Tag Archives: palaeolithic diet

Paleolithic Diet Improved Metabolic Syndrome in Just Two Weeks

Wish I were here

Wish I were here

A Paleolithic-type diet over two weeks improves several heart disease risk factors in folks with metabolic syndrome, according to Netherlands-based researchers.

The investigators wondered if the paleo diet, independent of weight loss, would alter characteristics of the metabolic syndrome. They seem to be the first scientists to do a study like this.

“Metabolic syndrome” may be a new term for you. It’s a collection of clinical features that are associated with increased future risk of type 2 diabetes and atherosclerotic complications such as heart attack and stroke. One in six Americans has metabolic syndrome, including almost one in four of adults. The most common definition of metabolic syndrome (and there are others) is the presence of at least three of the following characteristics:

  • high blood pressure (130/85 or higher, or using a high blood pressure medication)
  • low HDL cholesterol: under 40 mg/dl (1.03 mmol/l) in a man, under 50 mg/dl (1.28 mmol/l) in a women (or either sex taking a cholesterol-lowering drug)
  • triglycerides over 150 mg/dl (1.70 mmol/l) (or taking a triglyceride-lowering drug)
  • abdominal fat: waist circumference 40 inches (102 cm) or greater in a man, 35 inches (88 cm) or greater in a woman
  • fasting blood glucose over 100 mg/dl (5.55 mmol/l)

These five criteria were identical to the ones used in the study at hand. But the study participants were required to have only two of the five, not three, for unclear reasons. I found no consensus definition elsewhere that would define metabolic syndrome as only two of the five conditions. Study participants ate either a paleo-style diet or a reference/control diet. Those eating the reference diet didn’t quite have the metabolic syndrome since they had a mean (“average”) of 2.7 metabolic syndrome characteristics. The paleo group had 3.7 characteristics.

How Was the Study Done?

Average age of the 34 study participants was 53 and they were generally healthy. None had diabetes, cardiovascular disease, or systolic pressure over 180 mmHg. Smokers were excluded. Mean body mass index was 32 (obese). Only 9 of the 34 subjects were men. Subjects were randomized to either a Paleolithic-type diet (n=18) or a “healthy reference diet based on the guidelines of the Dutch Health Council” (n=14). Efforts were made to keep body weight stable during the two-week study. Participants were nearly all caucasian.

All meals were home-delivered free of charge by a catering service.

The Paleolithic-type diet “…was based on lean meat, fish, fruit, leafy and cruciferous vegetables, root vegetables, eggs and nuts. Dairy products, cereal grains, legumes, refined fats, extra salt and sugar were not part of it.” [I like their version of the paleo diet.] Protein supplied 24% of calories while carbohydrate was 32% and fat 41%.

You can consult the full text of the published article for details of the Dutch Health Council diet. Calories were 17% from protein, 50% from carbohydrate, and 29% from fat. Alcohol isn’t mentioned at all.

Despite randomization, the paleo diet group had more metabolic syndrome characteristics than the reference diet group. For instance, 78% of the paleo group had elevated fasting glucose compared to 44% of the reference group. And 67% of the paleo group had low HDL cholesterol compared to just 13% of the reference group. These glucose and HDL differences were statistically significant. 39% of the paleo had high triglycerides compared to 19% of the others. Furthermore, the paleos’ average body weight was 98 kg (216 lb) compared to 86 kg (189 lb) in the others. The paleo group had 3.7 characteristics of the metabolic syndrome versus 2.7 in the other cohort.

Go John trail at Cave Creek Regional Park in Scottsdale, Arizona

Go John trail at Cave Creek Regional Park in Scottsdale, Arizona

Results

Compared to the reference diet, the paleo-style diet:

  • lowered systolic pressure by 9 points and diastolic by 5
  • total cholesterol fell by 0.52 mmol/l (20 mg/dl)
  • triglycerides fell by 0.89 mmol/l (79 mg/dl)
  • HDL cholesterol (good) rose by 0.15 mmol/l (6 mg/dl)
  • body weight fell by 1.32 kg (3 lb)
  • one metabolic syndrome characteristic resolved

No significant changes were seen in intestinal permeability ( by differential sugar absorption test on urine), salivary cortisol, and inflammation (hsCRP, TNFα).

