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Thursday 19 July 2018

Ketones and Autism Part 2 - Ketones as a Brain Fuel to treat Alzheimer’s, GLUT1 Deficiency and perhaps more



Today’s post looks at the role ketones can play as a fuel for the brain.

The research has already shown that in young babies there is insufficient glucose to fuel their power-hungry growing brains and so ketones provide up to 40% of the fuel to their brains.
Glucose or Ketones at the pump?

This does show any sceptics that you can indeed safely combine two sources of fuel at the same time in humans; we have all done it.
This process works in tiny babies because their diet is rich in medium chain fatty acids, which become the ketones.
Only mitochondria in your brain and your muscles can be fuelled by ketones; some elite athletes take advantage of this.
People who are overweight have excess adipose tissue (fat) and when in ketosis, fatty acids from this tissue are released into your blood and travel to the liver where they produce ketones. Mitochondria can also burn fatty acids directly. People losing weight on the ketogenic diet are burning fat and ketones as their main fuel source. To lose weight you do have to be in calorie deficit, you cannot just eat unlimited fat.
Athletes want to improve their performance and some use ketones to achieve this. The fat they are burning is from diet, not from accumulated over-eating.
Ketones as a brain fuel is a niche subject, but a growing one.

Low brain glucose uptake
Low brain glucose uptake is a feature or Alzheimer’s disease and also of a rare inborn condition called GLUT1 deficiency, which appears as epilepsy, MR/ID and with features of autism. Infants with GLUT1 deficiency syndrome have a normal head size at birth, but growth of the brain and skull is slow, in severe cases resulting in an abnormally small head size (microcephaly).

GLUT1, GLUT3 and GLUT4
GLUT1 (glucose transporter 1) occurs in almost all tissues, with the degree of expression typically correlating with the rate of cellular glucose metabolism. It is expressed in the endothelial cells of barrier tissues such as the blood brain barrier.
Glucose delivery and utilization in the human brain is mediated primarily by GLUT1 in the blood–brain barrier and GLUT3 in neurons.
GLUT3 is most known for its specific expression in neurons and was originally designated as the neuronal glucose transporter.
GLUT4 is the insulin-regulated glucose transporter found primarily in adipose tissues (fat) and striated muscle (skeletal and cardiac), but also in the brain.
So, in neurological disorders it is important to optimize GLUT1, GLUT3, GLUT4 and insulin.  In GLUT1 deficiency, as the name suggests, there is an inadequate supply of glucose crossing the blood brain barrier. In people with insulin resistance (T2 diabetes, Alzheimer’s etc) GLUT4 may be impaired.

Insulin resistance in the brain
Insulin resistance in the brain is highly complex and only partially understood; but it does lead to numerous problems. Glucose in the blood does not get taken up adequately into neurons which then become starved of fuel. We will see how this can be overcome by reverting to ketones as an alternative fuel.
At this point I digress a little into the detail of insulin resistance and glucose transport.                                                                             

Insulin resistance is a condition in which cells fail to respond normally to the hormone insulin. The body produces insulin when glucose starts to be released into the bloodstream from the digestion of carbohydrates  in diet. Under normal conditions of insulin reactivity, this insulin response triggers glucose being taken into body cells, to be used for energy, and inhibits the body from using fat for energy, thereby causing the concentration of glucose in the blood to decrease as a result, staying within the normal range even when a large amount of carbohydrates is consumed. During insulin resistance, excess glucose is not sufficiently absorbed by cells, even in the presence of insulin, causing an increase in the level of blood sugar.

The following paper is very interesting, if you can access the full text version


Considerable overlap has been identified in the risk factors, comorbidities and putative pathophysiological mechanisms of Alzheimer disease and related dementias (ADRDs) and type 2 diabetes mellitus (T2DM), two of the most pressing epidemics of our time. Much is known about the biology of each condition, but whether T2DM and ADRDs are parallel phenomena arising from coincidental roots in ageing or synergistic diseases linked by vicious pathophysiological cycles remains unclear. Insulin resistance is a core feature of T2DM and is emerging as a potentially important feature of ADRDs. Here, we review key observations and experimental data on insulin signalling in the brain, highlighting its actions in neurons and glia. In addition, we define the concept of 'brain insulin resistance' and review the growing, although still inconsistent, literature concerning cognitive impairment and neuropathological abnormalities in T2DM, obesity and insulin resistance. Lastly, we review evidence of intrinsic brain insulin resistance in ADRDs. By expanding our understanding of the overlapping mechanisms of these conditions, we hope to accelerate the rational development of preventive, disease-modifying and symptomatic treatments for cognitive dysfunction in T2DM and ADRDs alike. 

Sources of insulin in the brain. Insulin levels in cerebrospinal fluid (CSF) are much lower than in plasma but these levels are correlated, indicating that most insulin in the brain derives from circulating pancreatic insulin. Insulin enters the brain primarily via selective, saturable transport across the capillary endothelial cells of the blood–brain barrier (BBB).
Despite glucose being the major energy source for the brain, the uptake, transport and utilization of glucose in neurons is only influenced by insulin and is not dependent on it
The insulinindependent glucose transporter GLUT3 is the major glucose transporter in neurons and is present in very few other cell types in the body. The density and distribution of GLUT3 in axons, dendrites and neuronal soma correlates with local cerebral energy demands. Insulin is not required for GLUT3mediated glucose transport; instead, NMDA receptormediated depolarization stimulates consumption of glucose, which prompts glucose uptake and utilization via GLUT3. 
Although most glucose uptake in neurons occurs via GLUT3, insulinregulated GLUT4 is also coexpressed with GLUT3 in brain regions related to cognitive behaviours — at least in rodents. These regions include the basal forebrain, hippocampus, amygdala and, to lesser degrees, the cerebral cortex and cerebellum. 
Activation by insulin induces GLUT4 translocation to the neuron cell membrane via an AKTdependent mechanism and is thought to improve glucose flux into neurons during periods of high metabolic demand, such as during learning. Interestingly, GLUT4 is also expressed in the hypothalamus, a key area for metabolic control. Deletion of GLUT4 from the CNS in mice results in impaired glucose sensing and tolerance, which might be due in part to an absence of GLUT4 in the hypothalamus.

