The Nutrition Debate #57: What is Ketogenic Nutrition?

A few months ago a very well read fellow blogger, Beth Mazur, commented on a post of mine. She said she shared my view that as lay bloggers we play a valuable intermediary role as generalists, or “foxes,” in a world of specialists, “the hedgehogs.” She was referring to a recent essay by Harry Rutter in The Lancet (sorry, log-in required). Rutter was referring to a popular 1953 essay, “The Hedgehog and the Fox,” by British philosopher Isaiah Berlin. It’s a good read.

In a separate post on her own blog, Weight Maven, Beth introduced me to Lucas Tafur with a piece he wrote on the “Old Friends Hypothesis,” referring to gut flora. Gut flora is an emerging and interesting area of nutrition research. It seems even my favorite MD, Kurt Harris, is telling us “to look at other things” besides “NAD’s.” Harris was referring to Neolithic Agents of Disease, his construct and original prescription of dietary constituents to avoid: wheat, fructose and Omega 6 fatty acids. His lengthy comment on Paleo Hacks, here, which Beth brought to my attention, was pretty cryptic, though. Harris’s thinking is apparently “evolving,” but that is one of the aspects I like best about his approach to dietary science.

Lucas Tafur is also an interesting story. Before he created the Luca Tafur site, his blog was called Ketogenic Nutrition. It is inactive now but still “up.” It provided me with a nostalgic look back at what proved for me to be a very effective way to lose weight (170 pounds). Tafur, whose bio is on both websites, quotes one of the world’s leading experts on ketone bodies, Dr. Richard L. Veech of the National Institutes of Health: "Doctors are scared of ketosis. They're always worried about diabetic ketoacidosis. But ketosis is a normal physiologic state. I would argue it is the normal state of man.” Put into context, in the continuum of our day-to-day existence, we’re either in a fed or a fasting state. The fed state begins with eating and continues until the food has been digested and absorbed. The fasting state then begins and continues until we eat again. When fasting, the body is said to be in ketosis.

When we are in a fed state, we derive our energy largely from glucose. This is called a glycogenic state. When we are in a fasting state, the body derives its energy from our fat stores, both from the liver and from our adipose (fat) tissue, which breaks down by lipolysis. Who can doubt that it has been that way for thousands of generations? We were hunters and gatherers, not grazers. That is the way we were “designed.”  For just a few generations, we have gone astray, with disastrous consequences. Of course, what has happened in the last few generations is not an evolutionary adaption; it is but an aberration. It is also a completely reversible change once we come to see and accept what “we” (complicit with our agricultural/industrial enterprise and the associated “public health” and media establishments) have done to ourselves. We can return to a fed and then fasting Way of Eating in which ketosis is one of “the normal states of man.”

The scenario: We hunted, we ate and we were satisfied. Think of the lion lying around after consuming a kill. After a while he became hungry and hunted again while he continued to get his energy from fat stores. The body shifted from being a “sugar burner” to a “fat burner.” As Dr. Veech said: “the normal state of man.” The fed state is when the body uses carbs to make glucose for energy. The fasting state is when the body uses fat to make ketone bodies for energy. But, as Tafur then points out, ketosis can “either be triggered by fasting or by diet.” Therein lies the key for us today.

The rest of this column is excerpted from Lucas Tafur’s Ketogenic Nutrition  website, where he provides footnotes as well: “Fasting ketosis develops after a few days of fasting, when liver glycogen stores are depleted. The body, as an acquired evolutionary mechanism, shifts from a glucose-based metabolism to a fat-based one.” “Studies have shown that the adaptive response to fasting is regulated not by energy restrictions per se, but by carbohydrate restriction. This is because the rate limiting enzyme of ketogenesis…is controlled by insulin levels.”

