Month: November 2012

Assorted Links

Seth Roberts2 Comments
  • Olive oil and the Willat Effect. “You can read about great olive oils, and their vast superiority over bad oils, all you want. . . . But until you try first-rate olive oil for yourself – actually put the good stuff in your mouth, and compare that experience to the bad stuff you’ve eaten in the past – you won’t really get it. . . . . Once you taste fine olive oils and their low-class imitations [side by side], though, you start to care.”
  • Petraeus Affair: The journalism of what we don’t know.
  • Tucker Max on book publishing. Disruptive innovation for popular authors.
  • Animal self-medication. Sick animals eat differently than healthy animals.

Thanks to Alex Blackwood.

Bayesian Shangri-La Diet

Seth Roberts7 Comments

In July, a Cambridge UK programmer named John Aspden wanted to lose weight. He had already lost weight via a low-carb (no potatoes, rice, bread, pasta, fruit juice) diet. That was no longer an option. He came across the Shangri-La Diet. It seemed crazy but people he respected took it seriously so he tried it. It worked. His waist shrank by four belt notches in four months. With no deprivation at all.

Before he started, he estimated the odds (i.e., his belief) of three different outcomes predicted by three different theories. What would happen if he drank 300 calories (2 tablespoons) per day of unflavored olive oil (Sainsbury’s Mild Olive Oil)? Aspden considered the predictions of three theories.

I called my three ideas of what would happen [= three theories that make different predictions] if I started eating extra oil Willpower, Helplessness and Shangri-La. (1) Willpower (W) is the conventional wisdom. If you eat an extra 300 calories a day you should get fatter. This was the almost unanimous prediction of my friends. Your appetite shouldn’t be affected. (2) Helplessness (H) was my own best guess. If you eat more, it will reduce your appetite and so you’ll eat less at other times to compensate, and so your weight won’t move. Whether this appetite loss would be consciously noticeable I couldn’t guess. This was my own best guess. (3) Shangri-La (S) is your theory. The oil will drop the set point for some reason, and as a result, you should see a very noticeable loss of appetite.

More about these theories. His original estimate of the likelihood of each prediction being true: W 39%, H 60%, S 1%. He added later, “I think I was being generous with the 1%”. After the prediction of the S theory turned out to be true, the S theory became 50 times more plausible, Aspden decided.

I like this a lot. Partly because of the quantification. If you were a high jumper in a world without exact measurement, people could only say stuff like “you jumped very high.” It would be more satisfying to have a more precise metric of accomplishment. It is a scientist’s dream of making an unlikely prediction that turns out to be true. The more unlikely, the more progress you have made. Here is quantification of what I accomplished. Although Aspden could find dozens of online reports that following the diet caused weight loss, he still believed that outcome very unlikely. Given that (a) the obesity epidemic has lasted 30-odd years and (b) people hate being fat, you might think that conventional wisdom about weight control should be assigned a very low probability of being correct.

I also like this because it is the essence of science: choosing between theories (including no theory) based on predictions. The more unlikely the outcome, the more you learn. You’d never know this from 99.99% of scientific papers, which say nothing about how unlikely the actual outcome was a priori — at least, nothing numerical. I can’t say why this happens (why an incomplete inferential logic, centered on p values, remains standard), but it has the effect of making good work less distinguishable from poor work. Maybe within the next ten years, a wise journal editor will begin to require both sorts of logic (Bayesian and p value). You need both. In Aspden’s case, the p value — which would indicate the clarity of the belt-tightening — was surely very large. This helped Aspden focus on the Bayesian aspect — the change in belief. This example shows how much you lose by ignoring the Bayesian aspect, as practically all papers do. In this case, you lose a lot. Anyone paying attention understands that the conventional wisdom about weight control must be wrong. Here is guidance towards a better theory. If not mine, you at least want a theory that predicts this result.

 

 

 

 

 

Assorted Links

Seth Roberts2 Comments

Thanks to Anne Weiss and Dave Lull.

Measuring Yourself to Improve Your Health? Want to Guest-Blog?

