Coming from another low-carb forum and writing from Europe so forgive my english.
What I wanted to say is that I suggest anyone to read a great paleodiet book called "The Garden of Eating" by By Albert and Rachel Matesz.
The book is very political uncorrect providing evidences that saturate fats are harmless and essential for human body and that dietary cholesterol is not dangerous.
There was also an Ebook by researcher Dec Twohig which unfortunately is not online anymore.
While Matesz book provides the evidence for an omnivorous produce based diet Twohig DNA reseachers proved what others including the reseacher Diamond had already said: the diet of man in the paleolithic was not meat based by any extent, man was a fisher and scavenger and the gatherer foods like young leaves, fruits and nuts far from being a supplement to a meat centered diet were the staple of the diet.
And yes paleolithic man had access to a greater variety of fruits and nuts we have today, most of the zones where paleo-sites have been found not only are mild climate nowadays but were warmer in the past.
The Bushmen tribe in Africa comprised of healthy and fit individuals consume a diet which is 60% nuts. The bone density of paleolithic humans can only be achieved consuming an high amount of calcium while preventing the body from pulling calcium from the bone. Since they didn't abolutely consumed any milk at all such high intake of calcium could have only been provided by high amounts of dark green leafy vegetables.
But an high intake of calcium would have been useless if they didn't maintain a positive net-alkaline balance. This balance is achieved when the produce part of the diet is twice the meat part. This is less food than one may imagine, the consumption of 15 ounces of meat would requires 30 ounces of plantfood to maintain a net alkaline balance, and 1 medium banana is 9 ounces.
A net acid overload is more dangerous and unhealthy than many people could think. It can be considered the source of many degenerative and inflamatory diseases as it slowly erodes the tissues and force the body to pull calcium from the bone and the teeth.
Few have attempted to claim that humans are natural carnivorous and the reason is clear: human have nothing of the unique characteristics of obligate carnivorous animals. We don't even have the unique characteristics of hearbivorous animals. We have both characteristics that prove our need or ability to consume animal foods and characteristics our need or ability to consume plant foods.
If one want to be biased he/she could point out our meat eating characteristics, ignoring our plant eating characteristics and claim that we're carnivorous.
And of course one could point out our plant eating characteristics, ignoring our meat eating characteristics and claim that we're herbivorous.
Since we share characteristics from both realms we're more able to suit to different diets, we're less obliged to follow one diet and can divert from long period of times. Even the innuits could genetically adapt to an hard environment their body providing them with a unique fat distribution that is optimal for saving body heat and higher metabolism. In spite of this incomplete adapatation Innuits still suffer from liver enlargement (yes, I'm talking about the traditional ones) and have still high rate of osteoporosis whose rate is lower among Innuits that abandoned their traditional diets in favour of alcohol and modern foods. Stefansoon himself said that a 55 years old Inuit person looked like what an average 80 years old looks in america. The very high rate of aging which also explains the low bone density and fractures is caused by a steady net acid overload. Althought they consume on average 1900 mg of calcium daily that's not enough to counteract their acidosis. And keep in mind that traditional Innuits consume plants as they eat daily the stomach content of Caribou which contains the partly digested grass consumed by the animal.
If Innuits are proven to be physiologically and genetically adpated generation after generation to a peculiar lifestyle and diet few other hunter-gatherer societies who are known to consume a very high intake of animal foods either don't eschew from fruits and vegetables totally or consume non-pasteurized milk from escluvely grass fed animals. It isn't only an high sugar food but also high in net alkaline producing electrolites. Of course milk is not a paleo food. Even grains are more paleo than milk actually, since wild grains have been found on the ashes of paleolithic sites.
As for Vitamin C: preventing scurvy is the least important factor vitamin C is needed for. I would suggest everyone to read the research of Linus Pauling about vitamin C, which are anything but politically correct and are not motivated by economic gains. Vitamin C is a vital element in all animals, that's why all animals who are alive including primates like us are consuming or synthezing vitamin C. Innuits get their vitamin C from the subcutaneous fat of Caribou which is particularly high in ascorbic acid. All primates consume Vitamin C and carnivorous produce their own. The difference between us and other higher primates are not that big, we're both suited to a diet of both plant and animal foods and we have a similar anatomy. Nothing exists in humans that would suggest we overcame the need for Vitamin C, neither we're supposed to get it from food and neither we're supposed to synthezise our own. Nothing makes us that alien to differentiate that much us from other animals.
Either we're carnivorous and can synthesize our Vitamin C or either we're omnivorous, or gathere scavenger opportunistic primates who are both suited to animal food consumption and meat consumption, and we are natural eater of food rich in vitamin C so much that producing our own plus the one we get from the food we naturally eat would intoxicate us.
There's a reason why we see so many shades of colors and carnivorous don't. We need them to detect fresh fruits.
If there must be any debate whether eating only meat is cultural conditioning or eating fruits and vegetables is cultural conditioning the first one would result more close to the truth. We have a sweet tooth that carnivorous animals don't have and have a huge quantity of taste buds for sweet flavours, our milk is way more sweet and contains more sugar other mammals milk and we see colors whose only purpose for us as animals and primate is to detect fruits.
As for insulin: it's not true that without plant foods we would not produce insulin and would solve the problem of diabete.
