Friday Links: eat your egg yolks, avoid antimicrobial soap

Most of this post will be about egg yolks, but I'll start with the following PSA: if a soap is labeled "antimicrobial," don't use it. Just don't use it.

http://cebulka26.wordpress.com/2012/08/16/triclosan-its-in-everything-but-is-it-warranted/

If I see antimicrobial soap at a restaurant, I don't use it. I just wash with hot water. This concise and informative blog post from Ania (fellow MD/PhD) reminded me of why I do this. The active ingredient is triclosan, but I doubt it's very active anymore because it's in a bazillion products. Many of the microbes that we would theoretically want to kill are probably already immune to it. Continued use will just give microbes more and more chances to evolve resistance to not just it but also all related antibiotics, resulting in antibiotic-resistant bacteria that could kill a lot of people. The Black Death wasn't much fun, so I hear.

The fact is, there's currently zero evidence that antimicrobial soap helps prevent infection compared to regular soap. And given the potential health risks that Ania outlines (triclosan could affect your hormones, muscles, cancer…), why the hell would you use it? You're better off not using soap at all.

Egg yolks OMG!!

http://www.dailymail.co.uk/health/article-2188265/Eating-egg-yolks-bad-smoking-speeding-coronary-artery-disease.html?ito=feeds-newsxml

For some reason, the least-significant studies seem to get the most publicity, and the media likes to create outrageous headlines like "eating eggs yolks as bad as smoking." Incredibly misleading and not at all implied by the paper- especially when you consider that the audience is the public-at-large. For some people cutting back on egg yolks is prudent (but not at all proven to be beneficial), but should average 25 year olds avoid egg yolks as they should avoid smoking? Absolutely not, and the lack of context in this article is irresponsible.

First, some conceptual background: when you drink a lot of water, do you get water intoxication? No, you pee it out. Guess what? You excrete cholesterol through your liver into your digestive tract, and you can simply make less cholesterol. Your body reacts to greater cholesterol intake by decreasing cholesterol synthesis, and you end up with the same amount in your blood. The cholesterol that your body makes on a daily basis is significantly greater (about 3-5 fold) than what is recommended in your diet. Thus, your body can easily handle twice as much cholesterol consumption as normal, and eating more cholesterol per se does not increase your blood cholesterol. Your body needs cholesterol, and it will handle it as needed.

If you don't eat this, your body will probably make it instead and you'll end up with the same blood cholesterol either way. OK, maybe not for this many egg yolks, but you get the idea.

Of course, if you drink TONS of water (>12L), you can get water intoxication (this happens to ill-informed marathon runners). So there's a point at which cholesterol intake will start adversely affecting your blood cholesterol, and yes high blood cholesterol is a huge risk factor for heart disease. Furthermore, individuals with kidney disease will not be able to deal with water overload. Similarly, if you already have cholesterol imbalances (due to genetics, age, obesity, microbiome perturbation, whatever) then you should start watching your cholesterol intake, because the mechanisms to keep your blood cholesterol in check have already been overwhelmed.

Getting to the study, I have many objections:

1. Glaring source of recall bias. Egg yolk intake is self-reported in a questionnaire. But how many people actually keep track of their egg yolks? I'm guessing extremely few- and any variable that people do not consciously track is subject to huge memory bias. Furthermore, egg yolk intake is really hard to estimate, because eggs are used in all sorts of foods (bakery items, etc). I certainly would not trust my own estimation. And there is a huge source of memory bias in this study: people with the worst heart disease (regardless of the cause) are far more likely to "remember" that they ate a lot of egg yolks. We know that people's memories are heavily biased by their situation, and there is a pre-conceived notion out there that egg yolks are "supposed" to clog your arteries. People naturally look for an explanation for their disease, and if they find an easy explanation (eg egg yolks), then they will sub-consciously alter their memories to believe that they ate more egg-yolks. The memory effect should get stronger with greater severity of disease, and so all of the results of this paper could be explained by recall bias. Furthermore, the study itself can influence people's memories. You're going around a clinic full of worried people asking them how many eggs they eat. At least subconsciously, people are going to start blaming eggs for their health, even if they ate the same # of eggs as the next person.
2. The study population is heavily biased. The patients are already attending a vascular clinic! As I mentioned, there are likely sub-populations for whom cholesterol intake will increase their blood cholesterol (morbidly obese individuals, patients with familial hypercholesterolemia who are genetically unable to regulate their own cholesterol, etc). Those are the sub-populations whose cholesterol homeostasis mechanisms are already out of whack, and they are the ones most likely to be attending the clinic.
3. The data is nothing but correlative. Eating egg yolks (self-reported, again) is shown to be correlated with artery blockage. Sure, they use some statistical analysis to show that the effect is still present after you adjust for "coronary risk factors" but many risk factors are still unknown (yay science!), so you can't adjust for everything. The problem is that there are thousands of variables out there, and they are all correlated with each other to different degrees. People who live in a certain part of the country might eat foods rich in cholesterol, but guess what- that might also be the most polluted part of the country. Or there is a virus circulating in warm climates that increases your risk. Or people in that part of the country might be older, etc. If you look at 1000 variables, eventually you'll find one that fits simply by chance.
4. Simplistic clinical endpoint. Small point, but they just looked at neck artery blockage. Artery blockage, even if systemic, does not translate to disease. It's a risk factor like any other, and like all risk factors it doesn't affect all individuals in the same way.

Plant Zen

http://www.disneyresearch.com/research/projects/hci_botanicus_drp.htm

http://www.benchfly.com/blog/forget-wireless-keyboards-and-touch-your-plant-instead/

Finally, I have no idea what to make of this. You can hook up a plant (any plant, like a potted plant) to your computer, and somehow an electrode in the soil can tell what part of the plant you're holding. So you can control your computer by touching a plant. Is this a hoax?

I predict that eventually we'll be able to hook up anything to computers. But I think it will take a little more than just sticking an electrode into the soil.

wtf?