Seth Roberts6 Comments

What surprised me most about my self-experimental discoveries was that they were outside my area of expertise (animal learning). I discovered how to sleep better but I’m not a sleep researcher. I discovered how to improve my mood but I’m not a mood researcher. I discovered that flaxseed oil improved brain function but I’m not a nutrition researcher. And so on. This is not supposed to happen. Chemistry professors are not supposed to advance physics. Long ago, this rule was broken. Mendel was not a biologist, Wegener (continental drift) was not a geologist. It hasn’t been broken in the last 100 years. As knowledge increases, the “gains due to specialization” — the advantage of specialists over everyone else within their area of expertise — is supposed to increase. The advantage, and its growth, seem inevitable. It occurs, say economists, because specialized knowledge (e.g., what physicists know that the rest of us, including chemists, don’t know) increases. My theory of human evolution centers on the idea that humans have evolved to specialize and trade. In my life I use thousands of things made by specialists that I couldn’t begin to make myself.

Here we have two things. 1. A general rule (specialists have a big advantage, within their specialty, over the rest of us) that is overwhelmingly true. 2. An exception (my work). How can this be explained? What can we learn from it? I’ve tried to answer these questions but I can add to what I said in that paper. The power of specialization is clearly enormous. Adam Smith, who called specialization “division of labor”, was right. The existence of an exception to the general rule suggests there are forces pushing in the opposite direction (toward specialists being worse than the rest of us in their area of expertise) that can be more powerful than the power of specialization. Given the power of specialization, the countervailing forces must be remarkably strong. Can we learn more about them? Can we harness them? Can we increase them? The power of specialization has been increasing for thousands of years. How strong the countervailing forces may become is unclear.

The more you’ve read this blog, the more you know what I think the countervailing forces are. Some of them weaken specialists: 1. Professors prefer to be useless rather than useful (Veblen). 2. A large fraction (99%?) of health care workers have no interest in remedies that do not allow them to make money. 3. Medical school professors are terrible scientists. 4. Restrictions on research. Some of them strengthen the rest of us: 1. Data storage and analysis have become very cheap. 2. It is easier for non-scientists to read the scientific literature. 3. No one cares more about your health than you. These are examples. The list could be much longer. What’s interesting is not the critique of health care, which is pretty obvious, but the apparent power of these forces, which isn’t obvious at all.

I want to learn more about this. I want learn how to use these opposing forces and, if possible, increase them. One way to do this is find more exceptions to the general rule, that is, find more people who have improved their health beyond expert advice. I have found some examples. To find more, to learn more about them, and to encourage this sort of thing (DIY Health), I offer the opportunity to guest-blog here.

I think the fundamental reason you can improve on what health experts tell you is that you can gather data. Health experts have weakened their position by ignoring vast amounts of data. Three kinds of data are helpful: (a) other people’s experiences, (b) scientific papers and (c) self-measurement (combined with self-experimentation). No doubt (c) is the hardest to collect and the most powerful. I would like to offer one or more people the opportunity to guest-blog here about what happens when they try to do (c). In plain English, I am looking for people who are measuring a health problem and trying to improve on expert advice. For example, trying to lower blood pressure without taking blood pressure medicine. Or counting pimples to figure out what’s causing your acne. Or measuring your mood to test alternatives to anti-depressants. I don’t care what’s measured, so long as it is health-related. (Exception: no weight-loss stories) and you approach these measurements with an open mind (e.g., not trying to promote some product or theory). I am not trying to collect success stories. I am trying to find out what happens when people take this approach.

Guest-blogging may increase your motivation, push you to think more (“ I blog, therefore I think“) and give you access to the collective wisdom of readers of this blog (in the comments). If guest-blogging about your experiences and progress (or lack of it) might interest you, contact me with details of what you are doing or plan to do.

Assorted Links

Seth Roberts2 Comments

Thanks to Edward Jay Epstein, Bryan Castañeda, Paul Nash, Jay Barnes and Dave Lull.

The Power of the Willat Effect: Rinsed versus Unrinsed Tea

Seth Roberts11 Comments

During my last visit to New York I bought a new black tea. I started drinking it a few weeks ago. I brewed it various ways (different amounts of tea, different steeping times, etc.) but had a hard time telling which way was best. This morning I decided I would learn how to brew it by making paired comparisons (two cups of tea made the same way at the same time except for one difference). The fascinating thing, as I’ve said, about these side-by-side comparisons is that they produce hedonic changes. They change how much you like this or that. I call this the Willat Effect after my friend Carl Willat who caused me to notice it.

