Mortality and Lifespan of the Inuit

One of the classic counter-arguments that's used to discredit accounts of healthy hunter-gatherers is the fallacy that they were short-lived, and thus did not have time to develop diseases of old age like cancer. While the life expectancy of hunter-gatherers was not as high as ours today, most groups had a significant number of elderly individuals, who sometimes lived to 80 years and beyond. Mortality came mostly from accidents, warfare and infectious disease rather than chronic disease.

I found a a mortality table from the records of a Russian mission in Alaska (compiled by Veniaminov, taken from Cancer, Disease of Civilization), which recorded the ages of death of a traditionally-living Inuit population during the years 1822 to 1836. Here's a plot of the raw data:

Here's the data re-plotted in another way. I changed the "bin size" of the bars to 10 year spans each (rather than the bins above, which vary from 3 to 20 years). This allows us to get a better picture of the number of deaths over time. I took some liberties with the data to do this, breaking up a large bin equally into two smaller bins. I also left out the infant mortality data, which are interesting but not relevant to this post:


Excluding infant mortality, about 25% of their population lived past 60. Based on these data, the approximate life expectancy (excluding infant mortality) of this Inuit population was 43.5 years. It's possible that life expectancy would have been higher before contact with the Russians, since they introduced a number of nasty diseases to which the Inuit were not resistant. Keep in mind that the Westerners who were developing cancer alongside them probably had a similar life expectancy at the time. Here's the data plotted in yet another way, showing the number of individuals surviving at each age, out of the total deaths recorded:


It's remarkably linear. Here's the percent chance of death at each age:


In the next post, I'll briefly summarize cancer data from several traditionally-living cultures other than the Inuit.

Cancer Among the Inuit

I remember coming across a table in the book Eat, Drink and Be Healthy (by Dr. Walter Willett-- you can skip it) a few years back. Included were data taken from Dr. Ancel Keys' "Seven Countries Study". It showed the cancer rates for three industrialized nations: the US, Greece and Japan. Although specific cancers differed, the overall rate was remarkably similar for all three: about 90 cancers per 100,000 people per year. Life expectancy was also similar, with Greece leading the pack by 4 years (the data are from the 60s).

The conclusion I drew at the time was that lifestyle did not affect the likelihood of developing cancer. It was easy to see from the same table that heart disease was largely preventable, since the US had a rate of 189 per 100,000 per year, compared to Japan's 34. Especially since I also knew that Japanese-Americans who eat an American diet get heart disease just like European-Americans.

I fell prey to the same logic that is so pervasive today: the idea that you will eventually die of cancer if no other disease gets you first. It's easy to believe, since the epidemiology seems to tell us that lifestyle doesn't affect overall cancer rates very much. There's only one little glitch... those epidemiological studies compare the sick to the sicker.

Here's the critical fact that modern medicine seems to have forgotten: hunter-gatherers and numerous non-industrial populations throughout the world have vanishingly small cancer rates. This fact was widely accepted in the 19th century and the early 20th, but has somehow managed to fade into obscurity. I know it sounds unbelievable, but allow me to explain.

I recently read Cancer, Disease of Civilization by Vilhjalmur Stefansson (thanks Peter). It really opened my eyes. Stefansson was an anthropologist and arctic explorer who participated in the search for cancer among the Canadian and Alaskan Inuit. Traditionally, most Inuit groups were strictly carnivorous, eating a diet of raw and cooked meat and fish almost exclusively. Their calories came primarily from fat, roughly 80%. They alternated between seasons of low and high physical activity, and typically enjoyed an abundant food supply.

Field physicians in the arctic noted that the Inuit were a remarkably healthy people. While they suffered from a tragic susceptibility to European communicable diseases, they did not develop the chronic diseases we now view as part of being human: tooth decay, overweight, heart attacks, appendicitis, constipation, diabetes and cancer. When word reached American and European physicians that the Inuit did not develop cancer, a number of them decided to mount an active search for it. This search began in the 1850s and tapered off in the 1920s, as traditionally-living Inuit became difficult to find.

