Category Archives: Paleo Diet

Short-Term Effects of a Paleolithic Diet in Healthy Medical Students

Posted on February 20, 2012 | 6 comments

Stockholm Palace

Swedish investigators at Karolinska Institutet found diminished weight, body mass index, blood pressure, and waist circumference in 14 healthy medical students eating a paleo diet for three weeks.

Published in 2008, this seems to be one of the seminal scientific studies of the paleo diet in modern Europeans.

Their version of the paleo diet:

  • Allowed ad lib: All fresh or frozen fruits, berries and vegetables except legumes, canned tomatoes w/o additives, fresh or frozen unsalted fish and seafood, fresh or frozen unsalted lean meats and minced meat, unsalted nuts (except peanuts – a  legume), fresh squeezed lemon or lime juice (as dressing), flaxseed or rapeseed oil (as dressing), coffee and tea (w/o sugar, milk, honey, or cream), all salt-free spices.
  • Allowed but with major restrictions: dried fruit, salted seafood, fat meat, potatoes (two medium-sized per day), honey, cured meats
  • Prohibited: all milk and dairy products, all grain products (including corn and rice), all legumes, canned food except tomatoes, candy, ice cream, soft drinks, juices, syrups, alcohol, sugar, and salt

What Did They Find After Three Weeks?

  • Average weight dropped from 65.2 kg (144 lb) to 62.9 (139 lb) 
  • Average body mass index fell from 22.2 to 21.4
  • Average waist circumference decreased from 74.3 cm (29.25″) to 72.6 cm (28.58″) 
  • Average systolic blood pressure fell from 110 to 104 mmHg
  • plasminogen activator inhibitor-1 decreased from 5.0 kIE/l to 2.8 kIE/l
  • All of these changes were statistically significant

The researchers looked at a number of other blood tests and didn’t find any significant differences. 

Five men and nine women completed the study.  Of the 20 who originally signed up, one could not fulfill the diet, three became ill (no details), two failed to show up.

So What?

That’s a remarkable weight loss over just three weeks for slender people eating ad lib.

The study authors concluded that these paleo diet-induced changes could reduce risk for cardiovascular disease.  They called for a larger study with a control group.  (If it’s been done, I haven’t found it yet.)

Sounds reasonable.

Steve Parker, M.D.

PS: You’d think they would have said more about the three participants who got sick, rather than leave us wondering if the diet made them ill.

Reference:  Österdahl, M; Kocturk, T; Koochek, A;Wändell, PE.  Effects of a short-term intervention with a paleolithic diet in healthy volunteers.  European Journal of Clinical Nutrition, 62 (2008): 682-685.

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Posted in Heart Disease, Paleo Diet, Weight Loss

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Random Thoughts On Paleo Eating For People With Diabetes

Posted on February 18, 2012 | 16 comments

Not really pertinent, but I like buffalo

I was interviewed  yesterday by Amy Stockwell Mercer, author of Smart Woman’s Guide to Diabetes.  All I knew beforehand was that she was interested in my thoughts on the paleo diet as applied to diabetes.

In preparation, I collected some random thoughts and did a little research.

What’s the paleo diet?

Fresh, minimally processed food.  Meat (lean or not? supermarket vs yuppiefied?), poultry, eggs, fish, leafy greens and other vegetables, nuts, berries, fruit, and probably tubers.

Non-paleo: highly processed, grains, refined sugars, industrial plant/seed oils, legumes, milk, cheese, yogurt, salt, alcohol.

Is the paleo diet deficient in any nutrients?

A quick scan of Loren Cordain’s website found mention of possible calcium and vitamin D deficits.  Paleoistas will get vitamin D via sun exposure and fish (especially cold-water fatty fish).  Obtain calcium from broccoli, kale, sardines, almonds, collards.  (I wonder if the Recommended Dietary Allowance for calcium is set too high.)

What About Carbohydrates and Diabetes and the Paleo Diet?

Diabetes is a disorder of carbohydrate metabolism.  In a way, it’s an intolerance of carbohydrates.  In type 1 diabetes, there’s a total or near-total lack of insulin production on an autoimmune basis.  In type 2 diabetes, the body’s insulin just isn’t working adequately; insulin production can be high, normal or low.  In both cases, ingested carbohydrates can’t be processed in a normal healthy way, so they stack up in the bloodstream as high blood sugars.  If not addressed adequately, high blood glucose levels sooner or later will poison body tissues .  Sooner in type 1, later in type 2.  (Yes, this is a gross over-simplification.) 