In fact nothing could be farther from the truth: the author of the glycemic index himself found out that the GI is not a good predictor of insulin output. That's why he coined another index specific for insulin which is the Insulin Score. The insulin score unlike the GI tells how much insulin is produced after a certain food is ingested. I would advise anyone to take a look at the IS chart. Beef causes a greater insulin production than white refined pasta! Or in other words the body is forced to produce more insulin when beef in eaten than when white cooked refined high-carb pasta is eaten.
So much for the only meat = no insulin theory
An interesting aspect I find and that proves the body need for homeostasis is that if we look at the whole picture of our anatomy, or comparative anatomy evidences, and we see that we lack certain characteristic that all carnivorous animals must have to be such and we lack certain characteristics that all herbivorous animals must have to be such we see that our natural dietary guidelines are written within our physiology, anatomy and instinct and that it is more likely that kind of diet that paleolithic humans consumed according to modern evidences on analysis of fossilized feaces and that the majority of modern hunter-gatherer societies are consuming.
Carnivorous animals can't be harmed by a lack of alkaline net producing foods because of their physiology, we share certain traits of their physiology but not this one. Health and longevity in humans and other higher non-carnivorous primates depends on maintaining a net alkaline balance and avoiding a net acid overload. No wonder that many unorthodox modern researches on diseases are based on electrolites. According to Dr Beddoe for example all diseases in the human body are triggered by a lack of electrolites by a disequilibrium of minerals. The most important of which is a calcium balance, when enough calcium is consumed and no calcium is pulled from the bones and the teeth. When we think Paleo there is only a thing that meets these criteria: dark green leafy vegetables.
We can consider the electrolites balance and net alkaline terrain the most important factor to humans health. Such condition is met when plant food is twice the amount of animal food. That means fruits, nuts and dark green leafy vegetables. No wonder we have a sweet tooth, we see colors to detect fruits and can grasp, open and break things with our higher primate hands. No wonder we don't synthesize our own Vitamin C and no wonder human stomach is no more than 22% of the whole volume of the digestive tract with 70% located in the small intestine while real carnivorous stomach is 70% of the whole volume of the digestive tract with less than 30% located in the small intestine no wonder our appendix produce starch-splitting enzimes while carnivorous are born with no appendix at all and that our body, like other primates and no wonder we can synthesize niacin while carnivorous animals need to get it from meat and we can synthesize vitamin A and can toxify our body consuming excessive vitamin A while carnivorous animals need to get it from animal food and suffer no ill consequences when they consume huge amount of this vitamins.
Where the natural instictive balance I'm talking about?
The most significant difference between humans and carnivorous is that we need a net alkaline balance and are severely harmed by acidic averload, so much that new researches are focused on minerals unbalance as the condition that triggers all diseases especially cancer.
This in turn makes our body suited for the consumption of plant foods and provides us with features that only herbivorous animals and with characteristics that are meant to help us find and consume plant foods (ability to see colors, ability to grasp, break, and pick up with our hands, ability to taste sweet and have the sweetest mother milk)
This in turn makes us ill equipped to massive hunting and more suited for fishing and preying small mammals. Oh ... and insenct, insect meat is one of the most nutricious and it's very likely that most animal food consumed by paleolithic humans was insects.
This translates in animal food eating as the smallest part of the diet and gathering fruits, nuts and leaves as the larger part of the diet. The Bushmen who consumed 140 grams of protein daily and almost 2200 calories each and hunt very rarely and have a diet which is more than 80% plant food work 12 hours weekly on average. Yes, gathering enough food for everyone takes them 12 hours weekly which is less time spent working/surviving than any modern worker spend. The rest is free time. It has been estimated that if they increased their hunting the amount of work time would increase likewise. As humans they're best equipped to gathering and that's why it is so natural for them that even if they're been exiled in one of the least rich zone of the planet, they can get all their need to survive in a small amount of time, leaving the rest of their life to be enjoyed since they're healthy and fit.
What I mean by this is that if we remember our need to maintain a net alkaline balance by consuming twice the amount of animal food as plant food, which is what would naturally happen in the natural human environment having humans characteristics specific to plant consumption and to plant food attraction and being therefore best equipped to gathering, then aeverything else would sort out by itself.
You can try this with whatever realiable nutritional analisys software: make sure that daily the amount of plant food is twice the amount of animal food and see the result. You will see that not only an optimal amount of minerals, vitamins and phytonutrients is consumed but lot of health condition that are often seeked through complex calculus and diets are effortlessly and automatically met. The calcium intake will be optimal, the carbohydrate intake will be low and the protein intake will be high, vitamin C and vitamin A intake will be high but not toxic, sodium intake will be low and potassium intake will be high (another condition necessary for good health, health problems begins when we retain more potassium and excrete more sodium, in other words when sodium intake is high and potassium intake is low) and will achieve a net alkaline balance at the end of the day.
We shouldn't forget either the importance of phytonutrients. They have been considered non-vital elements, but this is going to change. Phytonutrients found only in plant foods not only are known to prevent the degenerative effects of free radicals and oxydization (which can't be prevented by consuming meat alone) but they also appear to be fundamental in helping the body completing several metabolic and physiological processes.
If we make sure to maintain a net alkaline balance by consuming twice the weight of meat and fish as fruits and veggies all the need of the body sort themselves automatically and all the criteria to maintain an healthy human body are met and in nature our instinct, physiology and anatomy would oblige us to maintain this balance by attracting ourselves to colored and sweeth foods, by equipping us with features specific to gathering while ill equipping us with features specific to big hunting.
My two cents