Advanced Mediterranean Diet

I recently read Secrets for a Healthy Diet: What to Eat, What to Avoid, and What to Stop Worrying About by Monica Reinagel (2011).  I give it five stars on Amazon’s rating system (I love it).

This indispensible book cuts through the malarky of nearly all recent nutrition fads, sharing with us the science-based nutrition ideas that prevent disease and prolong life.  If you’re eating the Standard American Diet (SAD), you need this book.  The author gives highly practical suggestions on how to make your diet healthier immediately. 

In short, Ms. Reinagel focuses on minimally processed, whole foods, and preparing your own meals.  But there’s so much more here.  As you might expect, the Mediterranean diet was discussed in very favorably.

I’ve been following Monica Reinagel’s nutrition writing carefully for the last three years.  She knows the nutrition science literature as well as anyone, if not better.

The book starts with an unusually detailed table of contents that helps you find what you’re interested in without wasting time.

As promised by the subtitle, the author tells you what you DON’T need to worry about.  Is mercury in fish a problem?  What about bisphenol-A in plastic containers and canned foods?  Does red meat cause cancer?  Is pesticide residue on our food a problem?  Is salt a killer?  

I stay up to date on nutrition much more than the average physician, but the author introduced me to several new concepts, such as hemp milk, oat milk, and the idea that “pregnant women and small children should avoid cured meats altogether.”  I was particularly interested in her thoughts on the intersection of nutrition and exercise since I recently started an exercise program called Core Performance.

She successfully debunks many nutrition myths, such as 1) the need to eat every 2-3 hours, 2) saturated fat is bad for your heart and arteries, 3) eggs are bad for you (too much cholesterol, you know), 4) grain products are essential for health.

Any deficiencies in the book?  The font size is on the small side for people over 45.  On page 150, vitamin K is confused with vitamin D - undoubtedly a simple misprint.  No mention of the raw milk controversy.  When discussing potassium chloride as a salt substitute, she doesn’t mention the potential risk to people with kidney impairment or taking certain fluid pills. Tips on how to select fresh fish would have been helpful.

In summary, this is a great book for anyone wanting to get healthier via nutrition, but who’s confused by all the recent controversies.  The book is without peer.  If everything you learned about healthy eating was acquired over 10 years ago, you’re way out of date and need this book.  I hope the author does an updated edition every five years or so.

Steve Parker, M.D., author of Conquer Diabetes and Prediabetes: The Low-Carb Mediterranean Diet and The Advanced Mediterranean Diet: Lose Weight, Feel Better, Live Longer.

Disclosure: Other than a free advance review copy of the book from the publisher, I received nothing of value for writing this review.

Gary Taubes’s new book, Why We Get Fat: And What To Do About It, comes on the market later this month.  I give it five stars per Amazon.com’s ranking system (I love it).

♦   ♦   ♦

At the start of my medical career over two decades ago, many of my overweight patients were convinced they had a hormone problem causing it.  I carefully explained that’s rarely the case.  As it turns out, I may have been wrong.  And the hormone is insulin.

Mr. Taubes wrote this long-awaited book for two reasons: 1) to make the ideas in his 2007 masterpiece (Good Calories, Bad Calories) more accessible to the public, and 2) to speed up the process of changing conventional wisdom on overweight.  GCBC was the equivalent of a college-level course on nutrition, genetics, history, politics, science, physiology, and biochemistry. Many nutrition science geeks loved it while recognizing it was too difficult for the average person to digest.

Paradigm Shift

The author hopes to convince us that “We don’t get fat because we overeat; we overeat because we’re getting fat.”  We need to think of obesity as a disorder of excess fat accumulation, then ask why the fat tissue isn’t regulated properly.  A limited number of hormones and enzymes regulate fat storage; what’s the problem with them?

Mr. Taubes makes a great effort convince you the old “energy balance equation” doesn’t apply to fat storage.  You remember the equation: eat too many calories and you get fat, or fail to burn up enough calories with metabolism and exercise, and you get fat.  To lose fat, eat less and exercise more.  He prefers to call it the “calories-in/calories-out” theory.  He admits it has at least a little validity.  Problem is, the theory seems to have an awfully high failure rate when applied to weight management over the long run.  We’ve operated under that theory for the last half century, but keep getting fatter and fatter.  So the theory must be wrong on the face of it, right?  Is there a better one?

So, Why DO We Get Fat?

Here is Taubes’s explanation.  The hormone in charge of fat strorage is insulin; it works to make us fatter, building fat tissue.  If you’ve got too much fat, you must have too much insulin action.  And what drives insulin secretion from your pancreas?  Dietary carbohydrates, especially refined carbs such as sugars, flour, cereal grains, starchy vegetables (e.g., corn, beans, rice, potatoes), liquid carbs.  These are the “fattening carbs.”  Dozens of enzymes and hormones are at play either depositing fat into tissue, or mobilizing the fat to be used as energy.  It’s an active process going on continously.  Any regulatory derangement that favors fat accumulation will CAUSE gluttony (overeating) or sloth (inactivity).  So it’s not your fault. 

What To Do About It

Cut back on carb consumption to lower your fat-producing insulin levels, and you turn fat accumulation into fat mobilization.

Before you write off Taubes as a fly-by-night crackpot, be aware that he’s received three Science-in-Society Journalism Awards from the National Association of Science Writers.  He’s a respected, professional science writer.  Having read two of his books, it’s clear to me he’s very intelligent.  If he’s got a hidden agenda, it’s well hidden.

One example  illustrates how hormones control growth of tissues, including fat tissue.  Consider the transformation of a skinny 11-year-old girl into a voluptuous woman of 18. Various hormones make her grow and accumulate fat in the places we now see curves.  The hormones make her eat more, and they control the final product.  The girl has no choice.  Same with our adult fat tissue, but with different hormones. If some derangement is making us grow fatter, it’s going to make us more sedentary (so more energy can be diverted to fat tissue) or make us overeat, or both.  We can’t fight it.  At not least very well, as you can readily appreciate if look at the people around you at any American shopping mall.

This’N'That

Taubes’s writing is clear and persuasive.  He doesn’t beat you over the head with his conclusions. He lays out a logical series of facts and potential connections and explanations, helping you eventually see things his way.  If insulin controls fat storage by building and maintaining fat tissue, and if carboydrates drive insulin secretion, then the way to reduce overweight and obesity is carbohydrate-restricted eating, especially avoiding the fattening carbohydrates.  I’m sure that’s true for many folks, perhaps even a majority.

If you’re overweight and skeptical about this approach, you could try out a very-low-carb diet for a couple weeks or a month at little expense and risk (but not zero risk).  If Mr. Taubes and I are right, there’s a good chance you’ll lose weight.  At the back of the book is a university-affiliated low-carb eating plan.

