Are Saturated Fats Really All That Bad?

Posted on March 12, 2012 | 14 comments

This is an epic post of mine from the old Advanced Mediterranean Diet blog, originally dated July 6, 2009. That was a watershed year for me in terms of accepting nutritional dogma, because of the ideas in this article.  This was also before I ever gave serious consideration to the paleo diet.

I’ve been thinking a lot lately about saturated fats. Weird, huh?

No saturated fat in grapes

The American Heart Association recommends that Americans limit the amount of saturated fats they eat to less than 7 percent of total daily calories. If you eat 2,000 calories a day, no more than 140 of them should come from saturated fats. That’s about 16 grams of saturated fats.

In over two decades of clinical practice, I’ve never run across a patient willing to do that calculation. Not many physicians could tell you the “seven percent rule.”

One of the two major themes of Gary Taubes’ book, Good Calories, Bad Calories, is that dietary saturated fats are not particularly harmful to our health, if at all. From what I’ve been taught, this is sacrilegious. “Saturated fats are a major cause of heart disease and strokes,” I’ve heard and read over and over. In brief, this is the Diet-Heart Hypothesis or the “lipid hypothesis”: Dietary saturated fat, total fat, and cholesterol are directly related to coronary heart disease and other forms of atherosclerosis (aka hardening of the arteries).

In his review of Taubes’ book, Dr. George Bray didn’t even address Taubes’ point about saturated fats, writing instead, “read and decide for yourself.”

That started me thinking either that the Diet-Heart Hypothesis is indefensible or that Dr. Bray is lazy. I don’t think he’s lazy. Dr. Bray is a Grand High Pooh-Bah in the fields of obesity and nutrition.

The American Heart Association in 1957 recommended that polyunsaturated fats replace saturated fats.

U.S. public health recommendations in 1977 were to reduce fat intake to 30% of total calories to lower the risk of coronary heart disease. Slowly, some fats were replaced mostly with carbohydrates, highly refined ones at that. This shift tends to raise triglycerides and lower HDL cholesterol levels, which may themselves contribute to atherosclerosis. Current recommendations are, essentially, to keep saturated fatty acids as low as possible.

One concern about substituting carbohydrates for fats is that blood sugar levels rise, leading to insulin release from the pancreas, in turn promoting growth of fat tissue and potentially leading to weight gain. Some believe that the public health recommendation to reduce total fat (which led to higher carbohydrate intake) is the reason for the dramatic rise in overweight and diabetes we’ve seen over the last 30 years.

Note that if intake of saturated fats is inadequate, our bodies can make the saturated fats it needs from carbohydrates. These are generally the same saturated fats that are present in dietary fats of animal origin. The only exceptions are the two essential fatty acids: alpha-linolenic acid and linoleic acid.

Why would saturated fats be harmful? Apparently because they raise blood levels of cholesterol (including LDL cholesterol – “bad cholesterol”), which is thought to be a cause of atherosclerosis, which increases the risk of coronary heart disease and stroke. I don’t recall seeing any mention of a direct toxic effect of saturated fats (or fatty acids) on arterial walls, where the rubber meets the road. (Saturated fats are broken down in the small intestine to glycerol and fatty acids.)

Dietary saturated fats also raise HDL cholesterol – “good cholesterol” – although not to the degree they raise LDL.

You needed a break

Let’s not forget many other factors that cause, contribute to, or predict coronary heart disease and atherosclerosis: smoking, family history, high blood pressure, obesity, diabetes, oxidative stress, homocysteine level, systemic inflammation, high-glycemic index diets, C-reactive protein, lack of exercise, and others. I discussed dietary factors in my April 14, 2009, blog post.

Often overlooked in discussion of dietary fat effects is the great variability of response to fats among individuals. Response can depend on genetics, sex, fitness level, overweight or not, types of carbohydrates eaten, amount of total dietary fat, etc. And not all saturated fats affect cholesterol levels.

Many of the journal articles listed as references below support the idea that the link between dietary saturated fats and coronary heart disease is not strong, and may be nonexistent. Read them and you’ll find that:

  • Some studies show no association between dietary saturated fats and coronary heart disease.
  • Some studies associate lower rates of coronary heart disease with higher saturated fat intake.
  • Higher saturated fat intake was associated with less progression of coronary atherosclerosis in women.
  • Lowering saturated fat intake did not reduce total or coronary heart disease mortality.

“Read and decide for yourself,” indeed. I think you’ll begin to question the reigning dogma.

For example, here’s a conclusion from the Hooper article (from 2001):

In this review we have tried to separate out whether changes in individual fatty acid fractions are responsible for any benefits to health (using the technique of meta-regression). The answers are not definitive, the data being too sparse to be convincing. We are left with a suggestion that less total fat or less of any individual fatty acid fraction in the diet is beneficial.

And a conclusion of the J.B. German article:

At this time [2004], research on how specific saturated fatty acids contribute to coronary artery disease and on the role each specific saturated fatty acid play in other health outcomes is not sufficient to make global recommendations for all persons to remove saturated fats from their diet. No randomized clinical trials of low-fat diets or low-saturated fat diets of sufficient duration have been carried out; thus, there is a lack of knowledge of how low saturated fat intake can be without the risk of potentially deleterious health outcomes.

Zarraga and Schwartz (2006) conclude:

Numerous studies have been conducted to help provide dietary recommendations for optimal cardiovascular health. The most compelling data appear to come from trials that tested diets rich in fruits, vegetables, MUFAs [monounsaturated fatty acids], and PUFAs [polyunsaturated fatty acids], particularly the n-3 PUFAs. In addition, some degree of balance among various food groups appears to be a more sustainable behavioral practice than extreme restriction of a particular food group.