Fasting plasma insulin and HOMA-IR fell in the paleo group but not the other.[Good news for folks with diabetes or prediabetes.] Yet the authors write, “Regarding glucose intolerance we did not find significant changes in our study.”

Fasting blood glucose for the group as a whole at baseline was about 1o8 mg/dl (6.0 mmol/l). Fasting glucose fell in both groups: 16 mg/dl (0.9 mmol/l) in the paleo group, 6 mg/dl (0.35 mmol/l) in the other. This was not a statistically significant difference between the groups. These numbers are from the text of the report; looking at the tables, I calculate different and less impressive reductions. The falls in fasting glucose from baseline were statistically significant for both diets.

Nearly all the statistical analysis focused on comparing the paleo diet group to the reference diet group.

My Comments

Overall, I’m not very pleased with this study. My biggest problems are 1) the unfortunate randomization that created dissimilar experimental groups,  2) the use of two diet protocols, 3) some of the study participants didn’t even have metabolic syndrome, and 4) as is typical for paleo diet studies, not many experimental subjects were involved.

The randomization led to significant differences in the metabolic syndrome patients in the two diet groups. I’m puzzled why the authors don’t comment on this. It’s a problem with clinical studies involving low numbers of participants. Ideally, you want to apply the two different diets to groups of people that are as similar as possible. These groups weren’t that similar.

The investigators’ main goal was to study whether a paleo-style diet, independent of weight loss, alters characteristics of the metabolic syndrome. Then why introduce another variable, the Dutch Health Council diet? Is it the gold standard for treating metabolic syndrome? Has it even been used to treat metabolic syndrome? The authors don’t tell us. And why not restrict participation to subjects who meet the common international definition of metabolic syndrome (at least three of the five characteristics)? Why not just take all your subjects and switch them from their standard Netherlands diet to the paleo diet? That would increase your statistical power, and would have avoided the randomization mis-match in which some in the reference diet group didn’t even have metabolic syndrome.

Here we’ve got two different experimental groups, and we’re applying a different diet to each group. The results are going to be messy and difficult to interpret. It’s always better if you can alter just one variable.

Since the paleo and reference diet cohorts were so different at baseline, why not make it easy to simply compare the paleo diet group’s “before and after numbers”? Maybe the analysis is there and I’m just not smart enough to see it.

There weren’t enough men in the study to tell us anything about the paleo diet in men with metabolic syndrome.

The statistical analysis was difficult for me to read and understand. There’s a good chance I’ve missed or misinterpreted something.

This paleo diet reduced fasting blood sugar significantly, making me think it may help in management of diabetes and prediabetes.

I estimate that as much as a quarter of the experimental subjects didn’t even have metabolic syndrome, so the study title is a bit of a misnomer.

This paleo diet did result in resolution of one metabolic syndrome characteristic, which is a good thing. So you could say the diet improves metabolic syndrome, even resolves it in some folks if it drops their metabolic syndrome characteristics from three to two. It predominantly helps lower blood pressure and triglycerides, and reduces excess weight modestly. In white women. Compared to the healthy Dutch Health Council diet.

If I had metabolic syndrome, I’d do something about it in hopes of lowering my future risk of diabetes and atherosclerotic complications. Standard physician advice is to lose excess weight and exercise regularly. There’s no consensus on diet yet. I think carbohydrate restriction is important. If the study at hand is reproducible in a larger study population, the paleo diet is a reasonable approach. Dietitian Franziska Spritzler has a great review of nutritional management of metabolic syndrome at her blog. The Mediterranean diet supplemented with nuts helps improve metabolic syndrome. The Spanish Ketogenic Mediterranean Diet may cure metabolic syndrome.

Steve Parker, M.D.

Update: I took a fresh look at this study as if it were simply a paleo diet trial involving 18 subjects who had metabolic syndrome. If I’m interpreting Table 5 correctly, and I think I am, these are the statistically significant changes after two weeks:

  • abdominal circumference decreased by 3.1 cm
  • systolic and diastolic blood pressures dropped by 8.5 and 8, respectively
  • fasting glucose dropped by 0.4 mmol/l (7 mg/dl)
  • fasting insulin fell
  • HOMA-IR decreased (less insulin resistance)
  • total cholesterol decreased from 220 to 193 mg/dl (5.7 to 5.0 mmol/l)
  • LDL-cholesterol decreased from 135 to 124 mg/dl (3.5 to 3.2 mmol/l)
  • triglycerides decreased from 168 to 89 mg/dl (1.9 to 1.0 mmol/l)

HDL cholesterol was unchanged.

