Last updated: 18-Jan-18
By Diana Green
The Paleo diet has received a great deal of attention recently, with many, including Dean Karnazes, using it as a good nutrition plan for runners. On the assumption that our physiology should be optimised to the diet of our evolutionary past, athletes who follow the Paleo diet believe that it can enhance performance and aid recovery.
Diana Green, nutritionist, chef and keen runner, sets out the arguments for and against and cuts through the hype to give you considered advice, based on science not food fashion, on the paleo diet for runners.
What is the Paleo Diet?
The Paleo diet was first promoted by gastroenterologist, Dr Walter L Voegtlin. His book ‘The Stone Age Diet’, was published in 1975. The Paleolithic diet also known as the caveman diet or stone-age diet is based on foods presumed to have been available to Paleolithic man. The Paleolithic period extended from the earliest known use of stone tools 2.6 million years ago until the end of the Ice Age 10,000 years ago.
Although the interpretation varies, the diet typically includes vegetables, fruits, nuts, roots, fish and meat while excluding dairy products, grains, sugars, legumes, processed oils, salt, alcohol and coffee.
The diet is based not just on avoiding modern diets, but also foods that humans began to eat after the Neolithic Revolution, when the hunter gatherer lifestyle was replaced by agriculture and settlement.
THE CASE FOR & AGAINST THE PALEO DIET
Our physiology has been naturally selected over the course of millions of years and in spite of recent changes in our lifestyle and diet, our genetics have changed very little from those of our ancestors, the Paleolithic hunter-gatherers.
There has not been sufficient time for natural selection to make genetic adaptations to modern diets. To optimise our health and physical fittness we should follow a diet as it was when man was interacting naturally with the environment.
Humans have evolved to be flexible eaters and can live healthily on a wide variety of diets. Lactose tolerance is an example of how some humans have adapted to the introduction of dairy into their diet.
Although the Neolithic diet, which introduced grains, dairy and legumes, was considered to be less varied and balanced than that of the hunter-gatherers, the fact that populations expanded indicates nutritional adaptability and evolutionary change in human digestive abilities.
The increase in chronic diseases and degenerative conditions is evidence of the mismatch between stone age genes and modern diets. It is proposed that during the Paleolithic period mankind was at its healthiest and physically fittest.
The harsh and dangerous environment, however, would have resulted in high infant mortality and death from accidents and infections explaining the low average life span of the hunter-gatherer.
The hunter gatherers died at an early age and thus didn’t live long enough to develop heart disease, cancer and other chronic illnesses, therefore it is debatable as to whether or not they were healthier or fitter than modern man.
FOODS OF THE HUNTER GATHERERS
Advocates of the Paleo diet believe that humans were genetically adapted to eating specifically those foods that were readily available to them in their local environments and that modern humans should follow a diet that is nutritionally closer to that of their Paleolithic ancestors.
It is impossible to know exactly what the Paleo diet consisted of. If it was high in wild meat it is likely that not only the muscle tissue would have been eaten but also the organs, bone marrow and brain. The nutritional profile of modern domesticated plants and animals would differ drastically from their Paleolithic ancestors.
Even trying to devise an ideal diet by studying contemporary hunter-gatherers is difficult because of the great disparities that exist due to climate and environment. For example, the animal-derived calorie percentage ranges from 25% for the Gwi Bushman of Southern Africa to 99% for the Alaskan Nunamiut.
HIGH FAT, LOW CARBOHYDRATE KETOGENIC DIET
The Paleo diet was thought to be high in fats from meat, fish, nuts & seeds while low in carbohydrates. The Paleolithic hunters would therefore have been efficient at utilising fat stores as a major source of sustaining energy while pursuing their prey.
When carbohydrate is in short supply Ketone bodies are produced in the liver from fatty acids and converted into a fuel source in the mitochondria. A ketogenic diet can result in improved glucose metabolism, reduced body weight and decreased levels of triglycerides and LDL cholesterol, thereby promoting good health.
It is also suggested that for the Paleolithic hunter to exhaust prey and outpace other scavengers, fast running speeds would have been required. Glucose from the consumption of a larger amount of carbohydrates than is thought to have made up their diet might have been needed for such high level aerobic activity. Long-term elevated levels of blood ketones would have likely compromised reproduction function (of which there is no evidence).
HIGH PROTEIN – GLUCONEOGENESIS
Gluconeogenesis is the synthesis of glucose from non-carbohydrate sources – amino acids (proteins), glycerol (lipids) and lactate. With the body’s ability to rely on gluconeogenesis and ketone bodies as a fuel, it is debated whether dietary carbohydrates are essential for human nutrition.
Previous studies have highlighted the shift from primarily plant-based to primarily meat-based Paleolithic diets as critical in the development of the brain through providing a dietary source of the omega 3 fatty acid DHA.
The diets of traditional Arctic populations are given as an example of successful high protein diets and high fat diets.
Recent evidence from genetics, archaeology, physiology, and nutrition has supported the theory that our Paleolithic ancestors did eat starchy plants, cooking them to improve the digestibility and palatability. Researchers argue that the addition of carbs was necessary to accommodate the increased metabolic demands of the growing brain and high glucose requirements of red blood cells and the developing fetus.