If cutting carb consumption is so critical for long-term weight control, why is it that so many different diets—with no focus on carb restriction—seem to work, if only for the short run?  Taubes suggests it’s because nearly all diets reduce carb consumption to some degree, including the fattening carbs.  If you reduce your total daily calories by 500, for example, many of those calories will be from carbs.  Simply deciding to “eat healthy” works for some people: stopping soda pop, candy bars, cookies, desserts, beer, etc.  That cuts a lot of fattening carbs right there.

Losing excess weight or controlling weight by avoiding carbohydrates was the conventional wisdom prior to 1960, as documented by Mr. Taubes.  Low-carb diets for obesity date back almost 200 years.  The author attributes many of his ideas to German internist Gustav von Bergmann (1908).   

Taubes discusses the Paleolithic diet, mentioning that the average paleo diet derived about a third of total calories from carbohdyrates (compared to the standard American diet’s 55% of calories from carb).  My prior literature review  found 40-45% of paleo diet calories from carbohydrate.  I’m not sure who’s right.

Minor Bone of Contention RE: Coronary Heart Disease

Mr. Taubes provides numerous scientific references to back his assertions.  I checked out one in particular because it didn’t sound right.  Some background first. 

Reducing our total fat and saturated fat consumption over the last 40 years was supposed to lower our LDL cholesterol, thereby reducing the burden of coronary heart disease, which causes heart attacks.  Instead, we’ve experienced the obesity epidemic as those fats were replaced by carbohydrates.  Taubes mentions a 2009 medical journal article by Kuklina et al, in which Taubes says Kuklina points out the number of heart attacks has not decreased as we’ve made these diet changes.  Kuklina et al don’t say that.  In fact, age-standardized heart attack rates have decreased in the U.S. during the last decade. 

Furthermore, autopsy data document a reduced prevalence of anatomic coronary heart disease in people aged 20-59 from 1979 to 1994, but no change in prevalence for those over 60. The incidence of coronary heart disease decreased in the U.S. from 1971 to 1998 (the latest reliable data).  Death rates from heart disease and stroke have been decreasing steadily over the last 40 years in the U.S.; coronary heart disease death rates are down by 50%.  I do agree with Taubes that we shouldn’t credit those improvements to reduced total and saturated fat consumption.  [Reduced trans fat consumption may play a role, but that’s off-topic.] 

I think Mr. Taubes would like to believe that coronary artery disease is either more severe or unchanged in the last few decades because of low-fat, high-carb eating.  That would fit nicely with some of his theories, but it’s not the case.  Coronary artery disease is better now thanks to a variety of factors, but probably not diet (setting aside the trans-fat issue).

Going Forward

Low-carb dieting was vilified over the last half century partly out of concern that the accompanying high fat consumption would cause premature heart attacks, strokes, and death.  We know now that total dietary fat and saturated fat have little to do with coronary heart disease and atherosclerosis (hardening of the arteries), which sets the stage for a resurgence of low-carb eating.  

I advocate Mediterranean-style eating as the healthiest, in general.  It’s linked with prolonged life and lower risk of heart disease, stroke, dementia, diabetes, and cancer.  On the other hand, obesity is a strong risk factor for premature death and development of heart disease, stroke, diabetes, and cancer.  If consistent low-carb eating cures the obesity, is it healthier than the Mediterranean diet?  Maybe so.  Would a combination of low-carb and Mediterranean be better?  Maybe so.  I’m certain Mr. Taubes would welcome a decades-long interventional study comparing low-carb with the Mediterranean diet.  But that’s probably not going to happen in our lifetimes. 

Gary Taubes rejects the calories-in/calories-out theory of overweight that hasn’t done a very good job for us over the last 40 years.  Taubes’s alternative ideas deserve serious consideration.   

Steve Parker, M.D.

References:
Coronary heart disease autopsy data:  American Journal of Medicine, 110 (2001): 267-273.
Reduced heart attacks:  Circulation, 12 (2010): 1,322-1,328.
Reduced incidence of coronary heart disease:  www.UpToDate.com, topic: “Epidemiology of Coronary Heart Disease,” accessed December 11, 2010.
Death rates for coronary heart disease:  Journal of the American Medical Association, 294 (2005): 1,255-1,259.

Disclosure:  I don’t know Gary Taubes.  I requested from the publisher and received a free advance review copy of the book.  Otherwise I received nothing of value for this review.

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.

A Paleolithic diet lowered blood sugar levels better than a control diet in coronary heart disease patients with elevated blood sugars, according to Swedish researchers reporting in 2007.

About half of patients with coronary heart disease have abnormal glucose (blood sugar) metabolism.  Lindeberg and associates wondered if a Paleolithic diet (aka “Old Stone Age,” “caveman,” or ancestral human diet) would lead to improved blood sugar levels in heart patients, compared to healthy, Mediterranean-style, Western diet.

Methodology

Investigators at the University of Lund found enrolled 38 male heart—average age 61—patients and randomized them to either a paleo diet or a “consensus” (Mediterranean-like) diet to be followed for 12 weeks.  Average weight was 94 kg.  Nine participants dropped out before completing the study, so results are based on 29 participants.  All subjects had either prediabetes or type 2 diabetes (the majority) but none were taking medications to lower blood sugar.  Baseline hemoglobin A1c’s were around 4.8%.  Average fasting blood sugar was 125 mg/dl (6.9 mmol/l); average sugar two hours after 75 g of oral glucose was 160 mg/dl (8.9 mmol/l).

The paleo diet was based on lean meat, fish, fruits, leafy and cruciferous vegetables, root vegetables (potatoes limited to two or fewer medium-sized per day), eggs, and nuts (no grains, rice, dairy products, salt, or refined fats and sugar). 

The Mediterranean-like diet focused on low-fat dairy, whole grains, vegetables, fruits, potatoes, fatty fish, oils and margarines rich in monounsaturated fatty acids and alpha-linolenic acid. 

Both groups were allowed up to one glass of wine daily.

No effort was made to restrict total caloric intake with a goal of weight loss.

Results

Absolute carbohydrate consumption was 43% lower in the paleo group (134 g versus 231 g), and 23% lower in terms of total calorie consumption (40% versus 52%).  Glycemic load was 47% lower in the paleo group (65 versus 122), mostly reflecting lack of cereal grains.

The paleo group ate significantly more nuts, fruit, and vegetables.  The Mediterranean group ate significantly more cereal grains,oil, margarine, and dairy products.

Glucose control improved by 26% in the paleo group compared to 7% in the consensus group.  The improvement was statisically significant only in the paleo group.  The researchers believe the improvement was independent of energy consumption, glycemic load, and dietary carb/protein/fat percentages.

High fruit consumption inthe paleo group (493 g versus 252 g daily) didn’t seem to impair glucose tolerance. 

