DrG's Medisense Feature Article
17042-Paleo_Diet
The Paleo Diet
by Ann Gerhardt, MD
April 2017
Print Version
The Paleo Diet, popularized by the 2010 book by Loren Cordain, is based
on foods that “mimic those of our pre-agricultural,
hunter-gatherer ancestors”. The premise behind the diet is
four-fold: 1) we haven’t changed genetically from our Paleolithic
ancestors; 2) the diet consists of “foods we were designed to
eat;” 3) our ancestors did not suffer from diseases common in
Westernized societies; and 4) the foods out hunter-gatherer ancestors
ate were healthier than a typical Western diet and will aid weight loss.
All versions prohibit processed foods of any kind, because humans did
not invent such foods until after the Paleolithic period. This is
reasonable and common to many diets because processing cuts out
essential nutrients and adds carbohydrate and fat calories that are
‘empty’ of redeeming nutritional value.
The diet allows meat, seafood, eggs, tuber, most vegetables, fruits,
nuts, animal fats and seeds. “Healthy” oils are
allowed, but requires ‘processing’ nuts, olives, flax,
coconut and avocado, which strikes me as a bit arbitrary about the
rules. It eliminates sugar, dairy, grains, legumes, vegetable
oils, processed food and non-food ingredients like preservatives and
artificial sweeteners. Various versions allow some dairy, rice
(officially a grain, so it’s not clear why it would be an
exception) and honey. Others prohibit foods that come from a long
distance, because they are not eco-friendly and hunter-gatherers
didn’t eat food shipped in by truck.
The diet is supposed to be high in protein, fiber and potassium, low in
carbohydrate, sugar and sodium and have a moderate to high amount of
fat. Simply by eliminating most carbohydrate foods, the plan is
just another low-carb, high protein, moderate fat diet, fitting in
somewhere between South Beach and Atkins.
If one eats a moderate amount of a balance of all the allowed foods,
it’s not a bad diet, especially if it enables maintaining ideal
weight. Detractors mostly object to the verity of the underlying
premises.
Paleo fanatics say we are genetically the same as Paleo Homo sapiens,
designed to eat the foods they did. While some people may act
like our Paleolithic predecessors, we are not biologically identical to
them, nor do we have access to the foods they ate. Humans, animals and
plants have evolved.
If humans, the environment and available foods had not changed over
time, we would still be hunter-gatherers eating mammoths and
berries. We wouldn’t have been smart enough to harness
fire, make tools or breed animals and birds for optimal food value and
plants for variety and survival in different climates. Humans
today have larger brains and different teeth. Some genetic
mutations have led to disease resistance. Others, like the gene
for lactase, which enables milk sugar digestion, have changed what we
are capable of digesting.
The Paleolithic period spanned from 2.4 million to about 15,000 years
ago, before agricultural and industrial development.
That’s a lot of time, during which the Homo (humanoid) genus
evolved to Homo sapiens (anatomically modern humans) between 200,000
and 100,000 years ago. Theoretically the ancestors mentioned in
Paleo literature are Homo sapiens, because they really are genetically
similar. Previous humanoids had harnessed fire and may have used
it to cooking. They had fashioned tools for fishing and
hunting. In addition to animals, fish, nuts and berries, they
probably ate plant foods, but who knows what varieties were available
more than 15,000 years ago. Long before the end of the
Paleolithic period wild grains were gathered and consumed, but not yet
farmed.
We are not the same as any of the string of humanoids populating the
massive Paleolithic period. We don’t have the same animal
and plant species as they did to eat if we wanted to. Hunters
hunt species different from Paleolithic times. The rest of us eat
the flesh of animals and birds that, through breeding, no longer have
the lean bodies of wild animals. We eat farmed fish.
Farmers have bred vegetables and fruits for variety, size, flavor and
number of seeds. The vegetables of today certainly are different
from those of yesteryear.
Not all hunter-gatherer societies over millennia ate the same
foods. They ate the food available to them, unlikely mimicking
the extensive Paleo diet list. Current hunter-gatherer peoples
continue to do so. Alaskan Inuits eat mostly fish and seafood,
people in middle Africa subsist on tubers, and a sub-Saharan African
tribe consumes a varied, plant-based diet (seeds, nuts, vegetables and
fruits). None of these diets are ‘complete’ in terms
of an adequate variety of nutrients.
Paleo advocates lumped these food patterns together, cherry-picking
foods from a variety of hunter-gatherer diets to prevent
deficiencies. Someone who eats a balance of all the allowed foods
will not be malnourished. Someone who omits seeds and vegetables
won’t fare as well. Those who eschew animal products could
be protein and B12 deficient.
The notion that hunter-gatherer people are/were healthier and immune to
chronic diseases common in Western civilization is blind to the
facts. Paleolithic peoples’ life-span was about 33 years,
not long enough to acquire ‘chronic’ diseases that
typically don’t kill modern people until middle and old
age. A few may have lived longer, but many children died before
adulthood. They may not have died because of their diet, but they
didn’t live long enough to find out if their diet would have led
to heart disease and stroke.
A study of mummies’ arteries from Paleo hunter-gatherer societies
used CT scans to detect calcified deposits in arteries, which are
tell-tale signs of atherosclerosis. They found probable or
definite atherosclerosis of a variety to arteries in 34% of 137
mummies, 38% of 76 ancient Egyptians, 25% of 51 ancient Peruvians, 40%
of five Ancestral Puebloans of southwest U.S. and 60% of five Unangan
of the Aleutian Islands. The older the person was, the more
likely they had vascular disease and the more likely it involved more
arteries. The same is true now – eventually everyone gets
vascular disease with age, some later than others.
Even current hunter-gatherer tribes are not particularly healthy. The
Hiwi, a group that lives in Western Venezuela and eastern Colombia, are
smaller and less well-nourished. They are hungry, suffer from
endemic parasitic infections and have a low survival rate into
adulthood.
Is the Paleo diet any healthier or conducive to weight loss than any
other diet that prohibits whole food groups? Unfortunately so
far, studies have been of short duration (3 months or less), examined
small numbers of people and most often lacked a control group.
Diabetics following the Paleo diet generally had lower blood sugar than
those on a standard diabetic diet. Cholesterol and triglyceride
levels improved, but there were no control groups for comparison.
People lost some weight, three to eleven pounds over three to twelve
weeks. Without long term studies comparing people who don’t
cheat on the Paleo diet to people who don’t cheat on another diet
type, we can’t say if it is any better for us than any other
calorie-controlled food pattern.
This is similar to the high vs. low fat diet debate that raged on for
years. Those studies started with small, poorly designed studies
that suggested that high fat dieters fared better. Long-term
analyses disproved this, as outcomes converged on similar metabolic
outcomes and amount of weight lost in longer term studies. In
terms of health outcomes, such as disease and longevity rather than
sugar and cholesterol levels, ‘prudent’ diets that do not
eliminate whole food groups fare much better.
Homo sapiens were not designed to subsist on a single diet type.
In fact, humans are the only animal to adapt their diet according to
availability, social norms and health. A fascinating book,
Consuming Passions, The Anthropology of Eating by P. Farb and G.
Armelogos (1983, Washington Press), describes ways in which dietary
habits differ throughout the world and have changed over time in ways
that enabled survival of the species.
Ancient and current hunter–gatherers hunted and gathered out of
necessity. Modern day people with access to a huge variety of foods eat
according to their version of a hunter–gatherer diet because they
want to. Do it well and there’s no harm done. In my
experience, any diet that doesn’t accommodate the human desire to
eat dessert is bound to be short-lived, or at least conducive to
cheating.