One of these physicians was captain George B. Leavitt. He actively searched for cancer among the traditionally-living Inuit from 1885 to 1907. Along with his staff, he performed 50,000 examinations a year for the first 15 years, and 25,000 a year thereafter. He did not find a single case of cancer. At the same time, he was regularly diagnosing cancers among the crews of whaling ships and other Westernized populations. It's important to note two relevant facts about Inuit culture: first, their habit of going shirtless indoors. This would make visual inspection for external cancers very easy. Second, the Inuit generally had great faith in Western doctors and would consult them even for minor problems. Therefore, doctors in the arctic had ample opportunity to inspect them for cancer.

A study was published in 1934 by F.S. Fellows in the U.S Treasury's Public Health Reports entitled "Mortality in the Native Races of the Territory of Alaska, With Special Reference to Tuberculosis". It contained a table of cancer mortality deaths for several Alaskan regions, all of them Westernized to some degree. However, some were more Westernized than others. In descending order of Westernization, the percent of deaths from cancer were as follows:


Keep in mind that all four of the Inuit populations in this table were somewhat Westernized. It's clear that cancer incidence tracks well with Westernization. By "Westernization", what I mean mostly is the adoption of European food habits, including wheat flour, sugar, canned goods and vegetable oil. Later, most groups also adopted Western-style houses, which incidentally were not at all suited to their harsh climate.

In the next post, I'll address the classic counter-argument that hunter-gatherers were free of cancer because they didn't live long enough to develop it.

Cancer and the Immune System

My understanding of cancer has changed radically over the past few months. I used to think of it as an inevitable consequence of aging, a stochastic certainty. The human body is made of about 50 trillion cells, many of which replicate their DNA and divide regularly. It's only a matter of time until one of those cells randomly accumulates the wrong set of mutations, and loses the molecular brakes that restrict uncontrolled growth.

Strictly speaking, the idea is correct. That is how cancer begins. However, there's another check in place that operates outside the cancer cell itself: the immune system. A properly functioning immune system can recognize and destroy cancerous cells before they become dangerous to the organism. In fact, your immune system has probably already controlled or destroyed a number of them in your lifetime.

I recently read a fascinating account of some preliminary findings from the lab of Dr. Zheng Cui at Wake Forest university. His group took blood samples from 100 people and purified a type of immune cell called the granulocyte. They then evaluated the granulocytes' ability to kill cervical cancer cells in a cell culture dish. They found that it varied dramatically from one individual to another. One person's granulocytes killed 97% of the cancer cells in 24 hours, while another person's killed 2%.

They found some important trends. Granulocytes from people over 50 years old had a reduced ability to kill cancer cells, as did granulocytes from people with cancer. This raises the possibility that cancer is not simply the result of getting too old, but a very specific weakening of the immune system.

The most important finding, however, was that the granulocytes' kung-fu grip declined dramatically during the winter months. Here's Dr. Cui:

Nobody seems to have any cancer-killing ability during the
winter months from November to April.

Hmm, I wonder why that could be?? Vitamin D anyone??

In the next post, I'll talk about cancer in non-industrialized cultures.

Celiac and Fat-Soluble Vitamins

One of the things I've been thinking about lately is the possibility that intestinal damage due to gluten grains (primarily wheat) contributes to the diseases of civilization by inhibiting the absorption of fat-soluble vitamins. If it were a contributing factor, we would expect to see a higher incidence of the common chronic diseases in newly-diagnosed celiac patients, who are often deficient in fat-soluble vitamins. We might also see a resolution of chronic disease in celiac patients who have been adhering faithfully to a long-term, gluten-free diet.

One thing that definitely associates with celiac disease is bone and tooth problems. Celiac patients often present with osteoporosis, osteopenia (thin bones), cavities or tooth enamel abnormalities (thanks Peter).