Here’s another of my favorite quotes on this topic, from the J.B. German article:

If saturated fatty acids were of no value or were harmful to humans, evolution would probably not have established within the mammary gland the means to produce saturated fatty acids . . . that provide a source of nourishment to ensure the growth , development, and survival of mammalian offspring.

Take-Home Points

The connection between dietary saturated fat and coronary heart disease is weak.

I may be excommunicated from the medical community for uttering this. You won’t hear it from most physicians or dietitians. They don’t have time to spend 80 hours on this topic, so they stick with the party line. And maybe I’m wrong anyway.

The scientific community is slowly moving away from the original Diet-Heart/Lipid Hypothesis. It is being replaced with stronger anti-atherosclerosis theories that promote:

  • fruit and vegetable intake
  • whole grain intake
  • low-glycemic index eating
  • increased consumption of plant oils and fish
  • moderate intake of nuts
  • ? moderate intake of low-fat diary (e.g., DASH diet) (less consensus on this point)

So, saturated fats and dietary cholesterol are being crowded out of the picture, or ignored. In many cases, saturated fats have literally been replaced by poly- and monounsaturated fats (plant oils). Several clinical studies indicate that’s a healthy change, but it may be related more to the healthfulness of the plant oils than to detrimental effects of saturated fats.

The original Diet-Heart Hypothesis won’t die until the American Heart Association and U.S. public health agencies put a gun to its head and pull the trigger. That will take another 10 years or more.

If you want to hedge your bets, go ahead and limit your saturated fat intake. It probably won’t hurt you. It might help a wee bit. By the same token, I’m not going on an all-meat and cheese, ultra-high-saturated fat diet; I don’t want to miss out on the healthy effects of fruits, vegetables, whole grains, fish, nuts, and low-glycemic index carbohydrates. Some would throw red wine into the mix. This “prudent diet” reflects what I hereby christen The 21st Century Diet-Heart Hypothesis.

If you’re worried about coronary heart disease and atherosclerosis, spend less time counting saturated fat grams, and more time on other risk-reducing factors: diet modification as above, get regular exercise, control your blood pressure, achieve a healthy weight, and don’t smoke. More bang for the buck.

What do you think?

Steve Parker, M.D.

Disclaimer: All matters regarding your health require supervision by a personal physician or other appropriate health professional familiar with your current health status. Always consult your personal physician before making any dietary or exercise changes.

Selected References Contradicting or Questioning the Diet-Heart Hypothesis (updated February 19, 2012):

Astrup, A., et al (including Ronald Krause, Frank Hu, and Walter Willett). The role of reducing intakes of saturated fat in the prevention of cardiovascular disease: where does the evidence stand in 2010. American Journal of Clinical Nutrition, 93 (2011): 684-688. (The authors believe that replacing saturated fats with polyunsaturated fats (but not carbohydrates) can reduce the risk of coronary heart disease (CHD). For the last four decades, low-fat diets replaced fat with carbohydates. So they believe saturated fatty acids cause CHD or polyunsaturated fatty acids prevent it. I see no mention of total fat intake in this article written by major names in nutritional epidemiology and lipid metabolism. “In countries following a Western diet, replacing 1% of energy intake from saturated fatty acids with polyunsaturated fatty acids has been associated with a 2–3% reduction in the incidence of CHD.” “Furthermore, the effect of particular foods on CHD cannot be predicted solely by their content of total saturated fatty acids because individual saturated fatty acids may have different cardiovascular effects and major saturated fatty acid food sources contain other constituents that could influence coronary heart disease risk.”) A Feb. 19, 2012, press release from the Harvard School of Public Health covered much of the same ground. It’s titled “Time to Stop Talking About Low-Fat, say HSPH Nutrition Experts.”

Siri-Tarino, Patty, et al. Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. American Journal of Clinical Nutrition, January 13, 2010. doi:10.3945/ajcn.2009.27725

Skeaff, C. Murray and Miller, Jody. Dietary fat and coronary heart disease: Summary of evidence from prospective cohort and randomised controlled trials. Annals of Nutrition and Metabolism, 55 (2009): 173-201.

Halton, Thomas, et al. Low-carbohydrate-diet score and the risk of coronary heart disease in women. New England Journal of Medicine, 355 (2006): 1,991-2,002.

German, J. Bruce, and Dillard, Cora J. Saturated fats: What dietary intake? American Journal of Clinical Nutrition, 80 (2004): 550-559.

Ravnskov, U. The questionable role of saturated and polyunsaturated fatty acids in cardiovascular disease. Journal of Clinical Epidemiology, 51 (1998): 443-460.

Ravsnskov, U. Hypothesis out-of-date. The diet-heart idea. Journal of Clinical Epidemiology, 55 (2002): 1,057-1,063.

Ravnskov, U, et al. Studies of dietary fat and heart disease. Science, 295 (2002): 1,464-1,465.

Taubes, G. The soft science of dietary fat. Science, 291 (2001): 2535-2541.

Zarraga, Ignatius, and Schwartz, Ernst. Impact of dietary patterns and interventions on cardiovascular health. Circulation, 114 (2006): 961-973.

Mente, Andrew, et al. A Systematic Review of the Evidence Supporting a Causal Link Between Dietary Factors and Coronary Heart Disease. Archives of Internal Medicine, 169 (2009): 659-669.

Parikh, Parin, et al. Diets and cardiovascular disease: an evidence-based assessment. Journal of the American College of Cardiology, 45 (2005): 1,379-1,387.

Bray, G.A. Review of Good Calories, Bad Calories. Obesity Reviews, 9 (2008): 251-263. Reproduced at the Protein Power website of Drs. Michael and Mary Dan Eades.

Hooper, L., et al. Dietary fat intake and prevention of cardiovascular disease: systematic review. British Medical Journal, 322 (2001): 757-763.