Hemoglobin A1c’s did not change or differ significantly between the groups.

Neither group showed a change in insulin sensitivity (HOMA-IR method).

Comments

The authors’ bottom line:

In conclusion, we found marked improvement of glucose tolerance in ischemic heart disease patients with increased blood glucose or diabetes after advice to follow a Palaeolithic [sic] diet compared with a healthy Western diet.  The larger improvement of glucose tolerance in the Palaeolithic group was independent of energy intake and macronutrient composition, which suggests that avoiding Western foods is more important than counting calories, fat, carbohydrate or protein.  The study adds to the notion that healthy diets based on whole-grain cereals and low-fat dairy products are only the second best choice in the prevention and treatment of type 2 diabetes.

This was a small study; I consider it a promising pilot.  Results apply to men only, and perhaps only to Swedish men.  I have no reason to think they wouldn’t apply to women, too.  Who knows about other ethnic groups?

This study and the one I mention below are the only two studies I’ve seen that look at the paleo diet as applied to human diabetics.  If you know of others, please mention in the Comments section. 

The higher fruit consumption of the paleo group didn’t adversely affect glucose control, which is surprising.  Fruit is supposed to raise blood sugar.  At 493 grams a day, men in the paleo group ate almost seven times the average fruit intake of Swedish men (75 g/day).  Perhaps lack of adverse effect on glucose control here reflects that these diabetics and prediabetics were mild cases early in the course of the condition—diabetes tends to worsen over time.

Present day paleo and low-carb advocates share a degree of simpatico, mostly because of carbohydrate restriction—at least to some degree—by paleo dieters.  Both groups favor natural, relatively unprocessed foods.  Note that the average American eats 250-300 g of carbohydrates a day.  Total carb intake in the paleo group was 134 g (40% of calories) versus 231 g (55% of calories) in the Mediterranean-style diet.  Other versions of the paleo diet will yield different numbers, as will individual choices for various fruits and vegetables.  Forty percent of total energy consumption from carbs barely qualifies as low-carb. 

Study participants were mild, diet-controlled diabetics or prediabetics, not representative of the overall diabetic population, most of whom take drugs for it and have much higher hemoglobin A1c’s.

Lindeberg and associates in 2009 published results of a paleo diet versus standard diabetic diet trial in 13 diabetics.  Although a small trial (13 subjects, crossover design), it suggested advantages to the paleo diet in terms of heart disease risk factors and improved hemoglobin A1c.  Most participants were on glucose lowering drugs; none were on insulin.  Glucose levels were under fairly good control at the outset.  Compared to the standard diabetic diet, the Paleo diet yielded lower hemoglobin A1c’s (0.4% lower—absolute difference), lower trigylcerides, lower diastolic blood pressure, lower weight, lower body mass index, lower waist circumference, lower total energy (caloric) intake, and higher HDL cholesterol.  Glucose tolerance was the same for both diets.  Fasting blood sugars tended to decrease more on the Paleo diet, but did not reach statistical significance (p=0.08).

The paleo diet shows promise as a treatment or preventative for prediabetes and type 2 diabetes.  Only time will tell if it’s better than a low-carb Mediterranean diet or other low-carb diets. 

Steve Parker, M.D.

Reference:  Lindeberg, S., et al.  Palaeolithic diet improves glucose tolerance more than a Mediterranean -like diet in individuals with ischemic heart disease.  Diabetologia, 50 (2007): 1,795-1,807.  doi: 10.1007/s00125-007-0716-y

Italian researchers reviewed the medical/nutrition literature of the last three years and confirmed that the Mediterranean diet 1) reduces the risk of death, 2) reduces  heart disease illness and death, 3) cuts the risk of getting or dying from cancer, and 4) diminishes the odds of developing dementia, Parkinsons disease, stroke, and mild cognitive impairment.

These same investigators published a similar meta-analysis in 2008, looking at 12 studies.  Over the ensuing three years (as of June, 2010), seven new prospective cohort studies looked at the health benefits of the Mediterranean diet.  The report at hand is a combination of all 19 studies, covering over 2,000,000 participants followed for four to 20 years.  Nine of the 19 Mediterranean diet studies were done in Europe.

The newer studies, in particular, firmed up the diet’s protective effect against stroke, and added protection against mild cognitive impairment.

So What?

The Mediterranean diet: No other way of eating has so much scientific evidence that it’s healthy and worthy of adoption by the general population.  Not the DASH diet, not the “prudent diet,” not the American Heart Association diet, not vegetarian diets, not vegan diets, not raw-food diets, not Esselstyne’s diet, not Ornish’s diet, not Atkins diet, not Oprah’s latest diet, not the Standard American Diet, not the  . . . you name it. 

Not even the Low-Carb Mediterranean Diet.

Just as important, the research shows you don’t have to go full-bore Mediterranean to gain a health and longevity benefit.  Adopting  just a couple Mediterranean diet features yeilds a modest but sigificant gain.  For a list of Mediterranean diet components, visit Oldways or the Advanced Mediterranean Diet website. 

Steve Parker, M.D.

Reference:  Sofi F, Abbate R, Gensini GF, & Casini A (2010). Accruing evidence about benefits of adherence to the Mediterranean diet on health: an updated systematic review and meta-analysis. The American journal of clinical nutrition PMID: 20810976

Dieters on low-fat and low-carb diets both lost the same amount of weight after two years, according to a just-published article in Annals of Internal Medicine.  Both groups received intensive behavioral treatment, which may be the key to success for many.  Low-carb eating was clearly superior in terms of increased HDL cholesterol, which may help prevent heart disease and stroke.

The study was funded by the National Institutes of Health and was carried out in Denver, St. Louis, and Philadelphia.

How Was It Done?

Healthy adults aged 18-65 were randomly assigned to either a low-fat or low-carbohydrate diet.  Average age was45.  Average body mass index was 36 (over 25 is overweight; over 30 is obese).  Of the 307 participants, two thirds were women.  People over 136 kg (299 lb) were excluded from the study—I guess because weight-loss through dieting is rarely successful at higher weights. 

The low-carb diet:  Essentially the Atkins diet with a prolonged induction phase (12 weeks instead of two).  Started with maximum of 20 g carbs daily, as low-carb vegetables.  Increase carbs by 5 g per week thereafter as long as weight loss progressed as planned.  Fat and protein consumption were unlimited.  The primary behavioral goal was to limit carb consumption.

The low-fat diet:  Calories were limited to 1200-1500 /day (women) or 1500-1800 (men).  [Those levels in general are too low, in my opinion.]  Diet was to consist of about 55% of calories from carbs, 30% from fat, 15% from protein.  The primary behavioral goal was to limit overall energy (calorie) intake. 

Both groups received frequent, intensive in-person group therapy (lead by dietitians and psychologists) periodically over two years, covering such topics as self-monitoring, weight-loss tips, management of weight regain and noncompliance with assigned diet.  Regular walking was recommended.