“The body’s main energy store is adipose tissue. Fat is more calorie-dense, meaning that it yields more energy per gram than glucose. Fat is the body’s preferred fuel, ketones being a “super fuel” that can be used by some tissues that haven’t evolved to use free fatty acids (FFA) such as the brain. Ketone bodies help the body spare amino acids by reducing the need for glucose. This way muscle mass is maintained…. Without ketosis, body protein stores would be cannibalized…. “

“The body stores fat primarily as saturated fat because it is metabolically more efficient than glucose and produces less toxic residues when metabolized. Exogenous glucose is the first substrate to be used because it is toxic to the body. It produces metabolic disregulation caused by hyperglycemia, which triggers an inflammatory and autoimmune response. Ketosis represents the opposite scenario; it protects the body during a life threatening situation like starvation.” (end)

So, Tafur gives a fine description of fasting ketosis, but what is dietary ketosis? It is the subject of the next column.

© Dan Brown 7/1/12

The Nutrition Debate #56: Metabolic Disregulation

Readers of Dr. Kurt Harris’s Archevore website may have noticed that at the end of the Archevore Diet tab there is a footnote, the last clause of which is “…or it may just be too late.” Since Dr. Harris is not currently blogging, this cryptic remark has me wondering: “just…too late” for what? Can he mean too late to restore “normal” carbohydrate metabolism? And, most importantly (naturally), I’d like to know if this alarming news applies to me. I wonder if Dr. Harris ever explained that comment in one of his posts. It is a hard subject to Google. What are the key words: “Just too late”?

Anyway, I have noticed that many bloggers in the ‘nutrisphere,’ including many of the most cutting-edge, scientific ones, have drifted away from low-carb to Paleo to Paleo with “safe carbs.” Most of these bloggers do not clearly differentiate between “healthy people” and people who have developed issues with metabolic regulation. Significantly, neither do the American Diabetes Association, the USDA’s Dietary Guidelines for Americans or the public health establishment in general. Just ask almost any traditionally-schooled “certified” dietician or Certified Diabetes Educator (CDE).

The current trend in nutrition blogs is “healthy eating,” a good thing, but insufficient for the rapidly growing percentage of the population who are becoming carbohydrate intolerant. This manifests itself in weight gain, of course, but also in associated lipoprotein and blood glucose disregulation, known collectively as Metabolic Syndrome. I wonder sometimes if the blogger/researcher/clinician does not him or herself suffer from metabolic disregulation. I do, and by changing what I eat I found a fix.  So I think this is worth blogging about at length.

The largest audience of “seekers” on diet-related matters, I’ve noticed, are those with a weight issue. They may be a little overweight, a lot overweight, obese or even morbidly obese, and they all want to lose weight effectively and permanently. I was and still am one of those. When I weighed 375 pounds I wanted to lose weight. When my doctor suggested Atkins, I had no idea I would eventually lose 170 pounds. Nor did I realize that I would dramatically improve my lipid health and my T2DM and my hypertension. Neither, however, did I imagine that I would later regain 70 of the pounds I had lost and ‘give back’ some of my health gains, except interestingly my lipid panel gains.

I know that weight loss is the primary area of readers’ interest because my blog, The Nutrition Debate, covers a wide subject area, but my most popular columns (which Blogger tracks for me) are about diets and weight-loss. The problem of losing weight and keeping it off is intractable. That is not to say that there is not also a very large audience of people out there generally who follow nutrition who have a keen interest in “healthy eating.” These include a large cohort who wishes to avoid the Diseases of Civilization and others like the Paleo/Ancestral Health movement, the slow food people, the CSA movement and the fitness community. All of these do not necessarily need, and are not looking for, a therapeutic diet, unlike those of us who already have damaged metabolisms.

 So, that is the distinction that I think has to be made. I enjoy reading about neurotransmitters and hormones and enzymes and the latest, “our old friends” the gut flora. However, for me personally, I am keenly interested in what it means “…to be just too late”. There is a failed mechanism in MY metabolism such that for me it is “just too late?” By whatever name -- insulin resistance, or impaired glucose tolerance, or carbohydrate intolerance, or leptin resistance, or some consequence of any and/or all of these conditions, I must be resigned to what one commenter said on another blog, that: “Some of us cannot tolerate more than small amounts of carbs, and probably will never be able to do so.”

