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The Paleolithic Diet
A Review
by: Philip Rouchotas, MSc, ND
Bolton Naturopathic Clinic
64 King St. W, Bolton, Ontario L7E 1C7
[email protected]
What is the Paleolithic Diet?
Today’s modern diet may lead to numerous
chronic diseases, including type 2 diabetes
mellitus, obesity, and cardiovascular
disease. These health conditions are
strongly linked to affluence. The Paleolithic
Diet (or Paleo diet) has been extremely
popular in communities that are healthconscious. It has steadily been gaining
momentum and is now being featured on
television, in magazines, and on various
blogs. It is worthwhile being a bit cautious
before making any major changes, since
some of the marketing done around the
Paleo diet can sometimes be extreme. One popular website says: “The Paleo diet is
the healthiest way you can eat because it is the only nutritional approach that works
with your genetics to help you stay lean, strong and energetic”. The Paleo diet is also
known as the primitive diet, or the “caveman diet”. It consists of eating foods that were
available to humans before agriculture was fully developed. The Paleolithic period started
approximately 2.5 million years ago and ended approximately 10,000 years ago. Part
of the reasoning behind the diet is that since agriculture and animal domestication only
happened 10,000 years ago, there hasn’t been enough time for humans to properly
evolve to the resulting dietary changes. The core metabolic and physiological processes
have not adequately responded to these relatively new food practices. In other words,
today’s humans are not adapted to a modern diet, but are still adapted to a Paleo-type
diet.
The Paleo diet consists of eating wild-animal source and uncultivated plant-sourced foods,
including lean meat, fish, vegetables, fruits, roots, eggs, and nuts.[1] The diet removes
items like grains, legumes, dairy products, salt, refined sugar, and processed oils. The
removed items were not available before humans began cultivating plants and animals.
The Paleo diet will also include other generally accepted health recommendations, such
as removing candy, soft drinks, beer, and additional salt. So far, only a few studies
have examined the effects of a Paleo diet on disease and risk factors for disease, but
more studies are in progress. As we will discuss in this article, there is evidence for
improvements in type 2 diabetes and for decreasing cardiovascular risk factors. These
are only some of the better-studied outcomes, but the Paleo diet could potentially be
used as a treatment for other chronic degenerative conditions, or even for the average
person as a healthy baseline diet. Some of the research available promotes the positive
health outcomes of the foods included in the Paleo diet, while other research highlights
the negative health consequences of eating the excluded foods.
How Does the Paleo Diet Work?
The Paleo diet may be effective for a number
of different reasons. The macronutrient
content of the Paleo diet is closer to 40%
protein, 40% fat, and 20% carbohydrate
(as measured by energy). This varies a
good deal from the modern diet, which
focuses more emphasis on carbohydrates
as the key source of energy. The Paleo diet
might contain fewer calories and a lower
glycemic index than alternative diets. If
that is the case, then it may be better at
achieving weight loss and stabilizing blood sugar. It may also be more satiating; in other
words, it might make people feel full faster. This would prevent the ingestion of additional
food and could by itself cause weight loss, cause reductions in waist circumference, and
the accompanying health benefits of both. The higher amounts of fruit and vegetable
intake could cause the feeling of being full sooner because of their higher water content.
There is also a higher amount of protein in the Paleo diet compared to the modern diet.
Usually, a diet higher in protein is associated with favorable changes in body composition,
improvements in cholesterol levels, and improvements in the regulation of blood sugar.
The Paleo diet has been studied in terms of its vitamin and mineral composition.[2]
Overall, the argument is made that the Paleo diet has a larger quantity of healthy vitamins,
minerals, and antioxidants. For example, the Paleo diet has significantly less sodium
and larger amounts of potassium. Diets rich in potassium and low in sodium have been
demonstrated to be effective for conditions like hypertension, stroke, kidney stones,
and osteoporosis. There are exceptions. The Paleo diet contains less calcium than other
diets, in part because of the removal of dairy. This might cause a theoretical increase in
risk of osteoporosis and osteopenia due to weakened bones. However, the Paleolithic
ancestors had greater activity levels and greater sunlight exposure, so they would have
had better calcium absorption. Another concern is that the calcium may be lost due to
the high meat intake (this occurs due to a process that takes place in the kidneys), but
this is also countered by a high fruit and vegetable intake. These possible mechanisms
focus on the content of the included foods, but the Paleo diet may also be effective
because of the foods it removes. Grains, legumes, and dairy have all been associated
with negative health consequences, ranging from mild to more severe. The removal of
these potentially offending foods may help improve health directly.
What Effect Does a Paleo Diet
Have on Type 2 Diabetes?
One study published in 2009 examined the
effects of the Paleo diet on type 2 diabetes.
It was a randomized crossover study that
included 13 patients (3 women and 10
men).[3] The participants were instructed to
eat a Paleo diet based on lean meat, fish,
fruits, vegetables, root vegetables, eggs,
and nuts, and a diabetes diet designed
in accordance with dietary guidelines
during two consecutive 3-month periods.
