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The personal blog of Frank Lesko. Award-winning writer. Non-profit entrepreneur. Activist. Religious professional. Foodie. Musician. All around curious soul and Renaissance man.

See also my professional blog: The Traveling Ecumenist.

Thursday, May 29, 2008

Paleo Diet

The “Quest for the Paleo Diet” is the Holy Grail of modern nutritional research. There are no Indiana Jones tomb raids in competition with Nazi armies, but the drama is just as high. The goal is to deduce the diet that our ancestors would have eaten during the most defining phase(s) of our evolution. The hypothesis is solid: The closer we can imitate the diet & lifestyle of our Paleolithic ancestors, the healthier we can be—we would be living the lifestyle that we evolved to live.

Even if you have never heard the term “paleo diet,” you have felt its impact. The current fascination with low-carb diets and whole-foods are both based on its principles.

There is a lot at stake in the paleo diet. Food may seem so ordinary that we take it for granted, but it is big money and has substantial political implications. Just think back on the lashings Oprah Winfrey received in the wake of criticizing the beef industry or consider the always hot-button issue of farm subsidies. Vegetarians and meat-eating hunters trying to justify their lifestyles have big stakes in the paleo diet, as well (or steaks, as the case may be).

So what did the paleo diet consist of? The hunt is still on, but some characteristics of paleolithic eating are starting to form:

What is for certain is that widespread grain consumption was unlikely. Even though rice (in the east) and bread (in the west) have been the absolute pillars of civilization for thousands of years, their usage spans a relatively short period of time from an evolutionary point of view. Farming began at the earliest 10,000 years ago in the Middle East. Other places around the world followed suit, but in some cases thousands of years later. While that is an ample amount of time for a species to tolerate a new food source, it is often considered not enough time to fully adapt to a new diet. Our Paleolithic ancestors probably ate some grains in limited amounts, but it is unlikely that the earth could have provided enough wild grain to form a staple of human diet. If you consider that our species has been around for about 100,000 years, then we have lived 10 times as long before towns, cities, farming and grain-consumption.

The increase in grain consumption is linked to the “modern diseases” such as heart disease, cancer and diabetes. Even cows (designed to eat grass) develop these same illnesses when raised on a diet of refined grains with minimal exercise. The idea here is that species should eat the diet they are designed to eat.

There are many characteristics to our ancestors lifestyle that we would have difficulty re-introducing now. Virtually every group ate a significant amount of insects. There was probably a lot of passive nutrition from unfiltered water and lots of dirt. Regular exercise and exposure to the sun is a no-brainer. Considering that fire was domesticated about 300,000 years ago by homo erectus (and earlier species of humans from which we evolved), I think that is solid evidence that cooked foods have been an evolutionary staple for our species which came along much later. They ate whole foods--the animal (organs and all), the whole vegetable (peels and all) and the whole grain. Their environment was 100% organic and all animals were raised on diets healthy to them, too. Food choices came and went seasonally.

The evidence from Dr. Weston A Price is invaluable. In the 1930s, he and his wife researched diets of hunters & gatherers as well as those using some traditional farming and ranching lifestyles. While we often think of primitive peoples as unhealthy with buck teeth and bloated stomachs, his research showed the opposite: Most people living in traditional lifestyles had substantially better health than their westernized counterparts. Dental issues were almost non-existent--even among the elderly--even though few teeth (if any) were brushed. Cancer, heart disease and diabetes are almost unknown among these groups. While we tend to think of technologically advanced societies as being healthier, his findings are what you would expect from an evolutionary perspective.

He also documented such a wide array of different diets and lifestyles among these primitive societies that it is hard to establish what they had in common. There were near vegetarian communities ranging to those eating all meat. While that makes it harder to establish dietary guidelines, the good news is that a hugely varied diet for us is probably possible. The diet just needs to keep in line with whatever paleo principles underline it. Right now, we understand those characteristics as "whole foods" and "pasture raised animals" and "low carb", but in the coming years I am hopeful that we will come to an even better understanding of what really made those diets tick.