This morning I made two cups of the new tea. The two cups were brewed the same except in one case I “rinsed” the tea before brewing. Rinsing means I poured a bit of hot water on it and quickly got rid of the hot water. Rinsing tea removes from the final product whatever is transferred from the tea to the hot water in the first few seconds. In China, rinsing tea is common; in the United States, very rare.

I tasted the two cups (rinsed and unrinsed) side by side. The rinsed tea tasted much better. The unrinsed tea had something weird about it. Ugh, I thought, I can’t drink this. I threw out the unrinsed tea. Over the previous few weeks, I had happily drunk the new tea unrinsed many times. Now I found it repulsive.

Positive Psychology Talk by Martin Seligman at Tsinghua University

Seth Roberts7 Comments

Here at Tsinghua University, the Second Annual Chinese International Conference on Positive Psychology has just begun. The first speaker was Martin Seligman, a professor at the University of Pennsylvania and former president of the American Psychological Association (the main professional group of American psychologists). Seligman is more responsible for the Positive Psychology movement than anyone else. Here are some things I liked and disliked about his talk.

Likes:

1. Countries, such as England, have started to measure well-being in big frequent surveys (e.g., 2000 people every month) and some politicians, such as David Cameron, have vowed to increase well-being as measured by these surveys. This is a vast improvement over trying to increase how much money people make. The more common and popular and publicized this assessment becomes — this went unsaid — the more powerful psychologists will become, at the expense of economists. Seligman showed a measure of well-being for several European countries. Denmark was highest, Portugal lowest. His next slide showed the overall result of the same survey for China: 11.83%. However, by then I had forgotten the numerical scores on the preceding graph so I couldn’t say where this score put China.

2. Work by Angela Duckworth, another Penn professor, shows that “GRIT” (which means something like perseverance) is a much better predictor of school success than IQ. This work was mentioned in only one slide so I can’t elaborate. I had already heard about this work from Paul Tough in a talk about his new book.

3. Teaching school children something about positive psychology (it was unclear what) raised their grades a bit.

Dislikes:

1. Three years ago, Seligman got $125 million from the US Army to reduce suicides, depression, etc. (At the birth of the positive psychology movement, Seligman proclaimed that psychologists spent too much time studying suicide, depression, etc.) I don’t mind the grant. What bothered me was a slide used to illustrate the results of an experiment. I couldn’t understand it. The experiment seems to have had two groups. The results from each group appeared to be on different graphs (making comparison difficult, of course).

2. Why does a measure of well-being not include health? This wasn’t explained.

3. Seligman said that a person’s level of happiness was “genetically determined” and therefore was difficult or impossible to change. (He put his own happiness in “the bottom 50%”.) Good grief. I’ve blogged several times about how the fact that something is “genetically-determined” doesn’t mean it cannot be profoundly changed by the environment. Quite a misunderstanding by an APA president and Penn professor.

4. He mentioned a few studies that showed optimism (or lack of it) was a risk factor for heart disease after you adjust for the traditional risk factors (smoking, exercise, etc.). There is a whole school of “social epidemiology” that has shown the importance of stuff like where you are in the social hierarchy for heart disease. It’s at least 30 years old. Seligman appeared unaware of this. If you’re going to talk about heart disease epidemiology and claim to find new risk factors, at least know the basics.

5. Seligman said that China had “a good safety net.” People in China save a large fraction of their income at least partly because they are afraid of catastrophic medical costs. Poor people in China, when they get seriously sick, come to Beijing or Shanghai for treatment, perhaps because they don’t trust their local doctor (or the local doctor’s treatment failed). In Beijing or Shanghai, they are forced to pay enormous sums (e.g., half their life’s savings) for treatment. That’s the opposite of a good safety net.

6. Given the attention and resources and age of the Positive Psychology movement, the talk seemed short on new ways to make people better off. There was an experiment with school children where the main point appeared to be their grades improved a bit. A measure of how they treat each other also improved a bit. (Marilyn Watson, the wife of a Berkeley psychology professor, was doing a study about getting school kids to treat each other better long before the Positive Psychology movement.) There was an experiment with the U.S. Army I couldn’t understand. That’s it, in a 90-minute talk. At the beginning of his talk Seligman said he was going to tell us things “your grandmother didn’t know.” I can’t say he did that.

