Paleo diet

Paleo diet differs a great deal from the mainstream dietary advice you are used to hearing.  However rather than being a fad diet, this is based on the food we were designed to eat, a result of over a million years of evolution moulding our genes.  

This type of diet I believe represents a set of fundamental dietary principles from which you can optimise your health, and help prevent so many of the common modern days diseases, that are rarely present in those humans still consuming an ancient diet.  

What is the paleo diet?

This is an ancient diet that stretches over the course of our evolution.  Humans first appeared about 1.7 millions year ago, and since that time the environment and the foods consumed have shaped our genetics.

Various researchers have studied potential dietary habits over this time period, humans are versatile and have managed to adapt well to different types of diet.  However even though humans are adaptable, adaptation to rapid dietary shifts takes time. 

Massive and rather quick dietary changes occurred roughly 10000 years ago with the advent of agriculture – farming.  New foods quickly became the majority components of people’s diets.  These foods included: Grains, beans, potatoes and dairy.  It needs to be emphasized that these foods hardly figured in the eating habits of human’s pre 10000 years ago, and today they make up the majority of our diets all over the world.  Have human beings adapted to these foods? Well unfortunately not, this time period is only 500 human generations.  There is evidence of some adaptation among populations who have consumed these foods for a longer period over the last 10000 years.  However the experts say that this is not nearly enough time for our genetics to have adjusted enough to allow consumption of these foods without health consequences.

The problem foods introduced in the last 10000 years

Grains and beans contain compounds called enzyme inhibitors, phytates and lectins. These food components may well have a negative impact on human health.  Cooking only partially reduces the levels of these compounds in food.

· Enzyme inhibitors are capable of physically inhibiting the breakdown of the food that contains them, and may interfere with the correct functioning of the pancreas, which releases digestive enzymes that digest our foods.  Even more worryingly they have been potentially linked to an increase in the risk of pancreatic cancer.  Some of these enzyme inhibitors have been linked to allergy.

· Phytates bind to minerals, reducing their absorption.  So the minerals found in grains and beans cannot be easily accessed.  Plus grains in particular now form such a large proportion of our diets that they are relied upon to supply necessary minerals, which is not good news if they are bound to phytate.  Grains have been implicated in Iron deficiency anaemia and bone disorders related to calcium.

· Lectins can bind to many tissues and organs in the body, where they can intefer with normal metabolism and structure.  The lectins from wheat and some beans can cause damage to the intestinal brush border, which is essential for absorption of nutrients from our food.  This may well impact on nutritional status, leading to deficiencies of vitamins, minerals and amino acids.  Research is indicating that lectins may also interfere with proper insulin and leptin functioning.  Insulin is needed for proper blood sugar control, and leptin has important functions in the regulation of appetite, disturbances in these has been linked to diabetes, obesity and heart disease.  Added to all these, lectins have been linked to allergy.

Dairy is high in lactose, requiring the enzyme lactase to break it down; unfortunately this enzyme reduces dramatically a few years after birth.  Its high in hard to digest proteins such as casein, this may be a causative factor behind the status dairy has a common allergen or sensitivity.  

Potatoes contain toxins called glycoalkaloids, which are not even destroyed by high temperature cooking.  Green potatoes are particularly high in these compounds so do not eat them!

So what should we be eating according to the paleo diet

This is far from an exhaustive list, but it gives a rough overview:

· Proteins:  meat (includes organ meats), fish, seafood, eggs, and insects (not to everyone’s taste!)

· Carbohydrates: Root vegetables (carrots, turnips, parsnips and squash e.g. pumpkin)

· Fibre, micronutrients (vitamins and minerals), phytonutrients (plant based compounds that benefit health e.g. the red pigment lycopene in tomatoes):  Provided by Fruits and vegetables (good examples: Berries and apples, cruciferous vegetables e.g. broccoli, cabbage, cauliflower and Kale etc). 

· Fats and oils: Nuts and seeds.  Plus fish and seafood already mentioned 

Selected study’s supporting the benefits of a paleo diet

People living on a paleo style hunter gatherer diet on the island of Kitava that is part of Papua New Guinea, had remarkably good health.  Data from a number of these individuals aged 20-96 showed they had good heart health, good blood pressure and no obesity.  There diet was based around tubers, fish, fruit and coconut, and no western foods.  Amazingly the majority of these people smoked.  Indicating that smoking may need other factors to influence heart disease outcomes.

Diabetes type 2 sufferers placed on a paleo diet got better results than when placed on a standard diabetic diet.  They demonstrated better blood sugar control, improved measures of heart health, and greater weight loss.

A scientific review in 1991 of Australian aborigines showed that a move away from their hunter-gatherer diet onto a western style diet high in highly refined carbohydrates resulted in unhealthy metabolic changes.  These related to insulin resistance and its influence on increases in obesity, diabetes and heart disease among these aborigines.   

Frassetto (2009) et al tested a paleo diet on 9 non-obese outpatients.  The Paleo diet in this study was based around meat, veg, fruit and nuts; no grains, legumes or dairy were allowed.  The results showed that the patients in this study had a significant lowering of blood pressure, improved glucose tolerance, lower insulin levels and better sensitivity to this hormone, plus improved lipid profiles. 

References

Frassetto LA, Schloetter M, Mietus-Synder M, Morris RC Jr, Sebastian A (2009).  Metabolic and physiologic improvements from consuming a paleolithic, hunter-gatherer type diet.  Eur J Clin Nutr. 2009 Aug;63(8):947-55.

Jönsson T, Granfeldt Y, Ahrén B, Branell UC, Pålsson G, Hansson A, Söderström M, Lindeberg S (2009).  Beneficial effects of a Paleolithic diet on cardiovascular risk factors in type 2 diabetes: a randomized cross-over pilot study.  Cardiovasc Diabetol. 2009 Jul 16;8:35.

Lindeberg S, Nilsson-Ehle P, Terént A, Vessby B, Scherstén B (1994).  Cardiovascular risk factors in a Melanesian population apparently free from stroke and ischaemic heart disease: the Kitava study.  Intern Med. 1994 Sep;236(3):331-40. 

O’Dea K. (1991).  Westernisation, insulin resistance and diabetes in Australian aborigines.  Med J Aust. 1991 Aug 19;155(4):258-64.

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