I picked up the Ketonix Acetone Breathalyzer a little over a month ago and have been playing with it ever since. I wanted to know how accurate it was in detecting ketosis compared to the current gold standard, which are blood levels of beta-hydroxybutyrate (BHBA). I purchased this device directly from the source at www.ketonix.com based out of Sweden. The system I use to test my blood levels of BHOB is the Precision Xtra Blood Glucose and Ketone Meter (if you want to find out where to pick up strips for this you can check out this post). The way the ketonix works is very simple. You just have to blow into the mouth piece. That’s it! Then the machine displays a certain colored LED light which corresponds to a certain breath acetone range.
The device itself is about the size of a large marker. The USB cord is attached at the base. The cord itself is about 3 feet in length, giving plenty of slack when testing. The mouthpiece is detachable which makes it easy to wash, especially since the portion containing the electronics is not supposed to come into contact with water. It’s important to know that when reattaching the mouthpiece, there are tiny round cutouts in the plastic that need to be lined up in order to release the air the you blow into it. If these aren’t lined up, the air will have no where to go, and it will feel like you’re blowing into a closed system. I’m a little embarrassed to say that it took me a few tries of blowing into it with the air not moving anywhere to figure this out…
Here are the official instructions on the label affixed to the device:
- Connect to USB port
- Wait until LED turns blue
- Blow gently into mouthpiece for 10-20 seconds
- Read color after 30 seconds
This is what each different colored LED represents:
- Blue = 0 – 150 nmol/L
- Green = 150 – 400 nmol/L (Small)
- Yellow = 400 – 930 nmol/L (Moderate)
- Red = > 930 nmol/L (Large)
Before diving into my results I wanted to briefly review the biochemistry of it all:
- When entering ketosis, we are encouraging the body to utilize fat as fuel rather than carbohydrate (glycogen and glucose)
- Fat is broken down into three main ketone bodies which the body then uses for energy
- Beta-hydroxybutyrate (BHBA) – This is what is detected with blood ketone strips
- Acetoacetate – This is what is detected with the urine ketone strips
- Acetone – A break down product of acetoacetate which the body gets rid of via exhalation. Acetone is what the ketonix is detecting and quantifying.
Over the past month I’ve collected 29 separate data points where I measured both my breath acetone and my blood BHBA at the same time. The table to the left is the summary of what I’ve found arranged in order of ascending BHBA levels. I’ve also included my blood glucose levels for reference.
My results are nowhere near as neat as this guy’s. In fact I was surprised to see it register as ‘moderate’ with a blood ketone level of 0.1 mmol/L and ‘high’ with levels as low as 0.2 mmol/L. There definitely isn’t a linear correlation between breath acetone and blood BHBA… at least in my case.
So Why Isn’t The Correlation Linear?
Here are a few thoughts I had:
- Variation based on length and quality of breath – I’ve found that the value reflected by the ketonix can be dependent on both the strength of my exhalation as well as the length of my exhalation. The longer or harder I blow, the higher I can get it to read.
I can see this as causing some issues with reproducibility, especially if I can get different values in the span of 1-2 minutes if I accidentally blow too long (such as 20 seconds instead of the normal 10-15 seconds)… or if I blow too rigorously (much harder to standardize the strength of the breath).
- Context of testing – I think the context of when the test is done matters greatly. Factors such as when the most recent meal was eaten, what the macro nutrient profile of that meal was, when the most recent exercise was, what sort of exercise, etc. probably play a great deal in all this. I haven’t provided the context in my numbers, but I will in a few subsequent posts.
- Exercise – I’ve read in a few places that exercise can induce metabolism of BHOB without concomitant metabolism of acetone… and this can cause BHOB to lower while acetone remains high (here and here).
- Food – I also wonder how things like MCT oil affects the production of BHBA vs acetone (here, here, and here).
- Differences in ketone metabolism - There may be a lag between changes in blood BHOB appear in the breath acetone. I think there’s already data out there describing this. It’s generally well accepted that blood BHOB levels do not correlate with urine dipsticks which test acetoacetate (here, here, here, here, and here). Guess where acetone comes from? Acetoacetate.
- Insulin – I wonder how insulin affects acetone and BHOB differently. Sometimes I can eat a carb heavy meal and my BHOB will drop immediately… but my acetone will remain elevated.
- Length of ketoadaptation – I wonder if the fact that I’ve been ketoadapted for so long (over a year) has altered my metabolic efficiency regarding use of BHBA vs acetone as mentioned in some of the articles that I’ve linked to above. Perhaps if I was new to ketosis, the numbers would correlate more?
At this point, I don’t think the ketonix can replace my Precision Xtra Blood Ketone Meter readings since the correlation is so random. The only pattern I could discern was that I consistently registered as ‘high’ for blood ketone measurements 0.9 mmol/L and above.
After writing this I also discovered how little I know regarding ketone metabolism and how much more there is to read. So I’ll be spending the next couple of weeks trying to learn more about how ketones (BHBA vs acetone vs acetoacetate) are metabolized and how they are affected differently by diet, exercise and what not.
Response from Ketonix.com
Of course I brought up these findings with Michel Lundell (firstname.lastname@example.org), the man behind ketonix. Here is what he wrote regarding the non-linear correlation (he abbreviates beta hydroxybutyrate as BHOB):
The correlation between the Ac and the BHOB is what most users want. Im in the process of putting up a submission page on the ketonix site for users of Ketonix to upload their measures with Ketonix and BHOB meters. I still have the task of finding factors that could affect the readings before announcing the “study”. The ketone levels depends on many factors. Me and other users found the length of ketosis is one major factor. Switching between low carb and high carb and the length of being in ketosis before the switch is interesting situations which I really want to be able to explain. It is a complex process with many factors involved. For the majority of users these situations is rare, one eats low carb and moderate protein and the pattern is: readings in the mornings are lower than in the afternoons. Yes, I have had some serious thoughts of sending my BHOB meters into space a few times when I have seen low BHOB readings and high Ac in breath and also a constant high readings using diastix. The Ac does not come from the BHOB, it comes from the AcAc. Studies found that the BHOB is behaving like a buffer, which makes sense when one analyze the different situations when the readings are not “as expected”. Personally I found that I need to cut proteins more than what normally is recommended, but that is probably some kind of complex relationship of exercise, body composition, keto-adaptation-phase and of course food intake . My BHOB and breath ketones are much lower when having colds. Also the BHOB’s are used when exercising, converted into AcAc and oxidised into energy. This would lower the BHOB and raising the Ac from the AcAc oxidation. Being in ketosis and doing a “pizza and beer/coke” test will trigger processes of breaking down complex carbs in your intestines that generates methane-gas which could affect the readings. Unless one does not know that one eat a pizza (that is a serious problem) the readings after such event is could be harder to interpret.
This is his response to my observation that differences in breath strength and length can affect the ketonix reading:
The way one blows into the ketonix is of course a factor that could be manipulated a lot if one really wants different resultsIf taking a deep breath before blowing and not blowing all air out of the lungs … most air will be “clean”. It takes a small amount of time for acetone to mix with air. Air temperature also is a parameter, so If you blow into the device for a longer time, the device and gas will produce a higher value.What you want is the most concentration of acetone in your breath, to get consistent readings , I recommend is to follow the same procedure each time.
1) Plug in the Ketonix to a USB port to power it up. 2) Wait until the blue light is steady. 3) Take a “normal” breath (hard when you think of just doing it, but avoid a deep breath) 4) Exhale into the mouthpiece until all air is out 5) Read the value.