Weinberg, W.C. The Diet-Heart Hypothesis: a critique. Journal of the American College of Cardiology, 43 (2004): 731-733.

Mozaffarian, Darius, et al. Dietary fats, carbohydrate, and progression of coronary atherosclerosis in postmenopausal women. American Journal of Clinical Nutrition, 80 (2004): 1,175-1,184.

Related editorial: Knopp, Robert and Retzlaff, Barbara. Saturated fat prevents coronary artery disease? An American paradox. American Journal of Clinical Nutrition, 80 (2004): 1.102-1.103.

Yusuf, S., et al. Effect of potentially modifiable risk factors associated with myocardial infarction in 52 countries (the INTERHEART study): case-control study. Lancet, 364 (2004): 937-952. (ApoB/ApoA1 ratio was a risk factor for heart attack, so dietary saturated fat may play a role if it affects this ratio.)

Hu, Frank. Diet and cardiovascular disease prevention: The need for a paradigm shift. Journal of the American College of Cardiology, 50 (2007): 22-24. (Dr. Hu de-emphasizes the original diet-heart hypothesis, noting instead that “. . . reducing dietary GL [glycemic load] should be made a top public health priority.:)

Oh, K., et al. Dietary fat intake and risk of coronary heart disease in women: 20 years of follow-up of the Nurses’ Health Study. American Journal of Epidemiology, 161 (2005): 672-679.

Parker, Steve. Time to abandon the diet-heart hypothesis? Advanced Mediterranean Diet Blog, May 1, 2009.

Parker, Steve. New study confirms the heart-healthy Mediterranean diet. Advanced Mediterranean Diet Blog, April 14, 2009. (Examination of the Mente study listed above.)

Selected References Supporting the Diet-Heart Hypothesis (by no means exhaustive)

Ascherio, A. Epidemiologic studies on dietary fats and coronary heart disease. American Journal of Medicine, 113 (supplement) (2002): 9S-12S.

Griel, Amy and Kris-Etherton, Penny. Beyond saturated fat: The importance of the dietary fatty acid profile on cardiovascular disease. Nutrition Reviews, 64 (2006): 257-262. (Primarily a response to the Mozaffarian article above.)

Erkkila, Arja, et al. Dietary fatty acids and cardiovascular disease: An epidemiological approach. Progress in Lipid Research, 47 (2008): 172-187.

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Classic Australian Aborigine Study on Return to Ancestral Diet and Lifestyle

Posted on March 10, 2012 | 14 comments

Did you know kangaroo is edible?

The scientific article I review today is often cited by those who favor a Paleolithic diet for diabetics.  Cordain and Stefanson have written about it, for example.

Background

Urbanized Australian Aboriginal communities have a high prevalence of type 2 diabetes.   Kerin O’Dea writes:

The change from an urban to a traditional lifestyle involves several factors that directly affect insulin sensitivity: increased physical activity, reduced energy intake and weight loss, and changes in the overall dietary composition.  All of these factors improve insulin sensitivity and should, therefore, be of benefit to the insulin-resistant diabetic.

Methods

Ten urban type 2 diabetic and four nondiabetic full-blood Aborigines agreed to revert to their traditional lifestyle as hunter-gatherers in an isolated region of Australia for seven weeks.  Average age was 53.  Half of them were moderate to heavy alcohol drinkers.  Average diabetic weight was 82 kg (180 lb); nondiabetics averaged 77 kg (169 lb).  There were equal numbers of men and omen.  None of the diabetics was on insulin, and only one was on an oral diabetic drug (a sulfonylurea). 

Ayers Rock, Uluru National Park, Australia

The study was carried out at Pantijan, the traditional land of these Aborigines.  It’s a day-and-a-half drive in a four-wheel vehicle from Derby.  At least it was in 1984.

For seven weeks, the participants ate only what they hunted or collected.  Diet composition was dependent on whether they were travelling to the homeland (1.5 weeks), at the coastal location (2 weeks), or inland on the river (3.5 weeks). Protein sources were mainly beef, kangaroo, fish, birds, crocodiles, and turtles.  Carboydrate content ranged from under 5% to 33%.  Protein content varied from 50 to 80%.  Fat was 13 to 40%.  So, very high protein and low-carb.  Carb sources were yams, honey, and figs.  Yams were the predominant carb source.  They also eat yabbies (shrimp or crayfish (“crawdads” in Oklahoma)).  Average energy intake was a very low 1,200 calories a day. 

The author implies this was the traditional Aboriginal diet.

What did they eat back home in the city? 

The main dietary components were flour, sugar, rice, carbonated drinks, alcoholic drinks (beer and port), powdered milk, cheap fatty meat, potatoes, onions, and variable contributions of other fresh fruit and vegetables. 

O’Dea estimates a macronutrient breakdown of 50% carb, 40% fat, and 10% protein (similar to the Standard American Diet, then).

What Did O’Dea Find Out?

Everyone lost weight, a group average of 8 kg (18 lb) over the seven weeks.

Fasting blood sugars fell in the diabetics from 11.6 mmol/l to 6.6 mmol/l (209 to 119 mg/dl).  After-meal blood sugars also fell dramatically.

Fasting insulin levels fell from 23 to 12 mU/l.

Fasting triglycerides fell drastically. 

HDL cholesterol fell significantly, whereas LDL cholesterol tended to rise.

So What?

How often do you see a scientific article with just one author?  Rarely, these days.

The investigator wrote that, “Under the conditions of the study it is difficult to separate out effects of dietary composition, low energy intake, and weight loss.”

O’Dea estimates that experimental activity levels were probably higher than in the urban setting, but not dramatically more so.  (He was with the participants throughout the experiment.)

