Hypoglycemia: It’s Symptoms and Causes
One infrequently discussed problem of low carbohydrate diets is hypoglycemia symptoms. If you’ve never had hypoglycemia, be glad. The word hypoglycemia means “low” (hypo) “sugar” (glyc) “in blood” (emia) – Low blood sugar. The symptoms include sweating, shakiness, dizziness, irritability, cold extremities, lightheadedness, anxiety, and many others. There is reactive hypoglycemia, which occurs shortly after eating a meal that stimulates excess insulin release leading to low blood sugar and its accompanying symptoms. (I want to point out here that hypoglycemia should be determined based on overall symptoms and not the blood sugar level itself. If someone is used to a perpetually high blood sugar level and then it goes to normal, that person will have hypoglycemia symptoms even thought they don’t “technically” have low blood sugar). Insulin release can be caused by foods with a high glycemic index (those that are quickly converted into glucose) or a food sensitivity to whatever was ingested. Although the food sensitivity cause of hypoglycemia is hardly ever discussed in modern medicine, it is a fact and has been documented in historic medical literature.
In this model of hypoglycemia, the cause is excess insulin driving blood sugar down too low. Insulin takes the blame for a lot, but in order to truly understand this, we need to look at all sides of this equation.
Glucagon: Its Role and Importance
Insulin drives down blood sugar so that the blood sugar does not get too high. Glucagon has the opposite effect – it releases stored blood sugar from the liver and muscles during fasting. There are cells that simply must have glucose in order to survive. Red blood cells need glucose. The brain needs glucose. Because of how essential to life it is, we have the hormone glucagon to provide us glucose when we cannot get it from the environment.
So on the other hand, hypoglycemia during fasting can be a result of dysfunctional glucagon.
The Unacknowledged Importance of Vitamin A in Fuel Regulation and Hypoglycemia
Vitamin A makes an appearance here because it is essential to optimal function of both insulin and glucagon.
Vitamin A is essential on a low carbohydrate diet because the alpha cells of the pancreas cannot secret enough glucagon without it. This comes from a 1994 study titled “Effects of vitamin A deficiency and repletion on rat glucagon secretion.” (Pancreas. 1994 Jul; 9(4): 475-84. PMID: 7937697). In this study it was found that “glucagon secretion was markedly impaired in islets and pancreases of vitamin A-deficient rats or rats that had at some time been cycled through vitamin A deficiency (ever A-def) despite repletion with retinoids for 2-4 weeks.” Insulin secretion by beta cells was also impaired (the insulin secretion impairment has been confirmed many times since due to the obsession with insulin; no one cares about glucagon to research it enough). The researchers also found that this glucagon secretion impairment appeared early in the course of the vitamin A deficiency. So, in my opinion, hypoglycemia due to glucagon secretion impairment is the first sign of vitamin A deficiency, not problems with night vision, which is the cartoon-version of vitamin A deficiency in every lay person’s vitamin book.
Even when glucagon is functioning optimally, if one is on a low carbohydrate diet, the glucose release from glucagon cannot be the sole fuel of the body. There simply isn’t enough to power the whole body on the little amount of glucose that the body secretes from insulin. If you don’t have an alternate fuel source to rely on, you will be dependent on that little supply of glucose and feel pretty impaired. Remember, you are cutting carbohydrates on a low carbohydrate diet and your two other fuel sources are protein and fat; neither can supply much glucose. But the body can use fat for fuel.
But again, vitamin A steps in. The body can’t use fat for fuel effectively without vitamin A. When vitamin A is deficient, urea cycle enzymes are increased. The urea cycle is the process of metabolizing protein, not fat. The theory is that without vitamin A, the fuel to be relied on will switch to protein (a source of glucose) and not fat. (“Vitamin A deficiency increases protein catabolism and induces urea cycle enzymes in rats.” J. Nutr. 2010 Apr; 140(4): 792-8. PMID: 20181784). Then you are back to relying on glucose on a low carbohydrate diet, the need of which can never be met due to the insignificant amount of carbohydrates. To be successful on a low carbohydrate diet, you must be able to metabolize and use fat.
To conclude, if one is suffering from hypoglycemia on a low carbohydrate diet, the most likely cause is vitamin A deficiency. The secretion of glucagon in meeting the minimum glucose requirements of the body is dependent on sufficient vitamin A. And the effectiveness of the body in switching its fuel source to fat instead of continuing to rely on glucose through the urea-protein cycle is also dependent on vitamin A. The first symptom of vitamin A deficiency is hypoglycemia.