Gluten-rich Neolithic food

If you’re intolerant of lactose or gluten, you avoid those.  If you’re intolerant of carbohydrates, you could avoid eating them, or take drugs to help you overcome your intolerance.  Type 1 diabetics must take insulin.  Insulin’s more optional for type 2’s.  We have 11 classes of drugs to treat type 2 diabetes; we don’t know the potential adverse effects of most of these drugs.  Already, three diabetes drugs have been taken off the U.S. market or severely restricted due to unacceptable toxicity: phenformin, troglitazone, and rosiglitazone. 

Humans need two “essential fatty acids” and nine “essential” amino acids derived from proteins.  “Essential” means we can’t be healthy and live long without them.   Our bodies can’t synthesize them.  On the other hand, there are no essential carbohydrates.  Our bodies can make all the carbohydrate (mainly glucose) we need.

Since there are no essential carbohydrates, and we know little about the long-term adverse side effects of many of the diabetes drugs, I favor carbohydrate restriction for people with carbohydrate intolerance.  (To be clear, insulin is safe, indeed life-saving, for those with type 1 diabetes.)

That being said, let’s think about the Standard American Diet (SAD) eaten by an adult.  It provides an average of 2673 calories a day (not accounting for wastage of calories in restaurants; 2250 cals/day is probably a more accurate figure for actual consumption).  Added sugars provide 459 of those calories, or 17% of the total.  Grains provide 625 calories, or 23% of the total.  Most of those sugars and grains are in processed, commercial foods.  So added sugars and grains provide 40% of the total calories in the SAD.  Remember, we need good insulin action to process these carbs, which is a problem for diabetics.  (Figures are from an April 5, 2011, infographic at Civil Eats.)

Anyone going from the SAD to pure Paleo eating will be drastically reducing intake of added sugars and grains, our current major sources of carbohydrate.  Question is, what will they replace those calories with? 

That’s why I gave a thumbnail sketch of the paleo diet above. Take a gander and you’ll see lots of low-carb and no-carb options, along with some carb options. For folks with carbohydrate intolerance, I’d favor lower-carb veggies and judicious amounts of fruits, berries, and higher-carb veggies and

Will these cause bladder cancer? Pancreatitis?

tubers.  “Judicious” depends on the individual, considering factors such as degree of residual insulin production, insulin sensitivity, the need to lose excess weight, and desire to avoid diabetes drugs.

Compared to the standard “diabetic diet” (what’s that?) and the Standard American Diet, switching to paleo should lower the glycemic index and glycemic load of the diet.  theoretically, that should help with blood sugar control.

A well-designed low-carb paleo diet would likely have at least twice as much fiber as the typical American diet, which would also tend to limit high blood sugar excursions.

In general, I favor a carbohydrate-restricted paleo diet for those with diabetes who have already decided to “go paleo.”  I’m not endorsing any paleo diet for anyone with diabetes at this point—I’m still doing my research.  But if you’re going to do it, I’d keep it lower-carb.  It has a lot of potential.

Are There Any Immediate Dangers for a Person With Diabetes Switching to the Paleo Diet?

It depends on three things: 1) current diet, and 2) current drug therapy, and 3) the particular version of paleo diet followed. 

Remember, the Standard American Diet provides 40% of total calories as added sugars and grains (nearly all highly refined).  Switching from SAD to a low-carb paleo diet will cut carb intake  and glycemic load substantially, raising the risk of hypoglycemia if the person is taking certain drugs.

Drugs with potential to cause hypoglycemia include insulin, sulfonylureas, meglitinides, pramlintide, and perhaps thiazolidinediones.

Who knows about carb content of the standard “diabetic diet”?  Contrary to popular belief, there is no monolithic “diabetic diet.”  There is no ADA diet (American Diabetes Association).  My impression, however, is that the ADA favors relatively high carbohydrate consumption, perhaps 45-60% of total calories.  Switching to low-carb paleo could definitely cause hypoglycemia in those taking the aforementioned drugs.

One way to avoid diet-induced hypoglycemia is to reduce the diabetic drug dose.

A type 2 overweight diabetic eating a Standard American Diet—and I know there are many out there—would tend to see lower glucose levels by switching to probably any of the popular paleo diets.  Be ready for hypoglycemia if you take those drugs.

Paleo diets are not necessarily low-carb.  Konner and Eaton estimate that ancestral hunter-gatherers obtained 35 to 40% of total calories from carbohydrates.  I’ve seen other estimates as low as 22%.  Reality likely falls between 22 and 65%.  When pressed for a brief answer as to how many carbohydrate calories are in the paleo diet, I say “about a third of the total.”  By comparison, the typical U.S. diet provides 50% of calories from carbohydrate.