Body composition was measured periodically with dual X-ray absorptiometry.

What Did They Find?

Both groups lost about 11% of initial body weight, but tended to regain so that after two years, both groups average losses were only 7% of initial weight.  Weight loss looked a little better at three months in the low-carb group, but it wasn’t statistically significant. 

The groups had no differences in bone density or body composition.

No serious cardiovascular illnesses were reported by participants.  During the first six months, the low-carb group reported more bad breath, hair loss, dry mouth, and constipation.  After six months, constipation in the low-carb group was the only symptom difference between the groups.

During the first six months, the low-fat group had greater decreases in LDL cholesterol (with potentially less risk of heart disease), but the difference did not persist for one or two years.

Increases in HDL cholesterol (potentially heart-healthy) persisted throughout the study for the low-carb group.  The increase was 20% above baseline.

About a third of participants in both groups dropped out of the study before the two years were up.  [Not unusual.]

My Comments

Contrary to several previous studies that suggested low-carb diets are more successful than low-fat, the study at hand indicates they are equivalent as long as dieters get intensive long-term group behavioral intervention. 

Low-carb critics warn that the diet will cause osteoporosis, a dangerous thinning of the bones that predisposes to fractures.  This study disproves that.

Contrary to widespread criticism that low-carb eating—with lots of fat and cholestrol— is bad for your heart, this study notes a sustained elevation in HDL cholesterol (”good cholesterol”) on the low-carb diet over two years.  This also suggests the low-carbers  followed the diet fairly well.  The investigators also note that low-carb eating tends to produce light, fluffy LDL cholesterol, which is felt to be less injurious to arteries compared to small, dense LDL cholesterol.

A major strength of the study is that it lasted two years, which is rare for weight-loss diet research.

A major weakness is that the investigators apparently didn’t do anything to document the participants’ degree of compliance with the assigned diet.  It’s well known that many people in this setting can follow a diet pretty well for two to four months.  After that, adherence typically drops off as people go back to their old habits.  The group therapy sessions probably improved compliance, but we don’t know since it wasn’t documented. 

How often do we hear “Diets don’t work.”  Well, that’s just wrong.

Overall, it’s an impressive study, and done well. 

Individuals wishing to lose weight on their own can’t replicate these study conditions because of the in-person behavioral intervention component.  There are lots of self-help calorie-restricted balanced diets (e.g., Sonoma Diet, The Zone, Thin For Life,  Advanced Mediterranean Diet) and low-carb diets (e.g., the Atkins Diet,  the Low-Carb Mediterranean or Ketogenic Mediterranean Diets).  On-line support groups—e.g., Low Carb Friends and SparkPeople and 3 Fat Chicks on a Diet—could supply some necessary behavioral intervention strategies and support.  

Choosing a weight-loss program is not as easy as many think.  [Well, I’ll admit that choosing the wrong one is easy.]  I review the pertinent issues in my “Prepare for Weight Loss” page.

Steve Parker, M.D.

Reference: Foster GD, Wyatt HR, Hill JO, Makris AP, Rosenbaum DL, Brill C, Stein RI, Mohammed BS, Miller B, Rader DJ, Zemel B, Wadden TA, Tenhave T, Newcomb CW, & Klein S (2010). Weight and metabolic outcomes after 2 years on a low-carbohydrate versus low-fat diet: a randomized trial. Annals of internal medicine, 153 (3), 147-57 PMID: 20679559

The enduring popularity of the Mediterranean diet is attributable to three things:

1.       Taste

2.       Variety

3.       Health benefits

 

For our purposes today, I use “diet” to refer to the usual food and drink of a person, not a weight-loss program.

 

The scientist most responsible for the popularity of the diet, Ancel Keys, thought the heart-healthy aspects of the diet related to low saturated fat consumption.  He also thought the lower blood cholesterol levels in Mediterranean populations (at least Italy and Greece) had something to do with it, too.  Dietary saturated fat does tend to raise cholesterol levels.

 

Even if Keys was wrong about saturated fat and cholesterol levels being positively associated with heart disease, numerous studies (involving eight countries on three continents) strongly suggest that the Mediterranean diet is one of the healthiest around.  See References below for the most recent studies.

 

Relatively strong evidence supports the Mediterranean diet’s association with:

■ increased lifespan

■ lower rates of cardiovascular disease such as heart attacks and strokes

■ lower rates of cancer (prostate, breast, uterus, colon)

■ lower rates of dementia

■ lower incidence of type 2 diabetes

Weaker supporting evidence links the Mediterranean diet with:

■ slowed progression of dementia

■ prevention of cutaneous melanoma

■ lower severity of type 2 diabetes, as judged by diabetic drug usage and fasting blood sugars

■ less risk of developing obesity

■ better blood pressure control in the elderly

■ improved weight loss and weight control in type 2 diabetics

■ improved control of asthma

■  reduced risk of developing diabetes after a heart attack

■ reduced risk of mild cognitive impairment

■  prolonged life of Alzheimer disease patients

■ lower rates and severity of chronic obstructive pulmonary disease

■ lower risk of gastric (stomach) cancer

■ less risk of macular degeneration

■ less Parkinsons disease

■ increased chance of pregnancy in women undergoing fertility treatment

■  reduced prevalence of metabolic syndrome (when supplemented with nuts)

■ lower incidence of asthma and allergy-like symptoms in children of women who followed the Mediterranean diet while pregnant

 

Did you notice that I used the word “association” in relating the Mediterranean diet to health outcomes?  Association, of course, is not causation. 

The way to prove that a particular diet is healthier is to take 20,000 similar young adults, randomize the individuals  in an interventional study to eat one of two test diets for the next 60 years, monitoring them for the development of various diseases and death.  Make sure they stay on the assigned test diet.  Then you’d have an answer for that population and those two diets.  Then you have to compare the winning diet to yet other diets.  And a study done in Caucasians would not necessarily apply to Asians, Native Americans, Blacks, or Hispanics.

 

Now you begin to see why scientists tend to rely on observational  rather than interventional diet studies.

 

I became quite interested in nutrition around the turn of the century as my patients asked me for dietary advice to help them lose weight and control or prevent various diseases.  At that time, the Atkins diet, Mediterranean diet, and Dr. Dean Ornish’s vegetarian program for heart patients were all prevalent.  And you couldn’t pick three programs with more differences!  So I had my work cut out for me. 

After much scientific literature review, I find the Mediterranean diet to be the healthiest for the general population.  People with particular medical problems or ethnicities may do better on another diet.  People with diabetes or prediabetes are probably better off with a carbohydrate-restricted diet, such as the Low-Carb Mediterranean Diet. 

