeding my brain the most efficient fuels.  If we evolved primarily to support such big and “expensive” (energy consumption-wise) brains this would seem a very important thing to do to maintain good overall health.  However, after reading all this I am left wondering: How am I supposed to get all this lactate to feed my brain?  I can’t eat lactate. Also, with all these fuels for our brain, is there an optimal ratio of fuels?  Let’s take a look.