The main carbohydrate sources in this ancestral diet were yams, honey, and figs.  Modern Australian honey is probably similar to the honey of 100,000 years ago.  But what about yams and figs? 

These folks had to have been eating twice as many calories, at least, back in their urban environment.  O’Dea didn’t comment on how well the participants tolerated calorie restriction.  Did they complain?  Did they eat to satiety?  They had no access to food other than what they could hunt and gather.  Was food in short supply?  It’s not documented.  You’d think O’Dea would mention these issues if they were a problem. 

This particular ancestral diet was extremely high in protein: 50–80% of calories.  (Eaton and Konner suggest that an average ancestral diet provides only 25–30% of total calories from protein.  A typical modern high-protein diet derives about 30% of calories from protein, compared with 15–18% in the standard American diet.)  Protein helps combat hunger.  But halving caloric intake for seven weeks is extreme.  Don’t believe me?  Just try it.  This degree of caloric restriction by itself would tend to lower blood sugar levels and body weight in most humans, regardless of macronutrient ratios and ethnicity.

I know nothing about Australian Aborigines as an ethnic and genetic group.  Is their diabetes similar to European diabetes?  Pima Indian diabetes?   

O’Dea never called the study diet Paleolithic, because it wasn’t. It was a modern hunter-gatherer diet eaten by rural, isolated Australian Aboriginal communities.

This calorie-restricted, very-high-protein, natural diet was very effective for weight loss and blood sugar control in this tiny, seven-week study on a specific ethnic population.  I bet the caloric restriction was the most effective component of the lifestyle change.  Restriction of refined sugars and starches also helped. 

This ancestral diet was beneficial for a few Australian Aborigines.  Are the lessons widely applicable?  Not yet.  As they say, “further studies are needed.”  You can’t just cite this study to say that paleo diets are healthy for diabetics.

It does jibe with plenty of other research that shows severe calorie restriction leads to weight loss and lower blood sugar levels.

Steve Parker, M.D.

Reference: O’Dea, Kerin.  Marked improvement in carbohydrate and lipid metabolism in diabetic Australian Aborigines after temporary reversion to traditional lifestyle.  Diabetes, 33 (1984): 596-603.

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Book Review: The Smarter Science of Slim

Posted on March 9, 2012 | 5 comments

I  recently read The Smarter Science of Slim, by Jonathan Bailor, published in 2012.   I post this here because the author considers his eating plan to be a Paleolithic-style (Stone Age) diet.  Per Amazon.com’s rating system, I give it four stars (“I like it”).

♦   ♦   ♦

Mr. Bailor’s weight-management diet avoids grains, most dairy, oils, refined starches, added sugars, starchy veggies, corn, white potatoes.  You eat meat, chicken, eggs, some fruit, nuts, seeds, and copious low-starch vegetables.  No limit on food if you eat the right items.   

It’s high-fiber, high-protein, moderate-fat, moderate-carb (1/3 of calories from carbohydrate,  1/3 from protein, 1/3 from fat).  He considers it paleo eating (aka Stone Age) even though he allows moderate legumes and dairy (fat-free or low-fat cottage cheese and plain Greek yogurt).  Paleo purists outlaw legumes and  milk products.

Will it lead to weight lose? Quite probably in a majority of followers, especially those eating the standard, low-quality American diet.  When it works, it’s because you’ve cut out the fattening carbohydrates so ubiquitous in Western societies.  The protein and fiber will help with satiety.  Is it a safe eating plan?  Yes.

For those with diabetes needing to lose weight, I prefer a lower carbohydrate content in the diet, something like Dr. Bernstein’s Diabetes Solution or  Conquer Diabetes and Prediabetes: The Low-Carb Mediterranean Diet.

I don’t recall any recipes or specific meal plans.  You put your own meals together following his guidelines.

Our major points of agreement:

  • Exercise isn’t terribly helpful as a weight-loss technique for most folks.
  • We’re overweight because we eat too many starches and sweets.
  • Natural, minimally processed foods are healthier than man-made highly refined items.
  • No need to emphasize “organic” /grass-fed beef/free-range chicken.
  • We don’t do enough high-quality exercise.

I have a few problems with the book:

  • It says we’re eating less.  U.S. caloric consumption over the last several decades has increased by about 150 cals (630 kJ) a day for men and 300 cals (1260 kJ) for women.  The author seems to contradict himself at one point by favorably quoting Hilda Bruch’s writing that “…overeating is observed with great regularity” in the obese. 
  • Scary graphs showing increasing instances of heart disease and diabetes over time aren’t helpful because they ignore population growth.  The population-adjusted diabetes rate is indeed increasing whereas heart disease rates are decreasing.
  • It says the Calories In/Calories Out theory of overweight has been proven wrong.  This is by no means true.  It just hasn’t helped us much to reverse the overweight epidemic.  Sure, it’s often said that if you just cut a daily tablespoon of butter out of your diet, you’d lose 11 lb (5 kg) in a year, all other things being equal.  Problem is, all other things are never equal.  In reality, we replace the butter with something else, or we’re slightly less active.  So weight doesn’t change or we gain a little.
  • It says the “eat less, exercise more” mantra has been proven wrong as a weight loss method.  Not really.  See above.  And watch an episode of TV’s The Biggest Loser.  Exercise can burn off fat tissue.  The problem is that we tend to overeat within the next 12 hours, replacing the fat we just burned. I agree with the author that “eat less, exercise more” is extremely hard to do, which is the reason it so often fails over the long run.  As Mr. Bailor writes elsewhere: “Hard to do” plus “do not want to do” generally equals “it’s not happening.”  Mr. Bailor would say the reason it ultimately fails is because of a metabolic clog or dysregulation. 
  • He says there’s no relationship between energy (calorie) consumption and overweight.  Not true.  Need references?  Google these: PMID 15516193, PMID 17878287, PMID 14762332.  The author puts too much faith in self-reports of food intake, which are notoriously inaccurate.  And obese folks under-report consumption more than others (this is not to say they’re lying). 
  • Mr. Bailor’s assessments too often rely on rat and mice studies.
  • By page 59, I had found five text sentences that didn’t match up well with the numeric bibiographic references (e.g., pages 48, 50, 59).
  • S. Boyd Eaton is thrice referred to as S. Boyd.
  • How did he miss the research on high intensity interval training by Tabata and colleagues in 1996.  Gibala is mentioned often but he wasn’t the pioneer.
  • Several diagrams throughout the book didn’t print well (not the author’s fault, of course).
  • In several spots, the author implies that HIS specific eating and exercise program has been tested in research settings.  It hasn’t.