Brain insulin resistance definition. Insulin resistance in T2DM has been defined as “reduced sensitivity in body tissues to the action of insulin”. Similarly, brain insulin resistance can be defined as the failure of brain cells to respond to insulin. Mechanistically, this lack of response could be due to downregulation of insulin receptors, an inability of insulin receptors to bind insulin or faulty activation of the insulin signalling cascade. At the cellular level, this dysfunction might manifest as the impairment of neuroplasticity, receptor regulation or neurotransmitter release in neurons, or the impairment of processes more directly implicated in insulin metabolism, such as neuronal glucose uptake in neurons expressing GLUT4, or homeostatic or inflammatory responses to insulin. Functionally, brain insulin resistance can manifest as an impaired ability to regulate metabolism — in either the brain or periphery — or impaired cognition and mood 

Studies have yet to show whether T2DMassociated cognitive impairment and brain neuroimaging findings are a consequence of brain insulin resistance or are due to other factors that cooccur with systemic insulin resistance. Common comorbidities of systemic insulin resistance in T2DM — such as hyperglycaemia, advanced glycation end products, oxidatively dam aged proteins and lipids, inflammation, dyslipidaemia, athero sclerosis and microvascular disease, renal failure and hypertension — all have their own complex effects on brain function through a variety of mechanisms independent of insulin signalling. Furthermore, evidence suggests that systemic insulin resistance or high circulating levels of insulin affects the function of the BBB by downregulating endothelial insulin receptors and thus decreasing permeability of the BBB to insulin. This change in permeability is potentially of great importance as it could lead to decreased brain insulin levels and decreased insulinfacilitated neural and glial activity40. On the other hand, T2DM can lead to damage of the BBB, which results in increased permeability to a variety of substances

Brain insulin resistance in ADRDs
• Increasing age is associated with decreasing cortical insulin concentration and receptor binding in older adults without dementia 
•Brain tissue from those with Alzheimer disease (AD) shows major abnormalities in insulin signalling, including - Decreased insulin, insulin receptor and insulin receptor substrate 1 (IRS1) mRNA and/or protein expression levels
Decreased activation of insulin pathway molecules (for example, IRS1 and AKT) with ex vivo stimulation
Increased basal phosphorylation levels of multiple insulin–IRS1–AKT pathway molecules
 Positive correlation between phosphorylated IRS1 and other pathway molecules and AD pathology 
• Intranasal insulin administration improves cognitive functioning in humans with AD or mild cognitive impairment and improves measures of insulin signalling, amyloid-β and cognitive behaviours in AD model mice 
Brain insulin resistance might be a feature of other neurodegenerative diseases

Insulin receptor expression is decreased and AKT signalling is abnormal in the substantia nigra in Parkinson disease
Abnormal phosphorylated IRS1 expression is observed in tauopathies but is not seen in synucleinopathies or TDP-43 proteinopathies
Aside from treatment with insulin itself, insulinsensitizing medicines commonly used in T2DM have attracted growing interest as potential therapies for brain insulin resistance in ADRD. For instance, investigators have begun testing of metformin, the most commonly prescribed drug for T2DM, in nondiabetic individuals with MCI or early dementia due to AD, with some signs of benefit. In addition, thiazolidinedionebased nuclear peroxisome proliferatoractivated receptorγ (PPARγ) agonists, which were originally developed as insulin sensitizers for T2DM, have shown numerous beneficial neural effects in animal models of neuro degenerative diseases

Autism and GLUT1 deficiency:


Another excellent paper:-  


Brain energy metabolism in Alzheimer’s disease (AD) is characterized mainly by temporo-parietal glucose hypometabolism. This pattern has been widely viewed as a consequence of the disease, i.e. deteriorating neuronal function leading to lower demand for glucose. This review will address deteriorating glucose metabolism as a problem specific to glucose and one that precedes AD. Hence, ketones and medium chain fatty acids (MCFA) could be an alternative source of energy for the aging brain that could compensate for low brain glucose uptake. MCFA in the form of dietary medium chain triglycerides (MCT) have a long history in clinical nutrition and are widely regarded as safe by government regulatory agencies. The importance of ketones in meeting the high energy and anabolic requirements of the infant brain suggest they may be able to contribute in the same way in the aging brain. Clinical studies suggest that ketogenesis from MCT may be able to bypass the increasing risk of insufficient glucose uptake or metabolism in the aging brain sufficiently to have positive effects on cognition.

Push-pull: two distinct strategies to supply the brain with energy substrates. Glucose is the brain’s main fuel and is taken up by the brain in relation to demand. Hence, this is a “pull” strategy because glucose is pulled into the cell following neuronal activation and the subsequent decrease in neuronal glucose concentrations. Ketones are the brain’s main alternate fuel to glucose and are taken up by the brain in relation to their presence in blood. Hence, this is a “push” strategy because ketones are pushed into the brain in direct proportion to their concentrations in the blood.

5 Cognitive benefits of increasing brain ketone supply


Since brain ketone uptake is still normal in mild to moderate AD and the problem of low brain glucose uptake appears to be contributing to declining cognition in AD, it is reasonable to hypothesize that providing the brain with more ketones may delay any further cognitive decline. This hypothesis has been supported by results from acute and chronic studies in AD patients and in the prodromal condition to AD – mild cognitive impairment. Other trials with ketogenic supplements in AD are ongoing. Conditions involving acute or long-term cognitive problems including post-insulin hypoglycemia and epilepsy also respond to a ketogenic diet or supplement.

One of the reasons that type 2 diabetes is such an important risk factor for AD may be due to insulin resistance. The brain has long been thought to function independently of insulin, but this is now being challenged. Insulin resistance not only affects glucose uptake by peripheral tissues but it also blocks ketogenesis, thereby limiting production of ketones to be taken up by the brain. Indeed, if the insulin resistance of type 2 diabetes in some way impairs brain glucose metabolism, brain energy supply is in fact in double jeopardy because insulin excess also blocks ketogenesis from long chain fatty acids stored in adipose tissue thereby restricted access not just of the brain’s primary fuel (glucose) but its main back-up fuel (ketones) as well. One potential solution is that ketogenesis from MCFA appears to be independent of insulin, in which case a ketogenic MCFA supplement should still be able to supply the brain with ketones despite the presence of insulin resistance or type 2 diabetes. This is an active area of research.  

6 Ketones and infant brain development


Raising plasma ketones is commonly viewed as risky, primarily because ketosis is associated with uncontrolled type 1 diabetes, i.e. an acute and severe absence of insulin. However, pathological ketosis needs to be distinguished from nutritional ketosis: the former is associated with metabolic ketoacidosis, i.e. plasma ketones exceeding 15 mM, which is medically serious condition requiring rapid treatment. In contrast, the latter is associated with plasma ketones below 5 mM and can be safely induced by short- or long-term dietary modification. The very high fat ketogenic diet induces nutritional, not pathological ketosis. It has been used for nearly 100 years as a standard-of-care for intractable childhood epilepsy and is rarely associated with serious side-effects despite producing plasma ketones averaging 2–5 mM for periods commonly exceeding 2 years. Its mechanism of action is still poorly understood but the efficacy of this dietary ketogenic treatment for intractable epilepsy is greater in younger infants suggesting a possible link the well-established but often overlooked importance of ketones in infant brain development.