Dan Buettner makes a good argument for plant-based diets in his longevity book, The Blue Zones.  The Mediterranean diet qualifies as plant-based.

 

What do you consider the overall healthiest diet, and why?

 

Steve Parker, M.D.

 

References (updated September 6, 2010):

 

Sofi, Francesco, et al.  Accruing evidence about benefits of adherence to the Mediterranean diet on health: an updated systematic review and meta-analysis.  American Journal of Clinical Nutrition, ePub ahead of print, September 1, 2010.  doi: 10.3945/ajcn.2010.29673

 

Buckland, Genevieve, et al.  Adherence to a Mediterranean diet and risk of gastric adenocarcinoma within the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort study.  American Journal of Clinical Nutrition, December 9, 2009, epub ahead of print.  doi: 10.3945/ajcn.2009.28209

 

Fortes, C., et al.  A protective effect of the Mediterraenan diet for cutaneous melanoma.  International Journal of Epidmiology, 37 (2008): 1,018-1,029.

 

Sofi, Francesco, et al.  Adherence to Mediterranean diet and health status: Meta-analysis.  British Medical Journal, 337; a1344.  Published online September 11, 2008.  doi:10.1136/bmj.a1344

 

Benetou, V., et al.  Conformity to traditional Mediterranean diet and cancer incidence: the Greek EPIC cohort.  British Journal of Cancer, 99 (2008): 191-195.

 

Mitrou, Panagiota N., et al.  Mediterranean Dietary Pattern and Prediction of All-Cause Mortality in a US Population,  Archives of Internal Medicine, 167 (2007): 2461-2468.

 

Feart, Catherine, et al.  Adherence to a Mediterranean diet, cognitive decline, and risk of dementia.  Journal of the American Medical Association, 302 (2009): 638-648.

 

Scarmeas, Nikolaos, et al.  Physical activity, diet, and risk of Alzheimer Disease.  Journal of the American Medical Association, 302 (2009): 627-637.

 

Scarmeas, Nikolaos, et al.  Mediterranean Diet and Mild Cognitive Impairment.  Archives of Neurology, 66 (2009): 216-225.

 

Scarmeas, N., et al.  Mediterranean diet and Alzheimer disease mortality.  Neurology, 69 (2007):1,084-1,093.

 

Fung, Teresa, et al.  Mediterranean diet and incidence of and mortality from coronary heart disease and stroke in women.  Circulation, 119 (2009): 1,093-1,100.

 

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.

 

Salas-Salvado, Jordi, et al.  Effect of a Mediterranean Diet Supplemented With Nuts on Metabolic Syndrome Status: One-Year Results of the PREDIMED Randomized Trial.  Archives of Internal Medicine, 168 (2008): 2,449-2,458.

 

Mozaffarian, Dariush, et al.  Incidence of new-onset diabetes and impaired fasting glucose in patients with recent myocardial infarction and the effect of clinical and lifestyle risk factors.  Lancet, 370 (2007) 667-675.

 

Esposito, Katherine, et al.  Effects of a Mediterranean-style diet on the need for antihyperglycemic drug therapy in patients with newly diagnosed type 2 diabetes.  Annals of Internal Medicine, 151 (2009): 306-314.

 

Shai, Iris, et al.  Weight Loss with a Low-Carbohydrate, Mediterranean, or Low-Fat Diet.  New England Journal of Medicine, 359 (2008): 229-241.

 

Martinez-Gonzalez, M.A., et al.  Adherence to Mediterranean diet and risk of developing diabetes: prospective cohort study.  British Medical Journal, BMJ,doi:10.1136/bmj.39561.501007.BE (published online May 29, 2008).

 

Trichopoulou, Antonia, et al.  Anatomy of health effects of the Mediterranean diet: Greek EPIC prospective cohort study.  British Medical Journal, 338 (2009): b2337.  DOI: 10.1136/bmj.b2337.

 

Barros, R., et al.  Adherence to the Mediterranean diet and fresh fruit intake are associated with improved asthma control.  Allergy, vol. 63 (2008): 917-923.

 

Varraso, Raphaelle, et al.  Prospective study of dietary patterns and chronic obstructive pulmonary disease among US men.  Thorax, vol. 62, (2007): 786-791.

Here’s my review of Dr. Bernstein’s Diabetes Solution: The Complete Guide to Achieving Normal Blood Sugars, published in 2007.  Per Amazon.com’s rating scale, I give it five stars (I love it).

♦   ♦   ♦ 

Dr. Richard K. Bernstein gives away thousands of dollars’ worth of medical advice in this masterpiece, Diabetes Solution.  It’s a summation of his entire medical career and a gift to the diabetes community.

The book starts off with some incredible testimonials: reversal of diabetic nerve damage, eye damage, and erectile dysfunction.  They’re a bit off-putting to a skeptic like me, like an infomercial.  Dr. Bernstein is either lying about these or he’s not; I believe him.  His strongest testimonial is his own.  He’s been a type 1 diabetic most of his life, having acquired the disease at a time when most type 1’s never saw 55 candles on a birthday cake.  He’s in his mid-70s now and still working vigorously.

I only found one obvious error and assume it’s a misprint. He writes that 95% of people born today in the U.S. will eventually develop diabetes.  That’s preposterous.  The U.S. Centers for Disease Control predicts that one in three born in 2000 will be diagnosed.

Dr. Bernstein delivers lots of facts that I can neither confirm nor refute.  He’s a full-time diabetologist; I am not.

“Put down the bread and no one will get hurt!”

The central problem in type 1 diabetes is that, due to a lack of insulin,  ingested carbohydrates lead to spikes (elevations) in blood sugar.  The sugar elevations themselves are toxic.  The usual insulin injections are not good imitators of a healthy pancreas gland. So Dr. Bernstein is an advocate of low-carb eating (about 30 g daily compared to the usual American 250-300 g).  He says the available insulins CAN handle the glucose produced by a high-protein meal.

Dr. B reminds us that insulin is the main fat-building hormone, which is one reason diabetics gain weight when they start insulin, and why type 2 diabetics with insulin resistance (and high blood insulin levels) are overweight and have trouble losing weight.  You can have resistance to insulin’s blood sugar lowering action yet no resistance to its fat-building (fat-storing) action.  Insulin also stimulates hunger, so insulin-resistant diabetics are often hungry.

“Carbohydrate counting” is a popular method for determining a dose of injected insulin.  Dr. B says the gram counts on most foods are only a rough estimate—far too rough.  He minimizes the error by minimizing the input (ingested carbs).  From his days as an engineer, he notes “small inputs, small mistakes.”

Dr. B also cites problems with the absorption of injected insulin.  Absorption is variable: the larger the dose, the greater the variability.  So don’t eat a lot of carbs that require a large insulin dose.  For adult type 1 diabetics, his recommended rapid-acting insulins doses are usually three to five units.  If a dose larger than seven units is needed, split it into different sites.