An Italian study showed that among 642 heart transplant candidates, 1.9% had anti-endomyosal antibodies (a feature of celiac), compared with 0.35% of controls. That's more than a 5-fold enrichment! The majority of those patients were presumably unaware of their celiac disease, so they were not eating a gluten-free diet.

Interestingly, celiac doesn't seem to cause obesity; to the contrary. That's one facet of modern health problems that it definitely does not cause.

The relationship between cancer and celiac disease is very interesting. The largest study I came across was conducted in Sweden using retrospective data from 12,000 celiac patients. They found that adult celiac patients have a higher overall risk of cancer, but that the extra risk disappears with age. The drop in cancer incidence may reflect dropping gluten following a celiac diagnosis. Here's another study showing that the elevated cancer risk occurs mostly in the first year after diagnosis, suggesting that eliminating gluten solves the problem. Interestingly, celiac patients have a greatly elevated risk of lymphoma, but a lower risk of breast cancer.

There's a very strong link between celiac and type I diabetes. In a large study, 1 in 8 type I diabetic children had celiac disease. This doesn't necessarily tell us much since celiac and type I diabetes are both autoimmune disorders.

One last study to add a nail to the coffin. Up to this point, all the studies I've mentioned have been purely observational, not able to establish a causal relationship. I came across a small study recently which examined the effect of a high-fiber diet on vitamin D metabolism in healthy (presumably non-celiac) adults. They broke the cohort up into two groups, and fed one group 20g of bran in addition to their normal diet. The other group got nothing extra. The bran-fed group had a vitamin D elimination half-life of 19.5 days, compared to 27.5 for the control group. In other words, for whatever reason, the group eating extra bran was burning through their vitamin D reserves 30% faster than the control group.

Unfortunately, the paper doesn't say what kind of bran it was, but it was probably wheat or oat (**Update- it's wheat bran**). This is important because it would determine if gluten was involved. Either way, it shows that something in grains can interfere with fat-soluble vitamin status, which is consistent with the staggering negative effect of wheat products on healthy non-industrialized cultures.

Add to this the possibility that most people may have some degree of gluten sensitivity, and you start to see a big problem. All together, the data are consistent with gluten grains interfering with fat-soluble vitamin status. As I discussed earlier, this could strongly contribute to the diseases of civilization. These data don't prove anything conclusively, but I do find them thought-provoking.

Thanks to Dudua for the CC photo

Had 3 meals today!

For breakfast I had half a pancake.

For lunch I had some Hungarian 'Gnoccedly' and 'Perkerd'. Y U M! I have absolutely NO idea how to spell these, so they are phonetic versions of what we were served up. Gnoccedly is a kind of homemade pasta put through a utensil that looks like a blunt cheese grater straight into boiling water. The result is a kind of pasta that looks like mini cumulus clouds... like the italian Gnocci but smaller and very tasty. This is then covered in this stuff called 'Perkerd'. Its chicken drumsticks cooked in an onion puree with pepper and paprika, tomato and sour cream sauce. Its wonderful. I managed a bowl of the pasta and a little of the sauce on it. I didn't even bother with the chicken.

For dinner I had a full Sunday Roast. 1 sprig of broccoli, 1 spoon carrots, 1/2 slice beef, 1/2 roast potato and a Yorkshire pudding smothered in gravy and horseradish served up on a tea plate. It was delish!

Two Things That Get on My Nerves, Part II

Confusing Correlation and Causation

Recently, a paper was published that examined the association between sleep duration and the risk of death. Ferrie et al. showed that in their study population, subjects who slept either more or less than 7 hours a night had an increased overall risk of death. Here's how it was reported in Medical News Today:

Too Little Or Too Much Sleep Increases Risk Of Death

And here's a gem of a quote from one of the study's authors (excerpt from the article above):

In terms of prevention, our findings indicate that consistently sleeping around 7 hours per night is optimal for health and a sustained reduction may predispose to ill-health.

