Category Archives: Uncategorized

Why Does Body Size Vary Geographically?

Paleo diet proponents may be interested in the article below. I new that Norwegians tended to be very tall, but didn’t know that folks from the Netherlands and Balkan countries were taller.

I don’t know much about deer and elk hunting, but my impression is that colder climates tend to produce to larger animals.

Much larger than Coue’s deer we have in hot Arizona

Abstract:

Humans show marked variation in body size around the world, both within and among populations. At present, the tallest people in the world are from the Netherlands and the Balkan countries, while the shortest populations are central African Pygmies. There are genetic, genetic plasticity, developmental, and environmental bases for size variation in Homo sapiens from the recent past and the present. Early populations of Homo species also have shown considerable size variation. Populations from the present and the past are also marked by sexual dimorphism, which, itself, shows group variation. There is abundant evidence for the effects of limited food and disease on human growth and resultant adult body size. This environmental influence has been reflected in “secular trends” (over a span of years) in growth and adult size from socioeconomic prosperity or poverty (availability of resources). Selective and evolutionary advantages of small or large body size also have been documented. Heritability for human height is relatively great with current genome-wide association studies (GWAS) identifying hundreds of genes leading to causes of growth and adult size variation. There are also endocrinological pathways limiting growth. An example is the reduced tissue sensitivity to human growth hormone (HGH) and insulin-like growth factor (IGF-1) in Philippine and African hunter-gatherer populations. In several short-statured hunter-gatherer populations (Asian, African, and South American), it has been hypothesized that short life expectancy has selected for early maturity and truncated growth to enhance fertility. Some island populations of humans and other mammals are thought to have been selected for small size because of limited resources, especially protein. The high-protein content of milk as a staple food may contribute to tall stature in East African pastoral peoples. These and other evolutionary questions linked to life history, male competition, reproduction, and mobility are explored in this paper.

Source: Evolutionary Strategies for Body Size. – PubMed – NCBI

Steve Parker, M.D.

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Would We Be Healthier If We Imitated the Resting Postures of Hunter-Gatherers?     #squatting

Should she be squatting instead? Is sitting the new smoking?

An abstract from Science Advances:

Recent work suggests human physiology is not well adapted to prolonged periods of inactivity, with time spent sitting increasing cardiovascular disease and mortality risk. Health risks from sitting are generally linked with reduced levels of muscle contractions in chair-sitting postures and associated reductions in muscle metabolism. These inactivity-associated health risks are somewhat paradoxical, since evolutionary pressures tend to favor energy-minimizing strategies, including rest. Here, we examined inactivity in a hunter-gatherer population (the Hadza of Tanzania) to understand how sedentary behaviors occur in a nonindustrial economic context more typical of humans’ evolutionary history. We tested the hypothesis that nonambulatory rest in hunter-gatherers involves increased muscle activity that is different from chair-sitting sedentary postures used in industrialized populations. Using a combination of objectively measured inactivity from thigh-worn accelerometers, observational data, and electromygraphic data, we show that hunter-gatherers have high levels of total nonambulatory time (mean ± SD = 9.90 ± 2.36 h/d), similar to those found in industrialized populations. However, nonambulatory time in Hadza adults often occurs in postures like squatting, and we show that these “active rest” postures require higher levels of lower limb muscle activity than chair sitting. Based on our results, we introduce the Inactivity Mismatch Hypothesis and propose that human physiology is likely adapted to more consistently active muscles derived from both physical activity and from nonambulatory postures with higher levels of muscle contraction. Interventions built on this model may help reduce the negative health impacts of inactivity in industrialized populations.