Mr. Bailor’s exercise prescription is the most exciting part of the book for me.  His review of the literature indicates you can gain the weight-management and health benefits of exercise with just 10 or 20 minutes a week.  NOT the hour a day recommended by so many public heath authorities.  And he tells you how to do the exercises without a gym membership or expensive equipment.  That 20 minutes is exhausting and not fun.  You have fun in all the hours you saved.  If this pans out, we’re on the cusp of a fitness revolution.  Gym owners won’t be happy.  Sounds too good to be true, doesn’t it?

One component of the exercise program is high intensity interval training (HIIT), which I’m convinced is better than hours per week of low-intensity “cardio” like jogging. Better in terms of both fitness and weight management.

The resistance training part of the program focuses on low repetitions with high resistance, especially eccentric slow muscle contraction.  This is probably similar to programs recommended by Doug McGuff. John Little, Chris Highcock, and Skyler Tanner.  I’m no authority on this but I’m trying to learn.  By this point in the book, I was tired of looking up his cited references (76 pages!).  I just don’t know if this resistance training style is the way to go or not.  I’ll probably have to just try it on myself.  What do you think?

I admire Mr. Bailor’s effort to digest and condense decades of nutrition and exercise research.  He succeeds to a large degree.

Steve Parker, M.D.
 

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Link to Evidence in Favor of High-Intensity Interval Training

Posted on February 29, 2012 | 4 comments

Tabata's team used stationary bicycles

I ran across this recent scientific review article on HIIT (high-intensity interval training) and thought you might be interested.  Looks like it’s slated for publication in The Journal of Physiology.

I’m interested in HIIT as a means to achieve fitness in much less time than the 150 minutes a week of exercise recommended by various public health authorities.

Why didn’t the authors at least mention the oft-cited and apparently pioneering work of Izumi Tabata et al from 1996?

Steve Parker, M.D.

References:

Gibala et al.  Adaptations to low-volume, high-intensity interval training (preliminary draft).  Journal of Physiology, doi: 10.1113/jphysiol.2011.224725

Tabata, I., et al.  Effects of moderate-intensity endurance and high-intensity intermittent training on anaerobic capacity and VO2max.  Medicine and Science in Sports and Medicine, 1996 Oct;28(10):1327-30.

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Frustration

Posted on February 22, 2012 | 6 comments

I just realized I started this blog six months ago with the idea that I’d “…share my investigation into whether the paleo diet and lifestyle are potentially therapeutic for people with diabetes.”

I’m frustrated that I haven’t made more progress.

Only a few clinical studies have looked at use of the paleo diet in diabetics.  And only type 2’s at that.  The Swedes (Steffan Lindeberg/Tommy Jonsson group) and Californians (Team Frassetto) own this field, at this point.

Loren Cordain is at Colorado State University.  Don’t they have a research department?

Are S. Boyd Eaton and Melvin Konner still in academia?

Namesake of the Cabbage Soup Diet

I found an article from 1984 looking at return of diabetic Australian aborigines to their traditional lifestyle.  I’ll report here after I analyze it.

Dr. Jay Wortman has done work with aboriginal peoples of Canada.  They have lots of diabetes, like the Pima in my neck of the woods.  I’ll look for his results.

If the paleo diet is ever going to be more than a fad, we need clinical studies that support it.  Shoot, even the cabbage soup diet has glowing anecdotal reports from individuals, but it hasn’t stood the test of time.

Am I missing any clinical studies?

Steve Parker, M.D.

PS: I still expect a flurry of paleo diet studies to be published in the next 5-10 years, involving several types of human participants (diabetics, overweight and obese, heart patients, hypertensives, etc.).  Then again, maybe I’m wrong.

PPS: Instead of “paleo diet,” you may prefer Old Stone Age diet, Stone Age diet, caveman diet, hunter-gatherere diet, Paleolithic diet, or Ancestral diet

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Short-Term Effects of a Paleolithic Diet in Healthy Medical Students

Posted on February 20, 2012 | 6 comments

Stockholm Palace

Swedish investigators at Karolinska Institutet found diminished weight, body mass index, blood pressure, and waist circumference in 14 healthy medical students eating a paleo diet for three weeks.

Published in 2008, this seems to be one of the seminal scientific studies of the paleo diet in modern Europeans.

Their version of the paleo diet:

  • Allowed ad lib: All fresh or frozen fruits, berries and vegetables except legumes, canned tomatoes w/o additives, fresh or frozen unsalted fish and seafood, fresh or frozen unsalted lean meats and minced meat, unsalted nuts (except peanuts – a  legume), fresh squeezed lemon or lime juice (as dressing), flaxseed or rapeseed oil (as dressing), coffee and tea (w/o sugar, milk, honey, or cream), all salt-free spices.
  • Allowed but with major restrictions: dried fruit, salted seafood, fat meat, potatoes (two medium-sized per day), honey, cured meats
  • Prohibited: all milk and dairy products, all grain products (including corn and rice), all legumes, canned food except tomatoes, candy, ice cream, soft drinks, juices, syrups, alcohol, sugar, and salt

What Did They Find After Three Weeks?

