Salivary amylase helps us digest starches like wheat
A recent scientific paper proposes that carbohydrates—starches specifically—played a larger role in the ancestral human diet than previously thought. I’ll call this paper the Hardy study since she’s the first named author. The only author I recognize is Jennie Brand-Miller, of glycemic index fame.
A key part of the hypothesis is that our ancestors’ use of fire made starchy foods much more digestible. That’s not controversial. Wrangham thinks hominins have been using fire for cooking for over a million years. Humans, remember, arrived on the scene about 200,000 years ago.
I’m not saying I agree or disagree with the researchers. Read the paper and decide for yourself. I do feel somewhat vindicated in my inclusion of potatoes and other tubers in my version of the Paleolithic diet.
Steve Parker, M.D.
PS: The article references the Pleistocene Epoch. You’ll find various definitions of that, but the Pleistocene ranged from about 1.8 million to 11,000 years ago .
Grain-based high-carb Neolithic food
The paleo diet averages about 30% of total calories from carbohydrates, with a range of about 22 to 40%. That 30% average is much lower than the standard 50–60% in the developed world. Is that lower percentage healthy or not? It depends on the quality of the carbs and the remainder of the diet. It most certainly can be healthy.
As much as possible, I base my nutrition and medical recommendations on science-based research published in the medical literature. In the early 2000s, a flurry of scientific reports demonstrated that very-low-carb eating (as in the style of Dr. Robert Atkins) was safe and effective for short-term weight management and control of diabetes. Eighty hours of literature review in 2009 allowed me to embrace low-carbohydrate eating as a logical and viable option for many of my patients. The evidence convinced me that the relatively high fat content of many low-carb diets was nothing to worry about long-term.
I’d like to share with you some of the pertinent low-carb research findings of the last few years.
- Low-carb diets reduce weight, reduce blood pressure, lower triglyceride levels (a healtlhy move), and raise HDL cholesterol (another good trend). These improvements should help reduce your risk of heart disease. (In the journal Obesity Reviews, 2012.)
- Dietary fat, including saturated fat, is not a cause of vascular disease such as heart attacks and atherosclerosis (hardening of the arteries). (Multiple research reports.)
- If you’re overweight and replace two sugary drinks a day with diet soda or water, you’ll lose about four pounds over the next six months. (American Journal of Clinical Nutrition, 2012.)
- United States citizens obtain 40% of total calories from grains and added sugars. Most developed countries are similar. Dr. Stephan Guyenet notes that U.S. sugar consumption increased steadily “…from 6.3 pounds [2.9 kg] per person per year in 1822 to 107.7 pounds [50 kg] per person in 1999. Wrap your brain around this: in 1822 we ate the amount of added sugar in one 12-ounce can of soda every five days, while today we eat that much sugar every seven hours.”
- A very-low-carb diet improves the memory of those with age-related mild cognitive impairment. Mild cognitive impairment is a precursor to dementia. (University of Cincinnati, 2012.)
- High-carbohydrate and sugar-rich diets greatly raise the risk of mild cognitive impairment in the elderly. (Mayo Clinic study published in the Journal of Alzheimers’ Disease, 2012.)
- Compared to obese low-fat dieters, low-carb dieters lose twice as much fat weight. (University of Cincinnati, 2011.)
- Diets low in sugar and refined starches are linked to lower risk of age-related macular degeneration in women. Macular degeneration is a major cause of blindness. (University of Wisconsin, 2011.)
- A ketogenic (very-low-carb) Mediterranean diet cures metabolic syndrome (Journal of Medicinal Food, 2011.)
- For type 2 diabetics, replacing a daily muffin (high-carb) with two ounces (60 g) of nuts (low-carb) improves blood sugar control and reduces LDL cholesterol (the “bad” cholesterol). (Diabetes Care, 2011.)
- For those afflicted with fatty liver, a low-carb diet beats a low-fat diet for management. (American Journal of Clinical Nutrition, 2011.)
- For weight loss, the American Diabetes Association has endorsed low-carb (under 130 g/day) and Mediterranean diets, for use up to two years. (Diabetes Care, 2011.)
- High-carbohydrate eating doubles the risk of heart disease (coronary artery disease) in women. (Archives of Internal Medicine, 2010.)
- One criticism of low-carb diets is that they may be high in protein, which in turn may cause bone thinning (osteoporosis). A 2010 study shows this is not a problem, at least in women. Men were not studied. (American Journal of Clinical Nutrition.)
- High-carbohydrate eating increases the risk of developing type 2 diabetes (American Journal of Clinical Nutrition, 2010.)
- Obesity in U.S. children tripled from 1980 to 2000, rising to 17% of all children. A low-carb, high-protein diet is safe and effective for obese adolescents. (American Journal of Clinical Nutrition, 2010.
Steve Parker, M.D.
PS: The paleo diet is also referred to as the caveman diet, Paleolithic diet, hunter-gatherer diet, Stone Age diet, and ancestral diet.
Posted in Dietary Carbohydrate, Heart Disease, Weight Loss
Tagged carbohydrate, caveman diet, hunter-gatherer diet, low-carb, low-carbohydrate, paleo diet, paleolithic diet, research, Stone Age diet
How many brain cells with this roll kill?
The Mayo Clinic recently reported that diets high in carbohydrates and sugar increase the odds of developing cognitive impairment in the elderly years.
Mild cognitive impairment is often a precursor to incurable dementia. Many authorities think dementia develops more often in people with diabetes, although some studies refute the linkage.
Researchers followed 940 patients with normal baseline cognitive functioning over the course of four years. Diet was assessed via questionnaire. Study participants were ages 70 to 89. As the years passed, 200 of them developed mild cognitive impairment.
Compared with those eating at the lowest level of carbohydrate consumption, those eating at the highest levels were almost twice as likely to go to develop mild cognitive impairment.
The scientists note that those eating lower on the carbohydrate continuum were eating more fats and proteins.
Steve Parker, M.D.
ScienceNordic has an article about the diet of Paleolithic humans who lived in what is now Denmark. It’s brief and written for the general public. The author mistakenly characterizes the “modern paleo” diet as no- or very-low-carb. It’s lower in carb content than the standard American diet, but by no means no-carb.
Dr. Jay Wortman has been thinking about whether our bodies prefer to run on carbohydrates (as a source of glucose) or, instead, on fats. The standard American diet provides derives about half of its energy from carbs, 35% from fats, and 15% from proteins. So you might guess our bodies prefer carbohydrates as a fuel source. Dr. Wortman writes:
Now, consider the possibility that we weren’t meant to burn glucose at all as a primary fuel. Consider the possibility that fat was meant to be our primary fuel. In my current state of dietary practice, I am burning fat as my main source of energy. My liver is converting some of it to ketones which are needed to fuel the majority of my brain cells. A small fraction of the brain cells, around 15%, need glucose along with a few other tissues like the renal cortex, the lens of the eye, red blood cells and sperm. Their needs are met by glucose that my liver produces from proteins. The rest of my energy needs are met with fatty acids and these come from the fats I eat.
Dr. Wortman, who has type 2 diabetes, in the same long post also writes about oolichan grease (from fish), an ancestral food of Canandian west coast First Nations people.
Drs. Jeff Volek and Stephen Finney have done research on athletes using a low-carb, high-fat diet.
Steve Parker, M.D.
Posted in Dietary Fat, Exercise, Low-Carb
Tagged athletes, carbohydrate, exercise, fat as energy source, fat metabolism, fatty acids, Jay Wortman, Jeff Volek, Stephen Phinney
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.