The fall in AUC (area under the curve) for insulin approached but didn’t reach statistical significance (p=0.08)

Body weight fell from 98 kg (216 lb) to 95.3 kg (210 lb) but I found no p value. HDL-cholesterol was unchanged (the higher HDL I mentioned above is only in comparison to the reference diet, in which HDL fell)

All of these changes (except the lack of change in HDL-chol) would tend to promote health in someone with metabolic syndrome, prediabetes, or overweight type 2 diabetes.

Reference: Boers, Inga, et al. Favorable effects of  consuming a Palaeolithic-type diet on characteristics of the metabolic syndrome: a randomized controlled pilot-studyLipids in Health and Disease. 2014 Oct 11;13:160. doi: 10.1186/1476-511X-13-160.

The Mellberg Study: Paleo Diet and Obese Postmenopausal Women

Sweden's Flag. Most of the researchers involved with this study are in Sweden

Sweden’s Flag

Swedish researchers compared a Paleolithic-type diet against a lower-fat, higher-carb diet so often recommend in Nordic countries and in the U.S. Test subjects were obese but otherwise healthy older women. The study lasted two years. Dieters could eat as much as they wanted.

They found that the paleo-style dieters lost more weight, lost more abdominal fat, and lowered their trigyceride levels. When measured six months into the study, the paleo dieters had lost 6.5 kg (14 lb) of body fat compared to 2.6 (6 lb) kg in the other group.

Measured at two years out, the paleo dieters had lost 4.6 kg (10 lb) of body fat compared to 2.9 kg (6 lb) in the other group, but this difference wasn’t statistically significant.

The greatest weight loss was clocked at 12 months: Paleo dieters were down 8.7 (19 lb) kg compared to 4.4 kg (10 lb)  in the other group.

But this study was about more than weight loss. The investigators were also interested in cardiometabolic risk factors and overall body composition.

The Set-Up

I don’t know what the researchers told the women to get them interested. Weight loss versus healthier diet versus ?  This could have influenced the type of women who signed up, and their degree of commitment.

A newspaper ad got the attention of 210 women in Sweden; 70 met the inclusion criteria, which included a body mass index 27 or higher and generally good health. Average age was 60. Average BMI was 33. Average weight was 87 kg (192 lb). Average waist circumference was 105 cm (41 inches). The women were randomized into one of two diet groups (N=35 in each): paleolithic-type diet (PD) or Nordic Nutrition Recommendations diet (NNR). There were no limits on total caloric consumption. (Were the women told to “work on weight loss”? I have no idea.)

We don’t know the ethnicity of these women.

Here’s their version of the paleo diet:

  • 30% of energy (calories) from protein
  • 40% of energy from fat
  • 30% of energy from carbohydrate
  • high intake of mono- and polyunsaturated fatty acids
  • based on lean meat, fish, eggs, vegetables, fruits, berries, and nuts
  • additional fat sources were avocado and oils (rapeseed [canola] and olive) used in dressings and food preparation
  • cereals (grains), dairy products, added salt and refined fats and sugar were excluded
  • no mention of legumes, potatoes, or tubers

The NNR diet:

  • 15% of energy from protein
  • 25-30% of energy from fat
  • 55-60% of energy from carbohydrate
  • emphasis on high-fiber products and low-fat dairy products

Over the 24 months of the study, each cohort had 12 group meetings with a dietitian for education and support, including “dietary effects on health, behavioral changes and group discussion.”

Various blood tests and body measurements were made at baseline and periodically. Body measurements were made every six months. Body composition was measured by dual energy x-ray absorptiometry. Diet intake was measured by self-reported periodic four-day food records.

Stockholm Palace

Stockholm Palace

Results

30% of participants (21) eventually dropped out by the end of the study and were lost to follow-up, leaving 27 in the PD group and 22 in the NNR cohort.