Someone could end up with a high-carb paleo diet easily, by emphasizing tubers (e.g., potatoes), higher-carb vegetables, fruits, berries, and nuts (especially cashews). Compared with the SAD, this could cause higher or lower blood sugars, or no net change.

A diabetic on a Bernstein-style diet or Ketogenic Mediterranean Diet (both very-low-carb) but switching to paleo or low-carb paleo (50-150 g?) would see elevated blood sugars.  Perhaps very high glucoses.

Any person with diabetes making a change in diet should do it in consultation with a personal physician or other qualified healthcare professional familiar with their case.

Steve Parker, M.D.

Fun Facts!

  • A typical carbonated soda contain the equivalent of 10 tsp (50 ml) of sugar.
  • The typical U.S. adult eats 30 tsp  (150 ml) daily of added sweeteners and sugars.
  • U.S total grain product consumption was at record lows in the 1970s, at 138 pounds per person.  By 2000, grain consumption was up by 45%, to 200 pounds per person.
  • Total caloric sweetener consumption (by dry weight) was 110 pounds per person in the  1950s.  By 2000, it was up 39% to 150 pounds.
  • Between 1970 and 2003, consumption of added fats and oils rose by 63%, from 53 to 85 pounds.  [How tasty would that be without starches and sugars?  Not very.]
  • In 2008, “added fat” calories in the U.S. adult diet were 641 (24% of total calories).

Fun Facts provided by the U.S. Department of Agriculture. 

(The paleo diet is also referred to as the Paleolithic, Old Stone Age, Stone Age, Ancestral, Hunter-Gatherer, or Caveman diet.)

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Posted in Diabetic Diet, Glucose, Grains, Low-Carb, Paleo Diet

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Evidence for Human Grain Consumption 100,000 Years Ago

Posted on December 26, 2011 | 8 comments

ScienceDaily December 17 reported findings of a Canadian archeological team who found evidence of systematic grain consumption by ancient humans in Africa:

The consumption of wild cereals among prehistoric hunters and gatherers appears to be far more ancient than previously thought, according to a University of Calgary archaeologist who has found the oldest example of extensive reliance on cereal and root staples in the diet of early Homo sapiens more than 100,000 years ago.

 

Neolithic technology

In case you’re new to the paleo diet, grains are considered verboten by most adherents.  (Paleo diet is also known as the Stone Age diet, caveman diet, and Paleolithic diet.)  The cereal grain mentioned in the ScienceDaily article is wild sorghum.

Many in the paleosphere believe that such ancient humans didn’t have the technical skills to transform wild grains into something edible on a regular basis.  I haven’t read the source material, nor do I have an opinion on whether the archeologists are correct.  I’m just sayin’…

Steve Parker, M.D.

Reference: Mercader, Julio,  et al.  Mozambican grass seed consumption during the Middle Stone Age. Science, December 18, 2009.

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UCSF Investigating Paleolithic Diet for Diabetics

Posted on November 6, 2011 | 3 comments

A May, 2010, press release from University of California San Francisco outlines the university’s research into use of the Paleolithic diet (aka Stone Age or caveman diet) for people with type 2 diabetes.  From the press release:

The initial research findings are striking. Without losing weight, participants in a preliminary study improved blood sugar control, blood pressure control and blood vessel elasticity. They lowered levels of blood fats such as cholesterol. And most amazingly, participants achieved these results in less than three weeks — simply by switching to a Paleolithic diet.

The lead researchers are nephrologist Lynda Frassetto and endocrinologist Umesh Masharani.  Frassetto and team had previously looked at metabolic improvements linked to the paleo diet.

We await publication of their current findings in a peer-reviewed scientific journal.

Steve Parker, M.D.

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Metabolic Improvements From a Paleolithic Diet in San Francisco

Posted on October 28, 2011 | 3 comments

A Paleolithic diet improved metabolic status with respect to cardiovascular and carbohydrate physiology, according to a 2009 study at the University of California San Francisco.

Here are the specific changes, all statistically significant unless otherwise noted:

  • total cholesterol decreased by 16%
  • LDL cholesterol (“bad cholesterol”) decreased by 22% (no change in HDL)
  • triglycerides decreased by 35%
  • strong trend toward reduced fasting insulin (P=0.07)
  • average diastolic blood pressure down by 3 mmHg (no change in systolic pressure)
  • improved insulin sensitivity and reduced insulin resistance; i.e., improved glucose tolerance

Methodology

This was a small, preliminary study: only 11 participants (six male, three female, all healthy (non-diabetic), average age 38, average BMI 28, sedentary, mixed Black/Caucasian/Asian).