 

 

Japanese Discouragement of Foreign Visitors

Seth Roberts2 Comments

In a post about Tokyo, I said it was a tragedy that there were so few foreigners there. You might think that someone in power in Japan would figure out that America’s biggest strength is that foreigners want to move there (for example), but apparently not. A Tokyo University student told me today that at her school, the dormitory for foreign students is one hour away from the campus.

Journal of Personal Science: How Much Salt Should I Eat?

Seth Roberts11 Comments

by Greg Pomerantz

The Journal of Personal Science, suggested by Tom and encouraged by Bryan Castañeda, will contain articles about using science to help yourself. This is the first one. It previously appeared on Greg’s blog. If you have written something or plan to write something or are thinking about writing something that might be included, please let me know. — Seth

I spent a few weeks this summer conducting a self-experiment on salt sensitivity and blood pressure. The experiment included a three week phase on a low carb whole foods diet with no added salt, followed by a moderately extreme salt loading phase. This post is a summary of my results.

I learned a lot from the experiment and came out of it with at least one bit of useful information. Will I try to restrict salt in my diet? No, I don’t think salt restriction can work for me. From now on I will ensure that I get sufficient salt on a daily basis.

Summary

These are the main points I learned during the experiment, from most to least interesting.

1. Salt restriction caused impaired thermoregulation. In hot weather, my cardiovascular system was not able to sufficiently lower my body temperature. This resulted in an elevated heart rate and hypethermia (up to 101.5 degrees in one instance). This can be dangerous, so be careful if you try this at home.

2. No clinically meaningful change in blood pressure. Systolic pressure was unchanged, though salt loading may have caused a small rise in diastolic pressure. This does not rule out long term negative effects from chronic salt loading (see discussion below), but it does show that, as previously discussed, my kidneys seem to basically work and can regulate my blood pressure through the maintenance of fluid and electrolyte balance in response to changes in my sodium intake.
3. Salt reduction may increase susceptibility to skin infections. Three days into the salt restriction phase, I came down with what was probably a staph infection in my right eyelid. This responded to antibiotics but it came back once I went off them. Since adding back salt I have had no problems with skin infections and no more antibiotics.
4. Possible strength loss. I did not perform well in the gym on my usual strength training program.
5. My taste for salt adapts quickly to restriction and loading. I experienced no cravings even when my sodium intake was too low. I can’t just “listen to my body”. Likewise, while the salt loading phase was difficult for the first two or three days, my taste rapidly adjusted to the added salt.
6. Bodyweight changes. I experienced substantial changes in body fluid levels (e.g. 6 pound weight gain within two hours of the transition from the salt restriction to the salt loading phase).

Conclusion: A low carb paleo diet must include added salt (for me). Can others do without? Perhaps, and some scientists such as Loren Cordain and Tim Noakes (e.g. this podcast episode 18 at 1:03:50) seem to think they can. Skip ahead to read my further musings on this question.

Study Design

The experiment had three phases. First, I did a one week lead-in phase (phase I) where I made no changes to diet or salt consumption. The purpose of phase I was to establish a blood pressure baseline through daily morning measurements (see Measurement Methods below).

This was followed by a three-week sodium restricted phase (phase II) during which I did not add any salt to my food. In addition, during phase II only, I avoided naturally salty foods such as shellfish. My sodium intake during phase II was limited to the sodium in the foods I was eating. Note however that there were one or two restaurant meals per week during this time where I was not able to strictly control for added salt. Sodium consumption on phase II was estimated to be between 800mg and 1000mg per day. phase II was originally scheduled for two weeks, but was extended due to the aforementioned infection and antibiotic use.

Finally, phase III was a salt-loading phase during which I added an additional 5 grams of sodium to my diet, for a total of nearly 6 grams of sodium per day including the sodium naturally occurring in my food. The supplemental salt during phase III consisted of hand harvested French Celtic sea salt (Eden Foods, Inc.) and was measured daily on an AMW-1000 digital scale. Because the Eden French Celtic sea salt is approximately 1/3 sodium by weight according to the label, the 5 grams of supplemental sodium per day was provided by approximately 15 grams of sea salt. Note that different varieties of salt will contain different percentages of sodium by weight. Sea salts vary significantly due to variations in residual water content (not, as commonly assumed, by the presence of other minerals). Please consult the label or a friendly analytical chemist for guidance.