He recommends diabetics aim for normal glucoses (90 mg/dl or less) almost all the time, and hemoglobin A1c of 5% or less.  This is extremely tight control, tighter than any expert panel recommends.  He says this is the best way to avoid the serious complications of diabetes. 

Here’s a smattering of “facts” in the book that made an impact on me, a physician practicing internal medicine for over two decades.  I want to remember them, incorporate into my practice, or research further to confirm:

• Hemoglobin A1c of 5% equals an average blood sugar of 100 mg/dl (5.56 mmol/l).  For each one % higher, average glucose is 40 mg/dl (2.22  mmol/l) higher.
• He’s against any drugs that overstimulate (“burn out”) the remaining pancreas function in type 2 diabetics: sulfonylureas, meglitinides, “phenylalanine derivatives”.  Pancreas-provoking agents cause hypoglycemia and destroy beta cell function.
• The insulin sensitizers are metformin and thiazolidinediones.  He likes these.
• Blood sugar normalization in type 2 diabetes and early-stage type 1 can help restore beta cell function.
• He often speaks of preserving beta cell function.
• He believes in “insulin-mimetic agents” like alpha lipoic acid (especially R-ALA, and take biotin with either form) and evening primrose oil.  These  are no substitute for insulin injections but allow for lower insulin doses.  ALA and evening primrose oil don’t promote fat storage like insulin does.
• He says many cardiologists take ALA for its antioxidant properties [news to me]
• He says rosiglitazone works within two hours [news to me] but later admits it may take 12 weeks to see maximal benefit
• One of his goals is to preserve beta cell function if at all possible
• He prefers rosiglitazone over pioglitazone due to fewer drug interactions
• “Americans are fat largely because of sugar, starches, and other high-carbohydrate foods.”
• He’s convinced that people who crave carbohydrates have inherited the problem, which also predisposes to insulin resistance and type 2 diabetes.  Low-carb diets decrease the cravings for many, in his experience.
• In small amounts, alcohol is relatively harmless: dry wine, beer, spirits.  Very few doctors have the courage to say this.
• If you’re in a restaurant, you can use urine sugar test strips and saliva to test for presence of sugar or flour in food
• A rule of thumb: one gram of carbohydrate will raise blood sugar about 5 mg/dl (0.28  mmol/l) or less for most diabetic adults weighing 140 lb (64  kg) and about 2.5 mg/dl (0.139 mmol/l) in a 280-pounder (127  kg).  This must refer to type 1 diabetics or a type 2 with little residual pancreas beta cell function; variable degrees of insulin resistance and beta cell reserve in many type 2s would make this formula unreliable.
• Be wary of maltodextrin in Splenda: it does raise blood sugar.
• Much new to me in his section on artificial sweeteners.  Be wary of them.
• He avoids all grains, breads, crackers, barley, oats, rice, and pasta.
• Most diet sodas are OK.
• Coffees with 1-2 tsp milk is OK.  Cream is OK.
• He eats NO fruit and recommends against it.
• He avoids beets, corn, potatoes, and beans. A slice of tomato in one cup of salad is OK.  A small amount of onion is OK.
• String beans and snow peas are OK.
• Cooked vegetables tend to raise blood sugar more rapidly than raw.
• Use “Equal” aspartame tabs as a sweetener.  Don’t use “powdered” Splenda.
• Avoid nuts: too easy to overeat.
• For desert: sugar-free Jell-O Brand Gelatin.
• Yogurt?  Plain, whole milk, unsweetened.  Flavor with cinnamon, Da Vinci syrups, baking flavor extracts, stevia or Equal.
• Avoid balsamic vinegar.
• Need fiber?  Bran crackers or soybean products.
• “Ideally, your blood sugar should be the same after eating as it was before.”  85 mg/dl (4.72  mmol/l) is his usual goal.  If blood sugar rises by more than 10 mg/dl (0.56 mmol/l) after a meal, either the meal has to be changed or medication changed.
• Protein is a source of glucose: keep protein amounts at meals constant from day to day, especially if taking glucose-lowering drugs.
• The lowest-carb meal of the day should be breakafast.  Why?  Dawn phenomenon.
• He promotes strenuous, prolonged exercise, especially weight training (extensive discussion and instruction in book).
• Many diabetics on insulin need dose adjustments in 1/2 and 1/4 unit increments [news to me: if I ordered 4 and 1/4 units of insulin at the hospital, the nurses would laugh].
• Typical rapid-acting insulin doses for his adult type 1 patients are 3-5 units.  The “industrial doses” of insulin seen or recommended by many physicians reflect diets too high in carbohydrate.
• He says Lantus only acts for nine hours (nighttime injection) or 18 hours (AM injection).
• He doesn’t like mixed insulins (e.g., 70/30).
• Humalog and Novolog are more potent than regular insulin, so the dose is about 2/3 of the regular insulin dose
• “Only a few of the 20 available [home glucose monitoring] machines are suitably accurate for our purposes.”  “None are suitably accurate or precise above 200 mg/dl [11.11 mmol/l].”
• Vitamin C in doses over 250 mg interferes with fingertip glucose monitors.  Later he says doses over 500 mg cause falsely low readings.
• He prefers regular insulin (45 minutes before meal) over Novolog and Humalog, because of its five-hour duration of action.
• Insulin users need to check glucose levels hourly while driving.
• His personal basal insulin is 3 units Lantus twice daily.
• He urges use of glucose (e.g., Dextrotabs) to correct hypoglycemia.
• He says hypoglycemia is rare on his regimen.
• He has an entire chapter on gastroparesis.

Dr. Bernstein’s recommended eating program in a nutshell:

• Some similarities to the Atkins diet, which he never mentions.
• No simple sugars or “fast-acting” carbs like bread and potatoes, because even type 2s have impaired or nonexistent phase 1 insulin response.
• Limit carbs to an amount that will work with your injected insulin or your remaining phase 2 insulin response, if any.
• “Stop eating when you no longer feel hungry, not when you’re stuffed.”
• Follow a predetermined meal plan (each meal: same grams of carb and ounces of protein)
• Six g (or less) of carbs at breakfast, 12 g (or less) at lunch and evening meal.  So his patients count carb grams and protein ounces.
• Supplements are not required IF glucoses are controlled and eating a variety of veggies.  Otherwise you may need B-complex or multivitamin/multimineral supplement.
• Recipes are provided.

His has four basic drug treatment plans, tailored to the individual.  They are outlined in the book.  Dr. B provides detailed notes on what he does with his personal patients.

