Saturday, October 4, 2008

Paleolithic Diet Clinical Trials

If Dr. Ancel Keys (of diet-heart hypothesis fame) had been a proponent of "paleolithic nutrition", we would have numerous large intervention trials by now either confirming or denying its ability to prevent health problems. In this alternate reality, public health would probably be a lot better than it is today. Sadly, we have to settle for our current reality where the paleolithic diet has only been evaluated in two small trials, and medical research spends its (our) money repeatedly conducting failed attempts to link saturated fat to every ill you can think of. But let's at least take a look at what we have.

Both trials were conducted in Sweden. In the first one, lead by Dr. Per Wändell, 14 healthy participants (5 men, 9 women) completed a 3-week dietary intervention in which they were counseled to eat a "paleolithic diet". Calories were not restricted, only food categories were. Participants were told to eat as much as they wanted of fruit, vegetables, fish, lean meats, nuts, flax and canola oil, coffe and tea (without dairy). They were allowed restricted quantities of dried fruit, potatoes (2 medium/day) salted meat and fish, fat meat and honey. They were told not to eat dairy, grain products, canned food, sugar and salt.

After three weeks, the participants had:
  • Decreased their caloric intake from 2,478 to 1,584 kcal
  • Increased their percentage protein and fat, while decreasing carbohydrate
  • Decreased saturated fat, increased dietary cholesterol, decreased sodium intake, increased potassium
  • Lost 2.3 kg (5 lb)
  • Decreased waist circumference, blood pressure and PAI-1
Not bad for a 3-week intervention on healthy subjects. This study suffered from some serious problems, however. #1 is the lack of a control group as a means for comparison. Ouch. #2 is the small study size and resulting lack of statistical power. I consider this one encouraging but by no means conclusive.

The second study was conducted by the author of the Kitava study, Dr. Staffan Lindeberg. The study design was very interesting. He randomly assigned 29 men with ischemic heart disease, plus type II diabetes or glucose intolerance, to either a "Mediterranean diet" or a "paleolithic diet". Neither diet was calorie-restricted. Here's the beauty of the study design: the Mediterranean diet was the control for the paleo diet. The reason that's so great is it completely eliminates the placebo effect. Both groups were told they were being assigned to a healthy diet to try to improve their health. Each group was educated on the health benefits of their diet but not the other one. It would have been nice to see a regular non-intervention control group as well, but this design was adequate to see some differences.

Participants eating the Mediterranean diet were counseled to focus on whole grains, low-fat dairy, potatoes, legumes, vegetables, fruit, fatty fish and vegetable oils rich in monounsaturated fats and alpha-linolenic acid (omega-3). I'm going to go on a little tangent here. This is truly a bizarre concept of what people eat in the Mediterranean region. It's a fantasy invented in the US to justify the mainstream concept of a healthy diet. My father is French and I spent many summers with my family in southern France. They ate white bread, full-fat dairy at every meal, legumes with fatty pork, sausages and lamb chops. In fact, full-fat dairy wasn't fat enough sometimes. Many of the yogurts and cheeses we ate were made from milk with extra cream added. 

The paleolithic group was counseled to eat lean meat, fish, fruit, leafy and cruciferous vegetables, root vegetables (including moderate amounts of potatoes), eggs and nuts. They were told to avoid dairy, grain products, processed food, sugar and beer.

Both groups were bordering on obese at the beginning of the study. All participants had cardiovascular disease and moderate to severe glucose intolerance (i.e. type II diabetes). After 12 weeks, both groups improved on several parameters. That includes fat mass and waist circumference. But the paleolithic diet trumped the Mediterranean diet in many ways:
  • Greater fat loss in the the midsection and a trend toward greater weight loss
  • Greater voluntary reduction in caloric intake (total intake paleo= 1,344 kcal; Med= 1,795)
  • A remarkable improvement in glucose tolerance that did not occur significantly in the Mediterranean group
  • A decrease in fasting glucose
  • An increase in insulin sensitivity (HOMA-IR)
Overall, the paleolithic diet came out looking very good. But I haven't even gotten to the best part yet. At the beginning of the trial, 12 out of the 14 people in the paleo group had elevated fasting glucose. At the end, every single one had normal fasting glucose. In the Mediterranean group, 13 out of 15 began with elevated glucose and 8 out of 15 ended with it. This clearly shows that a paleolithic diet is an excellent way to restore glucose control to a person who still has beta cells in their pancreas.

This post is getting long, so I think I'll save the interpretation for the next post.


kat. said...

I've found your blog only recently, it's a great resource of knowledge. Thank you, great reading!