Source: Sitting, squatting, and the evolutionary biology of human inactivity. – PubMed – NCBI

Weight-Loss Pill Lorcaserin Linked to Cancer

From the U.S. Food and Drug Administration:

ISSUE: FDA has requested that the manufacturer of Belviq, Belviq XR (lorcaserin) voluntarily withdraw the weight-loss drug from the U.S. market because a safety clinical trial shows an increased occurrence of cancer. The drug manufacturer, Eisai Inc,. has submitted a request to voluntarily withdraw the drug. When FDA approved lorcaserin in 2012, we required the drug manufacturer to conduct a clinical trial to evaluate the risk of cardiovascular problems. A range of cancer types was reported, with several different types of cancers occurring more frequently in the lorcaserin group, including pancreatic, colorectal, and lung.

BACKGROUND: In January 2020, FDA announced we were reviewing clinical trial data and alerted the public about a possible risk of cancer associated with lorcaserin based on preliminary analysis of the data.

RECOMMENDATION: PatientsPatients should stop taking lorcaserin and talk to your health professionals about alternative weight-loss medicines and weight management programs.

Source: Belviq, Belviq XR (lorcaserin) by Eisai: Drug Safety Communication – FDA Requests Withdrawal of Weight-Loss Drug | FDA

Steve Parker, M.D.

PS: I think there are better alternatives to pills for weight loss.

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No: Should Your DNA or  Gut Microbiome Determine What You Eat or Your Nutritional Supplements?

I take this to help control blood pressure

From Scott Gavura at Science Based Medicine:

Our ability to collect DNA data is progressing quickly, and in time we may have more evidence to inform decisions about nutrition and possibly even supplements. At this time, however, there is a big gap between what we know, and what, if anything, to do with that information. You don’t need a DNA test or a stool sample to know that eating a varied, healthy diet, minimizing highly processed foods, eliminating trans fats, and keeping alcohol consumption moderate are reasonable approaches to designing your diet. It’s worth noting again, as we have blogged about many times before, that the evidence for taking supplementary vitamins, in general, is neutral to negative. In the absence of a specific medical need (e.g., pregnancy) there a few circumstances where routine supplementation is necessary or warranted. There is no robust evidence to date to show that personalized, “DNA-based” or “microbiome-based” nutritional recommendations give useful, actionable nutrition advice that actually improve health outcomes.

Source: “DNA-based” personalized nutrition advice: Not ready for prime time – Science-Based Medicine

Hucksters use sciency terms to convince you they know the best weight-loss diet or supplements for you. Don’t believe it.

Steve Parker, M.D.

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Paleo Ketogenic Diet Put Crohn’s Disease Into Remission

Have you ever tried to catch a wild rabbit by hand?

The study at hand is an isolated case report, so we can’t get too excited about it. But it does suggest that a “paleolithic ketogenic diet” may be helpful in Crohn’s disease. “Carnivore diet” may be a better description of the treatment.

The problem with case reports is that an individual’s response to intervention may simply reflect placebo effect or spontaneous improvement of the underlying condition, rather than a true response to the treatment applied.

Crohn’s disease is one of two “inflammatory bowel diseases,” the other being ulcerative colitis. Both of these are felt to be autoimmune, meaning the body is attacking its own tissues as if they were foreign invaders, like germs. Crohn’s disease causes abdominal pain, diarrhea (sometimes bloody), bloating, nausea, malnutrition, and other effects. Ulcerative colitis is similar in presentation. I wrote many years ago about a paleo diet improving at least one case of ulcerative colitis.

Moving along….

Hungarian physicians (?) reported a case of a 16-year-old who was diagnosed with Crohn’s disease at age 14 and wasn’t doing well at all despite standard medical therapy. At one point, intestinal surgery was recommended but he (or his parents) declined.

On the paleolithic ketogenic diet, the patient went into remission within months, off medications, and has been in remission for 15 months. The patient’s BMI rose from 17.7 to 19.5.

So, what was this diet?

  • “animal fat, meat, offal and eggs with an approximate 2:1 fat:protein ratio” [is that ratio grams or calories? Not stated]
  • no grains, milk, dairy, refined sugars, vegetable oils, oilseeds (sic), nightshades, and artificial sweeteners
  • honey OK in small amounts
  • poultry OK but discouraged
  • at one point the patient added small amounts of vegetables and fruits but the authors favor “no plants at all”
  • no supplements

The authors mention good ol’ Walter Voegtlin, author of 1975’s The Stone Age Diet. Voegtlin, by the way, was or is a gastroenterologist. Here’s an iconoclastic quote from Voegtlin.

