Friday, July 4, 2008

Cancer Among the Inuit

I remember coming across a table in the book Eat, Drink and Be Healthy (by Dr. Walter Willett) 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 unusually low cancer rates. This idea was widely accepted in the 19th century and the early 20th, but has somehow managed to fade into obscurity.  Allow me to explain.

I recently read Cancer, Disease of Civilization by Vilhjalmur Stefansson (thanks Peter). 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 mostly carnivorous, eating a diet of raw and cooked meat and fish almost exclusively. Their calories came primarily from fat. They alternated between seasons of low and high physical activity, typically enjoyed an abundant food supply yet also periodically faced famines.

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 claims to have performed tens of thousands of examinations. 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 US 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, although other factors could be involved in producing this result (such as poorer diagnosis in less Westernized regions). 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.

10 comments:

Anna said...

The folks who make a big deal about the hunter gathers having a short average lifespan also fail to remember/notice that until the 20th century, the life expectancy in many US and European industrial-urban areas was very, very low, as well. Infant/childhood mortality was high, and industrial accidents were common. But there were still people who lived to a ripe old age, just like always.

Stephan said...

Definitely. It's mostly through medicine that we're able to live so long now despite an unhealthy lifestyle.

Mel Visser said...

Stephan,
Thank you for providing this history of Inuit cancer.
It is amazing that cancer rates in northern indigenous populations has gone from zero to multiples of southern rates.
In "The China Study," T. Colin Campbell describes a very convincing set of studies indicating that high animal protein and fat diets accelerate cancer, while plant based diets retard cancer.
Could it be thet the Inuit diet is very healthy in the absense of tobacco and persistent pesticides, but once with these carcinogens are added to their diet, the once healthy diet becomes a killer?
Inuit consuming sea mammals ingest eight times the tolerable daily intake of chlordane and four times the tolerable daily intake of toxaphene.
See my web site at coldclearanddeadly.com
Mel Visser

Stephan said...

Hi Mel,

I don't subscribe to Campbell's theories. They're based mostly on epidemiological associations, which are not hard evidence (but are still useful for formulating hypotheses). He also cites animal studies, but in my opinion the studies he cites are deeply flawed.

Humans have been eating meat for a long time and we're well adapted to it. Many contemporary hunter-gatherers were carnivores or nearly, not just the Inuit. None were vegetarians, none were vegans, although there were healthy groups eating up to 80% calories from plants.

Another amazing thing is that they didn't eat many vegetables. They went after things that had a lot of calories for the most part, so veg wasn't worth wasting time on except for a little flavor.

I hear your theory about the combination of animal foods and toxins being a problem. I just think a simpler explanation is that modern industrially processed foods are toxic and natural animal foods aren't.

Of course you're right about the huge amounts of chemicals modern Inuit are eating, that can't be good. But I think the problem is the chemicals, not the animal foods themselves. We still thankfully have access to clean, healthy animal foods in our culture.

primeval_sea said...

The reason that the Inuit's traditionally have not experiences a High incidence of Cancer, Heart Disease and other diseases that afflict westerners is because their High Fat diet is high in Omega 3 oils, while westerners diets are high in Omega 6 oils. Although they do not consume plants for the most part(except for some berries and seaweed), they do get plenty of antioxidants from their meat sources.

Sarahskane@gmail.com said...

From my own experience living in Northern Alaska, I know that the Eskimos there seemed to prefer seal oil and other animal foods that had aged. Wouldn't the fact that the oils are aged mean they are oxidized, meaning not good as omega 3 anymore?

CSuvlu said...

The mind-body connection is now solidly documented. There are many sources for this info but one of the pioneers whom I'm sure you must be familiar with is Candace Pert. Everything is multifactorial and I do not think you can discount the effect of the oppression of Inuit since the introduction of Western culture on their physical health. I'm supportive of the traditional diet being a path back to good health but it plays a singlular part in a much much larger picture!

Marija R said...

This article is higly misleading. The Arctic region, and its wildlife accumulates alarming quantities of environmental pollutants (POPs, lead, mercury) and they are found in very high quantities in indigenous diet. People in the Arctic suffer from health deterioration at an alarming rate and this story about them not having cancer due to their diet is furthering the mythology about indigenous populations and their "natural" lifestyle.

Evan said...

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3417551/

What is the explanation for this article?

Viktoria Pataki said...

Evan... the explanation lies within the article itself "Evidence indicates that these patterns may be changing, possibly due to changes to diet and lifestyle in recent decades, so that previously relatively rare cancers among Inuit are increasingly experienced."
The blog post presented is about the rarity of cancer cases among the Inuit in the beginning of the 20th century. At that time they pursued a more traditional lifestyle and diet (animal fat and protein based), with plenty of vitamins gained from eating raw meat/fish and fat-soluble vitamins from animal livers, and also plenty of physical activity - they had to hunt,right?
Now the situation is very different, many of them are unemployed, they do not hunt anymore, not get the necessary vitamins due to change in diet, they eat grain-based cheap food and many of them are diabetic and obese. Healthy foods (even cabbage) are extremely expensive, so out of their reach.