Methuselah said...

Stephan - one of the Swedish studies received interest from the British press - such as here:

Eat like a caveman for a healthy heart

...which was great news for me who had, until then, been seen as the office diet nutcase, but then acquired a slightly less crack-pot reputation.

Ancel Keys gets an unflattering starring role in this short but very amusing video, in case you haven't seen it:

Sometimes a video is worth a thousand words...

Pay Now Live Later

Unknown said...

Wonderful blog ! I always learn so much from it. Thanks a lot !

Alex said...

The veganistas have been tooting their horns over a study they did on the effect of a vegan diet on type 2 diabetes compared to the ADA diet. (LINK). I would love to see a comparison of paleo vs. vegan with respect to type 2 diabetes.

Dr. B G said...

Grandmere (and Jacque Pepin) was RIGHT!! Have you tried Brown Cow yogurt? Cream on top!

You ROCK -- thx and lookin forward to the interpretation, fat boy.

Anna said...

You are so right about the mythical Mediterranean diet. I've probably already shared this in a comment on another post, but while in Italy this summer for two weeks I had one week preparing my own foods while staying in a farmhouse apartment (agriturismo) and one week dining "out" while staying in hotels in cities.

During the farm week, we enjoyed lots of produce, rustic artisan salamis from the local pig farms, heavy cream, rich eggs from the farm, local olive oil, and local wine. My BG stayed as it usually does, in the mid-high normal range.

Later, during the hotel/dining out week, I decided to experiment with this "Med diet" but with attempts to reduce the carbs in the standard high carb meals - by only eating about half the wheat carbs that came with our meals, such as 1/2 the pasta course or removing the top slice of bread on a panini (and sometimes avoiding high carb meals entirely by dining at takeaway kebab places. Even so, my post-prandial BG ran quite high (150+) and at the end of the week, my FBG was running in the 110-120 daily. Keep in mind, I am glucose intolerant, a normal glucose system would probably have been able to handle all the carbs, but with a high insulin output. By the end of the week I was bloated (especially my legs) and very eager to get back to "my food". Though I do miss the great rustic salamis, cheeses, and the atmosphere.

Granted, this was restaurant food, not homecooked, so it's hard to say how people eat in their homes (but I did see more heavy local people with obvious signs of diabetes and weight-related health difficulties than I have in France or Spain). But I had to go to more effort to eat LC while dining out in Italy than I do at home in California and other parts of the US (I got strange looks if I paid for a salami & cheese plate for breakfast instead of accepting the free brioche pastry or croissant that came with my hotel ticket). A la carte entrees were great (osso buco, for instance, or ) but didn't come with veggies or salad unless they were ordered separately. Even with fixed price 4 or 5 course meals, the veggies were good, but skimpy portions, but the starches and sugars were always more than ample. But the food definitely wasn't vegetarian or low fat. Lots of animal fat.

Unknown said...

This post made me interested in trying out the Paleolithic Diet. A quick search for recipes brought up many interesting sites like this one:

Richard Nikoley said...

"I'm going to go on a little tangent here. This is truly a bizarre concept of what people eat in the Mediterranean region. It's a fantasy invented in the US. My father is French and I spent many summers with my family in southern France. They ate white bread, full-fat dairy at every meal, legumes only if they were smothered in fatty pork, sausages and lamb chops. In fact, full-fat dairy wasn't fat enough sometimes. Many of the yogurts and cheeses we ate were made from milk with extra cream added. Want to get a lecture from Grandmere? Try cutting the fat off your pork chop!"

You tell 'em, Stephan!

I lived in Toulon 90-92 and never ate so much, and with so much fat. I devoured cheese daily, my favorite being a very ripe Munster -- nothing like the stuff in the supermarkets folks -- chased with just a sip of red wine. Once I explained to my French friends about that ripe cheese red wine olfactory rush, my friend, Edouard Servan-Screiber (father a famous French politician and author), said to me: "Tu a tout compris!"

Indeed. Anyway, for those two years I returned to my college weight and upon returning to the US in '92, I immediately put on 10-15 pounds, in a matter of months.

I did eat a lot of baguettes, but not much other bad stuff.

Anonymous said...

Why do these studies tell people to eat lean meat? The results might be more impressive if people were told to eat fatty meats and avoid seeds, nuts, and PUFA vegetable oils. Most nuts and seeds are sky-high in PUFA with a very high n-6/n-3 ratio. For example, almonds are about 28:1. In comparison, grain-fed beef is 6:1.

