Thursday, August 16, 2012

Eggs will kill ya dead!

Today I happened to catch on the local news a story about how eggs are going to kill ya! They're going to kill ya dead, just like cigarette smoking! I just had to go find this study. Luckily the school I teach at subscribes to the journal it was in.

I have some huge problems with this study. The first is, it's not a random clinical trial. They only surveyed (yeah, nice waste of money) people coming to a vascular prevention clinic. Uh, is it just me, or do you think that people who are unhealthy, sick, and/or have a family history of illness are the most likely to go to a clinic like that?

Looking at Table 1 in the study, mean Triglycerides are high and so is BMI. So a lot of the participants are overweight. I wonder if there are any normal, healthy people in this survey? There's also a few diabetics thrown in for good measure. I didn't see where they controlled for that. But wait, because it gets better.
Table 1, click for larger version

Looking at Table 2, I almost fell out of my chair. From laughing. The people who ate the least eggs, <50 in "egg years", were the youngest. Their ages were 55.70 +/- 17.03 at first visit, so some of them were as young as 38.67 years. Now as the egg consumption goes up, so do the ages.  The people who ate the most eggs were much older. Their ages were 69.77 +/-11.38 at first visit. The youngest in the high consumption group was 58.39. That seems like some underhanded chicanery if you ask me!

Table 2, click for larger version

Of course the older people are going to have more instances of heart disease and thicker arteries too because of their age. They even state that in the article, that the older people have more plaque. Oh, but wait! The study says they "adjusted" for age. Why instead of poking around with numbers, actually study the same age groups? Or would that be because there wouldn't be any correlation? (Never mind causation.)

One could easily draw the conclusion that eggs have nothing to do with the thickness of the plaque, but with age. I could just as easily draw the conclusion that as you get older you eat more eggs. That's valid right? Or maybe the more eggs you eat, the older you get. Maybe if you never eat eggs you'll never get old? I'm screwed in that case!

It's interesting that they say that there were 2831 patients with data on egg yolk consumption, but only 1231 were used for various reasons. I'm sure those reasons were all good right, like not anything to do with throwing out data we didn't like, right? Right?

Also of interest, is that they found that fasting cholesterol, BMI, Triglycerides, HDL cholesterol and LDL cholesterol were not significant predictors of the thickness of plaque. Just egg yolks! 

In my humble opinion, considering that the sample was unbalanced, not random in the least and that more than half of the data they had access to was thrown out, that this amounts to someone with an agenda, with an axe to grind. Because if you really wanted to help people, and you really wanted to find out what was causing heart disease, you wouldn't have such poor research methods. However, if what you really want is to push an agenda, you won't care about data or ethics or anything else. You won't care if you kill people, so long as yours is the voice that is heard, so long as yours is the message that is received. Because diet is a religion to quite a few people out there, on all sides.

Just so you know, I'm my own experiment in this case. I eat at least three eggs almost every day. If I drop dead of heart disease, well, we won't know if it was the eggs that caused it, or my propensity for fountain diet cokes :P

Wednesday, August 15, 2012

Low carb, Hypothyroidism, and How to Lie with Statistics

I'm just an artist. An artist that read Darrell Huff's "How to Lie with Statistics". It's an old book, published sixty years ago now. Apparently people have been using statistics to lie about things for a while now.

I had heard something about low-carb diets causing hypothyroidism (repeat after me, correlation is not causation). As it stands, it seems to me that there is no way to know definitively whether they do or not, because the subject has never been studied. Oh, but you say, what about all those studies that are cited by so many bloggers. One of the first posts I found when I delved into this notion, was by blogger Anthony Colpo, and I read his post on the matter. Not withstanding the rudeness (which is not just on his side of the argument but rather all about the blogosphere as it were [did y'alls mothers not teach basic manners?]), I did think he might-could-be on to something. Until of course I looked at the studies he cited.

I never understood exactly why an underpowered study was, well, underpowered until I read Huff's book. You see, if you don't have enough of a sample size, what you have is chance. Yes that's right, pure unadulterated chance. The same sort of chance that you have flipping a coin. The explanation that Huff gives is crystal clear, and I urge you to buy his book and read it. If you flip a penny ten times (let's say to represent the outcome of ten patients in a study), you might get that it comes up heads eight out of the ten times. But you might get that it comes out heads two of the ten times. You would have to flip thousands of times (or maybe study 100k participants because humans have more than two variables) to come out with any sort of reasonable data to study.
"The importance of using a small group is this: With a large group any difference produced by chance is likely to be a small one and unworthy of big type...How results that are not indicative of anything can be produced by pure chance--given a small enough number of cases--is something you can test yourself at small cost. Just start tossing a penny... Only when there is a substantial number of trials [or participants] involved is the law of averages a useful description or prediction."--Darrell Huff, How to Lie with Statistics p.39-40
The two studies Colpo cites in his article, Dietary-induced Alterations in Thyroid Hormone Metabolism during Overnutrition and Isocaloric carbohydrate deprivation induces protein catabolism despite a low T3-syndrome in healthy men are woefully underpowered. The first one used three, yes THREE participants to conclude that no carbohydrates induces low T3 over a week. Yes, a week. The second study had a total of six participants over the course of eleven days (the abstract doesn't say if that's 11 days for each diet, or 11 days total, but whether it is one or the other it adds up to bull-hockey). I suppose that's twice as good as the first study. Bull-hockey times two equals twice as much bull-hockey for your grant money.

There could be something to this and there might not be. If there is a higher incidence of thyroid problems among people who eat low-carb (and I don't even know that that is true, but IF it is) how do you know that the problems weren't triggered by the diet they ate before they ate low-carb, the crappy Standard American Diet? Or that since most people who do low-carb want to lose weight, maybe the obesity triggered their thyroid to go out of whack. Or maybe it was a virus they were exposed to. It could be absolutely any of the above, or none at all. A week long study is not enough for your endocrine system to adjust to the changes of going from a Standard diet to a low-carb diet. Six males or three random participants tells you nothing other than chance. It seems like most of the medical studies I read are run by Vegas gambling addicts. Let's throw the dice and see what we come up with! This is not science. This is nonsense.