Can Nutritional Ketosis Provide An Alternate Brain Fuel And Protect Us From Hypoglycemia?
Another topic of research that needs to be done is to measure the degree to which ketones created by the liver by following a ketogenic diet can act as a brain fuel and lead to a reduction in or lack of symptoms of hypoglycemia in those with T1DM. We know from the study done by Drenick et. al. (ref 9) that in non-diabetic obese persons who fasted for 2 months and achieved blood beta-hydroxybutyrate (BHB) levels of 8 mM when given a single dose of insulin to induce severe hypoglycemia suffered no symptoms despite BG values as low as 9 mg/dl (0.5 mmol/l). However, the applicability of this study to those with diabetes following a ketogenic diet is questionable given that the BHB levels are typically in the 0.5 to 3 mM range from nutritional ketosis. Another study (ref 10) in rats found that the cerebral metabolic rate of glucose decreased by 9% for each 1 mmol/l increase in total plasma ketone body concentration in ketotic rats induced by 3 weeks of a ketogenic diet. “The brain’s ability to switch from glucose oxidation towards ketone bodies requires a type of ‘cerebral metabolic adaptation’. This process is not well understood but is thought to be highly associated with the duration and level of ketosis. Ketones are considered to supply up to 70% of the total energy demands once maximal metabolic adaptation occurs.” Another study (ref 11) of 8 healthy male students found that mental alertness was significantly reduced by moderate hypoglycemia (40 mg/dl or 2.2 mmol/l) after an overnight fast while similar hypoglycemia did not reduce mental alertness after a 72 hour fast. BHB levels were not reported in the abstract (I did not purchase the full article). Finally in this study (ref 12), the effect of hyperketonemia on counter-regulatory hormone responses to hypoglycemia was examined in six healthy subjects. The peak adrenaline (epinephrine) response to hypoglycemia fell from 7.97 to 2.6 nmol/l during ketone infusion and the peak noradrenaline, cortisol and growth hormone responses were also significantly lower during ketone infusion at a rate of 3 mg/min/kg body weight which resulted in a 0.58 mmol/l BHB concentration which as you know is achievable with nutritional ketosis. In addition, the study found that the BG required to elicit the counter-regulatory hormone response was lower during the ketone infusion (BG was 2.5 mmol/l (45 mg/dl) during ketone infusion compared to 3.0 (54 mg/dl) mmol/l without ketones).