Baseline diet characteristics were determined by dietitians, then all participants were placed on a paleo diet, starting with a 7-day ramp-up (increasing fiber and potassium gradually), then a 10-day paleo diet.

The paleo diet: meat, fish, poultry, eggs, fruits, vegetables, tree nuts, canola oil, mayonnaise, and honey.  No dairy legumes, cereals, grains, potatoes.  Alcohol not mentioned ever.  Caloric intake was adjusted to avoid weight change during the study, and participants were told to remain sedentary.  They ate one meal daily at the research center and were sent home with the other meals and snacks pre-packed.

Compared with baseline diets, the paleo diet reduced salt consumption by half while doubling potassium and magnesium intake.  Baseline diet macronutrient calories were 17% from protein, 44% carbohydrate, 38% fat.  Paleo diet macronutrients were 30% protein, 38% carb, 32% fat.  Fiber content wasn’t reported. 

I’m guessing there were no adverse effects.

Comments

This study sounds like fun, easy, basic science: “Hey, let’s do this and see what happens!”

I don’t know a lot about canola oil, but it’s considered one of the healthy oils by folks like Walter Willett.  It sounds more appealing than rapeseed, from whence it comes.

I agree with the investigators that this tiny preliminary study is promising; the paleo diet (aka Stone Age or caveman diet) has potential benefits for prevention and treatment for metabolic syndrome, diabetes, and cardiovascular disease such as heart attack and stroke.

The researchers mentioned their plans to study the paleo diet in patients with type 2 diabetes.  Any results yet?

Are you working with a physician on a medical issue that may improve or resolve with the paleo diet?  Most doctors don’t know much about the paleo diet yet.  You may convince yours to be open-minded by trying the diet yourself—not always a safe way to go—and showing her your improved clinical results.  Or show her studies such as this.

Steve Parker, M.D.

Disclaimer:  All matters regarding your health require supervision by a personal physician or other appropriate health professional familiar with your current health status.  Always consult your personal physician before making any dietary or exercise changes.

Reference:  Frassetto, L.A., et al.  Metabolic and physiologic improvements from consuming a paleolithic, hunter-gatherer type diet.  European Journal of Clinical Nutrition, advance online publication, February 11, 2009.   doi: 10.1038/ejcn.2009.4

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Posted in Glucose, Heart Disease, Insulin, Lipids, Paleo Diet

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Paleo Diet Is More Satiating Than Mediterranean-Style in Small Study

Posted on October 14, 2011 | 4 comments

Swedish researchers reported in 2010 that a Paleolithic diet was more satiating than a Mediterranean-style diet, when compared on a calorie-for-calorie basis in heart patients.  Both groups of study subjects reported equal degrees of satiety, but the paleo dieters ended up eating 24% fewer calories over the 12-week study.

The main differences in the diets were that the paleo dieters had much lower consumption of cereals (grains) and dairy products, and more fruit and nuts.  The paleos derived 40% of total calories from carbohydrate compared to 52% among the Mediterraneans.

Even though it wasn’t a weight-loss study, both groups lost weight.  The paleo dieters lost a bit more than the Mediterraneans: 5 kg vs 3.8 kg (11 lb vs 8.4 lb).  That’s fantastic weight loss for people not even trying.  Average starting weight of these 29 ischemic heart patients was 93 kg (205 lb).  Each intervention group had only 13 or 14 patients (I’ll let you figure out what happened to to the other two patients).

I blogged about this study population before.  Participants supposedly had diabetes or prediabetes, although certainly very mild cases (average hemoglobin A1c of 4.7% and none were taking diabetic drugs)

As I slogged through the research report, I had to keep reminding myself that this is a very small, pilot study.  So I’ll not bore you with all the details.

Bottom Line

This study suggests that the paleo diet may be particularly helpful for weight loss in heart patients.  No one knows how results would compare a year or two after starting the diet.  The typical weight-loss pattern is to start gaining the weight back at six months, with return to baseline at one or two years out.

Greek investigators found a link between the Mediterranean diet and better clinical outcomes in known ischemic heart disease patients.  On the other hand, researchers at the Heart Institute of Spokane found the Mediterranean diet equivalent to a low-fat diet in heart patients, again in terms of clinical outcomes.  U.S. investigators in 2007 found a positive link between the Mediterranean diet and lower rates of death from cardiovascular disease and cancer. 

