Another Estimate of Paleolithic Man’s Diet

Not many edible leafy greens around this time of year

I see no reason to disagree with this abstract.


We review the evolutionary origins of the human diet and the effects of ecology economy on the dietary proportion of plants and animals. Humans eat more meat than other apes, a consequence of hunting and gathering, which arose ∼2.5 Mya with the genus Homo. Paleolithic diets likely included a balance of plant and animal foods and would have been remarkably variable across time and space. A plant/animal food balance of 40-60% prevails among contemporary warm-climate hunter-gatherers, but these proportions vary widely. Societies in cold climates, and those that depend more on fishing or pastoralism, tend to eat more meat. Warm-climate foragers, and groups that engage in some farming, tend to eat more plants. We present a case study of the wild food diet of the Hadza, a community of hunter-gatherers in northern Tanzania, whose diet is high in fiber, adequate in protein, and remarkably variable over monthly timescales. Expected final online publication date for the Annual Review of Nutrition, Volume 41 is September 2021. Please see for revised estimates.

Dietary Salt Restriction Lowers Blood Pressure in Type 2 Diabetes

A pinch of salt may cut the bitterness in a cup of coffee

Yes, according to an article in Nutrition, Metabolism & Cardiovascular Disease. The systolic pressure lowering is 5-6 points, but only 1-2 points on average for diastolic pressure. This degree of BP lowering is not dramatic, but might prevent an escalation of antihypertensive drug dosing or initiation of an additional drug.

Steve Parker, M.D.

Is the Paleo Diet the Easiest to Stick With?

I’ve never eaten rabbit, but would try it. A patient in Florida cooked squirrel for me. Tastes like chicken, as I recall.

An article at Public Health Nutrition suggests that, yes, the paleo diet is one of the last to be abandoned. I’m not paying the $35 for access to the full article, so I don’t know which diets were considered. I assume all the popular ones.


Objective: To use Internet search data to compare duration of compliance for various diets.

Design: Using a passive surveillance digital epidemiological approach, we estimated the average duration of diet compliance by examining monthly Internet searches for recipes related to popular diets. We fit a mathematical model to these data to estimate the time spent on a diet by new January dieters (NJD) and to estimate the percentage of dieters dropping out during the American winter holiday season between Thanksgiving and the end of December.

Setting: Internet searches in the USA for recipes related to popular diets over a 15-year period from 2004 to 2019.

Participants: Individuals in the USA performing Internet searches for recipes related to popular diets.

Results: All diets exhibited significant seasonality in recipe-related Internet searches, with sharp spikes every January followed by a decline in the number of searches and a further decline in the winter holiday season. The Paleo diet had the longest average compliance times among “new January dieters” (5.32 ± 0.68 weeks) and the lowest dropout during the winter holiday season (only 14 ± 3 % dropping out in December). The South Beach diet had the shortest compliance time among NJD (3.12 ± 0.64 weeks) and the highest dropout during the holiday season (33 ± 7 % dropping out in December).

Conclusions: The current study is the first of its kind to use passive surveillance data to compare the duration of adherence with different diets and underscores the potential usefulness of digital epidemiological approaches to understanding health behaviours.

Steve Parker, M.D.

Introducing the “Paleo Ratio” as an Assessment of Paleo Diet Compliance

The study at hand did not find an improvement in hemoglobin A1c in type 2 diabete after 12 weeks of intervention. I’m surprised. I haven’t read the whole report yet.


This study is a secondary analysis of a randomized controlled trial using Paleolithic diet and exercise in individuals with type 2 diabetes. We hypothesized that increased adherence to the Paleolithic diet was associated with greater effects on blood pressure, blood lipids and HbA1c independent of weight loss. Participants were asked to follow a Paleolithic diet for 12 weeks and were randomized to supervised exercise or general exercise recommendations. Four-day food records were analyzed, and food items characterized as “Paleolithic” or “not Paleolithic”. Foods considered Paleolithic were lean meat, poultry, fish, seafood, fruits, nuts, berries, seeds, vegetables, and water to drink; “not Paleolithic” were legumes, cereals, sugar, salt, processed foods, and dairy products. A Paleo ratio was calculated by dividing the Paleolithic calorie intake by total calorie intake. A multiple regression model predicted the outcome at 12 weeks using the Paleo ratio, group affiliation, and outcome at baseline as predictors.

