Tuesday, May 30, 2006

Paleolithic Nutrition

One of my hobbies is Nutrition. Specifically Paleolithic nutrition.

The following is an extract from this website (slightly modified but true to the original intent).

The Paleolithic lasted from about 200 000 years ago to about 12000 years ago and was characterized by a hunting and gathering lifestyle for humans. During this time the food supply consisted almost exclusively of lean wild meats, fish, vegetables and fruits. These provided all the nutrients necessary for a very active lifestyle which involved far more exercise than our current way of living. Most importantly, because humans slowly adapted to this food supply over 2000000 years, the human genome was very compatible with all the various types of proteins, fats, carbohydrates and micro-nutrients found in these foods as well as various anti-nutrients that the plants and animals evolved to discourage their consumption. Thus it is very unlikely that the normal constituents of the food supply (excluding bacteria etc) would have caused any common biochemical malfunctions (i.e. disease) because those not compatible with such foods would have been naturally selected from the gene pool over the hundreds of thousands of years this food supply was consumed. Thus a diet of lean meat, fish, fruits and vegetables is now considered to represent a Paleolithic Diet and such a diet is basically that to which humans are genetically adapted.

With the rapid increase of the human population and a consequent dwindling of the standard foods, humans added new foods to their diet and these included grains (cultivated grass seed) and milk and meat products from domesticated animals. This change to a "grow your own" food supply of the agricultural revolution began about 12000 years ago in the Middle East and slowly spread westward, reaching Scandinavia and the British Isles about 6000 years ago.

There can be little doubt that in the early days of agriculture there must have been a broad spectrum of genetic incompatibilities with these new foods which contained a great variety of new, never-seen-before proteins as well as a much greater abundance of saturated fat than the Paleolithic foods. Such incompatibilities likely varied from very high to minor. Over the last 6000 years most of the genes which were very incompatible with the new foods were probably eliminated from the gene pool because of the biochemical failures (illnesses) which would have hit those with such genes before the age of reproduction. However those with lesser genetic incompatibilities and who were not affected by adverse reactions until after the age of reproduction (~18-30) have passed on such genes to our current generations. Thus most diseases associated with the new foods of dairy, grains and high saturated fat meats do not appear until later in life. These include heart disease, stroke, some cancers (prostate, breast, colon), many autoimmune diseases and a variety of chronic degenerative diseases (e.g. Parkinson’s, Alzheimer’s).

Notably a few of these diseases do occur in young people and include juvenile diabetes and arthritis. These "exceptions to the rule" most likely relate to the very recent practice of supplementing babies with the new foods (milk, wheat, soy) in the first year of life. Such a practice will identify another group of individuals with very specific food incompatibilities and who would have probably been fine for a long time if they had not had such an early exposure to the problematic foods.

In summary it only makes sense that if our genes are compatible with a supply of a great variety of chemicals from lean meat, fish, fruits and vegetables that any deviation from this is going to have a negative effect on part of the gene pool. Thus it is not surprising that epidemiological studies have shown that the more dairy, grains and high fat meats a society eats the greater the prevalence of all the various non-infectious, "lifestyle" diseases which were listed above. The fact that the people of the outposts of Newfoundland who eat mainly fish and home grown vegetables have one tenth the amount of multiple sclerosis than do genetically similar Albertans whose diet is dominated by red meats, grains and dairy products is a fine example of the relationship between disease prevalence and dietary habits. If your car was built for diesel, don’t be surprised if you have a variety of malfunctions when you start filling it with high octane petrol!

It can be instructive to compare a Paleolithic diet with a standard Western one to understand where the main problems lie.

PROTEIN-In a Paleolithic diet protein makes up about 25-30% of calories and is derived almost exclusively from lean meats and fish. This contrasts with the Western diet which consists of only 10-15% protein which is derived from high fat meats, grains, dairy products and legumes. Thus both the amount and sources vary greatly between the two dietary practices. Proteins play a major role in autoimmune disease and thus these new sources of proteins (dairy, grains, and legumes) which present the immune system with completely new protein fragments, are very problematic. Celiac disease is a fine example of an autoimmune disease driven by these novel proteins. These newly introduced proteins also play a major role in MS, rheumatoid arthritis, Crohn’s and type 1 diabetes.

CARBOHYDRATES-Paleolithic carbohydrates were gained mainly from fruits and vegetables which have a low glycemic index and which are associated with abundant micro-nutrients and fibre. They made up about 30-35% of the calorie intake. Once again the contrast with the Western diet is huge. In the Western diet carbohydrates are derived mainly from grains and refined sugars with fruits and vegetables being a minor supply. Furthermore carbohydrates make up 50-60% of calories, nearly twice that of the Paleolithic diet. These new sources of carbohydrates have a high glycemic index and this, in combination with the great increase in intake, significantly stresses the glucose-insulin system. This results, in a myriad of diseases most often led by type 2 diabetes. These new carbohydrates also have much less fibre and micro-nutrients which also has a very negative health effect.

FATS-Fats comprise about 35-40% of Paleolithic calories and consisted mainly of mono-saturated and poly-unsaturated fats. In the poly-unsaturated fats substantial amounts of omega 3 EFAs (Essential Fatty Acids)were included such that the omega 6/omega 3 ratio was less than 4. Saturated fats made up less than 40% of fat supply. The main sources of fat were lean wild animals, fish and nuts. Currently the Western diet contains similar amounts of fat (35-40%) but the amounts of the various types of fats are very different. The main fat types eaten today are saturated fat from fatty red meats and dairy products and trans fatty acids from margarines and processed baked goods. Omega 3 fats are almost non existent in the diet and the ratio of omega 6 to omega 3 EFAs exceeds 10. The overabundance of saturated fat, the introduction of an entirely new fat type (trans fatty acids) and a major deficiency in omega 3 EFA have resulted in major health problems including heart disease, stroke, hypertension, cancer and chronic degenerative diseases.

MICRONUTRIENTS-The Paleolithic diet contains many more micronutrients (vitamins, minerals, antioxidants) than does the Western diet. Vitamin consumption was about three times that of today in the Paleolithic due to the high intake of fruits and vegetables. Similarly intake of Zn (Zinc), Ca (Calcium), K (Potassium) and Fe (Iron) was much higher in the Paleolithic. Only sodium (Na) and perhaps iodine (I) are consumed much more today. Sodium consumption is about eight times that of the Paleolithic and this overabundance of Na along with a very low consumption of most minerals and vitamins not surprisingly has serious consequences for health.

In summary our current diet is very different from that consumed in the Paleolithic and with which humans are genetically compatible. These major differences are having a major effect on the health of the Western population and MS is just one of a broad spectrum of lifestyle diseases driven by our radically new dietary habits.

1 comment:

Catherine said...

The thought just occured to me to start a "Paleo Food lovers w/children" Meetup.com group I'll check into it.