As I mentioned in a previous post, our family has been on the paleolithic diet since the middle of 2008. There I described the diet - of modern equivalents to what we were evolutionarily adapting to eating during the paleolithic, basically fresh meat, fruit, and vegetables - and the reasons we switched to that diet. For me, those reasons really boiled down to, "it should be healthier because it's what we're adapted to".
I was really only hoping for subtle long term health benefits in future decades, and I was pleasantly surprised at seeing short term benefits as well. In my previous post, I mentioned the disappearance of painful gas, an improvement in mental concentration, and cessation of creeping weight gain. There have been a few other noticeable improvements since - nothing earth shattering, but still interesting.
Two that I noticed early on were in my skin and eyesight. My skin had started to show wrinkles a few years earlier, which I didn't really mind; I was thus more bemused than anything else to see those wrinkles decrease to perhaps half of what they had been. My eyesight also improved. I had been starting to get farsighted - presbyopia, which is unfortunately not mutually exclusive with nearsightedness - to the point where I was often taking off my glasses when reading normal text. Like the wrinkles, the farsightedness has not been completely eliminated, but I am back to the point where it's a minor annoyance that affects me only when I have to deal with very small print.
I know, that sounds like the ravings of a diet fanatic. I thought I was imagining the effects myself at first. At this point, though, the effects are sufficiently significant that I can't ignore them. In addition, I think I've figured out why they happened.
Both skin wrinkles and farsightedness, despite their apparent unrelatedness, are caused by similar effects: loss of protein elasticity, in one case in the skin, and in the other case in the lens of the eye. In the skin, it's known what causes this effect: crosslinking of the proteins through glycation, where sugar molecules basically form bridges between protein chains. In the lens, it's less well known what the causes are, but glycation may still be one of them.
The paleo diet is a low carbohydrate diet - fruit are only about 10% sugar or sugar chains, compared to nearly 100% for grain based foods - so one doesn't get much in the way of blood sugar spikes. Lower circulating blood sugar levels should reduce glycation - and the early stages of glycation are reversible. I think it's that reversal that I saw in my skin and eyes.
Another benefit was with respect to arthritis. I had been starting to become a little bit arthritic in a few joints, such as the last joint of my index finger. Someone on a paleo diet discussion site pointed me to the Arthritis Nightshades Research Foundation. It looks a bit like a quack site, but nightshades - tomatoes, peppers, and potatoes - are questionably paleo anyway, so I tried eliminating them for a couple weeks. The arthritis disappeared. It comes back, temporarily, if I have a substantial tomato based meal, so I'm convinced.
I've also noticed that my hemorrhoids, which would recur for a week or two every few months, have not recurred at all since I started the paleo diet. I don't have a good explanation for this one. My best guess is that I suffered from a low level of gut inflammation from my previous neolithic diet, but that's just a guess.
Finally, before the paleo diet, I'd wake up tired and aching along my spine - and in other places, if I didn't sleep in just the right position. That doesn't happen any more. Waking up fresh rather than exhausted is probably the biggest improvement for me - well, comparable to the constant painful gas going away - but I don't have an explanation for why it happened.
Now, these improvements may seem to be entirely unrelated to each other - just weird advantages claimed by a diet fanatic. They do, however, have one thing in common: evolution should have selected against the maladies that disappeared. I think the correct interpretation of what happened is that a modern diet contains many different foods to which we're not fully adapted, and those foods cause a variety of problems for us. Dropping modern foods - by which I mean anything we didn't eat before perhaps 50,000 years ago - and reverting to paleolithic foods fixes all these problems. Viewed from that evolutionary perspective, the improvements look more sensible, even inevitable.
There are a couple of downsides to the paleo diet. The biggest one is that cheating on the diet can have severe consequences. On a couple occasions, having significant amounts of refined carbohydrate seemed to cause me to catch a cold or flu. That's likely because when the carbohydrate break down to glucose it reduces immune effectiveness by displacing ascorbic acid in white blood cells, inhibiting phagocytosis. Eating too much candy really can make you sick! On a modern diet, that's compensated for the constantly elevated level of the immune system due to inflammatory foods, but the paleo diet doesn't include those foods. Evolution can't protect against such effects, since we weren't able to cheat with modern foods back during the paleolithic.
The other downside is that our choices are more limited when eating out, since it can be difficult to find paleolithic meals at many restaurants. However, given our normal fare consists mostly of delicious roasts, fish, and steaks all the time, and since our favorite restaurant closed down a few years ago, that's not as big a disadvantage as it might seem.