The Paleo ratio increased from 28% at baseline to 94% after the intervention. A higher Paleo ratio was associated with lower fat mass, BMI, waist circumference, systolic blood pressure, and serum triglycerides at 12 weeks, but not with lower HbA1c levels. The Paleo ratio predicted triglyceride levels independent of weight loss (p = 0.046). Moreover, an increased monounsaturated/saturated fatty acids ratio and an increased polyunsaturated/saturated fatty acids ratio was associated with lower triglyceride levels independent of weight loss. (p = 0.017 and p = 0.019 respectively).

We conclude that a higher degree of adherence to the Paleolithic diet recommendations improved fat quality and was associated with improved triglyceride levels independent of weight loss among individuals with type 2 diabetes.

Source: Using a Paleo Ratio to Assess Adherence to Paleolithic Dietary Recommendations in a Randomized Controlled Trial of Individuals with Type 2 Diabetes – PubMed

Steve Parker, M.D.

Paleo Diet Effect on Athletes

hunter, hunting, prehistoric, paleo diet, caveman, saber-toothed tiger, cavewoman

Judging from the article abstract below, it looks like the researchers didn’t find any major impact of the paleo diet on athletic performance, compared to “healthy” control diets. The title of the scientific report is “Paleolithic Diet-Effect on the Health Status and Performance of Athletes?” That sure made me think they were going to look at athletic performance. Here’s one of two sentences in the abstract that refer to athletic performance: “Lower positive impact of paleo diet on performance was observed it the group without exercise.” What does that even mean? Looks like even scientific journals are using click-bait now.

Before you read the abstract, remember that higher blood triglycerides, total cholesterol, and LDL cholesterol are linked in some studies to cardiovascular disease. Also, lower plasma glucose (sugar) and insulin levels are linked in some studies to less risk of cardiovascular disease. So the paleo diet may be healthful since it shifts those numbers in the right direction.

The aim of this meta-analysis was to review the impact of a Paleolithic diet (PD) on selected health indicators (body composition, lipid profile, blood pressure, and carbohydrate metabolism) in the short and long term of nutrition intervention in healthy and unhealthy adults. A systematic review of randomized controlled trials of 21 full-text original human studies was conducted. Both the PD and a variety of healthy diets (control diets (CDs)) caused reduction in anthropometric parameters, both in the short and long term. For many indicators, such as weight (body mass (BM)), body mass index (BMI), and waist circumference (WC), impact was stronger and especially found in the short term. All diets caused a decrease in total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and triglycerides (TG), albeit the impact of PD was stronger. Among long-term studies, only PD cased a decline in TC and LDL-C. Impact on blood pressure was observed mainly in the short term. PD caused a decrease in fasting plasma (fP) glucose, fP insulin, and homeostasis model assessment of insulin resistance (HOMA-IR) and glycated hemoglobin (HbA1c) in the short run, contrary to CD. In the long term, only PD caused a decrease in fP glucose and fP insulin. Lower positive impact of PD on performance was observed in the group without exercise. Positive effects of the PD on health and the lack of experiments among professional athletes require longer-term interventions to determine the effect of the Paleo diet on athletic performance.


Click for the full text article. The article title and abstract were so poorly written that I’m not wasting time on the full text. Let me know if you find anything interesting. Furthermore, this “research” was a meta-analysis, so I’m even more skeptical about any conclusions on athletic performance.

Steve Parker, M.D.

Paleo Diet Reduced Body Fat and Waist Circumference

Paleolithic populations weren’t plagued by overweight and obesity

An extremely small study of only seven healthy inactive experimental subjects (BMI 29.4. so almost obese, average age 32) found a drop in BMI to 27.7 but no change in the measured adipokines while following a paleo diet for eight weeks. The investigators write, “Adipokines are considered a class of biomarkers indicative of health and metabolic disease. They are secreted from adipose tissue and act in an autocrine, paracrine, or endocrine manner and have been implicated in the regulation of metabolic health and eating behaviors.”

Here’s a link to the full text article in International Journal of Exercise Science. The abstract:

The Paleolithic diet, characterized by an emphasis on hunter-gatherer type foods accompanied by an exclusion of grains, dairy products, and highly processed food items, is often promoted for weight loss and a reduction in cardiometabolic disease risk factors. Specific adipokines, such as adiponectin, omentin, nesfatin, and vaspin are reported to be dysregulated with obesity and may respond favorably to diet-induced fat loss. We aimed to evaluate the effects of an eight-week Paleolithic dietary intervention on circulating adiponectin, omentin, nesfatin, and vaspin in a cohort of physically inactive, but otherwise healthy adults.