During lactation, the human infant brain metabolises >50% of the fuel provided, despite the brain representing only 12–13% of body’s weight. Glucose supplies about 30% of the late term fetus’s brain energy requirements and about 50% of the neonate’s brain energy requirements; the difference is provided by ketones. Therefore, ketones are an obligate brain fuel during an infant’s development, as opposed to being an alternative brain fuel in the adult human, i.e. only needed when glucose is limiting. Ketones are more than just catabolic substrates (fuel) for the developing brain – they are also important anabolic substrates because they supply the majority of carbon used to synthesize brain lipids such as cholesterol and long chain saturated and monounsaturated fatty acids. 


                                        

Unique route of medium chain fatty acid (MCFA) absorption compared to other common long chain dietary fatty acids. The lymphatic and peripheral circulation1 distribute most common long chain fatty acids as chylomicrons throughout the body, whereas MCFA are mostly absorbed directly via the portal vein to the liver2  

MCFA are more rapidly absorbed from the gut directly to the liver via the portal vein compared to long chain fatty acids which are absorbed primarily via the lymphatic duct and into the peripheral circulation. MCFA are also more easily β-oxidized in mitochondria because they do not require activation to CoA esters by carnitine. Both the rapid absorption and β-oxidation of MCFA suggest these fatty acids have a physiologically important function. Theoretically, this function could include elongation to long-chain fatty acids but, in practice, is probably limited to ketogenesis, especially in infancy which is the only period when it is normal to be regularly consuming MCFA.

Long chain fatty acids are the main alternate fuel to glucose for most tissues. They can also be taken up by the brain but the reason they are not a useful fuel for the brain is because their rate of uptake is insufficient to meet the demand for energy once glucose becomes limiting. However, MCFA such as octanoate (caprylic acid) can be taken up rapidly and be metabolized by the brain. Whether MCFA have direct effects on the brain or are principally metabolized to ketones before exerting any effect as fuels, lipid substrates or lipid signalling molecules remains to be seen. 



Ketones for Alzheimer’s? AC1202/4 
A lot of money is being spent on developing variants of caprylic acid (C8) as a medical food to treat one feature of Alzheimer’s. This medical food market has even attracted Nestle, the Swiss chocolate to baby food giant, to invest in ketones.
Even though clinical trials have not yet been successfully completed, American doctors are already prescribing a product called Axona to people with Alzheimer’s.
It looks like there are plenty of sceptics, but it looks like plenty of people are paying $80 a month for their Axona (>95% C8 oil). One packet of Axona powder, contains 20 grams MCTs almost exclusively C8.
You can see from the clinicals trials that Accera have been comparing the effectiveness of generic (unpatentable) C8 vs their two proprietary powders called AC-1202 and AC-1204. Clearly Accerra want to maximize plasma BHB, but in a way that has patent protection.
Since C8 is not so expensive when bought in bulk, the obvious alternative is just to drink C8 and in the way that best promotes its absorption and the production of ketones, which would seem to be when you wake up and before you have eaten anything.


http://www.about-axona.com/us/en/cgp/how-axona-could-help/how-axona-works.html



CNS therapeutics company Accera's AC-1204 has failed to demonstrate a positive outcome in the Phase III trial for the treatment of patients with mild-to-moderate Alzheimer's disease. 
AC-1204 is a small-molecule drug compound designed to leverage the physiological ketone system in order to address the deficient glucose metabolism in Alzheimer's. 
The ketones are thought to have a potential to restore and improve neuronal metabolism, resulting in better cognition and function.
The trial results indicated that the drug did not show a statistically significant difference at week 26 when compared with placebo, as measured by the Alzheimer's disease assessment scale-cognitive subscale test (ADAS-Cog). 
"The formulation of the drug was changed between the Phase II and Phase III studies."
The double-blind, randomised, placebo-controlled, parallel-group Phase III (NOURISH AD) trial evaluated the effects of daily administration of AC-1204 in the subjects for 26 weeks.
Accera research and development vice-president Samuel Henderson said: "The formulation of the drug was changed between the Phase II and Phase III studies. 
"Unfortunately, this change in formulation had the unintended consequence of lowering drug levels in patients. We are confident that our newly developed formulation will provide increased exposure and allow a more conclusive test of drug efficacy." 
The primary and key secondary endpoints of the trial are the measure of AC-1204 effects on memory, cognition and global function. 
While the drug was found to be safe with high levels of tolerability, a detailed pharmacokinetic analysis showed that the modified formulation used in the study led to a decrease in drug plasma levels when compared to prior formulations. 


FDA hit Accera with a warning letter in 2013 on the grounds its marketing materials caused Axona to be classed as a drug. Accera continues to market Axona as a medical food for Alzheimer’s but has tweaked its website since the warning letter.
Axona and AC-1204 both provide patients with a source of caprylic triglyceride—also known as fractionated coconut oil—that is intended to increase the availability of ketones to the brain. The potential of the therapeutic approach has enabled Accera to pull in more than $150 million from backers including Nestlé, according to SEC filings.

Ketones for GLUT1 deficiency?  C7 Triheptanoin
It looks like the star clinician/researcher for people with GLUT1 deficiency is Dr. Juan Pascual, Associate Professor of Neurology and Neurotherapeutics, Pediatrics, and Physiology at UT Southwestern Medical Center.
As we saw earlier you need the transporter GLUT1 for glucose to cross the blood brain barrier and then provide fuel for the mitochondria in the brain. 
It has been known for some time that people with GLUT1 deficiency make improvements on the ketogenic diet.  Now in the previous post we saw how the effect on epilepsy of the KD comes via a change in the mix of bacteria in the gut; this eventually leads to a sharp increase in the ratio of GABA/Glutamate in the brain. This reduces seizures, which are a feature of GLUT1 deficiency.
Dr Pascual wants a second benefit from the ketogenic diet, having got the benefit from the gut bacteria he wants to benefit from the ketones as a fuel, just like some Alzheimer’s researchers.
This time though he has picked another MCT (medium chained triglyceride) he picked C7.
C7 is not something you can pick up from your specialist ketone supplier. It is still very much a research chemical.
Dr Pascual did not start with C8 because he has done his homework.  He actually wants some help for his GLUT1 deficient patients from some C5 ketones and a good way to produce them is from C7.
Using C7 oil Dr Pascual is also going to produce BHB (beta-hydroxybutyrate) and acetoacetate, just like all those athletes, body builders, slimmers and older people with Alzheimer’s are doing with the KD, C8 and BHB.