If so, as this becomes clearer to me, or perhaps as I come to accept what is already pretty clear, that will mean that I need to adopt for the rest of my days the Way of Eating that I followed when I lost 170 pounds. That is what someone who has T1DM or is gluten and/or casein intolerant has to do. Except that these folks – and I know a few people who have one or both of these disorders – don’t have a choice. They will die (the Type 1s), or wish they would (figuratively speaking), if they do not follow a strictly prescribed way of eating all day every day for the rest of their lives. In that sense I’m lucky. I can cheat and think I got away with it…at least in the short term. But there’s the rub. It is an insidious disease. I have to “own up” to it: I have a disregulated metabolism.  It is “just too late” for me. There, I said it.

© Dan Brown 6/24/12

The Nutrition Debate #55: The Beleaguered Gary Taubes

I’ve just reread Gary Taubes’s “The Soft Science of Dietary Fat,” first published March 31, 2001 in Science and available in PDF format on any search engine. I recommend it to anyone interested in taking a fresh look at this subject through a clear prism. It is a brilliant exposition on a subject that has been distorted beyond recognition for more than 50 years.

I was motivated to read it again in search for a way to understand why and how so many intelligent people who should be informed about such things (including a friend who has been a Type I diabetic for over 60 years) “believe absolutely” that saturated fat and dietary cholesterol are “bad” for our health and should be avoided.  I’m not trying to change what she believes. She’s certainly an expert in her disease (T1DM) and a survivor of it. I just want to understand why.

Gary Taubes doesn’t need me to defend him. He “studied applied physics at Harvard and aerospace engineering at Stanford (MS, 1978,”) and then got “a master’s degree in journalism at Columbia University in 1981.” “He has won the Science in Society Award of the National Association of Science Writers three times,” according to his website. After “The Soft Science of Dietary Fat,” he became famous (and controversial) with his July 7, 2002 New York Times Sunday Magazine cover story, “What If It’s All Been a Big Fat Lie?” A polar-opposite rebuttal from The Center for Science in the Public Interest, a powerful vegan lobby group in Washington, DC, was published in their November 2002 newsletter.

Taubes went on in 2007, after 5 years of research and writing, to publish “Good Calories – Bad Calories” (“The Diet Delusion” in the UK, 2008), a seminal text for “the initiated.” In an “Afterwords” in the paperback edition, Taubes admits he had less impact on the medical establishment, particularly clinicians, than he would have liked. A more approachable text, “Why We Get Fat: And What to Do About It,” came out in 2010. Since then, he has been back on the cover of The New York Times Magazine with “Is Sugar Toxic” (April 13, 2011). Clearly Taubes’s books and articles all deal with controversy in medicine and nutrition.

Many physicians and researchers openly attribute Taubes for inspiring them in their career direction. He certainly has inspired me. He may even be the inspiration for the title of this blog, The Nutrition Debate. The debate needs to be continually renewed. We need to be constantly reminded at all levels, from simple nutrition “groupies” like me, who bundle ideas of others to put it out there for the world to consider. If the light level behind the mirror of conventional thinking is raised, perhaps the world will update their thinking with the “alternate hypothesis” that Taubes describes in “Good Calories – Bad Calories.” Perhaps, the silver back of the mirror will dissolve and become transparent. Following is an excerpt from Taubes’s 8,000 word essay in the 2001 Science magazine article “The Soft Science of Dietary Fat.”

“The original simple story in the 1950s was that high cholesterol levels increase heart disease risk. The seminal Framingham Heart Study, for instance, which revealed the association between cholesterol and heart disease, originally measured only total serum cholesterol. But cholesterol shuttles through the blood in an array of packages. Low-density lipoprotein particles (LDL, the “bad” cholesterol) deliver fat and cholesterol from the liver to tissues that need it, including the arterial cells, where it can lead to atherosclerotic plaques. High-density lipoproteins (HDLs, the “good” cholesterol) return cholesterol to the liver. The higher the HDL, the lower the heart disease risk. Then there are triglycerides, which contain fatty acids, and very low density lipoproteins (VLDLs), which transport triglycerides.