Methods: Seven inactive adults participated in eight weeks of adherence to the Paleolithic Diet. Fasting blood samples, anthropometric, and body composition data were collected from each participant pre-and post-intervention. Serum adiponectin, omentin, nesfatin, and vaspin were measured. Results: After eight weeks of following the Paleolithic diet, there were reductions (p<0.05) in relative body fat (−4.4%), waist circumference (− 5.9 cm), and sum of skinfolds (−36.8 mm). No changes were observed in waist to hip ratio (WHR), or in adiponectin, omentin, and nesfatin (p>0.05), while serum vaspin levels for all participants were undetectable.

Conclusions: It is possible that although eight weeks resulted in modest body composition changes, short-term fat loss will not induce changes in adiponectin, omentin, and nesfatin in apparently healthy adults. Larger, long-term intervention studies that examine Paleolithic diet-induced changes across sex, body composition, and in populations with metabolic dysregulation are warranted.

Steve Parker, M.D.

High Blood Pressure: How Low Should You Go?

Not a bad monitor

First, remember that blood pressure is reported as two numbers: systolic and diastolic. E.g., 135/92. The first number is the systolic number. A systolic pressure goal of under 120 mmHg may be better than the traditional goal of under 140, at least if you’re “at increased risk for cardiovascular disease.” The study at hand excluded folks with diabetes or prior stroke.

We randomly assigned 9,361 participants who were at increased risk for cardiovascular disease but did not have diabetes or previous stroke to adhere to an intensive treatment target (systolic blood pressure, <120 mm Hg) or a standard treatment target (systolic blood pressure, <140 mm Hg). The primary outcome was a composite of myocardial infarction, other acute coronary syndromes, stroke, acute decompensated heart failure, or death from cardiovascular causes. Additional primary outcome events occurring through the end of the intervention period (August 20, 2015) were adjudicated after data lock for the primary analysis. We also analyzed post-trial observational follow-up data through July 29, 2016.


At a median of 3.33 years of follow-up, the rate of the primary outcome and all-cause mortality during the trial were significantly lower in the intensive-treatment group than in the standard-treatment group (rate of the primary outcome, 1.77% per year vs. 2.40% per year; hazard ratio, 0.73; 95% confidence interval [CI], 0.63 to 0.86; all-cause mortality, 1.06% per year vs. 1.41% per year; hazard ratio, 0.75; 95% CI, 0.61 to 0.92). Serious adverse events of hypotension, electrolyte abnormalities, acute kidney injury or failure, and syncope were significantly more frequent in the intensive-treatment group. When trial and post-trial follow-up data were combined (3.88 years in total), similar patterns were found for treatment benefit and adverse events; however, rates of heart failure no longer differed between the groups.

Click for article abstract at NEJM.

Steve Parker, M.D.

I Appreciate Your Support!

I published my first book in 2007 to extend my healing reach beyond the confines of the clinic and hospital room. I’m certain my writing has improved the health of many folks I’ll never know about, and that means more to me than any financial success I’ve had with the books. 

In 2020, my net profit from writing was $937.08, which is admittedly pitiful. The prior year’s net profit was $5,802.48. Pandemic effect, maybe? To lower my expenses in 2021, I’ll look into a private PO box instead of US Postal Service ($168/year), drop Amazon Prime ($129/year), and negotiate lower fees with Network Solutions.

I am blessed to have a hospitalist job that pays well. COVID-19 has caused major economic hardship for many of you, including unemployment.

My primary means of advertising has been blogging. Cross-posting on Facebook, Twitter, and LinkedIn has done almost nothing for book sales. A few years ago I could give my hospital patients a business card with links to my books, but my employer insisted I stop. 

If you care to support my writing, buy a book. If not for yourself, then for someone you care about. 

Steve Parker, M.D.

PS: All my books are here and at

PPS: Guesstimating my combined federal and state taxes being 40%, I have $562.25 left after paying taxes. And don’t forget sales tax on many things I might buy. 

Is “evolutionary-concordance lifestyle” the new “paleo diet”?

