Category Archives: Carbohydrate

November 20, 2010 · 6:15 AM

High-Carbohydrate Eating Promotes Heart Disease in Women

Women double their risk of developing coronary heart disease if they have high consumption of carbohydrates, according to research recently published in the Archives of Internal Medicine. 

Men’s hearts, however, didn’t seem to be affected by carb consumption. I mention this crucial difference because I see a growing trend to believe that “replacing saturated fat with carbohydrates is a major cause of heart disease.”  If true, it seems to apply only to women.

We’ve known for a while that high-glycemic-index eating was linked to heart disease in women but not men.  Glycemic index is a measure of how much effect a carbohydrate-containing food has on blood glucose levels.  High-glycemic-index foods raise blood sugar higher and for longer duration in the bloodstream.

High-glycemic-index foods include potatoes, white bread, and pasta, for example.

The study at hand includes over 47,000 Italians who were interrogated via questionnaire as to their food intake, then onset of coronary heart disease—the cause of heart attacks—was measured over the next eight years. 

Among the 32,500 women, 158 new cases of coronary heart disease were found.

ResearchBlogging.orgResearchers doing this sort of study typically compare the people eating the least carbs with those eating the most.  The highest quartile of carb consumers and glycemic load had twice the rate of heart disease compared to the lowest quartile. 

The Cleave-Yudkin theory of the mid-20th century proposed that excessive amounts of refined carbohydrates cause heart disease and certain other chronic systemic diseases.  Gary Taubes has also written extensively about this.  Theresearch results at hand support that theory in women, but not in men. 

Practical Applications

Do these research results apply to non-Italian women and men?  Probably to some, but not all.  More research is needed.

Women with a family history coronary heart disease—or other CHD risk factors—might be well-advised to put a limit on total carbs, high-glycemic-index foods, and glycemic load.  I’d stay out of that “highest quartile.”  Don’t forget: heart disease is the No. 1 killer of women.

See NutritionData’s Glycemic Index page for information you can apply today.

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.

References: Sieri, S., Krogh, V., Berrino, F., Evangelista, A., Agnoli, C., Brighenti, F., Pellegrini, N., Palli, D., Masala, G., Sacerdote, C., Veglia, F., Tumino, R., Frasca, G., Grioni, S., Pala, V., Mattiello, A., Chiodini, P., & Panico, S. (2010). Dietary Glycemic Load and Index and Risk of Coronary Heart Disease in a Large Italian Cohort: The EPICOR Study Archives of Internal Medicine, 170 (7), 640-647 DOI: 10.1001/archinternmed.2010.15

Barclay, Alan, et al.  Glycemic index, glycemic load, and chronic disease risk – a meta-analysis of observational studies [of mostly women].  American Journal of Clinical Nutrition, 87 (2008): 627-637.

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November 3, 2010 · 2:00 AM

Paleo and Low-Carb Diets: Much In Common?

My superficial reading of the paleo diet literature led me to think Dr. Loren Cordain was the modern originator of this trend, so I was surprised to find an article on the Stone Age diet and modern degenerative diseases in a 1988 American Journal of Medicine.  Dr. Cordain started writing about the paleo diet around 2000, I think.

What’s So Great About the Paleolithic Lifestyle?

In case you’re not familiar with paleo diet theory, here it is.  The modern human gene pool has changed little over the last 50,000 years or so, having been developed over the previous one or two million years.  Darwins’ concept of Natural Selection suggests that organisms tend to thrive if they adhere to conditions present during their evolutionary development.  In other words, an organism is adapted over time to thrive in certain environments, but not others.

The paleo diet as a healthy way to eat appeals to me.  It’s a lifestyle, really, including lots of physical activity, avoidance of toxins, adequate sleep, etc. 

The Agricultural Revolution (starting about 10,000 years ago) and the Industrial Revolution (onset a couple centuries ago) have produced an environment vastly different from that of our Paleolithic ancestors, different from what Homo sapiens were thriving in for hundreds of thousands of years.  That discordance leads to obesity, type 2 diabetes, atherosclerosis, high blood pressure, and some cancers.  Or so goes the theory.