“All of these particles have some effect on heart disease risk, while the fats, carbohydrates, and proteins in the diet have varying effects on all these particles. The 1950s story was that saturated fats increase total cholesterol, polyunsaturated fats decrease it, and monounsaturated fats are neutral. By the late 1970s – when researchers accepted the benefits of HDL – they realized that monounsaturated fats are not neutral. Rather, they raise HDL, at least compared to carbohydrates, and lower LDL. This makes them an ideal nutrient as far as cholesterol goes. Furthermore, saturated fats cannot be quite so evil because, while they elevate LDL, which is bad, they also elevate HDL, which is good. And some saturated fats – stearic acid, in particular, the fat in chocolate – are at worst neutral. Stearic acid raises HDL levels but does little or nothing to LDL. And then, there are trans fatty acids, which raise LDL, just like saturated fat, but also lower HDL. Today, none of this is controversial, although it has yet to be reflected in any Food Guide Pyramid.”

Taubes is taking a few hits today in the Paleo world because of one of his ten “certain conclusions” from “Good Calories – Bad Calories:” that “insulin is the principal regulator of fat metabolism.” Maybe “a bridge too far,” but nobody in the Paleo World would dispute his first conclusion: “Dietary fat, whether saturated or not, is not a cause of obesity, heart disease, or any other chronic disease of civilization.” But, take note Loren Cordain and Robb Wolf, et. al.: Taubes was touting stearic acid while you guys were still in short pants (figuratively speaking, of course).                                               

© Dan Brown 6/3/12

The Nutrition Debate #54: Loren Cordain, Robb Wolf and Kurt Harris

What do these three guys have in common? If you said Paleolithic nutrition, you would only get an argument from Kurt Harris. Although he started out with a huge bow to Gary Taubes, and then called his blog PaNu for Paleolithic Nutrition, he subsequently changed the name to Archevore. His thinking continues to evolve, and he no longer uses the word Paleo. His website says his thinking “is not derived from a single science or field of inquiry, but draws first on medical sciences like biochemistry and endocrinology, and only then looks back with history and paleoanthropology.” I like that.

Other differences between Harris and the other two is that Harris is an MD and has not (yet) written a book. Cordain has a PhD in exercise physiology, and Wolf has a BS in Biochemistry, a popular podcast on Paleolithic nutrition and exercise, and is a power lifting champ and weightlifting coach. He worked with Cordain in his biochemistry lab and describes Cordain as his mentor. Cordain’s book, “The Paleo Diet” (2002) was a best seller and has now come out in a revised edition (2011), which I have just read. I have also just read Wolf’s book, “The Paleo Solution,” published in 2010.

Both books preach essentially the basic Paleo prescription: no grains, no dairy, no added sugars, no legumes and very little salt. Eat only lean meat, non-starchy fruits and vegetables (for vitamins, phytochemicals and fiber) and mostly monounsaturated and some polyunsaturated fats.  Both diets cut you some slack in different ways. Cordain gives you a day or two “off diet” a week, to induce you to try it. Wolf says “just try it for a month” to see and feel the difference. Cordain allows a little honey; Wolf says, barring autoimmune problems, “it’s tough to build much of a case against grass-fed butter.” Both authors advocate lots of exercise.

Cordain’s “The Paleo Diet” is a useful introduction to the paleo way of eating, as are many online sources. It is designed for someone who doesn’t want to get “into the weeds” of the science, and asks the reader to trust in the author’s academic research credentials and lab staff. He assumes you won’t eat much organ meat, so he substitutes plant protein for the nutrients you would otherwise miss. He advises that you only eat “lean meat” and fats mostly from monounsaturated and polyunsaturated sources, the latter for the essential fatty acids (EFAs), n6 and n3, in the right balance. In the revised edition he says he has “softened his stance on the saturated fat issue,” allowing that stearic acid is “healthful,” unlike palmitic acid “which dominates the fat of feedlot cattle.”

