“Paleolithic Diet Clinical Trials (parts 1-4),” Stephen Guyenet, PhD, October 4, 2008, http://wholehealthsource.blogspot.com/2008/10/paleolithic-diet-clinical-trials.html

Johnw later wrote: “Of course absence of evidence isn’t evidence of absence.”

Glad we have that established. So we therefore cannot rule out the possibility that a Paleo-type diet might be beneficial, even extraordinarily beneficial based solely on the idea that there’s no “good evidence” that modern foods are harming people, or you specifically. We can also consider your assumption about a beneficial anecdote being due to a “placebo effect” as unsupported rhetoric, based on the same above logical fallacy. The anecdote doesn’t prove anything, but neither can we just assume it to be due to a “placebo effect” or any other presumed effect.

Re: whether there’s “good evidence” that modern foods are harming you–are you referring to scientific studies and people in general here or are you limiting it to your personal experience? What, if anything, would you consider as evidence that modern foods might be harming people or you? Is there any “good evidence” that trying a Paleo diet for a week would harm someone/you? Have you ever tried a Paleo approach for any length of time?

You are already in tune with one aspect of Paleolithic nutrition here: “eating some oily fish is probably good for you….” Perhaps there are other aspects of Paleo nutrition that you would also deem reasonable, if you investigated it?

Johnw wrote: “I’m not even sure why people would eat modern farm animals? They seem to differ considerably from the meat which would have been available in Paleo times.”

Experts in the field actually argue that modern farm animals are generally less nutritious to eat than wild animals of the Stone Age were, so this seems to be yet another area where you agree with Paleo nutrition theory. You’re beginning to come across as a promoter of Paleo nutrition yourself. ;)

The Paleo diet doesn’t even seem that compelling theoretically, putting aside the relatively limited empirical evidence. If the idea is to get close to what was eaten in Paleo times, I’m not even sure why people would eat modern farm animals? They seem to differ considerably from the meat which would have been available in Paleo times.

As Carl Sagan famously pointed out in The Demon-Haunted World: Science as a Candle in the Dark (p. 213), “absence of evidence is not evidence of absence” (see also http://en.wikipedia.org/wiki/Argument_from_ignorance). Besides, there is no shortage of evidence that Neolithic foods like processed sugars, grains and legumes can cause harm in humans and lead to what Dr. Stanislas Tanchou termed the “diseases of civilization” way back in 1843. Quite the contrary, there is now a mountain of evidence that can no longer be ignored and is sparking a scientific revolution. The evidence has inspired a new field of scientific inquiry called Paleolithic (or evolutionary) nutrition and has greatly developed the field of evolutionary medicine.

Plus, most people who try a Paleolithic-type diet DO have illnesses that have dietary links as evidenced by countless studies and observations of hunter-gatherer peoples. People who believe they are in optimal health are less likely to vary from the Standard American Diet because they have less reason to do so. However, I have seen even such people report that they tried a Paleo approach to improve their sports performance or give them added energy and they reported that some aspects of their health and functioning that they thought were “normal” improved. More and more scientists now no longer regard the average health parameters of Americans or Westerners as “normal”, but instead refer to information gathered from observations and studies of hunter-gatherer peoples as a better guide to what is “normal” in a more natural setting that more closely resembles what Dr. Kurt G. Harris terms “the evolutionary metabolic milieu (EM2)”.

From what I have seen, most people who actually try a Paleo-type diet find it to be a blessing, rather than a curse and this is why it is growing so rapidly in popularity. There are potential pitfulls to be aware of, as with any therapeutic approach, so people who decide to give it a try should educate themselves on them via good sources like the afore-mentioned Dr. Harris, Loren Cordain Phd, S. Boyd Eaton MD, Staffan Lindeberg MD PhD, Michael Eades MD, Stephan Guyenet PhD and many others. Opinions differ on some subjects in the field, so be sure to check out multiple sources.

The fact that a small number of people on this blog report health improvements after changing their diet is nice, but not exactly generalisable. I’d also note that a lot of the reported benefits could come from aspects of the paleo diet like cutting out some common allergens/causes of food intolerance and cutting out most junk food.

I’m in good health and enjoy eating well, so have no particular desire to change my diet. If I were to do so, there are a number with a better evidence (and which look more appealing to me!) that I’d try first.