           Metabolism of glucose, C7-derived heptanoate and 5-carbon (C5) ketones in the brain

Glial metabolism is distinct from neuronal metabolism. Glucose can access both glia (via GLUT1) and neurons (via GLUT3), fueling the TCA cycle (CAC). In glia, pyruvate is converted into oxaloacetate (OAA) via carboxylation, donating net carbon to the TCA cycle (anaplerosis). This reaction can be impaired in G1D. Like glucose, the C7 derivative heptanoate and related metabolites (i.e., the 5-carbon ketones beta-ketopentanoate and beta-hydroxypentanoate) also generate acetyl-coenzyme A (Ac-CoA) but, unlike the 4-carbon ketone bodies beta-hydroxybutyrate and acetoacetate, they can also be incorporated into succinyl-coenzyme A (Suc-CoA) via propionyl-CoA (Prop-CoA) formation, supplying net, anaplerotic carbon to the cycle. In addition to 5-carbon (C5) ketones, the 4-carbon ketone bodies beta-hydroxybutyrate and acetoacetate are also metabolites of C7.




Dr. Pascual led the JAMA study that relied on data from a worldwide registry he created in 2013 for Glut1 deficiency patients. The research tracked 181 patients for three years, finding that a modified Atkins diet that includes less fat and slightly more carbohydrates than the standard ketogenic diet helped reduce seizures and improved the patients' long-term health. The study also found earlier diagnosis and treatment of the disease improved their prognosis.
In addition, Dr. Pascual is overseeing national clinical trials that are testing whether triheptanoin (C7) oil improves the intellect of patients by providing their brains an alternative fuel to glucose. The trials will last five years and are funded with more than $3 million from the National Institutes of Health.

So far, the nearly 40,000 Americans potentially living with the disease have had only one primary option for treating symptoms: a high-fat, low-carbohydrate ketogenic diet that can limit seizures. The diet works in about two-thirds of patients but does not improve their intellect and carries long-term risks such as kidney stones and metabolic abnormalities.

Dr. Pascual expects the modified diet from the JAMA study and the C7 oil will prove at least as effective as the ketogenic diet in preventing seizures - without the health risks - while feeding the brain vital fuel to improve learning.


Background: Ketones are the brain's main alternative fuel to glucose. Dietary medium-chain triglyceride (MCT) supplements increase plasma ketones, but their ketogenic efficacy relative to coconut oil (CO) is not clear.

Objective: The aim was to compare the acute ketogenic effects of the following test oils in healthy adults: coconut oil [CO; 3% tricaprylin (C8), 5% tricaprin (C10)], classical MCT oil (C8-C10; 55% C8, 35% C10), C8 (>95% C8), C10 (>95% C10), or CO mixed 50:50 with C8-C10 or C8.

Methods: In a crossover design, 9 participants with mean ± SD ages 34 ± 12 y received two 20-mL doses of the test oils prepared as an emulsion in 250 mL lactose-free skim milk. During the control (CTL) test, participants received only the milk vehicle. The first test dose was taken with breakfast and the second was taken at noon but without lunch. Blood was sampled every 30 min over 8 h for plasma acetoacetate and β-hydroxybutyrate (β-HB) analysis.

Results: C8 was the most ketogenic test oil with a day-long mean ± SEM of +295 ± 155 µmol/L above the CTL. C8 alone induced the highest plasma ketones expressed as the areas under the curve (AUCs) for 0–4 and 4–8 h (780 ± 426 µmol h/L and 1876 ± 772 µmol h/L, respectively); these values were 813% and 870% higher than CTL values (P < 0.01). CO plasma ketones peaked at +200 µmol/L, or 25% of the C8 ketone peak. The acetoacetate-to-β-HB ratio increased 56% more after CO than after C8 after both doses.

Conclusions: In healthy adults, C8 alone had the highest net ketogenic effect over 8 h, but induced only half the increase in the acetoacetate-to-β-HB ratio compared with CO. Optimizing the type of MCT may help in developing ketogenic supplements designed to counteract deteriorating brain glucose uptake associated with aging. This trial was registered at clinicaltrials.gov as NCT 02679222. 

Brain glucose uptake is lower in Alzheimer disease (AD). This problem develops gradually before cognitive symptoms are present, continues as symptoms progress, and becomes lower than the brain glucose hypometabolism occurring in normal aging. In contrast to glucose, brain ketone uptake in AD is similar to that in cognitively healthy, age-matched controls. For ketones to be a useful energy source in glucose-deprived parts of the AD brain, the estimated mean daily plasma ketone concentration needs to be >200 μmol/L (21). With a total 1-d dose of 40 mL C8, plasma ketones peaked at 900 μmol/L and the day-long mean was 363 ± 93 μmol/L, whereas with the same amount of CO, they peaked at 300 and 107 ± 57 μmol/L, respectively. Our 2-dose test protocol (breakfast and midday) generated 2 peaks of plasma total ketones throughout 8 h, with the second dose inducing 3.5 and 2.4 times higher ketones with C8 than with CO, respectively. The first dose taken with a meal would be a more typical pattern but resulted in less ketosis that without a meal. One limitation of this study design is that the metabolic study period was only 8 h. A longer-term study lasting several weeks to months would be useful to assess the impact of regular MCT supplementation on ketone metabolism.




Conclusion
I hope Dr Pascual has read the UCLA study on bacteria mediating the effect of the ketogenic diet on seizures. I think this has big implications for how to best manage people with GLUT1 deficiency.
I can see why Nestlé are investing in C8 products to treat Alzheimer’s. It does makes sense to optimize bioavailability, but in the meantime drinking regular liquid C8 would seem a smart idea.

While C8 is being proposed for Alzheimer's as a means of compensating for reduced glucose uptake in the brain, it has other benefits.  In the next post we will look at the anti-inflammatory benefits of the ketone BHB; these benefits are very relevant to Alzheimer's, where we know that the pro-inflammatory cytokine IL-1B is over-expressed. We will discover how BHB reduces expression of IL-1B. 
The amount of C8 required to start partially fuelling the brain is trivial, just 40ml a day. If combined with BHB itself, you would need even less and if I was Nestlé that is what I would develop.
Unless you have GLUT1 deficiency I do not see why C7 is better than C8 as a brain fuel.
In autism you would only benefit from ketones as a brain fuel if you have reduced glucose uptake, reduced insulin sensitivity or a mitochondrial disorder. Clearly, some people diagnosed with autism should benefit from ketones as a secondary brain fuel to glucose. If intranasal insulin helps, ketones are particularly likely to help.