Wolf’s book, “The Paleo Solution,” starts off with a primer in Paleo biochemistry for the non-geek. He works hard, and mostly succeeds, at making it “accessible.” His book also has a lot more energy and is more fun to read. It seems to be geared to a younger demographic. Interestingly, Cordain’s book makes many references to the bogey man of a decade ago (“fad low-carb diets”), while Wolf’s target is vegans. Personally, being a (Type 2 diabetic) low-carber myself, and acutely aware of the vegan menace in public health policymaking in Washington, I side with Wolf. It is interesting that both authors seem to need an antagonist.

Cordain’s book has an index but no footnotes and the bibliography adds only gravitas (and pages) – it isn’t divided by chapter – so there is no easy way to dig deeper into any of the claims made. It does include brief menu and recipe sections. Wolf’s book has no index or footnotes either, but the bibliography is divided by chapter. His menus incorporate some recipes. Both books are commercial in that their primary purpose appears to be pecuniary, although much of Wolf’s material is available online, gratis.

My favorite of these three, though, is Dr. Harris. His approach is so sublime. He says at his website, for example, “An Archevore is someone who eats based on essential principles, and also someone who hungers for essential principles. Take your pick.” And, “After hearing Gary Taubes on the radio, I had an epiphany and ever since I've been exploring the field of nutrition through the lenses of medicine and evolutionary biology.” And, “I have had a lifelong interest in science and medicine as culture, and believe all claims to scientific authority should be subject to thoughtful skepticism.” How can you not like this guy? His intellectual curiosity is the driver; the scientific method his “mechanism”; his vision pure. Unfortunately, in recent months he hasn’t posted on his blog, but his website Archevore is still ‘up.’ Take a look at it.

© Dan Brown 5/27/12

The Nutrition Debate #53: On the Digestion and Absorption of Food

Food digestion physiology varies between individuals and with the composition and size of a meal. There are other factors, but a primer on what is most common and universal will be useful to understanding the various processes and their effect on our biological systems. This digest (note the pun) should provide some enlightenment.

Digestion, the hormonal process, has three phases. The cephalic phase begins when receptors in the head are stimulated by an emotional state (thought of food), sight, smell, taste and chewing. The cerebral cortex, the medulla oblongata and the hypothalamus are all involved. The vegus nerve is the messenger, triggering various enzymatic and hormonal activities. The gastric phase starts with distension, acidity, and the presence of amino acids and peptides in the stomach. The intestinal phase is initiated by distension, acidity, and osmolarity of digestive products in the intestine (we’ll explain).

Digestion, the mechanical and chemical process, begins with chewing. Chewing breaks food down to smaller units that are in turn broken down by enzymes to the smallest units to permit them to be absorbed, mostly in the small intestine, into the blood. Saliva containing mucus and the enzyme amylase is secreted from three pairs of salivary glands located in the mouth cavity. Mucus moistens the food and amylase partially digests polysaccharides (starches) into a disaccharide called maltose. About 30% of starch is broken down in the mouth (optimum pH: 6.8 or weakly acidic).

In addition, papillae on the surface of the tongue secrete the enzyme lingual lipase which begins the process of breaking down some fats from triglycerides into diglycerides. Long chain triglycerides cannot be absorbed unless completely broken down to monoglycerides, so the process starts here and continues in the stomach. As much as 30% of fat is broken down within 1 to 20 minutes of ingestion by lingual lipase alone, according to Wikipedia.