There's only one small problem: the study indicated no such thing. What the study showed is that people who sleep more or less than 7 hours tend to die more often than people who don't, not that the lack or excess of sleep caused the increased mortality. Have you ever noticed that you sleep more when you're not feeling well? Have you ever noticed that you sleep less when you're stressed? Could the increased mortality and sleep disturbances both be caused by some other factor(s), rather than one causing the other? We don't know, because the nature of the study doesn't allow us to answer that question!

The message the public ends up hearing is that no matter what feels right for your body, 7 hours of sleep is the optimum for health. Even though you'll have to go to work with bags under your eyes, feeling like crap, it's healthy. Even though you have the flu, you'd better not sleep more because it might give you a heart attack. That paper is just another example of perfectly good data being misinterpreted, and leading to an absurd conclusion.

The only way we could say that 7 hours of sleep is the healthiest amount (for the "average" person), would be to do an "intervention study", in which the subjects are manipulated rather than simply observed. Here's how it would work: we would take a large group of people and randomly assign them to either 5, 7 or 9 hours of sleep a night. We would then look at mortality over the course of the next few years, and see who dies more.

Intervention studies are the only way to establish causality, rather than simple association! At the end of our study, we could rightfully say that X amount of sleep causes an increase or decrease in mortality. Obviously, these types of studies are challenging and expensive to conduct, so it's tempting to over-interpret epidemiological studies like the one I mentioned initially.

This has to be one of the gravest, most frequent mistakes in the realm of health research and reporting. So many of the health recommendations we get from the media, the government, and even so-called scientists are entirely based on associations! Things like fiber is healthy and saturated fat is unhealthy. Those are conclusions that were drawn from studies that could only determine associations, yet neither has been consistently supported by intervention trials!

Misinterpreted data is worse than no data at all. Just say no to bad science!

Two Things that Get on My Nerves, Part I

The "Thrifty Gene" Hypothesis

The thrifty gene hypothesis is the darling of many obesity researchers. It was proposed in 1962 by the geneticist James V. Neel to explain the high rates of obesity in modern populations, particularly modernizing American Indians. It states that our species evolved under conditions of frequent starvation, so we're designed to store every available calorie. In today's world of food abundance, our bodies continue to be thrifty and that's why we're fat.

Obesity researchers love it because it dovetails nicely with the equally dim "calories-in, calories-out hypothesis", whereby calories alone determine body composition. You practically can't read a paper on overweight without seeing an obligatory nod to the thrifty gene hypothesis. The only problem is, it's wrong.

The assumption that hunter-gatherers and non-industrial agriculturalists lived under chronic calorie deprivation has been proven false. The anthropological evidence indicates that most hunter-gatherers had abundant food, most of the time. They did have fluctuations in energy balance, but the majority of the time they had access to more calories than they needed, just like us. Yet they were not fat.

The Kitavans are a good example. They are an agricultural society that eats virtually no grains or processed food. In Dr. Staffan Lindeberg's studies, he has determined that overweight is virtually nonexistent among them, despite an abundant food supply.

The cause of obesity is not the availability of excess calories, it's the deregulation of the bodyweight homeostasis system. We have a very sophisticated set of feedback loops that "try" to maintain a healthy weight. It's composed of hormones (insulin, leptin, etc.), certain brain regions, and many other elements, known and unknown. These feedback loops influence what the body does with calories, as well as feeding behaviors. When you throw a wrench in the gears with a lifestyle that is unnatural to the human metabolism, you deregulate the system so that it no longer maintains an appropriate "set-point".

Here's what Neel had to say about his own theory in 1982 (excerpts from Good Calories, Bad Calories):

The data on which that (rather soft) hypothesis was based has now largely collapsed.

And what does he think causes overweight in American Indians now?

The composition of the diet, and more specifically the use of highly refined carbohydrates.

RIP, thrifty gene.


For more information on bodyweight regulation, see:

Insulin Controls Your Fat
Leptin and Lectins
Thoughts on Obesity Part I
Thoughts on Obesity Part II
Body Composition