                                                            


                                                                                                                           

Wednesday 11 July 2018

Ketones and Autism Part 1 - Ketones, Epilepsy, GABA and Gut Bacteria




Today’s post is the first in a short series about ketones, that looks into very specific areas of the science.
There was an earlier post on the Ketogenic Diet (KD).

The Clever Ketogenic Diet for some Autism


We already know, anecdotally, that some people with autism respond well to the Ketogenic Diet (KD) and some to just ketone supplements. We also know from some very small clinical trials that a minority of those with autism benefit from the KD. 

What percentage of people with autism respond to ketones?
This is the important question and the simple answer appears to be a minority, albeit a significant minority. A lot depends on what you mean by autism and what you judge to be a response. From reading up on the subject I would estimate that about 20% respond well, but which 20%?

Why do some people with autism respond to ketones and how do you maximize the effect?
There is quite a lot of useful information in the literature, but it is clear that most people do not respond to ketones, so you really need to know if your case is one of the minority that do respond, before getting too carried away with changing diet. From research on people wanting to lose weight there are plenty of practical tips to maximize ketones, even drinking coffee produces more ketones; increasing the hours you fast each day also helps. 
If you have a healthy, sporty, child with autism you might want more ketones but you do not want to lose weight.

Do you have a responder? 
There does not yet appear to be a way to predict who will respond well to ketones, other than those people who have seizures. 
You can read all about ketones or just try them out. To try them out, a good place to start is with the exogenous ketone supplements mainly sold to people trying to lose weight. It looks like 10ml of C8 oil and 10ml of BHB ester is a good place to start and soon you may produce enough ketones to establish if someone is a responder, then you just have to figure out why they are a responder and then to maximize this effect, which might involve things other than ketone supplements.  
You can measure ketones in urine and so you can see whether you have reached the level found in trials that produces a positive effect in some people. If you can establish that you have indeed produced this level of ketones and you see no effect, then it is time to cross ketones and the ketogenic diet off your to-do list.  
If you are fortunate to find a responder, then you can move forward with trying to maximize the benefit. 

Ketone supplements
Ketone supplements can be extremely expensive when you use the recommended dosage and may contain quite large amounts of things that you might not want (sodium, potassium and calcium for example).  Always read the labels.
It is clear that some of these products are much more effective at producing ketones than others. For a change, you can measure their effectiveness and avoid wasting your money. Ketone testing strips are inexpensive. 

Ketone Posts 

·        Part1 - Ketones, epilepsy, GABA and gut bacteria

·        Ketones as a fuel, Alzheimer’s and GLUT1 deficiency

·        Ketones and microglia

·        Ketones as HDAC inhibitors and epigenetic modifiers

·        Ketones, exercise and BDNF

·        Maximizing ketones through diet, fasting, exercise, coffee and supplementation


Ketones, epilepsy, GABA and gut bacteria
Today’s post just looks at the effect of ketones on the neurotransmitter GABA, which should be inhibitory, but in much autism is actually excitatory. The GABA switch failed to flip just after birth and neurons remain in an immature state, due to too many NKCC1 chloride transporters and too few KCC2 chloride transporters. With too much chloride inside neurons GABA has an excitatory effect on neurons causing them to fire when they should not.
In epilepsy, too much excitation from Glutamate and too little inhibition from GABA may lead to seizures. So, in some types of epilepsy you want to increase GABA and reduce Glutamate, i.e. you want to increase the GABA/Glutamate ratio.
In autism it is not clear that increasing the GABA/Glutamate ratio is going to help, it all depends on the kind of autism. Much of this blog is about changing the effect of GABA (flipping the GABA switch) and not changing the amount of it.
In some people with autism and epilepsy ketones resolve the seizures but do not improve the autism.
In other people with autism and no seizures, ketones improve their autism. This may, or may not, be due to the effect ketones have on GABA.  
Two issues are looked into in this post: -
·        Do ketones affect NKCC1/KCC2 expression and hence the effect of GABA in the brain?

·        Do ketones affect the amount of GABA and Glutamate in key parts of the brain?
The good news is that research into epilepsy shows that ketones do indeed have an effect on GABA, but it is highly disputed whether they modify NKCC1/KCC2 expression and the GABA switch from immature to mature neurons. 

The KD and Epilepsy
The KD has been used to treat epilepsy for almost a century, but until very recently nobody really knew why it worked.
A recent very thoughtful study at UCLA has shown that the KD mediates its anti-seizure effects via changes to the bacteria in the gut. The researchers identified the two bacteria and then showed that, at least in mice, the same anti-seizure effect provided by the KD could be provided just by adding these two bacteria (i.e. no need to follow the ketogenic diet).

UCLA scientists have identified specific gut bacteria that play an essential role in the anti-seizure effects of the high-fat, low-carbohydrate ketogenic diet. The study, published today in the journal Cell, is the first to establish a causal link between seizure susceptibility and the gut microbiota — the 100 trillion or so bacteria and other microbes that reside in the human body’s intestines.