Food then passes through the pharynx and descends the esophagus to the stomach, a sac that stores and mixes and processes the food into a milky solution called chyme. Glands lining the stomach secrete hydrochloric acid, which is necessary for protein digestion by the enzyme pepsin. The stomach’s high acidity (optimum pH 1.8) inhibits the breakdown of carbohydrates within it, but it does produce a small amount of the enzyme lipase to continue the digestion of fats. So far, although the breakdown of food particles by enzymatic and mechanical action is continuing apace, virtually no absorption of nutrients into the bloodstream has occurred. The exceptions are water, some simple sugars, and other small molecules like alcohol that are absorbed in the stomach, passing through the membrane of the stomach and entering the circulatory system directly.

The final stages of digestion and most of the nutrient absorption occur in the next portion of the tract: the small intestine. The small intestine is divided into three segments – duodenum, jejunum and ileum. The duodenum in turn is connected to the hepato-pancreatic duct which connects to the liver and the gall bladder (to store and supply bile) and to the pancreas. These organs and glands provide digestive enzymes and an alkaline fluid (pH 8.5) to neutralize the acid being emptied from the stomach.

In the duodenum, dipeptides from protein in the stomach are broken down to amino acids by enzymes from the pancreas. The enzymes break down the disaccharides maltose, lactose and sucrose into the monosaccharides glucose, fructose and galactose.  The major portion of fat digestion, the breakdown of diglycerides by lipase into free fatty acids and glycerol, also happens here.

Absorption of nutrients occurs mostly in the jejunum and ileum. Amino acids (from protein) and the monosaccharides (glucose, fructose and galactose, all from carbohydrates) are water soluble nutrients and enter the blood directly through the villi and microvilli in the endothelial layer of the small intestine wall. The surface area of these many small structures (imagine a shag carpet) increases the absorption interface by 600 times, roughly equivalent to the surface of a tennis court. However, the products of fat digestion, fatty acids and glycerol, are not water soluble and therefore enter the circulation through the lymph system by a process called passive diffusion in which no energy is required.

Passive or simple diffusion requires no energy input from the body because it is driven by concentration. Fats, water and some minerals simply cross the membrane barrier because the concentration of the substance (fat, water, etc.) is lower on the other side. It is an equalization process. The small intestine is full of nutrients and the blood is not, so they cross over. This equalization process is also called osmosis, ergo ‘osmolarity of digestive products’ referred to above. 

Fructose is transported across the membrane barrier by a process called ‘facilitated diffusion,’ which means it may need a little help depending on the concentration gradient. Glucose and galactose, the other monosaccharides, as well as amino acids, also require energy for active transport, which occurs against a concentration gradient. See The Nutrition Debate #52, “The Thermic Effect of Foods,” for the energy requirements of protein digestion as compared to carbohydrates, especially of processed foods.

Finally, gastric emptying, which is the rate that food leaves the stomach to enter the small intestine, is tightly controlled. Liquids are emptied much more quickly than solids, and carbohydrates are emptied first, followed by protein, fat and fiber. Gastric emptying has attracted medical interest as “rapid gastric emptying is related to obesity and delayed gastric emptying syndrome is associated with Type 2 diabetes, aging and gastroesophageal (acid) reflux or GERD.” But that’s another subject. Next week: Paleo book reviews. 

© Dan Brown 5/20/12

The Nutrition Debate #52: The Thermic Effect of Food

Thermogenesis is the process of heat production in organisms, and heat is a form of expended energy. The unit of measurement is a calorie. Human metabolism is comprised of three components of energy expenditure: 1) the energy expended by the basal metabolic rate (to keep the resting organism “going,” i.e. alive), 2) the energy expended through exercise (motion), and 3) the energy expended due to the “cost” of processing food for storage and use. This last component is known as the thermic effect of food.  It is also sometimes called Diet-Induced Thermogenesis (DIT).

It is estimated that the thermic effect of food is about 10% of the caloric intake of any given meal, “though the effect varies substantially for different food components,” according to Wikipedia. Of the three food components (called macronutrients), fat has minimal thermic effect. Carbohydrates, especially simple sugars and carbs in highly processed, manufactured foods, are very easy to process and have very little thermic effect. Proteins, on the other hand (and whole food, complex carbohydrates to a lesser extent) are harder to process and have a much larger thermic effect. The ratio of protein to carb energy expenditure is generally between 2:1 and 3:1, depending on how “simple” the carb is.