Food record analysis indicated the PD group indeed reduced their carb intake while increasing protein and fat over baseline. Baseline macronutrient energy percentages were about the same for both groups: 17% protein, 45% carb, 34% (I guess the percentages don’t add to 100 because of alcohol, which wads not mentioned at all in the article.) Two years out, the PD group’s energy sources were 22% protein, 34% carb, 40% fat. For the NNR group, the energy sources at two years were 17% protein, 43% carb, and 34% fat. As usual, dietary compliance was better at six months compared to 24 months. The PD group failed to reach target amounts of protein energy (30%) at six and 24 months; the NNR group didn’t reach their goal of carbohydrate energy (55-60%). The PD group ate more mono- and poly unsaturated fatty acids than the NNRs.

In contrast to the food record estimates of protein intake, the urine tests for protein indicated poor adherence to the recommended protein consumption in the PD group (30% of energy). Both groups ate the same amount of protein by this metric. (This is an issue mostly ignored by authors, who don’t say which method is usually more accurate.)

“Both groups had statistically significant weight loss during the whole study, with significantly greater weight loos in the PD group at all follow up time points except at 24 months.” Largest weight loss was measured at 12 month: 8.7 kg (19 lb) in the PD group versus 4.4 kg (10 lb) in the NNRs.

The PD group lost 6.5 kg (14 lb) of body fat by six months but the loss was only 4.6 kg (10 lb) measured at 24 months. Corresponding numbers for the NNR group were 2.6 and 2.9 kg (about 6 lb). So both groups decreased their total fat mass to a significant degree. The difference between the groups was significant (P<0.001) only at six months. The greatest weight loss was clocked at 12 months: PD dieters were down 8.7 kg (19 lb) compared to 4.4 kg (10 lb) in the NNRs. Both groups saw a significant decrease in waist circumference during the whole study, with a more pronounce decrease in the PD group at six months: 11 versus 6 cm (4.3 versus 2.4 inches).

Fasting blood sugars, fasting insulin levels, and tissue plasminogen activator activity didn’t change.

Both groups had improvements in blood pressure, heart rate, c-reactive protein, LDL cholesterol, PAI-1 activity, and total cholesterol. The PD group saw a greater drop in triglycerides (by 19% at two years, but levels were normal to start with at 108 mg/dl or 1.22 mmol/l).

Reported daily energy intake fell over time for both groups, without statistically significant differences between them.

paleo diet, Steve Parker MD, diabetic diet

Sweet potato chunks brushed with olive oil, salt, pepper, and rosemary. Ready for the oven.

Discussion

As measured at six months, the paleo dieters lost 10% of their initial body weight, compared to 5% in the NNR group. That’s worth something to many folks. However, the researchers didn’t find much, if any, difference in the groups in terms of cardiometabolic risk factors. They wonder if that reflects the baseline healthiness of these women. Would a sicker study population show more improvement on one of the diets?

I’m surprised the NNR group lost any weight at all. In my experience it’s hard for most folks to lose weight and keep it off while eating as much as they want, unless they’re eating very-low-carb. We’ve seen short-term weight loss with ad libitum paleo diets before (here for example, and here, and here). I bet the women signing up for this study were highly motivated to change. 

Legumes and potatoes are a debatable part of the paleo diet. Most versions exclude legumes. We don’t know if these women ate legumes and potatoes. Other than this oversight, the study paleo diet is reasonable.

The authors noted that the paleo diet group failed to reach their protein intake goal (30% of total calories), and suggested reasons “such as protein-rich foods being more expensive, social influences on women’s food choices or a lower food preference for protein-rich food among women.”

The results of this study may or may not apply to other population subgroups and non-Swedes.

The authors write:

In conclusion, a Palaeolithic-type diet during two years with ad libitum intake of macronutrients, including an increased intake of polyunsaturated fatty acids and monounsaturated fatty acids reduces fat mass and abdominal obesity with significantly better long-term effect on triglyceride levels vs an NNR diet. Adherence to the prescribed protein intake was poor in the PD group suggesting that other component of the PD diet are of greater importance.