The ketogenic diet has numerous health benefits, including fewer seizures for children with epilepsy who do not respond to anti-epileptic medications, said Elaine Hsiao, UCLA assistant professor of integrative biology and physiology in the UCLA College, and senior author of the study. However, there has been no clear explanation for exactly how the diet aids children with epilepsy.
Researchers in Hsiao’s laboratory hypothesized that the gut microbiota is altered through the ketogenic diet and is important for the diet’s anti-seizure effects. Hsiao’s research team conducted a comprehensive investigation into whether the microbiota influences the ability of the diet to protect against seizures and if so, how the microbiota achieves these effects.
In a study of mice as a model to more thoroughly understand epilepsy, the researchers found that the diet substantially altered the gut microbiota in fewer than four days, and mice on the diet had significantly fewer seizures.
To test whether the microbiota is important for protection against seizures, the researchers analyzed the effects of the ketogenic diet on two types of mice: those reared as germ-free in a sterile laboratory environment and mice treated with antibiotics to deplete gut microbes.
“In both cases, we found the ketogenic diet was no longer effective in protecting against seizures,” said lead author Christine Olson, a UCLA graduate student in Hsiao’s laboratory. “This suggests that the gut microbiota is required for the diet to effectively reduce seizures.”
The biologists identified the precise order of organic molecules known as nucleotides from the DNA of gut microbiota to determine which bacteria were present and at what levels after the diet was administered. They identified two types of bacteria that were elevated by the diet and play a key role in providing this protection: Akkermansia muciniphila and Parabacteroides species.
With this new knowledge, they studied germ-free mice that were given these bacteria.
“We found we could restore seizure protection if we gave these particular types of bacteria together,” Olson said. “If we gave either species alone, the bacteria did not protect against seizures; this suggests that these different bacteria perform a unique function when they are together.”
The researchers measured levels of hundreds of biochemicals in the gut, blood and hippocampus, a region of the brain that plays an important role in spreading seizures in the brain. They found that the bacteria that were elevated by the ketogenic diet alter levels of biochemicals in the gut and the blood in ways that affect neurotransmitters in the hippocampus.
How do the bacteria do this? “The bacteria increased brain levels of GABA — a neurotransmitter that silences neurons — relative to brain levels of glutamate, a neurotransmitter that activates neurons to fire,” said co-author Helen Vuong, a postdoctoral scholar in Hsiao’s laboratory.
“This study inspires us to study whether similar roles for gut microbes are seen in people that are on the ketogenic diet,” Vuong said.
“The implications for health and disease are promising, but much more research needs to be done to test whether discoveries in mice also apply to humans,” said Hsiao, who is also an assistant professor of medicine in the David Geffen School of Medicine at UCLA.
On behalf of the Regents of the University of California, the UCLA Technology Development Group has filed a patent on Hsiao’s technology that mimics the ketogenic diet to provide seizure protection. It has exclusively licensed it to a start-up company Hsiao has helped to launch that will examine the potential clinical applications of her laboratory’s findings.
Here is Hsiao’s new start-up:

“We are hacking the ketogenic diet to identify microbes that have therapeutic potential for the treatment of epilepsy,” says Bloom CEO Tony Colasin.
The San Diego-based start-up isn’t announcing how much seed funding it raised, but Colasin plans to move fast and get a product on the market in a mere two to three years. That’s because Bloom will first develop a medical food based on the two kinds of bacteria identified in Hsiao’s study. Bloom also has plans to optimize the bacterial strains for specific kinds of epilepsy to develop a traditional approved drug.

The way the bacteria help control seizures actually appears to be similar to the mechanism of many commercial ant epilepsy drugs. The microbes’ metabolism increases the ratio of inhibitory to excitatory neurotransmitters in the brain—specifically, higher levels of gamma-aminobutyric acid (GABA) relative to levels of glutamate.
Bloom is also considering how the microbiome benefits of the ketogenic diet could be helpful in other neurological conditions, including autism, depression, and Parkinson’s disease. “It is early days, but we are excited about the potential,” Colasin says.

Here is the full paper: -

The ketogenic diet (KD) is used to treat refractory epilepsy, but the mechanisms underlying its neuroprotective effects remain unclear. Here, we show that the gut microbiota is altered by the KD and required for protection against acute electrically induced seizures and spontaneous tonic-clonic seizures in two mouse models. Mice treated with antibiotics or reared germ free are resistant to KD-mediated seizure protection. Enrichment of, and gnotobiotic co-colonization with, KD-associated Akkermansia and Parabacteroides restores seizure protection. Moreover, transplantation of the KD gut microbiota and treatment with Akkermansia and Parabacteroides each confer seizure protection to mice fed a control diet. Alterations in colonic lumenal, serum, and hippocampal metabolomic profiles correlate with seizure protection, including reductions in systemic gamma-glutamylated amino acids and elevated hippocampal GABA/glutamate levels. Bacterial cross-feeding decreases gamma-glutamyltranspeptidase activity, and inhibiting gamma-glutamylation promotes seizure protection in vivo. Overall, this study reveals that the gut microbiota modulates host metabolism and seizure susceptibility in mice.











Achieving the Gut Bacteria changes of the KD without the diet

Since the ketogenic diet (KD) is very restrictive, it would be much more convenient to achieve the GABA/Glutamate effect in a simpler way. You cannot currently just buy these two bacteria as a supplement.  There would seem to be 2 other obvious options: -

·        Take exogenous ketone supplements and hope this causes the same gut bacterial changes produced by the KD. No evidence exists.

·        Use other known methods to increase to increase Akkermansia muciniphila and Parabacteroides species in a similar way to that likely being developed by Bloom Sciences in San Diego. Bloom are developing a medical food to achieve this, so it will require a prescription and it will be costly. 

Increasing Akkermansia muciniphila can be achieved using fructooligosaccharides (FOS). FOS is included in many types of formula milk for babies and is sold as a supplement.
Metformin, a drug used to treat type 2 diabetes, greatly increases Akkermansia muciniphila. Vancomycin, the antibiotic that stays in the gut, also greatly increases Akkermansia muciniphila, but it is also going to wipe out many bacteria.
The research shows you also need the second bacteria Parabacteroides, of which there are many types. These bacteria are found in high levels in people following a Mediterranean type diet but it can be increased using Resistant Starch Type 4. This type of starch has been chemically modified to resist digestion. This starch is sold as food ingredient to add to bakery products.




Viable A. muciniphila and fructooligosaccharides contently promote A. muciniphila. 
Metformin and vancomycin also significantly promote A. muciniphila.



“Akkermansia can also be increased by consuming polyphenol-rich foods, including:

·         pomegranate (attributed to ellagitannins and their metabolites)

·      grape polyphenols (grape seed extract) (proanthocyanidin-rich extracts may increase mucus secretion, therefore creating a favorable environment for Akkermansia to thrive) 

·   cranberries “ 


The abundance of Parabacteroides distasonis (P = .025) and Faecalibacterium prausnitzii (P = .020) increased after long-term consumption of the Med diet and the LFHCC diet, respectively.






Resistant starches types 2 and 4 have differential effects on the composition of the fecal microbiota in human subjects.


Abstract


BACKGROUND:


To systematically develop dietary strategies based on resistant starch (RS) that modulate the human gut microbiome, detailed in vivo studies that evaluate the effects of different forms of RS on the community structure and population dynamics of the gut microbiota are necessary. The aim of the present study was to gain a community wide perspective of the effects of RS types 2 (RS2) and 4 (RS4) on the fecal microbiota in human individuals.