So, for total daily energy expenditure there's a resting metabolic rate component (60-70% of total), the physical activity component (15-30% of total), and the thermic effect of food component (~10%). While 10% is a small percentage, if the energy expended to digest, absorb and eliminate protein is two or more times the amount required for carbs and fat, wouldn’t replacing carbs with protein in an isocaloric diet thus increase the metabolic rate and help to burn more calories including stored fat? And if the difference in the burn rate was even greater for the simple sugars and processed carbs made easier to digest by manufacturing, couldn’t that account for why our metabolisms burn less on today’s modern processed-food diets? Thus, to naturally increase our metabolic rate, we should 1) increase the amount of protein in our diet and 2) replace simple sugars and processed-foods in the diet with whole foods, that is, unprocessed, complex carbohydrates. Note that 2) above assumes that you don’t already have insulin resistance (IR), pre-diabetes, or full-blown Type 2 diabetes, or are obese. It you are, you should severely restrict/limit the carbohydrates in your diet.

The typical American (or for my international readers, Western) diet currently gets about 15% of calories from protein. The Standard American Diet (SAD for short), espoused by the FDA and promoted on food packages in the Nutrition Facts Panel, is 10% protein. (On a 2,000 calorie diet, 50g/day x 4 cal/g = 200 cal.) I get about 25% of my calories from protein.

So, who’s looking at this? Barr SB and Wright JC, that’s who, in their paper, “Postprandial energy expenditure in whole-food and processed-food meals: implications for daily energy expenditure,” published online July 2010 in The Journal of Food and Nutrition Research. The abstract on PubMed explains: “Empirical evidence has shown that rising obesity rates closely parallel the increased consumption of processed foods (PF)… in the USA. Differences in postprandial thermogenic responses to a whole-food (WF) meal vs. a PF meal may be a key factor in explaining obesity trends, but currently there is limited research exploring this potential link.” And their conclusion: “Ingestion of the particular PF meal tested in this study decreases postprandial energy expenditure by nearly 50% compared with the isoenergetic WF meal. This reduction in daily energy expenditure has potential implications for diets comprised heavily of PFs and their associations with obesity” (Italics added by me).

The processed food meal decreased energy expenditure by nearly 50%. Wow! That’s a big difference in thermic effect. And the meals they were comparing were “either ‘whole’ or ‘processed’ cheese sandwiches; multi-grain bread and cheddar cheese were deemed whole, while white bread and processed cheese product were considered processed.” Imagine if they had chosen a real whole food instead of ‘multigrain bread’ which is a far, far cry from a real whole food as readers here know. And what if it had been a protein food instead? The authors explained, “A more strict WF would be one devoid of any processing, such as a specific fruit, vegetable, or meat. However, for the present study, we sought to compare two meals that were familiar to the Western diet, and could be easily interchangeable.”And while the much higher thermic effect of protein is probably too small to have a noticeable effect on weight loss in the short term, over a period of months or years this difference becomes significant. Have I discovered another cause for the obesity epidemic? Just joking, folks. I am just your humble commentator bringing you the insights of the cognoscenti.                   

© Dan Brown 5/13/12

The Nutrition Debate #51: Dietary Cholesterol

Pay attention - dietary cholesterol is the cholesterol you eat. Serum cholesterol is the cholesterol in your blood. They are not only distinct; they are largely independent of each other. The following excerpt from Wikipedia gets “into the weeds” a bit, but is necessary to provide a framework.

“While the absolute production quantities vary with the individual, group averages for total human body content of cholesterol, with the U.S population, commonly run about 35,000 mg (assuming lean build; varies with body weight and build) and about 1,000 mg/day ongoing production. Dietary intake plays a smaller role, 200-300 mg/day being common values; for pure vegetarians, essentially 0 mg/day, but this typically does not change the situation very much because internal production increases to largely compensate for the reduced intake.”

