Vasovagal Syncope (Fainting) and Paleo

So I try to listen to Robb Wolf's podcasts as they come out (available on his website robbwolf.com) because, if nothing else, it's entertaining to hear Greg Everett lose his temper over something seemingly inane. (I totally understand when something just really gets your goat though.) These podcasts, although lengthy are packed full of really great information. When I was looking at the topics tonight in episode 93, the first one really caught my eye. 

A girl named Katie wrote in about her condition, vasovagal syncope (fainting), and asked if Robb though a paleo diet change and maybe CrossFit style work out regimen would help her to avoid randomly passing out. Katie described herself: 23 years old, 5' 7", 125lbs, low but health blood pressure (90/60), generally very active and specifically with martial arts. I was taken aback because, I swear, I could be looking in a mirror right now. I have dealt with this condition, assumed to be vasovagal syncope because no doctor could figure out a better diagnosis, from my early adolescent life going forward. I'm 23, 5' 7", usually around 125lbs, have low blood pressure (last measured at 90/60), and was also very active in martial arts... Woah, long lost twin here.

I thought this was a fitting topic for my first post because I actually have a lot to say. As no doctor I saw during my early teen years could give me an idea of why I was fainting rather randomly, I started figuring things out for myself. These were the triggers for fainting that I noted: dehydration, standing for long periods of time, blood sugar crashes, exhaustion, extreme pain, and stress. Every time I passed out, the reasoning boiled down to one of these. Thankfully, I became aware of the early warning signs of an oncoming faint, and was almost always able to avert a crisis by hitting the deck and raising my feet.

First of all, let me say generally what fainting ala vasovagal syncope is. When a trigger activates the vagus nerve, excess acetylcholine is released, the heart rate slows and blood vessels dilate, making it harder for blood (and oxygen) to reach the brain. This causes syncope (fainting) in an effort to restore that blood flow. When one is prone, blood flows transversely along the body allowing blood to much more easily reach the brain, rather than fighting gravity when one is standing erect.

Now on to my physiological understanding of why I fainted (and the real moment I realized I love the subject of my bachelors degree). As I said before, I've always had low but healthy blood pressure. This is great, until it goes any lower. I realized my fainting episodes were caused generally due to a drop in blood pressure (which can be caused by activation of the vergus nerve, but doesn’t have to be).

Becoming dehydrated literally reduces the volume of blood pumping through the body, causing a general drop in blood pressure and making it much more difficult for the heart to pump blood to the brain. Blood pressure may also gradually decrease when, especially tall people or those with low blood pressure stand for extended periods of time. Blood must be pumped against gravity up the body to the brain in order to maintain normal physiological function. If a person is tall or has lower blood pressure, the body has to work harder than normal to get blood up there. Over time, blood pools in the lower half of the body. This decrease in blood flow, whether by dehydration or pooling causes fainting to occur to restore flood flow to the brain. Sudden but more mild decreases in blood pressure may also stimulate the vegas nerve and cause syncope by that mechanism.

I also came to the conclusion that I’m probably slightly hypoglycemic, but that it could be easily controlled by eating relatively frequently. (My friends know to keep me fed or I get really grumpy. The brain’s main fuel is glucose, and when it doesn’t have enough, it doesn’t work right.) Fainting occurs when blood glucose drops below 40mg. Usually my blood sugar crashes were caused by consuming a lot of sugar and the consequential whiplash reaction. Blood sugar regulation is a negative feedback system, and therefore has a delay. Upon eating in a hypoglycemic (low blood sugar state), the spike in blood sugar is detected by the pancreas, and insulin is secreted. Once blood sugar levels decrease to the normal level, insulin is temporarily still being secreted until the pancreases senses the reduced levels. The excess insulin still works to facilitate glucose storage, reducing blood glucose levels below the set point. This reaches a normal state with a little more time. When a high sugar meal is eaten however, lots of insulin is secreted and these effects are exaggerated. If blood sugar drops enough on the back end, fainting occurs. Additionally, sudden decreases in blood sugar can cause vagus nerve activation as well, and again fainting.

Quick anecdote: I remember one particular night during my 3^rd year (of 5) into my bachelors degree in Biomedical Engineering at the Georgia Institute of Technology. Several friends and I were holed up in the BME buiding, studying all night amid Monster cans, empty Dorito bags, and Poptart wrappers for a physiology exam we had the next morning. I was quickly approaching “the wall,” (you know, the one that unforgivingly breaks your figurative nose as you run into it at 4am) when I realized I had just read the majority of the reasoning for fainting over the last 10 years. I had reached the threshold at which what you learn in the classroom actually applies to your life. And boy did that apply big time for me. I was always interested in what my degree had to offer, but that was the point I decided I loved it. #nerd

Ok, finally to my paleo diet-related conclusions. Yes, a symptom of eating clean generally causes one to maintain lower blood pressure, which despite my myriad of problems is healthy. Chronically high blood pressure causes the heart to hypertrophy and become, as on of my professor eloquently stated “big and floppy” due to being constantly overworked. This eventually leads to heart failure. Frequent exercise, especially CrossFit-style workouts that involve large areas of the body (versus single muscle groups) and force the heart to work to pump blood to opposite ends of the body and an appropriate diet makes a strong heart and efficient vascular system that can deal with the effects of gravity and quickly react to changes in body positioning. 

It is crucial that one not abuse the functions of the body as I did in my adolescence, and that’s where paleo comes in. Not only are our bodies evolutionarily designed to eat meat and vegetables, these food do not elicit nearly as high of an insulinogenic response (causing insulin secretion) as modern food. This in turn corresponds to higher blood sugar stability and increased natural energy as blood sugar levels aren’t constantly cycled into peaks and crashes, and increased physiological sensitivity that allows for proper regulation of things like blood pressure.

Alright, I’m off my soap box and I pinky promise future posts won’t be anywhere near this long. :)