Dangers of Supplements

Seth Roberts2 Comments

Via Robin Hanson I found this study of the effects of antioxidant supplements. It studied five (e.g., Vitamins A and C). Overall they were slightly harmful, except selenium.

This isn’t intuitive — why should they differ? — but fits well with previous work:

1. Evidence for benefits of selenium is overwhelming. You can look at a county-by-county map of US cancer rates and see a sharp drop along a certain line in the northeast. The line separates different geology. There is much more selenium in the soil on the low-cancer side of the line. Yet another case where correlation is powerful evidence for causation. An experiment with selenium supplementation found a reduction in cancer.

2. Several years ago, two experiments found Vitamin A supplements increased lung cancer. (Another study.) Later experiments cast doubt on Vitamins C and E. As one of Robin’s readers put it: “two of which were previously well known to be bad for you.”

Given this previous research, which is far more persuasive than the current study, the interesting contribution of the new study is methodological: will a meta-analysis of epidemiological studies reach the right conclusions? Will the signal outweigh the many sources of bias and error? In fact, it did. Again suggesting that severe critics of epidemiology, such as John Ioannidis, go too far.

Shallows Net

Seth Roberts10 Comments

When I told my Chinese friend I read The New Yorker, she said she knew it was a very good magazine. A famous writer she knew of had written for it for 50 years. He was dead now. She didn’t remember his name. One of his books was Shallows Net.

She meant Charlotte’s Web by E. B. White.

A well-read and influential writer, she said.

Well-read, yes, influential, no, I said.

The Elements of Style might have been influential had its advice been good. Alas, it wasn’t. “Omit needless words.” “Be clear.” How to form the possessive. Please. I once took a short-story-writing class. When typing your story, the teacher said, put two spaces after a period.

Criticism of The Elements of Style here, here, and here.

In-Flight Fermented Foods?

Seth Roberts4 Comments

I’ve tried taking fermented foods on airplane flights. Here’s what I’ve learned:

1. The rules speak of “medicinal” exceptions to the no-liquid policy. In practice, this means: (a) You need a doctor’s note and (b) you must need the medicine during the flight.

2. The rules say no gels. It turns out that yogurt is a gel.

3. What about Japanese pickles in sake dregs? When they were in a glass jar, with a lot of dregs (50% dregs, 50% pickle), the answer was no: Dregs are like gels. When they were in a plastic package (98% pickle, 2% dregs), they were okay.

Placebo Non-Disclosure

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A new study in the Annals of Internal Medicine asked how often placebo-controlled medical studies made clear what the placebo was. The abstract says:

Most studies did not disclose the composition of the study placebo.

Which may give the wrong impression. About 90% of the studies they looked at did not say what the placebo was.

The paper illustrates the problem with an example:

In one of these studies [where the placebo was not described], the authors commented that “The lack of any overall effect in patients with myocardial infarction might be related to the unexpectedly low mortality rate in the placebo group.” The possibility that the placebo composition may have influenced this “unexpectedly low mortality” was apparently not considered.

Thanks to Gunnar Schröder.

My Experience of Sickness

Seth Roberts12 Comments

I am at a hotel. Yesterday I decided to take a walk. A short distance from the hotel I started to walk uphill. It was surprisingly hard. I realized I was sick.

I think this is what happens when your immune system is working properly: Sickness stops being obvious. I think my immune system is working well because I sleep well and eat plenty of fermented foods.

I have never heard sickness described like this by anyone else. I have heard it described in terms of obvious suffering thousands of times. Which suggests a lot of room for improvement.

The C.I.A. and Self-Experimentation

Seth Roberts1 Comment

I learned of The Human Factor: Inside the CIA’s Dysfunctional Intelligence Culture by Ishmael Jones (a pseudonym) from an interview on the New Yorker website. This comment by the author interested me:

Once the C.I.A. became a place to get rich, effective operations ended. Today, more than ninety per cent of C.I.A. employees live and work entirely within the United States, in violation of the C.I.A.’s founding charter [to supply only foreign intelligence].

I could say much the same about science: Once it became a place to get rich (or at least get large grants), effective science became a lot less common. A great deal of science is done by drug companies. They pay a lot. Some of their scientists are surely brilliant but their talents are wasted by the need to find solutions that will be highly profitable. My self-experimentation found solutions that cost nothing and make far more intellectual sense. I was able to do something that didn’t produce a lot of publications because it wasn’t my job.

Many skills make good full-time jobs. Science doesn’t. There is too much pressure for short-term results. Without short-term results, you may lose your job or your grant. (Or, in China, most of your income.) Nor is science a good source of status. If you want your science to provide your status, you will be under great pressure to conform. Yet for practically all scientists, it’s their full-time job and their main source of status. This may not make it impossible for them to do good work but I suspect it comes close to doing so. My self-experimentation was effective not only because it was fast and cheap (per experiment) but also because I could be slow (per publication) and do something low-status.