From the March 6, 2021, European Journal of Nutrition:

Sedentary lifestyle NOT an option back then


Evolutionary discordance may contribute to the high burden of chronic disease-related mortality in modern industrialized nations. We aimed to investigate the associations of a 7-component, equal-weight, evolutionary-concordance lifestyle (ECL) score with all-cause and cause-specific mortality.


Baseline data were collected in 2003-2007 from 17,465 United States participants in the prospective Reasons for Geographic and Racial Differences in Stroke (REGARDS) study. The ECL score’s components were: a previously reported evolutionary-concordance diet score, alcohol intake, physical activity, sedentary behavior, waist circumference, smoking history, and social network size. Diet was assessed using a Block 98 food frequency questionnaire and anthropometrics by trained personnel; other information was self-reported. Higher scores indicated higher evolutionary concordance. We used multivariable Cox proportional hazards regression models to estimate ECL score-mortality associations.


Over a median follow-up of 10.3 years, 3771 deaths occurred (1177 from cardiovascular disease [CVD], 1002 from cancer). The multivariable-adjusted hazard ratios (HR) (95% confidence intervals [CI]) for those in the highest relative to the lowest ECL score quintiles for all-cause, all-CVD, and all-cancer mortality were, respectively, 0.45 (0.40, 0.50), 0.47 (0.39, 0.58), and 0.42 (0.34, 0.52) (all P trend < 0.01). Removing smoking and diet from the ECL score attenuated the estimated ECL score-all-cause mortality association the most, yielding fifth quintile HRs (95% CIs) of 0.56 (0.50, 0.62) and 0.50 (0.46, 0.55), respectively.


Our findings suggest that a more evolutionary-concordant lifestyle may be inversely associated with all-cause, all-CVD, and all-cancer mortality. Smoking and diet appeared to have the greatest impact on the ECL-mortality associations.

Source: A novel evolutionary-concordance lifestyle score is inversely associated with all-cause, all-cancer, and all-cardiovascular disease mortality risk – PubMed

Steve Parker, M.D.

Some Diets Are Better Than Others at Lowering Blood Pressure

paleobetic diet, low-carb diet
Vegetarian: One cup of Waldorfian salad (search site for recipe)

Increasingly, I’m suspicious of results from meta-analyses. Anyway, here’s the abstract of one from American Journal of Clinical Nutrition in 2020. In case you’re like me and not familiar with the LDL-lowering, vegetarian, “portfolio diet,” click for an infographic.

Background: Many systematic reviews and meta-analyses have assessed the efficacy of dietary patterns on blood pressure (BP) lowering but their findings are largely conflicting.

Objective: This umbrella review aims to provide an update on the available evidence for the efficacy of different dietary patterns on BP lowering.

Methods: PubMed and Scopus databases were searched to identify relevant studies through to June 2020. Systematic reviews with meta-analyses of randomized controlled trials (RCTs) were eligible if they measured the effect of dietary patterns on systolic (SBP) and/or diastolic blood pressure (DBP) levels. The methodological quality of included systematic reviews was assessed by A Measurement Tool to Assess Systematic Review version 2. The efficacy of each dietary pattern was summarized qualitatively. The confidence of the effect estimates for each dietary pattern was graded using the NutriGrade scoring system.

Results: Fifty systematic reviews and meta-analyses of RCTs were eligible for review. Twelve dietary patterns namely the Dietary Approaches to Stop Hypertension (DASH), Mediterranean, Nordic, vegetarian, low-salt, low-carbohydrate, low-fat, high-protein, low glycemic index, portfolio, pulse, and Paleolithic diets were included in this umbrella review. Among these dietary patterns, the DASH diet was associated with the greatest overall reduction in BP with unstandardized mean differences ranging from -3.20 to -7.62 mmHg for SBP and from -2.50 to -4.22 mmHg for DBP. Adherence to Nordic, portfolio, and low-salt diets also significantly decreased SBP and DBP levels. In contrast, evidence for the efficacy of BP lowering using the Mediterranean, vegetarian, Paleolithic, low-carbohydrate, low glycemic index, high-protein, and low-fat diets was inconsistent.

Conclusion: Adherence to the DASH, Nordic, and portfolio diets effectively reduced BP. Low-salt diets significantly decreased BP levels in normotensive Afro-Caribbean people and in hypertensive patients of all ethnic origins.

Source: Efficacy of different dietary patterns on lowering of blood pressure level: an umbrella review – PubMed

Steve Parker, M.D.