  • Average weight dropped from 65.2 kg (144 lb) to 62.9 (139 lb) 
  • Average body mass index fell from 22.2 to 21.4
  • Average waist circumference decreased from 74.3 cm (29.25″) to 72.6 cm (28.58″) 
  • Average systolic blood pressure fell from 110 to 104 mmHg
  • plasminogen activator inhibitor-1 decreased from 5.0 kIE/l to 2.8 kIE/l
  • All of these changes were statistically significant

The researchers looked at a number of other blood tests and didn’t find any significant differences. 

Five men and nine women completed the study.  Of the 20 who originally signed up, one could not fulfill the diet, three became ill (no details), two failed to show up.

So What?

That’s a remarkable weight loss over just three weeks for slender people eating ad lib.

The study authors concluded that these paleo diet-induced changes could reduce risk for cardiovascular disease.  They called for a larger study with a control group.  (If it’s been done, I haven’t found it yet.)

Sounds reasonable.

Steve Parker, M.D.

PS: You’d think they would have said more about the three participants who got sick, rather than leave us wondering if the diet made them ill.

Reference:  Österdahl, M; Kocturk, T; Koochek, A;Wändell, PE.  Effects of a short-term intervention with a paleolithic diet in healthy volunteers.  European Journal of Clinical Nutrition, 62 (2008): 682-685.

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Random Thoughts On Paleo Eating For People With Diabetes

Posted on February 18, 2012 | 16 comments

Not really pertinent, but I like buffalo

I was interviewed  yesterday by Amy Stockwell Mercer, author of Smart Woman’s Guide to Diabetes.  All I knew beforehand was that she was interested in my thoughts on the paleo diet as applied to diabetes.

In preparation, I collected some random thoughts and did a little research.

What’s the paleo diet?

Fresh, minimally processed food.  Meat (lean or not? supermarket vs yuppiefied?), poultry, eggs, fish, leafy greens and other vegetables, nuts, berries, fruit, and probably tubers.

Non-paleo: highly processed, grains, refined sugars, industrial plant/seed oils, legumes, milk, cheese, yogurt, salt, alcohol.

Is the paleo diet deficient in any nutrients?

A quick scan of Loren Cordain’s website found mention of possible calcium and vitamin D deficits.  Paleoistas will get vitamin D via sun exposure and fish (especially cold-water fatty fish).  Obtain calcium from broccoli, kale, sardines, almonds, collards.  (I wonder if the Recommended Dietary Allowance for calcium is set too high.)

What About Carbohydrates and Diabetes and the Paleo Diet?

Diabetes is a disorder of carbohydrate metabolism.  In a way, it’s an intolerance of carbohydrates.  In type 1 diabetes, there’s a total or near-total lack of insulin production on an autoimmune basis.  In type 2 diabetes, the body’s insulin just isn’t working adequately; insulin production can be high, normal or low.  In both cases, ingested carbohydrates can’t be processed in a normal healthy way, so they stack up in the bloodstream as high blood sugars.  If not addressed adequately, high blood glucose levels sooner or later will poison body tissues .  Sooner in type 1, later in type 2.  (Yes, this is a gross over-simplification.) 

Gluten-rich Neolithic food

If you’re intolerant of lactose or gluten, you avoid those.  If you’re intolerant of carbohydrates, you could avoid eating them, or take drugs to help you overcome your intolerance.  Type 1 diabetics must take insulin.  Insulin’s more optional for type 2’s.  We have 11 classes of drugs to treat type 2 diabetes; we don’t know the potential adverse effects of most of these drugs.  Already, three diabetes drugs have been taken off the U.S. market or severely restricted due to unacceptable toxicity: phenformin, troglitazone, and rosiglitazone. 

Humans need two “essential fatty acids” and nine “essential” amino acids derived from proteins.  “Essential” means we can’t be healthy and live long without them.   Our bodies can’t synthesize them.  On the other hand, there are no essential carbohydrates.  Our bodies can make all the carbohydrate (mainly glucose) we need.

Since there are no essential carbohydrates, and we know little about the long-term adverse side effects of many of the diabetes drugs, I favor carbohydrate restriction for people with carbohydrate intolerance.  (To be clear, insulin is safe, indeed life-saving, for those with type 1 diabetes.)

That being said, let’s think about the Standard American Diet (SAD) eaten by an adult.  It provides an average of 2673 calories a day (not accounting for wastage of calories in restaurants; 2250 cals/day is probably a more accurate figure for actual consumption).  Added sugars provide 459 of those calories, or 17% of the total.  Grains provide 625 calories, or 23% of the total.  Most of those sugars and grains are in processed, commercial foods.  So added sugars and grains provide 40% of the total calories in the SAD.  Remember, we need good insulin action to process these carbs, which is a problem for diabetics.  (Figures are from an April 5, 2011, infographic at Civil Eats.)

Anyone going from the SAD to pure Paleo eating will be drastically reducing intake of added sugars and grains, our current major sources of carbohydrate.  Question is, what will they replace those calories with? 

That’s why I gave a thumbnail sketch of the paleo diet above. Take a gander and you’ll see lots of low-carb and no-carb options, along with some carb options. For folks with carbohydrate intolerance, I’d favor lower-carb veggies and judicious amounts of fruits, berries, and higher-carb veggies and

Will these cause bladder cancer? Pancreatitis?

tubers.  “Judicious” depends on the individual, considering factors such as degree of residual insulin production, insulin sensitivity, the need to lose excess weight, and desire to avoid diabetes drugs.

Compared to the standard “diabetic diet” (what’s that?) and the Standard American Diet, switching to paleo should lower the glycemic index and glycemic load of the diet.  theoretically, that should help with blood sugar control.