METHODS AND FINDINGS:


Ten human subjects consumed crackers for three weeks each containing either RS2, RS4, or native starch in a double-blind, crossover design. Multiplex sequencing of 16S rRNA tags revealed that both types of RS induced several significant compositional alterations in the fecal microbial populations, with differential effects on community structure. RS4 but not RS2 induced phylum-level changes, significantly increasing Actinobacteria and Bacteroidetes while decreasing Firmicutes. At the species level, the changes evoked by RS4 were increases in Bifidobacterium adolescentis and Parabacteroides distasonis, while RS2 significantly raised the proportions of Ruminococcus bromii and Eubacterium rectale when compared to RS4. The population shifts caused by RS4 were numerically substantial for several taxa, leading for example, to a ten-fold increase in bifidobacteria in three of the subjects, enriching them to 18-30% of the fecal microbial community. The responses to RS and their magnitudes varied between individuals, and they were reversible and tightly associated with the consumption of RS.

CONCLUSION:


Our results demonstrate that RS2 and RS4 show functional differences in their effect on human fecal microbiota composition, indicating that the chemical structure of RS determines its accessibility by groups of colonic bacteria. The findings imply that specific bacterial populations could be selectively targeted by well-designed functional carbohydrates, but the inter-subject variations in the response to RS indicates that such strategies might benefit from more personalized approaches.


Ketones and NKCC1/KCC2  
The next part of this post does get complicated and so it will be of interest to a smaller number of readers; the question is whether ketones play a role in the (miss) expression of those two critical chloride transporters NKCC1 and KCC2. If ketones play a role, then they might have therapeutic potential in all those people with autism and Down Syndrome who respond to bumetanide.
Some researchers think ketones play such a role but the bumetanide for autism researchers disagree.
The ongoing disagreement in the research is about the role played by a lack of ketones in why in immature neurons GABA is excitatory. Regular readers will know that in a large group of autism the GABA switch never flips and so neurons remain in the immature state that was only supposed to last weeks after birth. The debate in the research is to what extent ketone bodies play a role.
We know that in much autism and indeed in those with other problems like neuropathic pain, there can be elevated chloride due to over-expression of NKCC1 (through which chloride enters) and under-expression of KCC2 (through which chloride ions exit neurons). 

GABA action in immature neocortical neurons directly depends on the availability of ketone bodies. 


Abstract


In the early postnatal period, energy metabolism in the suckling rodent brain relies to a large extent on metabolic pathways alternate to glucose such as the utilization of ketone bodies (KBs). However, how KBs affect neuronal excitability is not known. Using recordings of single NMDA and GABA-activated channels in neocortical pyramidal cells we studied the effects of KBs on the resting membrane potential (E(m)) and reversal potential of GABA-induced anionic currents (E(GABA)), respectively. We show that during postnatal development (P3-P19) if neocortical brain slices are adequately supplied with KBs, E(m) and E(GABA) are both maintained at negative levels of about -83 and -80 mV, respectively. Conversely, a KB deficiency causes a significant depolarization of both E(m) (>5 mV) and E(GABA) (>15 mV). The KB-mediated shift in E(GABA) is largely determined by the interaction of the NKCC1 cotransporter and Cl(-)/HCO3 transporter(s). Therefore, by inducing a hyperpolarizing shift in E(m) and modulating GABA signaling mode, KBs can efficiently control the excitability of neonatal cortical neurons.

In the early postnatal period, energy metabolism in the suckling rodent brain relies to a large extent on metabolic pathways alternate to glucose such as the utilization of ketone bodies (KBs). However, how KBs affect neuronal excitability is not known. Using recordings of single NMDA and GABA activated channels in neocortical pyramidal cells we studied the effects of KBs on the resting membrane potential (Em) and reversal potential of GABA-induced anionic currents (EGABA), respectively. We show that during postnatal development (P3–P19) if neocortical brain slices are adequately supplied with KBs, Em and EGABA are both maintained at negative

levels of about )83 and )80 mV, respectively. Conversely, a KB deficiency causes a significant depolarization of both Em (>5 mV) and EGABA (>15 mV). The KB-mediated shift in EGABA is largely determined by the interaction of the NKCC1 cotransporter and Cl)/HCO3 transporter(s). Therefore, by inducing a hyperpolarizing shift in Em and modulating GABA signaling mode, KBs can efficiently control the excitability of neonatal cortical neurons. Keywords: cortex, development, energy substrates, GABA, ketone bodies, resting potential.

showed that in the presence of KBs, values of EGABA in neocortical pyramidal neurons were close to Em, and did not change significantly during postnatal development, being maintained at about )80 mV (see Fig. 3). We cannot exclude the possibility that these values may differ in dendritic (Gulledge and Stuart 2003) or axonal (Price and Trussell 2006; Trigo et al. 2007; Khirug et al. 2008) compartments, an issue for future studies. Additionally, in this study we have limited our investigations to pyramidal cells, and the effects of KBs on interneurons remain to be explored. Nevertheless, the present observations suggest that energy substrates in the developing brain are an important issue to consider when studying neonatal neuronal excitability. Indeed, the most straightforward explanation for the difference between the results of the current study and those of previous studies of the development of neonatal GABA signaling lies in the fact that the brain of the suckling rodent relies strongly on KBs (Cremer and Heath 1974; Dombrowski et al. 1989; Hawkins et al. 1971; Lockwood and Bailey 1971; Lust et al. 2003; Page et al. 1971; Pereira de Vasconcelos and Nehlig 1987; Schroeder et al. 1991; Yeh and Zee 1976). Glucose utilization is limited at this age (Dombrowski et al. 1989; Nehlig, 1997; Nehlig et al. 1988; Prins 2008) because of the delayed maturation of the glycolytic enzymatic system (Dombrowski et al. 1989; Land et al. 1977; Leong and Clark 1984; Prins 2008). Use of glucose as the sole energy substrate caused an increase in neonatal neuronal [Cl)]i in our experiments, similar to that observed previously, while the addition of KBs resulted in a hyperpolarizing shift in both Em and EGABA. These results highlighted the need for caution in the interpretation of results obtained from neonatal brain slices superfused with standard ACSF. The cation chloride cotransporters NKCC1 and KCC2have been suggested to be the main regulators of neuronal Cl) homeostasis both during development (Farrant and Kaila 2007; Fiumelli and Woodin 2007) and in pathology (Galanopoulou, 2007; Kahle and Staley, 2008; Kahle et al. 2008).Although the possible contribution of anion exchangers to neuronal Cl) homeostasis has been noted previously (Farrant and Kaila 2007; Hentschke et al. 2006; Hubneret al. 2004; Pfeffer et al. 2009), they have not attracted the same degree of attention. Results from our study demonstrate, however, that the Cl)/HCO)3 transporter system is strongly involved in the KB-mediated regulation of [Cl)]i during postnatal development. Within this family, the Na-dependent Cl)/HCO)3 transporter (NDCBE), is of particular interest as it is expressed in the cortex (Chen et al. 2008) and has a strong dependence on ATP for its action (Chen et al. 2008; Davis et al. 2008; Romero et al. 2004). In addition, the sodium driven chloride bicarbonate exchanger(NCBE),(Giffardet al. 2003; Hubner et al. 2004; Lee et al. 2006) was expressed in the brain early during prenatal development and its expression preceded that of KCC2 (Hubner et al. 2004).