Why did this carnivore diet seem to work? The authors propose it improves the pathological intestinal permeability seen in Crohn’s disease.

This is a radical diet compared to the Standard American Diet featuring dairy, grains, industrial seed oils, and ultra-processed foods. As usual, check with your personal physician before making any radical diet change. Odds are, however, your doctor doesn’t know much about this diet and won’t approve.

Steve Parker, M.D.

h/t P.D. Mangan

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Is Either Politically Correct?: PWT1D or PWT2D

paleobetic diet, low-carb diet

Totally unrelated: Waldorfian salad. Hit the search box for recipe and nutritional analysis.

A decade ago, some folks began to object being called diabetics. Instead, they proposed “person with diabetes” or “people with diabetes.” Or simply PWD.

Given the major differences between type 1 and type 2 diabetes, I now propose PWT1D (person or people with type 1 diabetes) and PWT2D.

And so no one’s left out: PWLADA. Person with Latent Autoimmune Diabetes in Adulthood.

Whadda u think?

Steve Parker, M.D.

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U.S. Life Expectancy Decreasing

Sir John Glubb studied various empires that existed over the last 4,000 years. He deduced that empires have predictable lifecycles, from origin to ascendence, to great power then decline and collapse. I’m not the only one to notice that the U.S. may be on the decline. Decreasing life expectancies are a potential marker of decline. Glubb died in 1986 at the age of 88.

From JAMA Network:

U.S. life expectancy increased for most of the past 60 years, but the rate of increase slowed over time and life expectancy decreased after 2014. A major contributor has been an increase in mortality from specific causes (eg, drug overdoses, suicides, organ system diseases) among young and middle-aged adults of all racial groups, with an onset as early as the 1990s and with the largest relative increases occurring in the Ohio Valley and New England. The implications for public health and the economy are substantial, making it vital to understand the underlying causes.

Source: Life Expectancy and Mortality Rates in the United States, 1959-2017 | Population Health | JAMA | JAMA Network

Steve Parker, M.D.

PS: Maybe we’d live longer if we ate food congruent with our evolution instead ultra-processed man-made foods.

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Merry Christmas, Everyone!

Credit: Zvonimir Atletic / Shutterstock.com

1 in 4 Young Adults in U.S. Has Prediabetes

I’m worried about the kid’s future health

Stats from JAMA Pediatics:

In the United States, about 1 of 5 adolescents [12-18 y.o.] and 1 of 4 young adults [19-34 y.o.] have prediabetes. The adjusted prevalence of prediabetes is higher in male individuals and in people with obesity. Adolescents and young adults with prediabetes also present an unfavorable cardiometabolic risk profile, putting them both at increased risk of type 2 diabetes and cardiovascular diseases.

Source: Prevalence of Prediabetes Among Adolescents and Young Adults in the United States, 2005-2016. – PubMed – NCBI

I’m doing my part to prevent conversion of prediabetes to type 2 diabetes.

Steve Parker, M.D.

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The Bees Have Recovered!

We had one of these swarms in our front yard a few years ago for several weeks. Yes, that’s hundreds of bees. And most in Arizona are Africanized.

Remember 8–10 years ago when scientists told us that bee colonies were mysteriously disappearing. My recollection is that they called it “colony decline syndrome.” Maybe caused by pesticides or other pollution. If the trend continued, crops wouldn’t be pollinated and we’d starve to death. Apocalypse within a few years.

Looks harmless enough, right?

Turns out it was Fake News. Thank God.

Another reason for science skepticism.

Steve Parker, M.D.

PS: See details at Issues & Insights, the source of the graphs above.

PPS: My recollection was wrong; they called it Colony Collapse Disorder.

Steve Parker MD, Advanced Mediterranean Diet

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