The Arctic populations probably ate more carbohydrates than is generally thought, obtained from eating the stomach contents of terrestrial prey animals and tundra plants. Also meat consumed raw immediately after slaughter will retain much of its muscle glycogen, providing another source of available carbohydrate.
The Arctic populations are also unique having enlarged livers with an increased capacity for gluconeogenesis, and have greater capacity for excreting urea to remove ammonia, a toxic byproduct of protein breakdown.
ACID ALKALINE BALANCE
Human life requires a tightly-controlled pH level in the blood of about 7.4 (slightly alkaline) to survive.The diet of our Paleolithic ancestors would have been net alkali due to the high consumption of fruits and vegetables and better matched to balancing pH levels than our modern diet.
The grains, dairy products and salty processed foods dominating our modern diet are acid producing, constantly challenging the bodies ability to maintain homeostasis. The body uses the alkaline salts sodium, potassium, calcium and magnesium held in the tissues to bind with, and neutralize, acids. The acids can then be eliminated from the body through the colon, kidneys, lungs and skin.
If there are inadequate reserves in the tissues, the body will pull these salts from the bones (calcium) and muscles (magnesium), potentially affecting bone health and causing muscle breakdown.
An alkaline diet can also result in an increase in intracellular magnesium, which is required for the function of many enzyme systems. Available magnesium, which is required to activate vitamin D, would also result in numerous added benefits.
The Counter Argument
High dietary protein of the Paleolithic diet from meats, fish, nuts and seeds is acid forming and could decrease bone density and result in muscle wasting if not buffered by ingestion of adequate fruits and vegetables.
Our Paleolithic ancestors consumed wild meats, fish, insects, eggs, wild fruits, berries, vegetables and nuts all foraged from their natural environment. A diet high in fibre, lean animal protein, essential fats, vitamins, minerals and phytonutrients.
It was not only the abundance of fresh food that was health promoting but also the variety providing the body with a wide range of nutrients working synergistically to support growth, metabolism and cellular repair.
The Counter Argument
Our modern busy lifestyle means limited time available for food preparation usually resulting in a less varied diet for the sake of convenience. Many fruits and vegetables have also traveled far from field to plate reducing levels of beneficial nutrients.
THE PALEO DIET FOR RUNNERS
Knowledge of the types and proportions of animal and plant foods consumed by our Paleolithic ancestors is incomplete. There is insufficient data to identify the exact composition of a genetically-determined optimal diet. However, adoption of an interpretation of the diet of our Paleolithic ancestors based on plant foods and lean protein has been shown to benefit athletes.
THE PALEO ADVANTAGE FOR RUNNERS
The contribution of fat to total energy needs can play a major role in fueling long distance runs. When the body burns fat, the body’s limited stores of carbohydrate are spared, delaying fatigue caused by glycogen depletion. Training improves the body’s ability to burn fat by increasing the rate of oxygen rich blood flow to the muscles and elevating levels of fat burning enzymes.
Branched Chain Amino Acids
Lean meats and fish are high in the branched chain amino acids, valine, leucine and isoleucine. Branched chain amino acids (BCAA) are potent stimulants for the building and repair of muscle. By consuming a combination of animal proteins together with sufficient carbohydrate following training the athlete can reverse the natural breakdown of muscle and thereby reduce recovery time.
The Paleo diet rich in alkaline-forming fruit and vegetables can prevent muscle protein breakdown which can be the result on a net-acid producing diet – high in grains, dairy products and processed foods.
Essential Fats, Vitamins & Minerals
Cutting out processed foods and replacing them with a diet of fruit, vegetables and fresh meat rich in antioxidant nutrients will support a healthy immune system allowing consistent training and improved performance. The anti-inflammatory effects of the essential fats omega 3 and 6 found in oily fish nuts and seeds will help to decrease recovery time.
The Paleo diet will naturally have a low glycaemic load, balancing blood sugar and energy levels vital for endurance running. Cutting out refined grains and sugars from the diet, often used as a quick and easy daily fuel, will force one to consider more carefully energy requirements and the role of proteins and fats in the diet.
THE PALEO MODIFICATION
High glycemic Carbohydrates
Most experts agree that the Paleo diet in its most strict interpretation is too low in carbohydrates to fuel hard training. Paleo slow-releasing carbohydrates, from fruits and root vegetables, can adequately fuel you up before a run, but foods with a higher glycemic index are needed efficiently to replace glycogen mid- and postrun.
The wild red meat of our Paleolithic ancestors would have been higher in essential fats and lower in saturated fat than modern meats. Although red meat is a good source of iron, zinc and B vitamins, some studies have linked high consumption with increased risk of cancer and heart disease. It might therefore be advisable to chose more fish and poultry as healthy sources of protein.
Whether or not eliminating grains, dairy and beans will improve your health and performance is debatable. However the benefits of focusing on more natural foods and cutting back on refined sugars, excessive alcohol and additive-laden meals will definitely be noticeable. Also, expanding the variety of different plant foods in your diet rather than relying on a limited number of foods will give you a wide range of protective phytonutrients needed to maintain good health.