We don’t yet have these kinds of studies looking at the potential benefits of the paleo diet.  I’m talking about hard clinical endpoints such as heart attacks, heart failure, cardiac deaths, and overall deaths.  The paleo diet definitely shows some promise.

I also note the Swedish investigators didn’t point out that weight loss in overweight heart patients may be detrimental.  This is the “obesity paradox,” called “reverse epidemiology” at Wikipedia.  That’s a whole ‘nother can o’ worms.

Keep your eye on the paleo diet.

Steve Parker, M.D.

Reference: Jonsson, Tommy, et al.  A paleolithic diet is more satiating per calorie than a mediterranean-like diet in individuals with ischemic heart disease.  Nutrition and Metabolism, 2010, 7:85.

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Paleo Diet for Heart Patients With Diabetes and Prediabetes

Posted on October 9, 2011 | 10 comments

A Paleolithic diet lowered blood sugar levels better than a control diet in coronary heart disease patients with elevated blood sugars, according to Swedish researchers reporting in 2007.

About half of patients with coronary heart disease have abnormal glucose (blood sugar) metabolism.  Lindeberg and associates wondered if a Paleolithic diet (aka “Old Stone Age,” “caveman,” or ancestral human diet) would lead to improved blood sugar levels in heart patients, compared to healthy, Mediterranean-style, Western diet.

Methodology

Investigators at the University of Lund enrolled 38 male heart patients—average age 61—patients and randomized them to either a paleo diet or a “consensus” (Mediterranean-like) diet to be followed for 12 weeks.  Average weight was 94 kg.  Nine participants dropped out before completing the study, so results are based on 29 participants.  All subjects had either prediabetes or type 2 diabetes (the majority) but none were taking medications to lower blood sugar.  Baseline hemoglobin A1c’s were around 4.8%.  Average fasting blood sugar was 125 mg/dl (6.9 mmol/l); average sugar two hours after 75 g of oral glucose was 160 mg/dl (8.9 mmol/l).

The paleo diet was based on lean meat, fish, fruits, leafy and cruciferous vegetables, root vegetables (potatoes limited to two or fewer medium-sized per day), eggs, and nuts (no grains, rice, dairy products, salt, or refined fats and sugar). 

The Mediterranean-like diet focused on low-fat dairy, whole grains, vegetables, fruits, potatoes, fatty fish, oils and margarines rich in monounsaturated fatty acids and alpha-linolenic acid. 

Both groups were allowed up to one glass of wine daily.

No effort was made to restrict total caloric intake with a goal of weight loss.

Results

Absolute carbohydrate consumption was 43% lower in the paleo group (134 g versus 231 g), and 23% lower in terms of total calorie consumption (40% versus 52%).  Glycemic load was 47% lower in the paleo group (65 versus 122), mostly reflecting lack of cereal grains.

The paleo group ate significantly more nuts, fruit, and vegetables.  The Mediterranean group ate significantly more cereal grains, oil, margarine, and dairy products.

Glucose control improved by 26% in the paleo group compared to 7% in the consensus group.  The improvement was statisically significant only in the paleo group.  The researchers believe the improvement was independent of energy consumption, glycemic load, and dietary carb/protein/fat percentages.

High fruit consumption inthe paleo group (493 g versus 252 g daily) didn’t seem to impair glucose tolerance. 

Hemoglobin A1c’s did not change or differ significantly between the groups.

Neither group showed a change in insulin sensitivity (HOMA-IR method).

Comments

The authors’ bottom line:

In conclusion, we found marked improvement of glucose tolerance in ischemic heart disease patients with increased blood glucose or diabetes after advice to follow a Palaeolithic [sic] diet compared with a healthy Western diet.  The larger improvement of glucose tolerance in the Palaeolithic group was independent of energy intake and macronutrient composition, which suggests that avoiding Western foods is more important than counting calories, fat, carbohydrate or protein.  The study adds to the notion that healthy diets based on whole-grain cereals and low-fat dairy products are only the second best choice in the prevention and treatment of type 2 diabetes.

This was a small study; I consider it a promising pilot.  Results apply to men only, and perhaps only to Swedish men.  I have no reason to think they wouldn’t apply to women, too.  Who knows about other ethnic groups?

The Mediterranean-style concensus diet here included low-fat dairy and margarine, items I don’t associate with the traditional healthy Mediterranean diet.

This study and the one I mention below are the only two studies I’ve seen that look at the paleo diet as applied to human diabetics.  If you know of others, please mention in the Comments section. 

