I left out one of the juicier tidbits from the last post because it was getting long. Investigators Kang-Jey Ho et al. wanted an explanation for why the Masai didn't have high serum cholesterol despite their high dietary cholesterol intake (up to 2,000 mg per day-- 6.7 times the US FDA recommended daily allowance).
They took 23 male Masai subjects aged 19 to 24 and divided them into two groups. The first group of 11 was the control group, which received a small amount of radioactive cholesterol in addition to a cholesterol-free diet that I will describe below. The second group of 12 was the experimental group, which they fed 2,000 mg cholesterol per day, a small amount of radioactive cholesterol as a tracer, and the exact same cholesterol-free diet as the control group. For the duration of the 24-week trial, the subjects ate the experimental diet exclusively. Here's what it was (in order of calories, descending): - Nondairy coffee creamer (made of corn syrup solids and vegetable oil)
- Beans
- Sugar
- Corn
- Corn oil
- A vitamin pill
Not a healthy diet by most peoples' standards, but those items are nevertheless widely eaten in the US. Over the course of the 24-week study, the investigators found no difference in serum cholesterol between the control and experimental groups. This isn't really surprising. The body has mechanisms for regulating blood cholesterol, and if you aren't eating any it just synthesizes more to stay at its preferred level.
The really interesting thing is that serum cholesterol increased dramatically in both groups. It went from 125 mg/100 mL to over 170 mg/100 mL, despite a large decrease in the saturated fat they were eating. The change took about two weeks to occur, and remained fairly stable for the remainder of the trial.
Both groups also gained weight. In the first week, they gained an average of 3 pounds each. To be fair, the initial gain was probably most water, which is what happens when a person increases their carbohydrate and salt intake. The investigators freaked out and cut their calorie intake by 400 kcal, only allowing them 3,600 kcal per day. Initially, they were voluntarily consuming 4,000 kcal per day. I find that interesting as well. Something tells me they weren't chugging non-dairy creamer because it was so delicious, but because their confused hormones were telling them to EAT.
Even after putting the subjects on calorie restriction (not letting them eat as much as they wanted, by an average of 400 kcal/day), they continued gaining weight. By the end of the study, the 23 subjects had gained an average of 7.8 lbs per person.
To summarize, this is what the investigators saw when they put 23 unfortunate Masai men on a bottom-rung industrially processed diet: elevated cholesterol, hyperphagia (excessive eating), and weight gain. Sounds familiar, doesn't it?
I've been digging deeper into the health of the Masai lately. A commenter on Chris's blog pointed me to a 1972 paper showing that the Masai have atherosclerosis, or hardening of the arteries. This interested me so I got my hands on the full text, along with a few others from the same time period. What I found is nothing short of fascinating. First, some background. Traditional Masai in Kenya and Tanzania are pastoralists, subsisting on fermented cow's milk, meat and blood, as well as traded food in modern times. They rarely eat fresh vegetables. Contrary to popular belief, they are a genetically diverse population, due to the custom of abducting women from neighboring tribes. Many of these tribes are agriculturalists. From Mann et al: "The genetic argument is worthless". This will be important to keep in mind as we interpret the data. At approximately 14 years old, Masai men are inducted into the warrior class, and are called Muran. For the next 15-20 years, tradition dictates that they eat a diet composed exclusively of cow's milk, meat and blood. Milk is the primary food. Masai cows are not like wimpy American cows, however. Their milk contains almost twice the fat of American cows, more protein, more cholesterol and less lactose. Thus, Muran eat an estimated 3,000 calories per day, 2/3 of which comes from fat. Here is the reference for all this. Milk fat is about 50% saturated. That means the Muran gets 33% of his calories from saturated fat. This population eats more saturated fat than any other I'm aware of. How's their cholesterol? Remarkably low. Their total serum cholesterol is about half the average American's. I haven't found any studies that broke it down further than total cholesterol. Their blood pressure is also low, and hypertension is rare. Overweight is practically nonexistent. Their electrocardiogram readings show no signs of heart disease. They have exceptionally good endurance, but their grip strength is significantly weaker than Americans of African descent. Two groups undertook autopsies of male Masai to look for artery disease. The first study, published in 1970, examined 10 males, 7 of which were over 40 years old. They found very little evidence of atherosclerosis, even in individuals over 60. The second study, which is often used as evidence against a high-fat diet, was much more thorough and far more interesting. Mann et al. autopsied 50 Masai men, aged 10 to 65. The single most represented age group was 50-59 years old, at 13 individuals. They found no evidence of myocardial infarction (heart attack) in any of the 50 hearts. What they did find, however, was coronary artery disease. Here's a figure showing the prevalence of "aortic fibrosis", a type of atherosclerotic lesion:
It looks almost binary, doesn't it? What could be causing the dramatic jump in atherosclerosis at age 40? Here's another figure, of total cholesterol (top) and "sudanophilia" (fatty streaks in the arteries, bottom). Note that the Muran period is superimposed (top). 
