Sunday, October 24, 2010

Carbohydrate Intake and Depression

It's hard to know where to start on this one.  Everywhere you look, if you look, you see surprisingly consistent correlations between carbohydrate intake and depression.  Some studies draw a direct link.  Others find strong correlations with certain long-term results of high carbohydrate consumption, such as insulin resistance (see here also), diabetes (and here), vitamin D deficiency (and here), obesity and so on.  Some of these, and many others, make the leap to causation and successfully attempt to treat depression by correcting specific deficiencies or excesses.  Still others observe a relationship between low-fat diets (independent of carbohydrate intake) and depression.

After a lot of searching, I managed to find a single study investigating the effects of a ketogenic diet on depression in humans.  Its loneliness in the literature was not lost on its author:

It is surprising, after so much clinical experience spanning a period of two thousand years, that this paper is the first [and last] by a psychiatrist describing the applications of the ketogenic diet in the treatment of anxiety, depression, and dysperception. Meanwhile, throughout this most advanced society of ours, in every modern psychiatric facility patients are exposed to an overdose of carbohydrates... It is time that the application of available knowledge in this field should be the rule rather than the exception. Ignorance and fear of controversy are no longer an excuse to withhold this basic and physiologically-oriented treatment from our patients.

Wednesday, July 28, 2010

Top 10 Mistakes on a Low Carb Diet

Generally this is a science blog, but I realize more and more that I came into this by a different path than most people, and it's hard to get everything across all at once when advocating a low carb diet.  Some of these are mistakes I had to learn from along the way, and others are things I was able to "un-learn" before I got started.  So, for those of you new to low-carb dieting, at least a few of these should steer you clear of some of the more common obstacles.

10. Jumping right in

If you've never eaten this way before, it can be hard.  When I say don't jump right in, I don't mean "don't go cold turkey."  I mean prepare first.  Sit down and make a grocery list that will get you through a week, ideally.  It should have enough meat, cheese, eggs and optionally green vegetables and sugar-free drinks for as many meals as you'll eat at home during that time.  And don't skimp on the snacks.  Lunch meat is one of my favorites.  When you get back from the grocery store, put it all away and get rid of things you shouldn't have, all at once.  That means cereal, pasta, chips... carbs!  If it's available, it's likely to be a temptation.  This can be a problem if the rest of the household isn't on board, so if you don't live alone, try to make that your first step.

9. Worrying about dietary cholesterol

A lot of people start a diet like this and avoid things like eggs.  Eggs!  I can't think of a more perfect food.  Except maybe ribeyes.  Anyway if you're still convinced that dietary cholesterol is harmful or risky, I won't be changing your mind in this post, but you absolutely must get down to the library or the book store and get your hands on this book.  It will square you away.  In the mean time, I'm comfortable asking you to take my word for it: you'll do more harm by avoiding cholesterol than by eating it, while you work on getting the book.

Tuesday, July 20, 2010

Mosquito repellent?

This one started out, for me, as a personal observation.  Our family's currently camping (I'm sitting at a picnic table right now), and something curious happened last night.  My wife, who had thoroughly doused herself with highly concentrated (25% DEET) OFF!®, was feasted upon just a foot or two from me, while I enjoyed a total but unexplained protection.  This is our first major exposure to mosquitoes since starting the diet, now that I think of it, and this was not the normal state of affairs pre-diet.  Mosquitoes positively loved me.

My wife, as it happens, is trying to get back on the proverbial wagon, but she is currently not in ketosis.  Naturally, I thought of this as a possible factor, even if I couldn't explain how it would work.  So I did some research.

It turns out that ketones (some of them more than others) are natural and effective mosquito repellents. According to some research, some of these compounds are considerably more effective (and less harmful) than DEET.  Now they're trying to productize ketones as spray-on repellents.

As an experiment, I'm planning to go the rest of the camping trip without using any artificial repellents, and see how I fare.  That's not exactly a rigorous double-blind, placebo-controlled trial, but it'll help me personally evaluate the voracity of this possibility.


Update 07/26/2010
As planned, I went the rest of the camping trip without the aid of artificial mosquito repellents, and I'm thrilled to report that I got not a single bite.  This has led me to consider how primitive sub-Saharan tribes have managed to survive the scourge of Malaria that has plagued the rest of the African continent.  I plan to keep looking into this.

Monday, May 31, 2010

Epilepsy

I haven't written (much) about epilepsy until now because it's so, well, uncontroversial.  But it's come to my attention that a lot of people who need to know about it, don't.  So I'll start with a bit of history.