The diet throughout this experiment consisted of meat, fish, eggs, coconut oil, butter, and non-starchy vegetables. In addition, I typically consumed a banana, an ounce (28g) of almonds and a bit of dark chocolate each day. Potassium intake was fairly consistent at around 4 g/day. Table 1 shows a typical day’s macronutrient intake. Given the macronutrient ratio, I believe it is likely that the diet was ketogenic.

Table 1. Approximate daily macronutrient intake.

Macronutrient
grams
 calories percent (calories)
Carbohydrate
50
 200 6.6%
Protein 155 620 20.5%
Fat 245 2205 72.9%
Total 3025
100%

 

Measurement Methods

I measured blood pressure daily first thing each morning while seated, with the cuff of an Omron HEM-711 placed on the left upper arm over the brachial artery. I followed guidelines described by Agena et al (see Chart 2 of the linked paper). Each day’s blood pressure value was determined by averaging the first three measurements taken that morning.

My first measurement of the day was typically higher than the average of the second and third measurements (systolic: +5, diastolic: +4, average over all three phases). This is referred to as the “alarm reaction” and is related to the more commonly known “white coat syndrome”, where the presence of a doctor elicits a stress response and therefore an innacurately high blood pressure reading. My alarm reaction seems to be due to the fact that I get slightly stressed out about seeing what my blood pressure is, even when I measure it myself. Therefore I experience a slight rise in blood pressure while waiting to see the first reading each day. I kept all three readings for this experiment. My “true” normal blood pressure is on average slightly lower than these results which include the first “alarm” reading.

Results

I summarized my qualitative findings in the executive summary above. If you skipped that because you are not an executive, you can go back and read it now. Below are graphs showing my blood pressure and bodyweight during the three phases.

Figure 1: Possible mild elevation in diastolic blood pressure during the salt loading phase. Each point is the average of the three morning blood pressure readings for the day. Red = phase I, green = phase II, blue = phase III. Curves from ggplot2 “geom_smooth()” using default parameters.

 

Figure 2. No change in systolic blood pressure.

 

Figure 3: Bodyweight.

Figure 3 shows my daily bodyweight, measured each morning before consumption of any food or fluids. Note that my previous health goal (the 415 deadlift) involved an intentional increase in bodyweight and therefore significant excess calorie consumption. My current diet is lower in calories and Figure 3 therefore should show a long term downward trend in bodyweight.

Salt restriction clearly resulted in a rapid decrease in bodyweight over the first few days of phase II. There appears to be a stabilization towards the end of the salt restricted phase. The salt loading in phase III produced a very large initial weight gain, followed again by stabilization around the same level seen at the end of the salt restriction phase. As salt is primarily stored in bones and extracellular fluids, an increase in salt would be expected to correspond to an increase in extracellular fluid (since the body’s bone mass should change slowly). The bodyweight changes shown in Figure 3 therefore reflect changes in extracellular fluid levels. While salt loading at the levels used in phase III produced a large acute change in body fluids, this was restored to normal over approximately 5 days.

Since my extracellular fluid volume was evidently restored within 5 days, it is not surprising that salt loading had no significant effect on my blood pressure. What is somewhat surprising was that there was no evidence of a temporary increase in blood pressure during the few days in which my extracellular fluid volume was in fact elevated. This suggests that there is an additional regulatory element working to restore blood pressure homeostasis at a shorter time scale than the dominant kidney-fluid mechanism previously discussed on the blog here.

Thanks to Mako Hill for guidance with ggplot2, without which these plots would look less nice.

Discussion

This experiment demonstrated to me that a low carb paleo diet with no added salt is potentially dangerous for me. Impaired thermoregulation is a big deal and would have been a life-threatening issue if I had to hunt for my food in a hot climate. Not only was my body temperature elevated in warm weather, but my pulse was elevated as well, suggesting my cardiovascular system was unable to restore my body temperature to normal. I’m clearly not salt sensitive, and I do not function well with a low salt diet. However, genetic studies suggest the ancestral human genotype is associated with high levels of salt sensitivity and ability to function with very low sodium intakes. How did humans evolve these traits? And why don’t I seem to have them?