It is ill-advised to cherry-pick certain attributes of the paleo diet, even if we are able to identify those aspects with certainity. For example, some paleolithic humans would have certainly eaten a diet consisting almost entirely of meat. There are modern hunter gatherers in the Arctic north who live this way. During several ice ages, our ancestors would have almost certainly had a similar diet since there would have been little else to eat. However, it would be wrong to translate that into the modern Adkins Diet. The Inuit eat the whole seal--vitamin-rich organs and all--and even get some vegetable matter from stomach contents. Much of the meat is raw, so it still contains many more microbes and vitamins than if it were thoroughly cooked. This is vastly different than a diet of cooked boneless, skinless chicken breasts and modern steaks from nutritionally deficient grain-fed cows. Both the Inuit and Adkins practitioners are eating a mostly-meat diet, but they couldn’t be further apart nutritionally. The Inuit have a virtually all-meat diet, true, but that fact alone does not tell the whole story.

In a previous post, I talked about vegans who were healthy living in India but developed nutritional deficiencies after moving to England. Their diet was identical, but in India they were getting additional nutrition from their surrounding environment that they weren't getting in England. This is another example that if a diet works for a particular group of people, we have to be careful not to extract isolated portions of it, because the diet functions as part of a whole system.

So low-carb diets have solid scientific rationale behind them, but like the above examples shows, how they are being implemented in the latest diet fads can often leave much to be desired.

It is difficult to determine which time period would be the most representative. Do we look at humans right as our species first developed in Africa or after our species split off and migrated around the globe? Is it right to compare equatorial groups with people who lived for tens of thousands of years in Ice Age Europe? The separation was significant enough to develop some regional (racial) differences among people (even though they are characteristically small changes), so was it enough to develop dietary differences, as well? Is is right to use the term "paleo diet" when the plural may be more accurate? The Paleolithic period covered 90,000 years, during and between several ice ages and geographically spans the globe.

Since humans evolved from vegetarian primates, some argue that we should be vegetarian, too. The problem with that theory is that our split from primates happened millions of years ago. Our protein-dependent large brains and migratory patterns into vegetation-scarce arctic territories gives weight that hunting has been a part of at least some human diets for quite a while. The inability of some modern people to thrive on vegan diets is further evidence for this. This does not rule out a possible vegetarian or near-vegetarian portion in our evolutionary history, but descending from the apes alone is not ample evidence due to the significant span of time alone.

The debate is by far not settled as to the amount of meats in our paleolithic past as well as the percentage of cooked food. An all-vegetarian or an all-meat diet are possible for isolated groups, but the human race as a whole most likely ate somewhere in between this. Big questions remain as to the amount of grains, whether they were refined or not, how much meat, how much raw food as a percentage, and how much nutrition came from unexpected sources, such as "contaminated" water and exposure to the sun and soil. Insects were an important part of the diet for most groups. Exercise and exposure to the sun in an all-organic environment probably helped our ancestors process their foods properly.

The huge variation among the diets of modern hunter gatherers should give us some joy that variety is available for us, as well. The main challenge for us now is to figure out what what the defining, underlying principles that seemed to make all of these varied diets work, even though they seem so different on the outside.

This is a nice website for assorted articles on the subject. I can't recommend the article from the Weston Price site enough (linked above). Be careful wading through the various paleo diet fads out there. The hard part is taking the theory and translating it into a workable diet we can eat today.

1 comment:

  1. CLARIFICATION: Even though grain consumption is a relatively new phenomenon in the human diet, that does not include all carbs. Tubers such as potatoes and yams had a central role in many of the diets of early humans. A number of sugar-intensive fruits and vegetables also occupied center stage.

    While the low-carb fascination in recent years has some merit, (especially in considering societies that got most of their food from animal fat and meat) the no-carb policy does not hold up when considering all paleolithic humans.

    In addition, some of the groups that Dr. Price studied were actually farmers and ranchers, who were living a traditional lifestyle but far beyond a paleolithic one--consuming grains, beans and cheeses, for example. They also had high marks for health in comparison to the hunter gatherers who would be closer to a paleolithic lifestyle.

    Carb consumption may not be the smoking gun that recent thinking has made it out to be. There is more at play than simply carbs. Perhaps a real probelm is simply grains, or refined grains, refined sugars, or some other combination of lifestyle choices (such as a high-carb, low-exercise lifestyle).

    So in other words: Don't be afraid to eat carbs or even grains! I would suggest making at least 50% of your grains whole, and stick to whole sugars, honey and maple syrup instead of the refined, bleached stuff.

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