A well-designed low-carb paleo diet would likely have at least twice as much fiber as the typical American diet, which would also tend to limit high blood sugar excursions.

In general, I favor a carbohydrate-restricted paleo diet for those with diabetes who have already decided to “go paleo.”  I’m not endorsing any paleo diet for anyone with diabetes at this point—I’m still doing my research.  But if you’re going to do it, I’d keep it lower-carb.  It has a lot of potential.

Are There Any Immediate Dangers for a Person With Diabetes Switching to the Paleo Diet?

It depends on three things: 1) current diet, and 2) current drug therapy, and 3) the particular version of paleo diet followed. 

Remember, the Standard American Diet provides 40% of total calories as added sugars and grains (nearly all highly refined).  Switching from SAD to a low-carb paleo diet will cut carb intake  and glycemic load substantially, raising the risk of hypoglycemia if the person is taking certain drugs.

Drugs with potential to cause hypoglycemia include insulin, sulfonylureas, meglitinides, pramlintide, and perhaps thiazolidinediones.

Who knows about carb content of the standard “diabetic diet”?  Contrary to popular belief, there is no monolithic “diabetic diet.”  There is no ADA diet (American Diabetes Association).  My impression, however, is that the ADA favors relatively high carbohydrate consumption, perhaps 45-60% of total calories.  Switching to low-carb paleo could definitely cause hypoglycemia in those taking the aforementioned drugs.

One way to avoid diet-induced hypoglycemia is to reduce the diabetic drug dose.

A type 2 overweight diabetic eating a Standard American Diet—and I know there are many out there—would tend to see lower glucose levels by switching to probably any of the popular paleo diets.  Be ready for hypoglycemia if you take those drugs.

Paleo diets are not necessarily low-carb.  Konner and Eaton estimate that ancestral hunter-gatherers obtained 35 to 40% of total calories from carbohydrates.  I’ve seen other estimates as low as 22%.  Reality likely falls between 22 and 65%.  When pressed for a brief answer as to how many carbohydrate calories are in the paleo diet, I say “about a third of the total.”  By comparison, the typical U.S. diet provides 50% of calories from carbohydrate.

Someone could end up with a high-carb paleo diet easily, by emphasizing tubers (e.g., potatoes), higher-carb vegetables, fruits, berries, and nuts (especially cashews). Compared with the SAD, this could cause higher or lower blood sugars, or no net change.

A diabetic on a Bernstein-style diet or Ketogenic Mediterranean Diet (both very-low-carb) but switching to paleo or low-carb paleo (50-150 g?) would see elevated blood sugars.  Perhaps very high glucoses.

Any person with diabetes making a change in diet should do it in consultation with a personal physician or other qualified healthcare professional familiar with their case.

Steve Parker, M.D.

Fun Facts!

  • A typical carbonated soda contain the equivalent of 10 tsp (50 ml) of sugar.
  • The typical U.S. adult eats 30 tsp  (150 ml) daily of added sweeteners and sugars.
  • U.S total grain product consumption was at record lows in the 1970s, at 138 pounds per person.  By 2000, grain consumption was up by 45%, to 200 pounds per person.
  • Total caloric sweetener consumption (by dry weight) was 110 pounds per person in the  1950s.  By 2000, it was up 39% to 150 pounds.
  • Between 1970 and 2003, consumption of added fats and oils rose by 63%, from 53 to 85 pounds.  [How tasty would that be without starches and sugars?  Not very.]
  • In 2008, “added fat” calories in the U.S. adult diet were 641 (24% of total calories).

Fun Facts provided by the U.S. Department of Agriculture. 

(The paleo diet is also referred to as the Paleolithic, Old Stone Age, Stone Age, Ancestral, Hunter-Gatherer, or Caveman diet.)

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Posted in Diabetic Diet, Glucose, Grains, Low-Carb, Paleo Diet

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Can Diabetes Be Prevented?

Posted on February 12, 2012 | Comments Off on Can Diabetes Be Prevented?
Not Paula Deen

Paula Deen’s recent announcement of her type 2 diabetes got me to thinking about diabetes prevention again.  If you’re at high risk of developing diabetes you can reduce your risk of full-blown type 2 diabetes by 58% with intensive lifestyle modification.  Here’s how it was done in a 2002 study:

The goals for the participants assigned to the intensive lifestyle intervention were to achieve and maintain a weight reduction of at least 7 percent of initial body weight through a healthy low-calorie, low-fat diet and to engage in physical activity of moderate intensity, such as brisk walking, for at least 150 minutes per week. A 16-lesson curriculum covering diet, exercise, and behavior modification was designed to help the participants achieve these goals. The curriculum, taught by case managers on a one-to-one basis during the first 24 weeks after enrollment, was flexible, culturally sensitive, and individualized. Subsequent individual sessions (usually monthly) and group sessions with the case managers were designed to reinforce the behavioral changes.

Although the Diabetes Prevention Program encouraged a low-fat diet, another study from 2008 showed that a low-fat diet did nothing to prevent diabetes in postmenopausal women. 

I don’t know Paula Deen.  I’ve never watched one of her cooking shows.  She looks overweight and I’d be surprised if she’s had a good exercise routine over the last decade.  I’m sorry she’s part of the diabetes epidemic we have in the U.S.  I wish her well.  Amy Tenderich posted the transcript of her brief interview with Paula, who calculates her sweet tea habit gave her one-and-a-half cups of sugar daily.  Not quite a paleo diet.