Does this study have anything to do with diabetes? Not directly. But it suggests that if an overweight diabetic needs to lose excess body fat without strict calorie control, a lower-carb paleo-style diet may be more effective than a low-fat, higher-carb diet. I would have liked to have seen lower fasting blood sugar and insulin levels in the paleo dieters, but wishing doesn’t make it so.

Steve Parker, M.D.

PS: Carbsane Evelyn has taken a look at this study and blogged about it here and here. I’ve not read those yet, but will now.

Reference: Mellberg, C., et al (including M. Ryberg and T Olsson). Long-term effects of a Palaeolithic-type diet in obese postmenopausal women: a 2-year randomized trial. European Journal of Clinical Nutrition, advance online publication January 29, 2014. doi: 10.1038/ejcn.2013.290

Notable Quotes From Kuipers’ “Multidisciplinary Reconstruction of Palaeolithic Nutrition”

Australian Aborigine in Swamp Darwin

I scored of copy of “A multidisciplinary reconstruction of Palaeolithic nutrition that holds promise for the prevention and treatment of diseases of civilisation” by RS Kuipers, JCA Joordens, and FAJ Muskiet. I’m not going to review it here. I’m just assembling some interesting “facts” for my files, so this could be boring. You won’t offend me much if you stop reading now.

This paper is from the University Medical Center Groningen and Human Origins Group (Faculty of Archaeology, Leiden University), both in The Netherlands. It’s 23 pages long, not counting the 450 references.

I’ll following the spelling conventions of the paper’s publisher.

Introduction

“…our genome has remained basically unchanged since the beginning of the Palaeolithic era.”

“Since the onset of the Agricultural Revolution, some 10 thousand years ago, and notably in the last 200 years following the start of the Industrial Revolution, humans have markedly changed their dietary habits. Consequently, it has been advocated that the current pandemic of diseases of civilization results in part from the mismatch between the current diet and our Palaeolithic genome.”

These are some of the diseases that may result from the mismatch of our Palaeolithic genome and modern lifestyle (including diet): type 2 diabetes, high blood pressure, osteoporosis, fertility problems (polycystic ovary syndrome), pregnancy complications (pre-eclampsia, gestational diabetes), some cancers (colon, breast, prostate), heart disease (such as coronary artery disease), major and postpartum depression, autism, schizophrenia, some neurodegenerative diseases (Parkinsons disease, Alzheimer’s disease). [Sorry, Dr. Cordain – no mention of acne. And I wonder about dental and eye problems.]

Evolutionary Medicine

“Many, if not all, diseases can become explained [sic] by both proximate and ultimate explanations. The science searching for the late explanations has become known as ‘evolutionary medicine.’ Unfortunately, modern medicine deals mostly with proximate explanations, while ultimate explanations seem more prudent targets for long-time disease prevention.”

The term “evolutionary medicine” was coined by Randolph M. Nesse and George C. Williams in the early 1990s. It’s also called Darwinian medicine.

“…about 20% of modern hunter-gatherers reach at least the age of 60 years.”

After the transition to the Agricultural Revolution about 10,000 years ago, life expectancy fell from about 40 years to about 20 years. This is astounding news to me, assuming it’s accurate.  (Remember that for most of human existence, infant and child mortality has been very high. If an infant dies at 6 months old and an adult dies at 40 years, average life expectancy for the two would be about 20 years.)

Average life expectancy among modern hunter-gatherers is about 40 years—same as it was for students of the Harvard College class born in 1880.

Life expectancy in the Neolithic era was stable until the late 18th century, rarely exceeding 25 years in civilized nations.  At that point, life expectancy started to improve dramatically thanks to sanitation, water and food hygiene, immunizations, and quarantine practices. (Thomas Jefferson was the third president of the U.S.  His wife Martha had six children but only two survived to adulthood.)

The earliest species in the genus Homo appeared about  two million years ago.   Homo sapiens appeared about 200,000 years ago in south or east Africa. Several different hominin lines co-existed with modern humans.

The current world population of humans may be derived for only 1000 or so individuals that survived a decimating event.

The ability to store fat is one of the things that differentiate us from other primates.

Hunting and Our Ancient Diet

The composition of the early human diet is still hotly debated.

Lotta work to snag one of these

In modern hunter-gatherers, only about 30% of diet energy is derived from hunting, with the rest coming from gathering plant food and aquatic animals.