Around 400 BC, the physician Hippocrates (of Hippocratic Oath fame) wrote a book called On the Sacred Disease, about epilepsy.  In it, he identifies the disease as a brain disorder rather than a demonic infestation, and recommends fasting as a treatment.  Some centuries later, as recounted in the Bible, a man brought an epileptic child to Jesus for an exorcism, His disciples having failed.  The child is miraculously cured on the spot, but Jesus takes a moment to point out that "this kind goeth not out but by prayer and fasting."

Hashimoto's Hypothyroidism and Graves' Disease

Most thyroid problems are caused by an underlying, often tissue-specific, autoimmune problem.  The same trigger (an attack on thyroid cells by the immune system) can produce opposite clinical outcomes - either Graves' Disease (hyperthyroidism) or Hashimoto's Thyroiditis (hypothyroidism).  Since they're both autoimmune disorders affecting the thyroid, I'm going to treat them as such, together.

First, I'll briefly cover autoimmune disorders in general for those who aren't familiar.  The main job of your immune system is to get rid of things that don't belong in your body.  To do that job without doing more harm than good, it's vitally important that it can distinguish self from nonself.  When it gets that wrong, such as with pathogens that masquerade as healthy cells, massive failure ensues.  Such is the case with autoimmune problems, where the immune system mistakenly identifies normal, healthy cells as nonself and attacks them.  This can be systemic as in lupus or multiple sclerosis, or tissue-specific as in Graves' or Hashimoto's.

Sunday, April 11, 2010

Conditioning and the Cephalic Phase Insulin Response

It's well known that we secrete insulin in response to dietary carbohydrates. Specifically, we convert most non-fiber carbohydrates into glucose, whose presence in the blood is sensed by cells in the pancreas, which secrete insulin in response. But there's been a lot of work done in recent decades showing that the insulin response doesn't always match what we'd expect from this simple explanation.

For example, certain artificial non-nutritive sweeteners have been shown to elicit an insulin response. Certain fatty foods have a similar effect, including foods with little or no carbohydrate content, like butter. Why is this? What produces this response, if not the glucose-sensing islet β-cells in the pancreas?  This study and others have posed the question, or at least acknowledged the gap in understanding: "the mechanism of the cephalic phase insulin response to meal ingestion has not been established in humans."  This study, which looks at the subjects' metabolic responses to the taste of fat, rather than the ingestion of it, may give us a clue: it's your brain.

I have a testable hypothesis that fits what we know so far, and explains the positive correlation between reflexive insulin release and obesity. If you're on a typical American high-carbohydrate diet, your body is likely conditioned to expect a spike in blood sugar any time you eat a meal. If this conditioning is responsible for the "cephalic phase" insulin response, the stimuli I mentioned above should be expected to produce this result.

Insulin secretion can be conditioned in rats in response to arbitrary environmental cues, like site and sound, very much like Pavlov's salivating dog. There's a considerable body of work on the cephalic phase insulin response in humans, but I haven't seen any work that investigates whether it's a conditioned response. What I'd like to see is a similar test comparing the response in subjects on a typical diet versus subjects on a long term low carbohydrate diet. My prediction would be that the experimental group (the low-carbers), being deconditioned, would display little if any cephalic phase response.

How does a curious guy with an interest in this subject get a study like this done without spending his own money on it?

Friday, April 2, 2010

Athletic Performance on a Ketogenic Diet

Bad blogger!  It's been almost two months.  I'm going to follow a suggestion I got in an encouraging email from a reader, and cover the effects of a ketogenic diet on athletic performance.  "Athletic performance" covers a fairly broad range of activities, from high-intensity exercise like sprinting, to extreme endurance efforts like marathons.  I'll try to be both brief and thorough.

Endurance Exercise

Most of the relevant research I've been able to find focuses on "submaximal exercise" or endurance training.  Here the results are inconsistent, and the inconsistencies are themselves interesting to examine.  In this study, titled "High fat diets and exercise performance", the author cites animal studies consistently showing significant performance enhancement after adaptation to high-fat diets.  He then describes several human trials, some of which showed improved endurance and some of which did not.  He proposes an interesting hypothesis to explain the disparity:

Part of the inconsistency between the animal and human results may be explained by differences in the percentage of calories from carbohydrate. The high fat diets given to animals contained little carbohydrate, usually 0-1% of total calories. The human diets on the other hand typically contained a moderate amount (10-20%) of their energy from carbohydrates.

A diet containing 10-20% carbohydrates is not likely to result in ketosis, unless the diet is also calorie-restricted.  I assume they were trying not to kill the athletes, since as we all know dietary carbohydrates are absolutely necessary.