In neonatal neocortical neurons the interaction of NKCC1 and the Cl)/HCO3) transporter(s) maintained [Cl)]i, with KCC2 playing a less significant role at this stage. In the absence of KBs, when Cl)/HCO3) transporter(s) were less effective, the role of NKCC1 as a Cl) loader was especially noticeable and resulted in a depolarizing EGABA. During development the contribution of KCC2 to neocortical neuronal Cl) homeostasis is likely to increase (Stein et al. 2004; Zhang et al. 2006), and the balance between the actions of the different Cl) transporters in adults should be studied in the future. In humans, blood levels of KBs increase considerably during fasting, strenuous exercise, stress, or on the high-fat, low-carbohydrate ketogenic diet (KD) (Newburgh and Marsh 1920). A rapidly growing body of evidence indicates that the KD can have numerous neuroprotective effects (Gasior et al. 2006). During treatment with the KD, levels of KBs increase in both blood and brain, and cerebral metabolism adapts to preferentially use KBs as an alternate energy substrate to glucose (Kim do and Rho 2008). In children, the KD has been used as an effective treatment for medically refractory epilepsy (Freeman et al. 2007; Hartman and Vining 2007). However, despite nearly a century of use, the mechanisms underlying its clinical efficacy have proved elusive (Morris 2005; Bough and Rho 2007; Kim do and Rho 2008). Suckling rodents provide a natural model of the KD because of the high ketogenic ratio (Wilder and Winter 1922) of rodent milk (Page et al. 1971; Nehlig 1999). We propose that the KB-induced modulation of GABA-signaling may constitute a mechanism of anticonvulsive actions of the KD.

Now for the opposing views: -

Summary
Brain slices incubated with glucose have provided most of our knowledge on cellular, synaptic, and network driven mechanisms. It has been recently suggested that γ‐aminobutyric acid (GABA) excites neonatal neurons in conventional glucose‐perfused slices but not when ketone bodies metabolites, pyruvate, and/or lactate are added, suggesting that the excitatory actions of GABA are due to energy deprivation when glucose is the sole energy source. In this article, we review the vast number of studies that show that slices are not energy deprived in glucose‐containing medium, and that addition of other energy substrates at physiologic concentrations does not alter the excitatory actions of GABA on neonatal neurons. In contrast, lactate, like other weak acids, can produce an intracellular acidification that will cause a reduction of intracellular chloride and a shift of GABA actions. The effects of high concentrations of lactate, and particularly of pyruvate (4–5 mm), as used are relevant primarily to pathologic conditions; these concentrations not being found in the brain in normal “control” conditions. Slices in glucose‐containing medium may not be ideal, but additional energy substrates neither correspond to physiologic conditions nor alter GABA actions. In keeping with extensive observations in a wide range of animal species and brain structures, GABA depolarizes immature neurons and the reduction of the intracellular concentration of chloride ([Cl]i) is a basic property of brain maturation that has been preserved throughout evolution. In addition, this developmental sequence has important clinical implications, notably concerning the higher incidence of seizures early in life and their long‐lasting deleterious sequels. Immature neurons have difficulties exporting chloride that accumulates during seizures, leading to permanent increase of [Cl]i that converts the inhibitory actions of GABA to excitatory and hampers the efficacy of GABA‐acting antiepileptic drugs.  


GABA depolarizes immature neurons because of a high [Cl]i and orchestrates giant depolarizing potential (GDP) generation. Zilberter and coworkers (Rheims et al., 2009; Holmgren et al., 2010) showed recently that the ketone body metabolite dl-3-hydroxybutyrate (dl-BHB) (4 mm), lactate (4 mm), or pyruvate (5 mm) shifted GABA actions to hyperpolarizing, suggesting that the depolarizing effects of GABA are attributable to inadequate energy supply when glucose is the sole energy source. We now report that, in rat pups (postnatal days 4–7), plasma d-BHB, lactate, and pyruvate levels are 0.9, 1.5, and 0.12 mm, respectively. Then, we show that dl-BHB (4 mm) and pyruvate (200 μm) do not affect (i) the driving force for GABAA receptor-mediated currents (DFGABA) in cell-attached single-channel recordings, (2) the resting membrane potential and reversal potential of synaptic GABAA receptor-mediated responses in perforated patch recordings, (3) the action potentials triggered by focal GABA applications, or (4) the GDPs determined with electrophysiological recordings and dynamic two-photon calcium imaging. Only very high non physiological concentrations of pyruvate (5 mm) reduced DFGABA and blocked GDPs. Therefore, dl-BHB does not alter GABA signals even at the high concentrations used by Zilberter and colleagues, whereas pyruvate requires exceedingly high non-physiological concentrations to exert an effect. There is no need to alter conventional glucose enriched artificial CSF to investigate GABA signals in the developing brain.

Very recent research shows that ketones do not affect the expression of NKCC1 or KCC2. This would tend to support the argument of Ben Ari and Tyzio.


  
Nonetheless it seems that ketone bodies do indeed have an effect on GABA; they appear to change the hippocampal GABA/Glutamate ratio. 
So Tyzio might not be as right as he thought in his rebuttal paper when he said.
“suggesting, contrary to Zilberter and colleagues, that the antiepileptic actions of ketone bodies are not mediated by GABA signalling
Tyzio is thinking about the resting membrane potential (Em) and reversal potential of GABA-induced anionic currents (EGABA).
At the end of that day a reduction in gamma-glutamylated amino acids, caused by changes in gut microbiota cause an increase in hippocampal GABA/Glutamate ratio. If you happen to have epilepsy this may mean less seizures.  

Conclusion
I think we can say with a fair degree of certainty that we now know why the ketogenic diet, and indeed the modified Atkins diet, greatly reduce seizures in many people with epilepsy. The diet changes the gut microbiota by increasing the amount of Akkermansia muciniphila and Parabacteroides species, the end result is an increase in GABA, the inhibitory neurotransmitter, inside the brain. In much epilepsy, more inhibition to neurons firing results is far less seizures.
GABA plays a key role in autism, albeit a complex one.
The ketone driven changes to GABA might explain why some people with autism respond to the KD or just ketone supplements, but ketones have many other effects relevant to autism that will be reviewed in later posts.