The higher fruit consumption of the paleo group didn’t adversely affect glucose control, which is surprising.  Fruit is supposed to raise blood sugar.  At 493 grams a day, men in the paleo group ate almost seven times the average fruit intake of Swedish men in the general population (75 g/day).  Perhaps lack of adverse effect on glucose control here reflects that these diabetics and prediabetics were mild cases early in the course of the condition (diabetes tends to worsen over time). 

Present day paleo and low-carb advocates share a degree of simpatico, mostly because of carbohydrate restriction—at least to some degree—by paleo dieters.  Both groups favor natural, relatively unprocessed foods.  Note that the average American eats 250-300 g of carbohydrates a day.  Total carb intake in the paleo group was 134 g (40% of calories) versus 231 g (55% of calories) in the Mediterranean-style diet.  Other versions of the paleo diet will yield different numbers, as will individual choices for various fruits and vegetables.  Forty percent of total energy consumption from carbs barely qualifies as low-carb. 

Study participants were mild, diet-controlled diabetics or prediabetics, not representative of the overall diabetic population, most of whom take drugs for it and have much higher hemoglobin A1c’s.

Lindeberg and associates in 2009 published results of a paleo diet versus standard diabetic diet trial in 13 diabetics.  Although a small trial (13 subjects, crossover design), it suggested advantages to the paleo diet in terms of heart disease risk factors and improved hemoglobin A1c.  Most participants were on glucose lowering drugs; none were on insulin.  Glucose levels were under fairly good control at the outset.  Compared to the standard diabetic diet, the Paleo diet yielded lower hemoglobin A1c’s (0.4% lower—absolute difference), lower trigylcerides, lower diastolic blood pressure, lower weight, lower body mass index, lower waist circumference, lower total energy (caloric) intake, and higher HDL cholesterol.  Glucose tolerance was the same for both diets.  Fasting blood sugars tended to decrease more on the Paleo diet, but did not reach statistical significance (p=0.08).

The paleo diet shows promise as a treatment or preventative for prediabetes and type 2 diabetes.  Only time will tell if it’s better than a low-carb Mediterranean diet or other low-carb diets. 

Steve Parker, M.D.

Reference: Lindeberg, S., Jönsson, T., Granfeldt, Y., Borgstrand, E., Soffman, J., Sjöström, K., & Ahrén, B. (2007). A Palaeolithic diet improves glucose tolerance more than a Mediterranean-like diet in individuals with ischaemic heart disease. Diabetologia, 50 (2007): 1795-1807.   doi 10.1007/s00125-007-0716-y

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Old Stone Age Diet Depended On Latitude

Posted on October 4, 2011 | 3 comments

There isn’t any single Stone Age diet, according to J.A.J. Gowlett, who (whom?) I assume is an archeologist with the University of Liverpool.

(I was tempted to write “there isn’t a monolithic Stone Age diet.”  Get it?  “Lith” is Greek or Latin for “stone.”)

This is probably old new for you guys who have been interested in the paleo diet for much longer than I.

Here are a few more of Gowlett’s ideas:

  • The Stone Age is is more accurately referred to as the Old Stone Age.
  • Hominids (the family of human ancestors) branched off from ape ancestors around eight to 10 million years ago.
  • Roots and tubers have been a part of our ancestral diet for perhaps as long as three million years,  which “places starchy carbohydrate consumption as part of the deep ancestry of human beings.”
  • Meat eating assumed greater importance about two million years ago.
  • Migration to colder environments necessitated more meat consumption because plant foods were more limited.
  • Our ancestors migrated from tropical to temperate latitudes about by 1.7 million years ago.
  • Early humans began using fire for cooking between 500,000 to 1.5 million years ago.
  • Neanderthals were heavily carnivorous.
  • “Ancestors of modern humans are now believed to have evolved in the tropics, probably in Africa, from about 200,000 years ago.”  Their diet was perhaps 70% plant-based.
  • “In contrast, modern humans entering Europe 40,000 years ago would have adopted a meat-based diet by necessity, and maintained this over hundreds of generations.”
  • “Modern hunters and gatherers echo the variety of past diets, ranging from largely plant based in the tropics, to being also heavily meat based in the arctic.”
  • No ancient human population depended heavily on cereals or non-human milk.  “Fruit certainly came first of all….”

Potential Implications For a Paleo Diabetic Diet (highly speculative)

Diabetics with tropical lineage may do better with a plant-based diet.  Those with northern European ancestry may do better with meat-based.