Assuming a “lean (body) build” for the U.S. population is a dubious proposition, as must be patently obvious to even the casual observer. My body is certainly not lean. Neither do I eat just 200-300mg/day of dietary cholesterol. I typically average 600-650 mg/day. I know this from the days (years, actually) when I tracked carefully. But, the HHS/USDA Dietary Guidelines for Americans age 2 and older urge us to eat no more than 300mg daily (200mg with CVD risk factors). Does this make any sense when we consider that most societies wean at 3 or 4, and breast milk is 55% fat, mostly saturated, and loaded with cholesterol? “Mother's milk is especially rich in cholesterol and contains a special enzyme that helps the baby utilize this nutrient. Babies and children need cholesterol-rich foods throughout their growing years to ensure proper development of the brain and nervous system,” says Dr. Mary Enig, the doyenne of lipid chemistry and the author of the definitive biochemistry guide, “Dietary Fats.”

“The brain is the most cholesterol-rich organ in the body, most of which comes from in situ synthesis,” begins the abstract of a paper, “Diabetes and insulin in regulation of brain cholesterol metabolism,” from the Joslin Diabetes Center and Harvard Medical School published in Cell Metabolism (2010 Dec 1; 12(6):567-79).Yet, many people have deprived themselves for decades of cholesterol-laden foods (shrimp, eggs, butter, cream, liver, even a marbled steak) in an effort to comply with the government’s public health guidelines. What a pity (for them)!

Perhaps the most telling statement in the quoted paragraph, however, is that vegetarians have serum cholesterol levels similar to omnivores “…because internal production increases to largely compensate for the reduced intake.” Vegetarians have avoided eating cholesterol-loaded foods altogether “but this typically does not change the situation very much.” Admittedly, they completely gave up eating animal-based foods – meaning they ate absolutely no cholesterol – for a different reason, but they did not thereby lower their serum cholesterol “very much.”

The reason, as the numbers In the Wiki-quoted paragraph above note, is that most cholesterol, typically 80-90% within the body, is created and controlled by internal production by all the cells in the body, with typically slightly greater relative production by hepatic (liver) cells. As described in The Nutrition Debate #24 cell structure relies on fat membranes to separate and organize intracellular water, proteins and nucleic acids, and cholesterol is one of the components of all animal cell membranes. More on cholesterol within this blog can be found at The Nutrition Debate #25 , “Understanding Your Lipid Panel,” and The Nutrition Debate #45 , “Do You Need to Lower Your Cholesterol?”

But get this: “For many,” the Wikipedia entry on atherosclerosis continues, “especially those with greater than optimal body mass and increased glucose levels, reducing carbohydrate intake (especially simple forms), not fat and cholesterol, is often more effective for improving lipoprotein expression patterns (i.e. cholesterol), weight and blood glucose values. For these reasons, medical authorities much less frequently promote the low dietary fat concept than was common prior to about the year 2005.” That’s certainly been true for me, as I have reported here with my own example (n = 1). Since switching to a high fat/high cholesterol, moderate protein and very low carbohydrate diet about 10 years ago, my HDL has doubled and my triglycerides have dropped by two-thirds, while my LDL has been constant and my T. Chol. has risen only slightly. Remember the common laboratory formula for serum cholesterol: T. Chol. = LDL + HDL + TG/5.

Finally, Ancel Keys, the father of the (infamous) Lipid (saturated fat/heart disease) Hypothesis, is equally famous in some circles for having said later in life, according to Malcolm Kendrick, author of “The Great Cholesterol Myth,” “There’s no connection whatsoever between cholesterol in food and cholesterol in blood. And we’ve known that all along.”

Given that we were born to drink mother’s milk, and our brain is mostly cholesterol, it strikes me as pretty natural and healthy to eat cholesterol rich foods. As the ‘70s margarine commercial said, “It’s not nice to fool Mother Nature.”

© Dan Brown 5/6/12