Because all participants would have tried both diets, the study is considered a crossover
study. The researchers measured changes in weight, waist circumference, serum
lipids, C‑reactive protein (which measures inflammation), blood pressure, and glycated
haemoglobin, as well as other insulin measures. They evaluated dietary intake by using
food records. The results of the study showed that the average participant had diabetes
for 9 years and was usually treated by medication (typically metformin). Compared to
the diabetes diet, the Paleo diet resulted in lower glycated haemoglobin, diastolic blood
pressure, BMI, and waist circumference (all generally healthy results). The Paleo diet
also resulted in higher levels of HDL cholesterol (which is protective). The Paleo diet
turned out to be lower in total energy, energy density, carbohydrate, dietary glycemic
load, and other dietary parameters. The glycemic load is the number that tells you how
much a food will increase a person’s blood sugar after eating it; it basically accounts
for how much carbohydrate is in the food. Since the Paleo diet was lower in glycemic
load, this means it didn’t increase blood sugar as much as the diabetes diet, which is a
positive outcome.
This study was limited by its small size, which did not recruit enough participants to be
very powerful. Another concern is that participants were not blinded as to which diet
they were ingesting, which can sometimes be a source of additional resulting benefit
not directly related to the diet being investigated. In addition, this study can be criticized
because the decrease in blood sugar did not reach statistical significance, and the
results did not show differences in insulin measures. Overall, the results certainly show
promise and demonstrate that the Paleo diet is safe. The results show the Paleo diet
may be more helpful than a diabetes diet for a variety of reasons. Unfortunately, this is
one of the only trials available that looks at the impact of the Paleo diet on diabetes and
as such, more research is warranted that includes more participants.
What Effect Does a Paleo Diet Have
on the Heart?
Similar to the diabetes study, there has
not been too much research conducted
on the cardiovascular impacts of a Paleo
diet. One study examined 29 patients with
diagnosed ischemic heart disease and
either diabetes or prediabetes.[4] They were
placed on a Paleo diet or a Mediterranean
diet (based on whole grains, low-fat dairy,
vegetables, fruit, fish, oils, and margarines).
Both groups improved in their blood sugar
regulation, but the improvement was better
for those who ate Paleo diets. Another trial
that was uncontrolled examined 14 healthy
participants on the Paleo diet. These
researchers found improvements in weight, body mass index, waist circumference,
systolic blood pressure, and in clotting markers. Similar results have been found in other
trials, with improvements in blood pressure, in the stiffness of arteries, and improvements
through reductions of harmful cholesterol values (like LDL and triglycerides). Even shortterm consumption of a Paleo diet can improve many of these parameters. Overall, the
Paleo diet appears to promote heart health without any negative consequences.
The Paleo diet focuses on foods that our Paleolithic ancestors used to eat over 10,000
years ago. These include fruits, vegetables, lean meats, seafood, nuts, seeds, and
healthy fats. The diet also excludes a number of different foods with the argument that
the human digestive system (and humans in general) have not properly adapted to these
foods. They include dairy, grains, processed foods, and legumes. The Paleo diet may
be effective for a number of different reasons. We discussed the macronutrient content
of the Paleo diet focusing more on protein and fat, rather than carbohydrates. The
Paleo diet may contain fewer calories and cause people to feel full faster, so people may
decrease their total intake of food (which in general is good for chronic degenerative
diseases). The Paleo diet is touted as having a higher vitamin and mineral composition. In
general the research supports this notion, but with a couple of exceptions. We identified
that when the Paleo diet had a lower quantity of a vitamin or mineral (for example less
calcium), it is often balanced by other factors that overall have a positive impact on
health. The removal of the potentially offending foods from the Paleo diet may also
help improve health. There is not much evidence supporting the use of the Paleo diet
for type 2 diabetes, or rather the research available is not powerful because of limited
participants and small sample sizes. However, the research available does indicate that
the Paleo diet is safe and likely quite effective in helping numerous outcome measures
both in diabetes and with regards to cardiovascular health.
References
1.
Klonoff, D.C. “The beneficial effects of a paleolithic diet on type 2 diabetes and other risk factors for cardiovascular disease”. Journal of Diabetes
Science and Technology Vol. 3, No. 6 (2009): 1229–1232.
2.
Cordain, L. “The nutritional characteristics of a contemporary diet based upon paleolithic food groups”. Journal of the American Nutraceutical
Association Vol. 5, No. 3 (2002): 15–24.
3.
Jonsson, T., et al. “Beneficial effects of a Paleolithic diet on cardiovascular risk factors in type 2 diabetes: a randomized cross-over pilot study”.
Cardiovascular Diabetology Vol. 8, No. 35 (2009): 1–14.
4.
Lindeberg, S., et al. “A Paleolithic diet improves glucose tolerance more than a Mediterranean-like diet in individuals with ischaemic heart
disease”. Diabetologia Vol. 50, No. 9 (2007): 1795–1807.