In contrast to the arid, hot, iconic savanna, “…the combined evidence strongly suggests that early hominins frequented the land-water ecosystem and thus lived there.” If rainfall and other conditions allowed, there would be wooded grasslands.

“…the proportion of the human gut dominated by the small intestine (>56%) suggests adaptation to a diet that is highly digestible, indicating a closer structural analogy with carnivores than to [animals that eat leaves and fruit].”

“The data of combined studies of early hominins and the more recent hominins suggest a gradual increase in dietary animal protein, a part of which may derive from aquatic resources. In the more recent human ancestors, a substantial part of the dietary protein was irrefutably derived from marine resources, and this habit was only abandoned in some cases after the introduction of agriculture at the onset of the Neolithic.”

Sea levels have risen over the past 17,000 years, up to 150 meters.

“In conclusion, there is ample archeological evidence for a shift from the consumption of plant towards animal foods.”

“For a long time period in hominin evolution, hominins derived large amounts of energy from (terrestrial and aquatic) animal fat and protein. This habit became reversed only by the onset of the Neolithic Revolution in the Middle East starting about 10,000 years ago.”

“The Homo genus has been on earth for at least 2.4 million years and for over 99% of this period has lived as hunter-gatherers.”

“We conclude that gathering plays, and most likely always played, the major role in food procurement of humans. Although hunting doubtlessly leaves the most prominent signature in the archaeological record, gathering of vegetables and the collection of animal, notably aquatic, resources (regardless of whether their collection is considered as either hunting or gathering), seems much easier compared with hunting on the hot and arid savanna. We suggest that it seems fair to consider these types of foods as an important part of the human diet, unless proven otherwise. Conversely, while hunting might have played a much more important role at higher latitudes, dietary resources in these ecosystems are rich in n-3-fatty acids (for example, fatty fish and large aquatic mammals), while the hominin invasion of these biomes occurred only after the development of more developed hunting skills.”

Even though traditional Maasai showed extensive atherosclerosis with fibrous changes and lipid infiltration, they had very few complicated arterial lesions and rarely had clinical cardiovascular disease events.

The Agricultural and Industrial Revolutions

“Contrary to earlier belief, the advent of agriculture coincided with an overall decline in nutrition and general health, but at the same time provided an evolutionary advantage since it increased birth rates and thereby promoted net population growth.”  [Both supporting references are from CS Larsen.]

Good news for birth rates

With the advent of the Industrial Revolution, nutritional quality and general health declined even more rapidly.

“Among the many dietary and lifestyle changes are: a grossly decreased n-3:n-6 fatty acid ratio, the combined high intakes of saturated fatty acids and carbohydrates, the introduction of industrially produced trans-fatty acids, reduced intakes of n-3 and n-6 long-chain polyunsaturated fatty acids, reduced exposure to sunlight, low intakes of vitamins D and K, disbalanced anti-oxidant status and high intakes of carbohydrates with high glycaemic indices and loads, such as sucrose and industrially produced high-fructose maize syrup.”  [Aren’t we eating more n-6 fatty acids, not less?]

Potential Benefits of a Palaeolithic Diet

The authors conclude with a review of the few medical scientific studies of Palaeolithic diets in modern humans. These are the ones by Frassetto, Osterdahl, Jönsson, and Lindeberg. I’ve already reviewed those here.  They missed O’Dea and Kerin’s study.

My Overall Impressions

This article seems very well researched.  It lays out a logical framework for the discipline of evolutionary medicine and should spur further clinical research.  It’s well worth a read if you have more than a passing interest in paleo lifestyle theory.

Bear in mind I’m not a paleontologist, anthropologist, paleo-anthropologist, or archeologist.  So caveat lector.

Steve Parker, M.D.  (B.S. degree in zoology)

Reference: Kuipers,RS; Joordens, JCA; and Muskiet, FAJ. A multidisciplinary reconstitution of Palaeolithic nutrition that holds promise for the prevention and treatment of diseases of civilization. Nutrition Research Reviews, 25 (2012): 96-129.  doi: 10.1017/S0954422412000017

PS: The Paleolithic diet is also called paleo, ancestral, hunter-gatherer, Stone Age,  Old Stone Age, and caveman diet.