The Paleolithic Diet

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 health-conscious. 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 short-term 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.