Paleo diets likely had very high fiber contents, reflecting the degree to which they were plant-based.  We’re looking at 70+ grams of fiber daily.  That much fiber would tend to reduce the effect of carbohydrate on blood sugar levels.

Fruits and roots have a high concentration of carbohydrate, with potential adverse effects on blood sugar (raising it, of course).  Diabetics eating paleo-style may need to avoid or limit certain fruits and roots: the ones with lower fiber content and higher glycemic index.  Blood sugar responses will vary from one diabetic to another.  Monitor blood sugar levels one or two hours after carb consumption to learn your idiosyncratic response.

Steve Parker, M.D.

Reference: Gowlett, J.A.J.  What actually was the Stone Age diet?  Journal of Nutritional and Environmental Medicine, 13 (2003): 143-147.

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Posted in Diabetic Diet, Low-Carb, Paleo Diet, Paleo Theory

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Paleolithic Nutrition: Twenty-Five Years Later

Posted on September 29, 2011 | 16 comments

Melvin Konner and S. Boyd Eaton wrote a review article for Nutrition in Clinical Practice that update’s their seminal New England Journal of Medicine  paleo nutrition article of 1985.  They took a fresh look at recent  data on modern hunter-gatherer societies as well as advances in anthropology. 

NEJM likely has much wider circulation, so it’s too bad the update wasn’t published there.

I’ve written previously about the history of the modern paleo movement.  I consider S. Boyd Eaton and Melvin Konner two of the founders. 

I wanted to share a few tidbits from the new article:

  • The transition from hunting/gathering to farming (about 10,000 year ago) saw a decrease in body size and robustness, plus evidence of nutritional stress
  • Modern humans migrated away from Africa between 50,000 and 100,000 years ago
  • Levels of muscular and aerobic fitness in ancestral groups are much higher than modern societies, with a concomittant higher level of calorie consumption
  • Average life expectancies in pre-industrial hunter-gatherer (H-G) groups was only 30-35 years, but much of this low number simply reflects high infant and child death rates
  • H-G deaths overwhelmingly reflect infectious diseases
  • H-G groups had a high degree of dependence on plant foods
  • Cooking has been important to humans for at least 230,000 years, if not longer
  • Fish and shellfish are more important food sources than these authors thought 25 years ago
  • Ancestral H-G groups derived 35 to 65% of diet (calories, I guess) from animal flesh
  • Game animals have more mono- and polyunsaturated fatty acids than supermarket meat
  • H-G diets are higher in fat than they once thought: the new range is 20 to 35% of calories
  • H-G diet omega-6: omega-3 ratio was 2:1, in contrast to the modern Western ratio of 10:1
  • H-G groups eat more protein than they once thought
  • Carbohydrate consumption of H-G groups varied from about 35 to 65% of calories.  (I’ve written elsewhere about the carb content of paleo diets.)
  • Nearly all H-G carbs are from vegetables and fruits, which have more favorable glycemic responses than grains and concentrated sugars
  • Uncultivated fruits and veggies have much more fiber than commercial ones (13 versus 4 g fiber per 100 g of food)
  • H-G diets have at least 70 g of fiber daily
  • Sodium in H-G diets is very low: 800 mg/day

The Diet-Heart Hypothesis is the idea that dietary total and saturated fat, and cholesterol, cause or contribute to atherosclerosis (hardening of the arteries), leading to heart attacks and strokes.  Konner and Eaton still believe the theory is valid for fats, but not cholesterol.  The latest evidence is that even total and saturated fat are minimally or unrelated to atherosclerosis. 

They also believe total fat, due to its caloric load, is an important contributor to obesity and type 2 diabetes.  (I agree that my be true if you eat a lot of carbs with fat.)

Konner and Eaton review the very few clinical studies—a grand total of four—that apply a paleo diet to modern humans.  Results support their theory that paleo-style eating has healthful metabolic effects.

Their conception of a paleo food pyramid is a base of high-fiber vegetables and fruits, the next tier up being meat/fish/low-fat dairy (!?) (all lean), then a possible tier for whole grain (admittedly very unusual), with a small peak of oils, fats, and refined carbohydrates.

They recommend high activity levels, including resistance exercise, flexibility, and aerobics, burning over 1,000 cals/day exclusive of resting metabolism.

They also seem to favor small amounts of alcohol—not generally considered paleo—to reduce heart disease risk, admitting that “…the HG model cannot answer all questions.”