Overall impressions:

• Too complicated for most, and they won’t give up higher carb consumption.  It requires a high degree of committment and discipline.  In fact, I’ve never had a patient tell me they were on the Bernstein program.
• If I had type 1 diabetes, I might well follow his plan or the Low-Carb Mediterranean Diet, NOT the high-carb diet recommended by the ADA and many dietitians.
• And if I had type 2 diabetes?  Low-Carb Mediterranean Diet first, Diabetes Solution as second choice.
• If one can get his hemoglobins A1c down to 5% with other methods, would that be just as good?  Dr. B would argue that all other methods have blood sugar swings that are too wide.
• Many new ideas and techniques here, at least to me.
• He pretty much reveals his entire program here, which is priceless.
• I’m not sure this plan will work unless the patient’s treating physician is on-board.
• His personal testimony and breadth of knowledge are very persuasive. 

Steve Parker, M.D.

Disclosure:  I was given nothing of value by Dr. Bernstein or his publisher in return for this review.

ORIGINS

It all starts with Ancel  Keys.

Keys was the leader of the team who put together the Seven Countries Study, which seemed to demonstrate lower rates of coronary heart disease in countries consuming less saturated fat.  [Coronary heart disease is the leading cause of death in Western cultures.]  He also found that cardiovascular disease rates rose in tandem with blood cholesterol  levels.  The two countries particularly illustrative of these connections were Italy and Greece, both Mediterranean countries.

The other countries he analyzed in “Seven Countries” were the United States, Yugoslavia, Japan, Finland, and the Netherlands.

Keys and his wife Margaret, a biochemist, drilled deeper in to the “Mediterranean diet” that was characteristic of Italy, Greece, and other countries on or near the Mediterranean Sea in the 1950s and 1960s.  [“Diet” in this context refers to the usual  food and drink of a person, not a weight-loss program.]  Their efforts culminated in the publication of several best-selling Mediterranean diet books in the 1970s, and Keys’ photo on the cover of Time magazine in 1961.

Thus began the still-popular Mediterranean diet.

Oldways Preservation Trust re-invigorated the Mediterranean diet around 1990, helping the public incorporate Mediterranean diet principals into everyday life.  Oldways founder, K. Dun Gifford, passed away just recently.

DEFINITION

There is no monolithic, immutable, traditional Mediterranean diet.  But there are similarities among many of the regional countries that tend to unite them, gastronomically speaking.  Greece and southern Italy are particularly influential in this context.

So here are the characteristics of the traditional, healthy Mediterranean diet  of the mid-20^th century:

•It maximizes natural whole foods and minimizes highly processed ones

•Small amounts of red meat

•Less than four eggs per week

•Low to moderate amounts of poultry and fish

•Daily fresh fruit

•Seasonal locally grown foods with minimal processing

•Concentrated sugars only a few times per week

•Wine in low to moderate amounts, and usually taken at mealtimes

•Milk products (mainly cheese and yogurt) in low to moderate amounts

•Olive oil as the predominant fat

•Abundance of foods from plants: vegetables, fruits, beans, potatoes, nuts, seeds, breads and other whole grain products

•Naturally low in saturated fat, trans fats, and cholesterol

•Naturally high in fiber, phytonutrients, vitamins (e.g., folate), antioxidants, and minerals (especially when compared with concentrated, refined starches and sugars in a modern Western diet)

•Naturally high in monounsaturated and polyunsaturated fats, particularly as a replacement for saturated fats

CONTROVERSIES

Keys has been criticized for “cherry-picking” the data that linked saturated fat consumption with increased heart disease.  Subsequent studies indicate a weak link, if any.  A list of the pertinent studies de-linking heart disease and saturated fat is at the Advanced Mediterranean Diet Blog.

The Seven Countries Study included only men.  It’s practical implications, therefore, may not apply to women.

The traditional Mediterranean diet is increasingly a thing of the past as Mediterranean countries adopt the Western diet characterized by “fast food” and highly processed foods.

FUN FACTS FOR FOOD GEEKS

Ever heard of K rations used by the U.S. military in World War II?  Keys invented them.  He earned Ph.D.s in biology and physiology.  Keys lived to age 100 and was said to be intellectually active through his 97^th year.

Steve Parker, M.D.

References:

Keys, Ancel (1970). Coronary heart disease in seven countries. Circulation, 41

Keys, Ancel.  Coronary heart disease in seven countries.  Circulation, 41, (1970) supplement I: I-1 through I-211.

Keys, Ancel.  Seven Countries:  A Multivariate Analysis of Death and Coronary Artery Disease.  Harvard University Press, 1980.

Oldways website.

Here’s my review of The New Atkins for  a New You, a weight-loss book by Dr. Eric Westman, Dr. Stephen Phinney, and Dr. Jeff Volek released a week ago.  The copyright holder is Atkins Nutritionals, Inc.  Under Amazon.com’s five-star rating system, I give it four stars (”I like it”).  

♦   ♦   ♦ 

The most exciting nutritional medicine development in recent memory is the fact that saturated fat consumption is not a significant cause of heart disease and premature death. The same goes for for total fat and cholesterol.  When enough physicians, nutritionists, and dietitians learn this, low-carb eating will take off like a rocket.

For those unfamiliar with the Atkins diet, it is designed for weight loss via high fat consumption and major carbohydrate restriction.  Protein intake is a bithigher than average.  As long as carbohydrates (carbs) are kept low, other foods are mostly unlimited.  Atkins has four phases.  As you graduate from one phase tothe next, more carbs are allowed, adding some carb sources before others (the Carb Ladder). 

Atkins has been around for years.  It’s not just a weight-loss diet; it’s a lifetime way of eating.

Doctors Westman, Phinney, and Volek are leaders in low-carb nutritional science.  The last time Atkins peaked (2003), we didn’t have the scientific studies backing up safety of the diet.  Now we do, in large part thanks to these guys. 

Physicians see beaucoup patients with overweight-related medical conditions.  We’re not going to recommend a diet that causes heart attacks, strokes, and other major medical complications.  Published research over the last eight years has established the relative safety of very low-carb diets, particularly Atkins.  Low-carb diets may even be healthier than the low-fat, high-carb diet that has been recommended by U.S. public health authorities for the last forty years.  Come to think of it, our current obesity and diabetes epidemics started around that same time.

The book covers nutrition basics, day-to-day practical application of Atkins eating, recipes and detailed meal plans, and the science behind the program.    

What’s New Since Dr. Atkins’ 2002 Book?