Also, beef is very low in PUFAs, so it would make more sense to eat fat beef than nuts and seeds, which are usually quite high in PUFAs. Even a conventional chicken has less PUFAs and a better ratio than almonds. It seems most "nutrition experts" just ignore these facts and stick to the dogma of eating nuts, seeds, canola oil, and other garbage. We can live quite well without such "foods."

Stephan Guyenet said...


Welcome to the blog.


I love the caption under the photo in that article: "Meat, as long as it is lean, is beneficial". Riiight... The video was good as well.


Took a quick look at the vegan study. A few thoughts. They were comparing a vegan diet to the ADA diet, which is basically poison to a diabetic. The only reason they improved at all on the ADA diet is it was calorie-restricted. It's important to note that the low-fat vegan diet was not calorie-restricted.

The low-fat vegan diet was only modestly better than ADA in most measures, with the notable exception of waist circumference and HbA1c. Those are meaningful measures and they did improve significantly, so I give the diet credit for it.

On the LF vegan diet, participants greatly reduced fat of all types (including refined vegetable oil) and ate a diet that was based more on vegetables and whole foods and less on processed foods.

When you eat a low-fat diet, your liver makes saturated fat from the carbs. So what they were effectively doing is lowering the amount of polyunsaturated (mostly n-6) fat in their blood and tissues and replacing it with saturated fat. That's what the low-fatters like to overlook. If you don't have saturated animal fat in your diet, your liver makes it for you. Add to that the shift toward whole foods, and I think that explains the result.

You could do a better version of the same diet by cutting out n-6 rich vegetable oils, eating mostly saturated animal fats and meat and focusing on whole foods. That way you wouldn't be vitamin deficient either, as the paper admitted the participants were.

By the way, the Paleo diet in the study I wrote about improved glucose tolerance much more in 12 weeks than the vegan diet did in 22.

I would not like to see the state of the vegan dieters' teeth in 5 years.

Stephan Guyenet said...


I have tried Brown Cow. I do like the cream top, but what do I do with all the low-fat yogurt when I've eaten the cream off?


That sounds like the Mediterranean I know and love!


Go for it man! Just don't follow their advice to trim the fat off your meat.

Stephan Guyenet said...


"Tu as tout compris" is a hell of a compliment coming from a French guy!

Losing weight spontaneously is a common experience for Americans going to Europe.


I agree. It would have been a great way to attack the animal-fat-is-bad idea. The fact that Lindeberg had people eat lean meat when the Kitavans he studied were healthy eating coconut is a bit odd. Maybe he succumbed to political pressure. Or maybe he just wants to fry one fish at a time. Anyway, he's a clever guy so I bet he knows what's really going on.

Christopher Wiechert, CNC said...

Hi Stephan,

I really like your blog. We seem to have similar interests and beliefs.

Maybe we could consider recommending each others Blogs for more exposure.

If you like mine, let me know and we can refer each other.


Stephan Guyenet said...

Thanks Christopher, I checked out your sites. I see a lot of products, and I wouldn't want people to interpret a link as an endorsement of products. Thanks for the offer.

Dr. Curmudgeon Gee said...

thanks. i have bookmarked your site.

Dr. Curmudgeon Gee said...

sorry me again.
hit return too fast.

this got me thinking maybe i should switch to more "neo-paleolithic" diet.

i have a friend who has severe Rosacea.

almost everything breaks him out (cold air, hot air, wind, sun, soy, dairy, egg, cranberry, detergent, etc). well, it is easier to write down a list that does not break him out than not.

he has eliminated most common food stuff. he uses no salad dressing. his diet is low fat.
olives is probably the only fat he eats.

but i think he eats way too much bread.

despite his effort, his skin still breaks out & looks dry & pale to me. he also tires easily.

i wonder perhaps his diet of low fat, high carb is not helping & make him actually more sensitive?

Anna said...

chaliDr. Gee,

Check out Dr. Art Ayer's blog Cooling Inflammation for your friend. He's had some discussion about rosacea in posts and comments this past year.

Unknown said...

sth to consider: "our finding that the effect of Palaeolithic diet on glucose tolerance was independent of carbohydrate intake agrees with earlier studies which do not indicate a beneficial effect of carbohydrate restriction on glucose tolerance" (quote from the above study)

steb said...

The med. Diet *is* badly named. The health data as I am sure you are aware reflects the dietary habits of Crete and the Greek islands of some decades past. Looked at that way it does make sense.

Anonymous said...

Hey, I want you to know that I'm gonna use your research for a class, and well, also for myself cuz I'm thinking about doing the paleo diet. I love how you give an objective view of the trials, telling the good and the bad. Thank you for putting yourself out there and writing all these articles. They are so helpful!