  • Nearly 27% of American adults age 65 or older have diabetes (overwhelmingly type 2)
  • Half of Americans 65 and older have prediabetes
  • 11% of U.S. adults (nearly 26 million) have diabetes (overwhelmingly type 2)
  • 35% of adults (79 million) have prediabetes, and most of those affected don’t know it

I think excessive consumption of concentrated sugars and refined carbohydrates contribute to the diabetes epidemic.  To the extent that paleo diets (aka Old Stone Age or caveman diets) restrict concentrated sugars and refined carbohydrates, they are likely to prevent type 2 diabetes. 

Avoiding overweight, obesity, and physical inactivity may be even more important. 

The Mediterranean diet has also been linked to lower rates of diabetes (and here).  Preliminary studies suggest the Paleo diet may also be preventative (and here).

Greatly reduce your risk of type 2 diabetes by eating right, keeping your weight reasonable, and exercising.

Steve Parker, M.D.

Reference:  Diabetes Prevention Program Research Group.  Reduction in the Incidence of Type 2 Diabetes with Lifestyle Intervention or Metformin.  New England Journal of Medicine, 346 (2002): 393-403.

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Washington Internist Sees Good Results in Diabetics Eating Paleo-Style

Posted on February 5, 2012 | 1 comment

Dr. Stephan Guyenet recently interviewed Dr. C. Vicky Beer about her experience with the paleo diet in her patients, diabetic or not.  Dr. Beer commented about people with diabetes specifically:

Every patient I have ever had with diabetes who has adhered to the paleo diet for most of the time has experienced dramatic results.  Every one of them has been able to reduce their blood sugars and reduce their medications significantly, and in some instances, stop their medicine altogether.  This is not unlike other more known popular diets such as South Beach or Zone, which are actually quite similar to the Paleo diet in composition.

Just thought you might like to know.

Steve Parker, M.D.

PS: When I write “paleo diet,” you could substitute Old Stone Age, Stone Age, or caveman diet.

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Review of Chris Highcock’s Hillfit

Posted on January 31, 2012 | 16 comments

 

Chris Highcock over at Conditioning Research has just released a new ebook on strength training for hikers: Hillfit: Strength.  Hiking is one of my favorite hobbies.  I particularly like walking up hills and mountains.  If you’re ready to reap the benefits of resistance training, this jargon-free plan is an excellent starting point, and may be all you’ll ever need.  Even if you never go hiking.

Chris is a fitness columnist for “TGO (The Great Outdoors).”  He lives and hikes in Scotland.  Chris’s goal with the program is to increase your enjoyment of hiking by increasing your level of fitness. 

He clearly presents four basic home exercises requiring no special equipment; they’re bodyweight exercises.  You get it done in 15 minutes twice a week!  The key is to do one set of each exercise, slowly, to exhaustion.  What’s slow?  Ten seconds for both lift and lowering.  For instance, when you do the push-up, you push up over  the course of 10 seconds, then let your body down slowly over 10 seconds.  The exercises are for both upper and lower body.

I’m reading about similar exercise ideas from Skyler Tanner, Doug McGuff, Nassim Taleb, Jonathan Bailor, and Doug Robb.  Bailor, in his recent book, also recommends only four exercises.  Highcock’s look a little safer for rank beginners. 

The idea is to recruit three different types of muscle fiber during the muscle’s movement.  If you move explosively and finish too soon (get your mind out of the gutter!), you’re only using  one type of muscle fiber (fast twitch, I think).  You want to stimulate a strength and growth response in all three types of muscle fiber.  And explosive or rapid movements are more likely to cause injury, without any benefit. 

Once you get the basic program down, Chris takes you through some easy variations (called progressions) to make the exercises gradually harder, so you continue to improve your strength and fitness. 

Chris understands that many folks can’t do a single push-up.  He takes you through pre-push-up movements to get you prepared  to do actual push-ups.  This goes for all four exercises.  I bet even my little old lady patients could use this program.  (This is not blanket clearance for everybody to use this program; I don’t need the lawsuits.  Get clearance from your own doctor first.)

The exercises incorporate our five basic movements: push, pull, squat, bend/hinge, walk/gait.  The four exercises are: wall sit (squat), push-up, modified row, and hip extension.

My only criticism of the book is that Chris should have used young, attractive, bikini-clad models to illustrate the exercises.  (That’s right, my wife doesn’t read this blog.)  The existing photos are clear and helpful, however.

But seriously, the only suggestion I have for the next version of Hillfit would be to mention that it will take a couple or three weeks to see much, if any, improvement in strength once you start the program.  Same for when you increase the workload with the exercise progressions.  Perhaps this is in there, but I missed it.  You don’t want people quitting in frustration that they’re not seeing progress soon enough.

The author provides scientific references in support of his program, so he didn’t just make this stuff up.  Only one of the references involved mice!

Several “take home” points for me personally are: 1) stretching before or after exercise does nothing to prevent injury or soreness, and may hurt short-term athletic performance, 2) don’t hold your breath, 3) train to “momentary muscular failure.”  I’m not entirely sure what momentary muscular failure means.  It may not be Chris’s term, but it’s prominent in one of his best scientific references.  I use free weights and don’t think I can safely go 100% to momentary muscular failure.  Hitting momentary muscular failure, by the way, is more important than the amount of weight you’re moving.

Highly recommended.

Steve Parker, M.D.

PS: I’d like to see Hillfit available on Amazon’s Kindle and Barnes and Noble’s Nook.

PPS: When you go to the Hillfit website to order, you’ll find the price is £9.95 (that’s GBP, British pounds sterling).  I’ve never ordered anything priced in GBP.  In today’s U.S. dollars, that’s a little under $16.00.  You can pay via PayPal or a major credit card.  I assume the conversion from one currency to another is automatic and seamless.  I don’t know if there’s a extra fee by the payment processor for doing the conversion.

Disclosure:  Chris kindly sent me a free digital copy of his ebook.  I don’t know Chris.  I will receive no remuneration for this review, nor for book sales.

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