• adaptations for vegetarians and vegans
• adaptations for Latinos
• coffee is now OK
• introduction of the term “foundation vegetables” and almost doubling the amount of vegetables allowed in Phase 1: “approximately six cups of salad and up to two cups of cooked vegetables, depending upon the ones you select”
• more flexility, such as the option to skip Phase 1 (induction)
• focus on adequate protein intake, based on your height
• emphasis on getting enough omega-3 fatty acids
• no emphasis on supplements and low-carb products sold by Atkins Nutritionals,Inc.
• diet journals—a personal record of your weight-loss journey—are recommended
• eliminate or minimize “induction flu” and constipation (in Phase 1) by eating at least 1/2 teaspoon of salt daily [I’m skeptical.]
• discussion of the trendy omega-6/omega-3 fatty acid ratio
• favor monounsaturated fatty acids (e.g., olive oil, canola oil) over certain polyunsaturated fats, as in oils from corn, soybeans, sunflower, cottonseed, and peanuts
• no mention of testing urine for ketosis
• more discussion of psychological aspects of weight

The lack of ads for Atkins Nutritionals products is welcome and refreshing.  Too many of the official Atkins books read like infomercials, which diminishes credibility.

A vegetarian or vegan “Atkins diet” is just not something I can visualize.

What Could Have Been Done Better?

• no specific amounts given for these recommended supplements: calcium, vitamin D, omega-3 fats, multivitamin, magnesium and other minerals (except “no iron”).  [Is the idea to encourage a visit the official Atkins website?]
• little guidance for physicians who are to advise diabetics doing Atkins.  Few physicians are familiar enough with the program to make the necessary changes in particular diabetic medications.
• little discussion of the constipation and leg cramps that often accompany very low-carb diets
• the hype on the cover: “How would you like to LOSE UP TO 15 POUNDS IN TWO WEEKS!”  [To their credit, the authors note that such results are not typical.]
• nearly all the measurements are U.S. Customary.  Metric users are out of luck.
• four phases seem a bit much.  The beauty of Atkins Phase 1 is its simplicity. 

My favorite sentence: “White flour is better suited to glue for kindergarten art projects than to nutrition.”

My least favorite sentence: “We can’t stress strongly enough that the best diet for you is one composed of foods you love.”  I love apple pie and Cinnabon cinnamon rolls, but they won’t help me manage my weight.

The only error I found worth mentioning is minor.  The authors state that the American Heart Association recommends consumption of fish three times a week. The official policy is still “at least twice weekly.”

The book is very practical and easily understood by average people.  Most will skip the science chapters at the end.  I know the basic Atkins program works at least short-term; many of my patients have done it.

In summary, the book has nearly everything you need to be successful with the Atkins diet. 

As far as I know, there are no comprehensive long-term studies (e.g., 10+ years) regarding health outcomes of Atkins-style eating.  In other words, does Atkins have any effect on longevity, cancer, heart attacks, strokes, etc.?  But very few of the popular diets have these data either.  The best researched ways of eating in this respect are the Mediterranean diet and vegetarian diets.

Numerous scientific studies document the long-term health benefits of the Mediterranean diet, including improved longevity and lower rates of heart disease, stroke, type 2 diabetes, cancer, and dementia.

Steve Parker, M.D.

Disclosure:  I was given nothing of value for this review by the authors, publisher, or Atkins Nutritionals, Inc.  It was written for the benefit of my patients and readers.

Paleo diets have been increasingly popular over the last few years.  The idea is that, for optimal health, we should be eating the things that we are evolutionarily adapted to eat.  Those foods pre-date the onset of large-scale agriculture 10-12,000 years ago.  So grains and modern fruits and vegetables play little or no role for someone who has “gone paleo.”

My recollection from college courses years ago is that average lifespan in paleolithic times was perhaps 25-30 years, or less.  If you’re going to die at 25, it may not matter if you eat a lot of  wooly mammath, berries, insects, cholesterol, saturated fats, Doritos, Ding Dongs, or Cheetos.  The diseases of civilization we worry about today—coronary heart disease, high blood pressure, cancer, dementia, type 2 diabetes, etc.—don’t usually appear until after age 30.  Paleolithic Man worried more about starvation.

Jenny Ruhl, at her Diabetes Update blog, recently put much more critical thought than I into the concept of paleo diets.  Recommended reading.    

Steve Parker, M.D. 

Extra credit: 

For purposes of discussion, let’s assume that human evolution actually occurred over millions, or at least hundreds of thousands, of years.  In other words, assume that God didn’t make Adam and Eve in human form in one day.

The theory of evolution proposes that genes that allow an animal to live and reproduce more vigorously in a particular environment will be passed on to the animal’s offspring.  Nature will select those genes to spread through the animal population over time, assuming the environment doesn’t change.  The offspring with those genes will be able to compete with other animals more successfully for food, shelter, and mates.  Factors that promote the persistence and inheritance of specific genes are called “selection pressure.”

Here’s an example of selection pressure.  Remember when you were in grade school on the playground, some people could naturally run faster than others?  Were you one of the fast ones?  If you’ve never seen it for yourself, take my word for it: Some people are naturally gifted with athletic genes.

Let’s say you and I are outside collecting berries and nuts in paleolithic times.  A saber-toothed tiger spots us and charges, hungry for a meal.  You don’t have to outrun the tiger: you just have to outrun me.  I’m slower than you, and get eaten.   I can no longer pass on my slow-running genes to the next generation.  You live another day and pass on your fast-running genes to your children. 

Viola!  Natural selection, via selection pressure, has promoted your genes over mine.

[The tiger also passes on her genes since she was fast and smart enough to catch me, preventing starvation of her and her offspring.] 

[I’m 99% sure I wrote the preceeding few paragraphs originally about a year ago.  My notes, however, hint that they may have been written by Dr. J., a regular contributor at CalorieLab.  Dr. J., let me know if I’ve plagiarized you and I’ll give you full credit and delete my writing.]

The paleo diet rationale seems to be based on an evolutionary argument: Certain foods were available to us during 99% of our evolution, so our bodies are adapted to work optimally with them.  For example, humans/humanoids/higher primates who were not suited to the available food did not survive and reproduce, so their genes were not passed on to us.

For most of human existence, maximum lifespan was probably 25-30 years, on average. If that’s as long as you’re going to live, it may not matter much what you eat. Eat paleo, vegetarian, McDonald’s, Atkins, or Mediterranean. Most diet-related conditions except overweight and under-nutrition are not going to be an issue before age 30. 

[The modern paleos argue that infant and childhood mortality were extremely high in paleolithic times.  If you survived childhood, you could easily live to be 50+.]

But now we live to be 80, long enough for diet-related diseases to appear. We have cancer, heart attacks, and strokes that paleo man never saw because he died of trauma or infection or starvation. We even see the expression of genes that were not subjected to survival or selection pressure: Alzheimers disease, Huntingtons chorea, some breast cancers, etc.  People with genes for these diseases reproduce before the genes do their damage.

In other words, we carry genes that don’t matter if you die at age 30. If you live longer, they express themselves, and I believe we can modify their expression through diet and lifestyle. And not necessarily the paleo diet.

I’m still thinking it through.

For the other side of the argument, visit Mark’s Daily Apple, At Darwin’s Table, or read Dr. Loren Cordain’s The Paleo Diet.

-Steve