A Faustian Kidney Bargain

Susumo Watanabe has proposed in interesting hypothesis about the evolution of sodium metabolism in hominids. The theory is laid out in a 2002 paper called “ Uric Acid, Hominid Evolution, and the Pathogenesis of Salit-Sensitivity,” published in the journal Hypertension. It goes something like this. At some point during the evolution of our common ancestor with gorillas and chimpanzees, a series of mutations inactivated the gene for urate oxidase, an enzyme that breaks down uric acid. As a consequence, we have much higher blood levels of uric acid than other mammals. These mutations seem to have occurred between 24 and 8 million years ago, during the miocene, when our ancestors were believed to be subsisting primarily on fruits and leaves. This diet would have been exceptionally low in sodium. Since there is evidence of multiple independent mutations in this gene in multiple primate lineages, it is thought that mutations deactivating urate oxidase were strongly selected.

In rats, uric acid raises blood pressure acutely, but also causes renal vascular disease via renin/angiotensin systems. This over time makes the rats more salt sensitive. If there is very little salt available, salt sensitivity can be a good thing. Watanabe argues that, where salt is scarce, high uric acid is beneficial (via multiple pathways) for preventing blood pressure from going too low.

In addition to causing kidney disease, high uric acid causes other problems, like gout, and is associated with heart disease. So this looks like an engineering tradeoff with a number of downsides, but some benefits in the context of a miocene diet that was even lower in sodium than the lowest current estimates for paleolithic diets. The organism with this adaptation is supposed to partially destroy its kidneys on purpose in order to maintain sufficiently high blood pressure. This miocene environment is long gone. However, it is much easier to break a gene than to put it back together. Our urate oxidase gene has been broken more than once and it would take quite a long time to fix it.

It’s kind of a crazy theory. I’m not sure I believe it but it is interesting to think about.

Some Hypotheses

During this experiment, I was eating almost exclusively meat, fish (often with bones), eggs and vegetables, plus added calories from butter, coconut oil and olive oil. The diet was grain, legume and dairy free and, as mentioned, possibly ketogenic. This would be considered by many online diet and health personalities to be a good low carb paleo diet, even though of course processed fats like butter and coconut oil are not Paleolithic foods.

So I want to discuss a few possible ways to resolve the apparent impossibility of eating this way without added salt.

Hypothesis 1: Low Carb, Low Crab, or Low Salt: choose any two

I have been eating a low carb diet, and my experiment suggests that, in that context, low salt is not a good idea. It is possible that a healthy human diet can be either low in carbohydrates or low in salt, but not both.

A great deal of evidence suggests that ketosis was not the norm for our paleolithic ancestors (see e.g. Kuipers et. al. 2012 for a thorough review of paleolithic diet research). In fact it would have been quite a struggle for me to eat this sort of macronutrient ratio without modern refined fats such as butter and coconut oil. Or ready access to marine mammal blubber (but then again the Inuit are not my paleolithic ancestors).

In contrast to the online paleo diet scene, most low carb diet advocates seem to line up behind the recommendation for ample supplementary salt. My result accord with that clinical experience. Low carbohydrate diets are usually said to have a diuretic effect in this community, at least in the initial stages (e.g. M.R. Eades, Jenny Ruhl). It is possible that my problems were caused by the interaction between diet-induced ketosis and salt restriction, and I would have done just fine without salt if I had some more carbohydrates. This hypothesis would be straightforward to test.

In order to keep my sodium intake sufficiently low during the salt restriction phase, I had to remove shellfish such as oysters and mussels from my diet. Crab is also salty and makes for a handy pun. It seems likely that daily shellfish consumption would have pushed my sodium intake into the healthy range. While shellfish does not get much attention these days in the paleo club, there is ample support (again see Kuipers et. al.) that it was an important contributor to actual paleolithic nutrition.

Hypothesis 2: Humans must drink blood. Or eat salt.

File this one in the “ teen paranormal romance” department. This hypothesis states that the ancestral human diet was not as low in salt as commonly assumed.

Sodium is the body’s primary extracellular cation, and most of it is located in the blood and other extracellular fluids. A pint of blood contains about 1.6 grams of sodium (see, e.g., these livestock reference ranges for blood sodium). That much blood per day should have been more than enough to push me into the healthy range of sodium consumption. On the other hand, salt depletion set in pretty quickly for me (probably 3-4 days), so this hypothesis assumes that fresh blood was consistently available to inland populations that did not have ready access to shellfish or sea water.

