The previous post was concerned with the problems with nutritional science in general. In this instalment, I plan to look at how these issues, and others, pertain to the science used to validate the concept of the paleo diet.
The basic argument for eating a paleo diet goes something like this:
“Our ancestors ate a hunter gatherer type diet comprised of wild game, fish, eggs, fruits and vegetables with small amounts of nuts and seeds. Grains, legumes, dairy, vegetable oils, processed foods and other products of agriculture and the food manufacturing industry were absent from their diets.
These same ancestors were free from the diseases of civilisation – They did not suffer from heart disease, diabetes, obesity, auto-immune disorders, cancer or mental illness (as are contemporary hunter gatherers still alive today).
We should therefore attempt to emulate their diet as closely as possible, in order to achieve optimum health and longevity”
I know this, as I’ve said it myself many times in the past.
If you were paying attention to the last post, however, you will have spotted one major issue with this concept:
This is observational evidence.
What we should really say is that within indigenous populations, eating a hunter gatherer type diet comprised of wild game, fish, eggs, fruits and vegetables with small amounts of nuts and seeds, free from grains, legumes, dairy, vegetable oils and processed foods, is correlated with the absence of the diseases of civilisation.
I find it ironic that the paleo community love to chant the mantra “correlation does not imply causation” each time a new shaky red meat kills you observational study is released, yet fail to apply the same logic to the basis of the paleo concept itself.
A good observational study attempts (though it is often nigh impossible) to control for confounding factors. What possible confounding factors could there be that might muddy the waters of this paleo diet/disease correlation?
Our Hunter Gatherer ancestors (and contemporaries) lived very different lives to us.
Our ancestors were not rudely woken by alarm clocks, only to sit in traffic for an age before spending all day staring at a screen stressing over deadlines and upset clients. They did not spend hours watching TV or reading blogs on the Net. They did not have to worry about mortgages, job interviews or exams. They were not concerned with ensuring they kept up to date with the latest fashions and technologies.
Although they may well have faced regular incidences of acute stress – Life or death situations – Their lives were relatively free of any form of chronic stress. They had much more leisure time, with an average time of only around 8-12 hours devoted to actually hunting and gathering (an activity many now consider a leisure activity!).
Although both the introduction of agriculture, and then industrialisation of food are both strongly correlated with a steep rise in degenerative disease, one could also argue that they are strongly correlated with a dramatic rise in chronic stress.
It has been documented by the likes of Dr Weston A. Price and others, that when traditional peoples switch from an ancestral diet, to the foods of modernity, they typically see a rapid degeneration in health. However, it must also be noted that they invariably undergo massive cultural change, and with it undergo huge amounts of stress – Often with outsiders coming in, destroying local habitats, introducing infectious diseases and generally wreaking havoc! Imagine aliens invading and completely turning your world upside down, totally changing your diet, and half of your friends and relatives dying of a strange disease. Stressful at all?
More and more research is showing stress to be a major contributing factor to Western Disease through its effect on inflammation. How are we to know it is not this change which is driving the obesity and degenerative disease epidemic rather than dietary changes?
Electric lights, TVs, Computers and the like, coupled with early morning starts mean that the vast majority of us are chronically sleep deprived.
Though it may not have been a classic 8 hours straight sleep now held to be the norm, our ancestors certainly got more than us – Having the freedom to sleep and wake as and when they felt like it, rather than when society dictates. As with stress, sleep is a growing area of research which is known to have wide-ranging impacts on our health and well-being.
Though they may have had a much shorter “work week”, and spent a lot more time sleeping, our ancestors were much more active than us, in a far wider range of activities. Day to day life would involve walking, climbing, balancing, carrying and lifting, with occasional bouts of high intensity activity during hunting expeditions, or while avoiding being hunted!
Today the average person does less than 30 mins of activity per day, a known contributing factor to the dilapidated health of our society.
The mainstream is slowly catching onto the fact that Vitamin D deficiency is endemic in modern society. Our ancestors spent their lives outside with most of their skin exposed to the sun. Now we live and work indoors all day, and when we do go out we cover up with clothes and “protect ourselves from the sun” with sun creams and lotions.
We are now exposed to a myriad of chemicals that our ancestors were not. Pesticides and herbicides on foods, BPAs from plastics, exhaust fumes from traffic, and who knows what chemicals leaching into the water table from the mining and chemical industries. Is it not possible that these all have an adverse affect on our health?
On the flip side, we now live in a much more sterile world – Disinfectants, an aversion to dirt, and indiscriminate use of antibiotics can lead to dysbiosis of our microbiome, which is now being linked to many, if not all aspects of degenerative diseases.
Genetic Factors and Lifespan
A frequent argument against the paleo diet, is that as average life expectancy of hunter gatherers was only around 30 years, the incidence of degenerative diseases is obviously going to be lower, as people would have died before the diseases would have had chance to develop.
The paleo rebuttal is that average life expectancy was low due to high infant mortality rates. Those that did survive into adulthood, and avoided nasty accidents or infectious disease, lived long and healthy lives, and maintained their strength, health, vitality and mental acuity all the way to the end of their lives.
One problem with this argument, is that it does not take into account the fact that some modern humans make it through to old age relatively unscathed by modern living, and that the major predictor for this is genetics, not lifestyle. Everyone knows of someone with “good genetics” who has lived to a ripe old age despite living a hedonistic lifestyle.
