My favorite Guinea pig, my Dad, is diabetic but he won't admit it, nor take pills for it. His fasting blood glucose (FBG) is near 200 most mornings. He's been potato hacking for three days now, and doing "a good job" according to a spy in the house (thanks, Mom!). Potatoes, according to every doctor and nutritionist, should be Dad's worst enemy, yet he's eaten nothing but spuds for three days and says:
...blood reading this a.m. was 102 haven't seen that number in ages. BP down too. Have done potatoes for 3 days, also dropped a few pounds. plan to keep it up a few more days...
Has my 70 year old dad suddenly become insulin sensitive and reversed his diabetes? I'd love to stick him with a continuous glucose monitor connected to a computer, but my prediction is that if Dad starts adding a bottle of Coke or a candy bar to his meals, the entire effect will quickly reverse itself, and he'll be greeted again with an FBG of 200.
I'm learning today that there is maybe a huge difference between a potato and a bag of sugar, despite the potato's reputation for being "a bag of sugar."
The Glycemic Index
In part 3, we talked about active vs. passive transport of glucose across the lining of the small intestine and into the blood stream. Scientists have used the observation that ingested carbs will cause a resultant spike in blood glucose within a short time. The size and duration of this spike in BG is used to determine the glycemic impact, or index (GI), of a food. Pure glucose is used as the standard, given a GI of 100, and all other foods are compared. Here's a typical GI list:
|Food||GI||Serving Size (g)|
|Jelly Beans||78||1 oz|
|Snickers Bar||68||60g (1/2 bar)|
|Table Sugar||68||2 Tsp|
|Strawberry Jam||51||2 Tbs|
|Peanut M&Ms||33||30 g (1 oz)|
|Dove Dark Chocolate Bar||23||37g (1 oz)|
|Potato||104||213g (1 med)|
|Parsnip||97||78g (1/2 cup)|
|Carrot, raw||92||15g (1 large)|
Diabetics and dieters alike are often told:
Low glycemic foods help you feel full longer; help keep blood sugar even.
Looking at the list above, which food would you immediately avoid if looking to lower the glycemic impact of foods? I lurrrves me some peanut M&Ms, though!
Why the disparity?
I have never even once thought that choosing foods according to the glycemic index charts was a good idea from a blood sugar point of view. The full list and methodology for building the list can be found here: International tables of glycemic index (1995). If you scroll through the 600 or so entries, you will see wide variances within each category, potatoes, for instance are rated with a GI of 54 (new potatoes) to 111 (baked potatoes), with an average of roughly 75. A raw potato, if it were on the list, would have a GI close to zero.
How can a "Dove Dark Chocolate bar" be 23 and a potato 111? Most likely because the chocolate bar is sweetened with high fructose corn syrup. Fructose, you see, does not cause a spike in blood sugar, and it will not register on a glucose meter. Fructose (and sucrose, etc...) are all sugars that have special concerns. Maybe some day we'll take a look, but for now, we'll stay focused on glucose.
The glycemic index does point out, however, that all "carbs" are not created equal, not even remotely so.
Passive vs. Active Transport Revisited
Friend to the Veggie Pharm, Dr. Art Ayers was consulted. He reminded me of some unfortunate biology that I have been overlooking: the glucose from a potato is different from the glucose in refined sugar.
Also remember that dietary starch does not yield glucose, but rather maltodextrins, the glucose oligosaccharides that are hydrolyzed to glucose on the surface of the intestinal epithelial cells. There is no glucose to leak across the junctions.
When we eat a potato, we do not get an intestine full of glucose, we get an intestine full of plant material that requires even further breakdown before it can be transported into the blood. Therefore, Dr. Ayers is suggesting that when eating an all-potato diet, there is no free glucose floating around that could get transported to the blood via leaking tight junctions (TJs).
I mentioned yesterday that passive transport is also called the Pappenhiemer Effect. Well, it turns out that Dr. Ayers actually knows Dr. Pappenheimer (even calls him "Pap!"). Dr. Ayers is not a big fan of my leaky gut theory of diabetes, but I have shown him a thing or two that got his nod of approval in the past...hopefully I can do it here.
There are many papers, including "Pap's" that describe a passive flow of glucose across TJs. There are no papers describing a sustained flow of glucose across TJs in an unhealthy state called "leaky gut." Yet, leaky gut is very real and the cause of such inflammatory diseases like Celiac disease, IBS, and arthritis. Much of the damage of a leaky gut is done by allowing things into the blood that should not be there, wheat gluten in celiac for instance. Leaky gut is also blamed for diabetes, but not because of the glucose issue.
The Potato Hack Effect
What can be going on then with an all-potato diet to lower BG from diabetic levels to normal? I had initially assumed that the potato hack was healing the leaky gut, but now I believe that the potato hack works because it provides a glucose source that MUST be hydrolized and actively transported across the gut lining.
All that will be needed to offset the potato hack effect is a sugar. Sugar, especially refined, white sugar is composed of glucose molecules that are easily liberated by salivary amylase. When this bolus hits the intestines, it's in a form that can be used by the body, so if it passively leaks across a leaky TJ, it will cause a rise in BG independent from glucose that arrives via the normal pathway of active transport.
If someone like my Dad sees dramatic improvements of blood glucose readings while potato hacking, the return to a normal diet needs to be carefully considered. I'd like to see my dad add back in all of his normal foods, except for any that contain sugar, including fruits, and bread. He should start eating his normal meals, including plenty of veggies. Snacks can be of the starchy variety if need be, nuts, etc. but no M&Ms or soda pop.
If my hypothesis holds true, by avoiding any form of easily transported glucose, his BG levels should remain normal. Only after he is satisfied of the "cure" should he add in his normal sugar snacks. My prediction is that his BG will skyrocket back to where it was before.
If so, this should be a massive wake-up call to all diabetics that a potato is NOT a bag of sugar, the Glycemic Index is crap, and their diet should be filled with starches instead of sugars.
I'll have to email this idea to my dad, no way he will read all this, lol. Mom, maybe.
Then what? Well, I guess I'll just have to sit down and write this all up for a medical journal and hope that someone can test my theory in a clinical setting. Will anyone care?
I think that's all for this series. I left out a LOT of the research I went through to get this far. There's a gut microbe angle, a magnesium/manganese angle, and a boat-load of old diets that were used to cure diabetes that look an awful lot like the potato hack in terms of glucose and nutrients.
Maybe this stuff can come out on the comments, and we'll get the rest of the gang to join in. Gabrielle Kadar has a lot to say on the subject, so does Gemma. Can we entice Art here? Maybe I'll email him, too.