Madame Bovary and Self-Experimentation

Seth Roberts4 Comments

Someone asked Lydia Davis: Why another translation of Madame Bovary? She replied:

In the case of a book that appeared more than 150 years ago, like Madame Bovary, and that is an important landmark in the history of the novel, there is room for plenty of different English versions. For example, 1) the first editions of the original text may have been faulty, and over the years one or more corrected editions have been published, so that the earliest English translations no longer match the most accurate original; 2) the earliest translators (as was the case with the Muirs rendering Kafka) may have felt they needed to inflict subtle or not so subtle alterations on the style and even the content of the original so as to make it more acceptable to the Anglophone audience; with the passing of time, we come to deem this something of a betrayal and ask for a more faithful version. 3) Earlier versions may simply not be as good in other respects as they could be—let another translator have a try.

This reminds me of my three-part answer to the question a journalist asked me: why it mattered that butter improved my arithmetic speed by 5%.

Just as I disliked my answer, I disliked Davis’s answer. It’s hypothetical (“may have been faulty”, “may have felt”, “may not be as good as they could be”). It’s flat and obvious (earlier versions may have room for improvement). It’s irrelevant (bad translation of Kafka does not justify new translation of Flaubert).

I had trouble figuring out a better answer to what I was asked, but I could instantly say what Davis should have written: The story of how she decided to do a new translation. (“I began to think about doing a new translation when . . . “) That would have been a lot more emotion-laden and not hypothetical, obvious, or irrelevant.

As soon as I thought what Davis should have said, I could see what I should have said. I should have answered the journalist’s question like this: Why does 5% matter? Let me tell you why I was so excited by this. . . .Â

Via Marginal Revolution.

Periodontitis and Omega-3

Seth Roberts6 Comments

A few years ago, after I started taking about 3 tablespoons/day of flaxseed oil, my dentist told me my gums were much healthier. They were less red, more pink. Friends and blog readers who took flaxseed oil in similar amounts noticed the same thing. Tyler Cowen’s gums improved so much he no longer needed gum surgery.

An epidemiological study in the November Journal of the American Dietetic Association reports correlations between omega-3 intake and periodontitis (an extreme form of inflamed gums). The more omega-3, the less periodontitis. I’m sure that sufficient omega-3 intake cures periodontitis so this study has methodological interest for me. One interesting point is that the study reached a correct conclusion — contrary to the nihilism of John Ioannidis. Another is that the correlations were weak. The risk of periodontitis was only 20% lower in the group (quintile?) with the highest omega-3 intake. Although there were 9000 subjects, there was no significant correlation with linolenic acid, the form of omega-3 found in flaxseed oil.

Thanks to Sean Curley.

Walnuts: Brain Food?

Seth Roberts20 Comments

At a Mr. Lee’s restaurant (a Chinese chain), I started chatting with a girl sitting near me. I told her I was a psychology professor. “You know what people are thinking,” she said. I lamely said, no, I study what foods make the brain work best.

“I don’t know the English word for it,” she said. She drew a walnut. Good for your brain, her parents had told her. I was astonished. When I got to China, my arithmetic scores mysteriously improved. I had expected them to get worse, if anything. I tried to duplicate my American diet in Beijing but it is hard to duplicate the flaxseed oil. (Chinese flaxseed oil is worthless. I can bring it from America but not easily, and it’s impossible to keep it cold the whole way.) I had tested various explanations of the improvement but none held up.

I was starting to believe the reason for the improvement was walnuts. I have two servings/day of yogurt, each time with walnuts. I ate a lot of yogurt with walnuts in Berkeley, too; this was not a dramatic change. But maybe I eat more walnuts in China, and maybe the walnuts have more omega-3. Maybe the walnuts are fresher. In Berkeley I put ground flaxseed in my yogurt (in addition to walnuts), without obvious improvement. Walnuts are lower in omega-3 than flaxseeds.

A Chinese friend of mine had told me the same thing — that her parents had said that walnuts are good for the brain. This is a common Chinese belief, mingled with the curious idea that they are good for the brain because they look like a brain. The Wikipedia entry for walnut, which includes its use in Chinese medicine, says nothing about improving brain function. This long article about the benefits of walnuts doesn’t connect them directly with better brain function. It does say they are considered “brain food” because of high omega-3 content and links to a page that says 1/4 cup of walnuts (25 g) has 2.3 g of omega-3. I am now consuming 2 tablespoons/day of flaxseed oil, which contains 14 g of omega-3. I have sometimes consumed 3 or 4 tablespoons/day (with 21 or 28 g omega-3). You can see why 2 g doesn’t impress me, especially when added to 14 g. I thought I was getting the optimal amount of omega-3 from flaxseed oil. Adding a small amount to the optimal amount shouldn’t have a noticeable effect. This article says walnuts are brain food because of their lecithin content. Lecithin is used to make acetylcholine, a neurotransmitter.

Miraculously I can gather better evidence by myself, in a month, than all the evidence I’ve found. I simply vary how much walnuts I eat and see what happens to my arithmetic score. The experiment is worth doing because of the common Chinese belief and my puzzlingly good scores. Maybe walnuts help a brain that is already getting plenty of omega-3. Maybe not.