I find this hypothesis intriguing because of the fact that my putative ancestors were commanded not to drink blood (Genesis 9:4, Leviticus 17:13, Deuteronomy 12:15-16), and that salt is used in this tradition specifically to remove blood from meat before it is eaten. Presumably blood drinking was outlawed because it was thought to spread diseases and not because of tacky pop-culture connotations. Were my ancestors salting their meat not just for its preservative qualities, but also to make up for the reduction in sodium intake due to their prohibition on drinking blood?

Hypothesis 3: I’m Not (Genetically) a Paleolithic Human

Some say the human genome has hardly changed in the past 10,000 years. However, the hard evidence points to a number of significant evolutionary changes since the advent of agriculture, the classic example being lactase persistance (see Cochran and Harpending 2009 for a thorough argument on the rapidity of recent human evolution). Genes associated with hypertension and salt sensitivity are also apparently under strong evolutionary pressure. Alan Weder discusses this in an article published in 2007 in the journal Hypertension about evolution and hypertension. It is worth reading as an example of excellent science writing.

My experiment clearly demonstrates that I am not salt sensitive. This is not surprising given my European ancestry. As discussed by Weber, the genetics of salt resistance seem to correlate with adaptations to colder climates. It seems possible that in the course of such adaptation, my ancestors lost the ability to function optimally on a low salt diet.

Is a High Salt Diet Safe?

It is possible that, as much of mainstream medicine believes, a high salt diet actually is unhealthy over the long term. There is nothing in this experiment that contradicts that belief. Just because I am resistant to the short term blood pressure effects of salt loading, that does not mean I am immune to whatever long term negative effects a high salt diet may have. While epidemiological studies have their problems, it seems unwise to discount their findings altogether.

Edward Frohlich has argued that, notwithstanding the fact that most people’s blood pressure does not respond to acute increases in sodium intake, sodium is nevertheless responsible long-term for increases in blood pressure. He argues that excess salt causes kidney damage over time (as with uric acid this is mediated by renin/angiotensin systems), resulting long-term in an increase in blood pressure. While much of this research is based on studies done on rats (including those of the “ spontaneously hypertensive” variety), this line of thought is worth looking into and I will continue to do so.

Want to Sleep Better? Through Personal Science?

Seth Roberts8 Comments

If someone sleeps well, it’s tough to kill them. If someone does not sleep well, it’s tough to keep them alive. Robb Wolf quoted someone to this effect at the last Ancestral Health Symposium. One reason it’s plausible is better sleep improves immune function. For example, why are colds are more common in winter? Well, flu bouts peak during the light minimum (December) rather than the temperature minimum (February). Less light makes sleep worse, so this supports the idea that colds are more common in winter due to worse sleep. Likewise, heart attacks are more common in the winter, suggesting that better sleep would reduce heart attacks. I stopped getting obvious colds when my sleep got much better. Vaccinations are much less effective if the person vaccinated is kept awake the following night.

I’ve found new ways to improve my sleep: avoid breakfast, standing a lot, morning light exposure, one-legged standing, and eating more animal fat. I’ve confirmed Tara Grant’s discovery of the value of Vitamin D3 in the morning. I’ve made these improvements via low-tech tracking, good experimental design and data analysis, and wise choice of treatment.

I want to find out if my method and findings can help others. I am looking for people who would like my (paid) help improving their own sleep. In my search for people to try brain tracking, I judged interest and motivation partly by willingness to pay and it worked well.. If you are interested, please submit an application (see below).

At least at first, I’ll only pick one or two people. I’ll do whatever I can to help the chosen applicants measure their sleep, choose wisely what to test, do useful experiments, and analyze the data. They can have as much contact with me as they want.

There are four ways you might benefit from this: (a) Sleep better. (b) Learn how to use personal science to improve your health in other ways. (c) Help everyone learn if the treatments you try have value. (I will try to publicize the results, whatever they are.) (d) Help everyone learn the value of personal science to being healthy.

If this might interest you, please email sleep.where@gmail.com with your answers to the following questions:

1. Name, age, sex, job, location.

2. Phone number (good times to call), skype id (if any).

3. What’s wrong with your sleep? For how long have you had this problem or problems?

4. How have you tried to improve your sleep? What happened?

5. How many colds do you get in a typical year? How long does a typical cold last?

6. How much would you pay for the first month (after a free consultation)?

7. How much would you pay per month after the first month?