The answer posted by Dr. Harris lead me to find many ketomyths in the "paleosphere" and "blogosphere". Although most don't think ketosis is dangerous, the common perception is that "more is not better", that is, being in ketosis 24/7 is not better than being only for short periods of time. According to Harris, there is no need to if you aren't sick. The main argument is that ketosis is not the natural state of the body and represents a metabolic stress. Keep in mind I never said that we should be in ketosis 24/7, I just said that ketosis should be the baseline physiological state (so most of the time you are in, but not necessarily 24/7*).
Initially, I was going to address the points made by Dr. Harris in his post but I found one ketomyth that has spread all over the internet which people use as an argument against glucose deprivation. Before I go on I must say that zero carb diets are only theoretically possible, unless you eat only yolks and oil.
It all started with the incidence of gastrointestinal cancers in long time OD's that were reported on Peter's blog. People started speculating on the origin of this issue trying to understand why the "Optimal" diet was not that optimal. The Jaminet's, authors of the Perfect Health Diet, posted an article attributing mucin deficiency as the cause. I think this can be a likely cause but only in OD dieters. The OD is characterized by restricting both protein and glucose. But somehow people misinterpreted this and started using it as an argument against all ketogenic diets.
But what exactly determines GI mucin production? Mucin biosynthesis is highly sensitive to protein malnutrition, specially threonine deficiency (1,2,3). Other aminoacids like serine, proline and cysteine can also promote mucin synthesis (4). When intestinal epithelial goblet cells are deprived of glucose, butyrate modulates MUC gene expression and becomes the main regulator of mucin synthesis (5). There is no evidence that the abscence of dietary glucose affects mucin synthesis. So any deficiency of mucin in ODs would occur because of a low protein intake, not because of a glucose deficiency (call it a secondary-glucose deficiency if you wish).
Thr, Ser, Pro and Cys are all glucogenic aminoacids. The demand for these amino acids increases when eating a very low carbohydrate diet because gluconeogenesis is increased to maintain a normal blood glucose level. Eating a diet low in these amino acids could compromise mucin production because they are redirected to glucose production instead of other biosynthetic pathways.
Dr. Jaminet goes on and explain:
Throughout my 2 years on this zero-carb diet, I had dry eyes and dry mouth. My eyes were bloodshot and irritated, and I had to give up wearing contact lenses. Through repeated experiments, I established that two factors contributed to the dry eyes – vitamin C deficiency and glucose deficiency. After I solved the vitamin C issue, I did perhaps 50 experiments over the following few years, increasing carbs which made the dry eyes go away and reducing them which made them immediately come back. This established unequivocally that it was a glucose deficiency alone that caused the dry eyes.I find this last line specially interesting, considering that bOHB has shown to be protective in different types of dry eye models (6, 7), although used as eye drop.
What about Vitamin C? Thats the topic for the next post.
I am not trying to put down Dr. Jaminet's work. On the contrary, I find it highly valuable, specially the emphasis he has on micronutrition. I also like n=1 experiments. But I think glucose deficiency is a misnomer. Think about protein deficiency and dehydration instead. These problems should not arise if you eat a proper amount of protein, drink enough water during the day and eat a fairly good amount of sodium (is salt paleo?) and potassium.