Eaton and Konner suggest the following as the “estimated ancestral diet“:

  • Carbohydrates, % daily energy                 35-40
  • Protein, % daily energy                                 25-30
  • Fat, % daily energy                                          20-35
  • Added sugar, % daily energy                            2
  • Fiber, g/day                                                        >70
  • EPA and DHA*, g/day                                    0.7-6
  • Cholesterol, mg/day                                       500+
  • Vitamin C, mg/day                                           500
  • Vitamin D, IU/day                                4,000 (sunlight)
  • Calcium, mg/day                                       1,000-1,500
  • Sodium, mg/day                                         under 1,000
  • Potassium, mg/day                                         7,000

*Eicosapentaenoic acid and docosahexaenoic acid

Konner and Eaton call for more randomized controlled studies of the paleo diet.  These studies will need to define the paleo diet carefully.  Their definition is probably as good as any, if not the best.  Of course, the listed nutrients should come from minimally processed, natural foods.  We just need Loren Cordain‘s and Staffan Lindeberg‘s  input on a concensus definition of the paleo diet, then we’re ready to rock’n’roll.

Steve Parker, M.D.

Reference:

Konner, Melvin and Eaton, S. Boyd.  Paleolithic Nutrition: Twenty-Five Years Later.  Nutrition in Clinical Practice, 25 (2010): 594-602.  doi: 10.1177/0884533610385702

Eaton, S.B. and Konner, M.  Paleolithic nutrition: a consideration of its nature and current implications.  New England Journal of Medicine, 312 (1985): 283-289.

 

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Paleo Diet and Diabetes: Improved Cardiovascular Risk Factors

Posted on September 26, 2011 | 2 comments

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Compared to a standard diabetic diet, a Paleolithic diet improves cardiovascular risk factors in type 2 diabetics, according to investigators at Lund University in Sweden.

Researchers compared the effects of a Paleo and a modern diabetic diet in 13 type 2 diabetic adults (10 men) with average hemoglobin A1c’s of 6.6% (under fairly good control, then).  Most were on diabetic pills; none were on insulin.  So this was a small, exploratory, pilot study.  Each of the diabetics followed both diets for three months.

How Did the Diets Differ?

Compared to the diabetic diet, the paleo diet was mainly lower in cereals and dairy products, higher in fruits and vegetables, meat, and eggs.  The paleo diet was lower in carbohydrates, glycemic load, and glycemic index.  Paleo vegetables were primarily leafy and cruciferous.  Cruciferous vegetables include broccoli, brussels sprouts, cauliflower, and cabbage.  Root vegetables were allowed; up to 1 medium potato daily.  The paleo diet also featured lean meats (why lean?), fish, eggs, and nuts, while forbidding refined fats, sugars, and beans.  Up to one glass of wine daily was allowed.

See the actual report for details of the diabetic diet, which seems to me to be similar to the diabetic diet recommended by most U.S. dietitians.

What Did the Researchers Find?

Compared to the diabetic diet, the paleo diet yielded lower hemoglobin A1c’s (0.4% lower—absolute difference), lower trigylcerides, lower diastolic blood pressure, lower weight, lower body mass index, lower waist circumference, lower total energy (caloric) intake, and higher HDL cholesterol (the good cholesterol).  Glucose tolerance was the same for both diets.  Fasting blood sugars tended to decrease more on the Paleo diet, but did not reach statistical significance (p=0.08, which is very close to significant).

So What?

The greater improvement in multiple cardiovascular risk factors seen here suggests that the paleo diet has potential to reduce the higher cardiovascular disease rates we see in diabetics.  This is just a pilot study.  Larger studies—more participants—are needed for confirmation.  Ultimately, we need data on hard clinical endpoints such as heart attacks, strokes, and death.

These diabetics had their blood sugars under fairly good control at baseline.  I wouldn’t be surprised if diabetics under poor control—hemoglobin A1c of 9%, for example—would see even greater improvements in risk factors as well as glucose levels while eating paleo.

There are so few women in this study as to be almost meaningless.

Results of this study may or may not apply to non-Swedes.

I see a fair amount of overlap between this version of the paleo diet and Dr. Bernstein’s Diabetes Solution diet and the Low-Carb Mediterranean Diet. 

Steve Parker, M.D.

Reference:  Jönsson, T., Granfeldt, Y., Ahrén, B., Branell, U., Pålsson, G., Hansson, A., Söderström, M., & Lindeberg, S.  Beneficial effects of a Paleolithic diet on cardiovascular risk factors in type 2 diabetes: a randomized cross-over pilot study.  Cardiovascular Diabetology, 8 (2009)  doi: 10.1186/1475-2840-8-35

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Posted in Diabetic Diet, Heart Disease, Paleo Diet

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