There appears to be a pattern here. Either the Masai men are eating nothing but milk, meat and blood and they're nearly free from atherosclerosis, or they're eating however they please and they have as much atherosclerosis as the average American. There doesn't seem to be much in between. Here's a quote from the paper that I found interesting:
We believe... that the Muran escapes some noxious dietary agent for a time. Obviously, this is neither animal fat nor cholesterol. The old and the young Masai do have access to such processed staples as flour, sugar, confections and shortenings through the Indian dukas scattered about Masailand. These foods could carry the hypothetical agent."
This may suggest that you can eat a wide variety of foods and be healthy, except industrial grain products (particularly white flour), sugar, industrial vegetable oil and other processed food. The Masai are just one more example of a group that's healthy when eating a traditional diet.
Why are we so soft today? Why is it that our ancestors were able to perform feats like killing bears and wooly mammoths in snow-swept grasslands? How do present-day tribesmen withstand days of ultra-cold temperatures in Northern Greenland and prolonged periods without water in scorching hot Kenyan deserts? Why is it that a century ago, children in the Swiss alps ran barefoot through ice-cold mountain streams on cold days, while now they get carpal tunnel syndrome playing video games? How did they do all this without succumbing to the chronic diseases that are so rampant today? I believe part of the answer lies in hormesis.
Hormesis is the process by which a mild or acute stressor increases resistance to other, more intense or chronic stressors. It can increase resistance to a variety of stresses, not only the one to which you are exposed.
It might sound like a foreign concept, but you're more familiar with it than you think. Exercise is a form of hormesis. It's a stress placed upon the body that increases resistance to a number of other stressors: physical exertion, cardiovascular disease, depression, diabetes, age-related cognitive decline, neurodegenerative disease, etc.
Intermittent fasting is one of the most promising forms of hormesis. It's consistent with the variable energy intake our hunter-gatherer ancestors probably experienced. As with some other forms of hormesis, it has broad-ranging effects on health and stress resistance. Alternate-day fasting, a version in which food is available for 24 hours ad libitum and then not available for the next 24 hours, increases mean lifespan in mice under some conditions without reducing calorie intake. It increases resistance to neurodegeneration, stroke, myocardial infarction, toxins, cancer and diabetes in rodents. It increases the expression of heat shock proteins and SIRT1, both implicated in general stress resistance. Basically, it makes them tougher all-around.
Although only a few studies have been performed in humans, IF looks promising for preventing or reversing diabetes, cardiovascular disease, overweight and possibly other health problems. It can also decrease fasting insulin and increase insulin sensitivity considerably. I fast for 24 hours, once a week. No calories, only water. It's not a form of caloric restriction, because I eat like horse the day after fasting. It's just a mild stressor that toughens my body to other stressors.
I also take cold showers. Here the scientific data are more sparse, but it has a long history of use as a form of "body hardening". I do it to increase my cold resistance by firing up my non-shivering thermogenesis. It seems to be working. It certainly wakes me up in the morning! Have you ever noticed how you can get into cold water and be surprisingly comfortable once you're used to it, even though you're practically naked and water is conducting heat away from your body 20 times faster than air would? That's probably your non-shivering thermogenesis kicking in.
There are probably many other ways to induce hormesis. Do any of you have techniques to share? By the way, hormesis is one of the central tenets of homeopathy. Solid principle, incorrect application. I'd be happy to sell anyone sugar pills for 50% less than his or her local homeopath is selling them. I promise mine are equally effective...
Soft living makes a soft body. Give it some controlled stress from time to time!
Thanks to Kirill Tropin for the CC photo.
Last night I was watching a little video clip of the Jack LaLanne show. LaLanne was an advocate of strength training and whole foods nutrition whose TV show ran from the 1950s through the 1980s. In the clip, he describes how his father died an early death due to heart and liver disease. A quote that really stuck with me was when he said his father died due to "disregarding nature's laws". That pretty much sums up my philosophy. Live in a way that generally mimics what our genes evolved to thrive on. Why did our paleolithic ancestors have strong, healthy bodies? Why are there still cultures that are free of chronic disease to this day, even into old age? Because they are following nature's laws. Break the law at your own risk. Jack LaLanne and I do differ a bit on what constitutes a natural diet. For example, I don't throw out my egg yolks... But hey, the man is 94 and going strong. Here's another quote of his: "If man made it, don't eat it". Words to live by. Quite literally.
Why are we so soft today? Why is it that our ancestors were able to perform feats like killing bears and wooly mammoths in snow-swept grasslands? How do present-day tribesmen withstand days of ultra-cold temperatures in Northern Greenland and prolonged periods without water in scorching hot Kenyan deserts? Why is it that a century ago, children in the Swiss alps ran barefoot through ice-cold mountain streams on cold days, while now they get carpal tunnel syndrome playing video games? How did they do all this without succumbing to the chronic diseases that are so rampant today? I believe part of the answer lies in hormesis. 