Imagine 10 pairs of identical twins are born, one of each pair is dropped off in the jungle somewhere to live with a tribe of hunter gatherers, the others stay in the West and live modern lives.
Of the hunter gatherers, 5 don’t make it past the first 2 years because of infections and illness, 2 die in early childhood, 2 more die in hunting accidents in early adulthood, and only one wily, resilient individual makes it through to old age.
In the modern world, meanwhile, thanks to vaccinations, emergency rooms and a generally much safer environment, all the babies make it through to old age.
Many of them have become old and infirm, both mentally and physically, but one is still as sharp as a fox and strong as an ox, despite his 40 a day habit and love for straight whiskey. Is it not possible the paleo baby made it through to old age in great shape primarily due to these same genetics, and the diet was coincidental?
Free images from FreeDigitalPhotos.net
Diet Does Matter – But What Aspects?
Undoubtedly, all the above factors have a significant impact on one’s health, well-being, physique and longevity, to the extent that it becomes impossible to distinguish from epidemiological evidence alone exactly what is causing what.
This does not mean that diet does not matter, however. On the contrary – I believe it to be at least as important as any one of those other factors.
Though scientists, doctors, government agencies and paleo bloggers may all disagree with one-another about what we should eat, pretty much everyone is in agreement that diet has a significant impact on our health.
The question is, if a paleolithic type diet is better for our health than a modern Westernised diet, what factors is it that make the difference?
Is it that we are missing crucial nutrients previously supplied by our ancestral diet, or is it that our modern diet is too high in anti-nutrients, plant toxins and industrial chemicals? Does food reward play a role? Macro-nutrient ratio? Processing techniques? Animal husbandry practices?
Hardcore advocates of the paleo diet might argue that it is because we don’t know exactly which elements of an ancestral diet contribute to its health promoting properties, that we should simply try and emulate it as closely as possible.
I take issue with this approach for a few reasons however:
There was no single paleo diet
Ancestral diets varied hugely, as did the lifestyles and the genetics of the people eating them, so which diet do you emulate?
The “paleo diet” followed by most modern Westerners bears little relation to any ancestral or traditional diet ever eaten by indigenous peoples
Grass fed beef steak with leafy greens seems to be a paleo diet staple, yet I’d argue it has seldom ever been eaten by true hunter gatherers. Ethnographic research I’ve seen shows rodents and insects eaten nose to tail to feature much more prevalently, and if veg was eaten it was starchy roots held in highest esteem. Larger animals were a rare treat, and if they were caught, it was the organs that were prised, not the muscle meat.
The optimum diet may depend on your lifestyle
People often reference the Inuit, and how they do very well on a super low carb diet. People fail to comment however that they aren’t into triathlons or ill advised high intensity cross training programs either (nor that many of them smoke 40 a day, a lifestyle habit you’d be unwise to emulate!).
Hunter-Gatherers eat what is avaiable, work hard to get it, and appreciate every mouthful
Now, before you interject, one could argue (correctly) that although the diets of ancestral/indigenous peoples are extremely varied, they do hold many common factors. Namely an absence of Krispy Kreme Donughts and KFC, instead being comprised solely of plant and animal foods in a relatively unprocessed state, so we should do the same.
Our ancestors, however, never had to deny themselves anything – Ignorance is bliss as they say! It is well documented that the stress of dieting can have profound negative impacts on your health. Not eating bread isn’t an issue if it hasn’t been invented and you’ve never heard of it, but if you have to walk past a bakery everyday, or sit at the table with your friends while they eat a delicious pizza, this could be a different story.
Other common arguments for the paleo diet rely on logical fallacies, for example:
The longer a food has been in the human diet, the better it is
The argument holds, that the longer we have consumed a food for as a species, the better adapted we must be to eating it, and therefore the more suited we are to eating it.
The problem with this argument is that all foods were new at some point in time, and in many species it is the discovery of a new food source that enables a species to make great advances.
Humans are no exception, and it is now widely accepted that it was the introduction of meat to the diet that led to the first great leap forward in intelligence.
The less processed a food the better it is
In his fantastic book, Catching Fire; How Cooking Made Us Human, Richard Wrangham puts forward compelling evidence that it was the cooking and processing of food, leading to its increased digestibility, that allowed our digestive tracts to shrink, in turn allowing our brains to grow.
A raw food diet may produce effective weight loss in the short term, but in the long term is very ill advised as we are now adapted to a cooked food diet. Does it really follow that processing to a certain food to a point led to the evolution of smaller stomachs and bigger brains, but over processing leads to obesity and metabolic syndrome?
I could go on with many more criticisms of the “science” behind the paleo diet, but as this post is now well overdue already, I’m going to call it a day here (I think you’ve probably got the point by now!).
Despite what might seem like an almighty diatribe against the paleo diet, I must at this point make it clear again that I’m certainly not suggesting you all give up eating real food and switch to a diet of pop tarts and pasties.
My aim is simply to point out that:
- There is no one “Paleo Diet”
- There is no optimum diet for all people
- Just because the Paleo Diet worked for you, doesn’t mean it will work for everyone
- The Paleo Diet doesn’t necessarily have to be an all or nothing approach
- Diet alone is not a panacea
In the following and final instalment, we shall be looking at how to make rational, evidence based decisions on what to eat, enabling you to find your own optimum way of eating, not based on dietary dogmatism or shaky pseudo science.