What’s the Paleolithic Lifestyle? (according to the article)

  • Average life expectancy about half of what we see these days
  • No one universal subsistence diet
  • Food: wild game (lean meat) and uncultivated vegetables and fruits (no dairy or  grain)
  • Protein provided 34% of calories (compared to about 12 in U.S. in 1988)
  • Carbohydrate provided 46% of calories (only a  tad lower than what we eat today)
  • Fat provided 21% of calories (42% today)
  • Little alcohol, but perhaps some on special occasions (honey and wild fruits can undergo natural fermentation) , compared to 7-10% of calories in U.S. today [I didn’t know it was that high]
  • No tobacco
  • More polyunsaturated than saturated fats (we ate more saturated than polyunsaturated fat, at least in 1988)
  • Minimal simple sugar availability except when honey in season
  • Food generally was less calorically dense compared to modern refined, processed foods
  • 100-150 grams of dietary fiber daily, compared to 15-20 g today
  • Two or three times as much calcium as modern Americans
  • Under a gram of sodium daily, compared to our 3 to 7 grams.
  • Much more dietary potassium than we eat
  • High levels of physical fitness, with good strength and stamina characteristic of both sexes at all ages achieved through physical activity

[These points are all debatable, and we may have better data in 2010.]

The article authors point out that recent unacculturated native populations that move to a modern Western lifestyle (and diet) then see much higher rates of obesity, diabetes, atheroslcerosis, high blood pressure, and some cancers.  “Diseases of modern civilization,” they’re called.  Cleave and Yudkin wrote about this in the 1960s and ’70s, focusing more on the refined carbohydrates in industrial societies rather than the entire lifestyle.  I expect Gary Taubes would blame the processed carbs, too. 

Paleo diet proponents agree that grains are not a Paleolithic food.  The word “grain” isn’t in this article.  The authors don’t outline the sources of Paleolithic carbs: tubers and roots, fruits, nuts, and vegetables, I assume.  Legumes and milk are probably out of the question, too.

Low-carb diet and paleo diet advocates often allign themselves, even though this version of the paleo diet doesn’t appear to be very low-carb.  The two share an affinity for natural, whole foods, and an aversion to grains, milk, and legumes.  Otherwise I don’t see much overlap.

ResearchBlogging.orgA 2010 article by Kuipers et al (reference below) sugggests that the East African Paleolithic diet derived, on average, 25-29% of calories from protein, 30-39% from fat, and 39-40% from carbohydrate.  That qualifies as low-carb.  Modern Western percentages for protein, fat, and carb are 15%, 33%, and 50%, respectively.

You can make a good argument that these paleo concepts are healthy: high physical activity, nonsmoking, consumption of natural whole foods while minimizing simple sugars and refined starches.  The paleo community is convinced that grains and legumes are harmful; many others disagree.  Also debatable are the role of dairy, polyunsaturated to saturated fat ratio, low sodium, and high potassium.  Modern diets tend to be high-sodium and low-potassium, which may predispose to high blood pressure and heart trouble—diseases of modern civilization.

For more on the paleo diet and lifestyle, visit Free the Animal, Mark’s Daily Apple, and PaNu. 

Steve Parker, M.D.

Update December 18, 2010:  I found a reference suggesting that Paleolithic diets may have derived about a third—22 to 40%—of calories from carbohydrate, based on modern hunter-gatherer societies.  See the Cordain reference I added below.

Reference:

Kuipers, R., Luxwolda, M., Janneke Dijck-Brouwer, D., Eaton, S., Crawford, M., Cordain, L., & Muskiet, F. (2010). Estimated macronutrient and fatty acid intakes from an East African Paleolithic diet British Journal of Nutrition, 1-22 DOI: 10.1017/S0007114510002679.  Note that one of the authors is Loren Cordain.  Good discussion of various Paleolithic diets.

Eaton, S., Konner, M., & Shostak, M. (1988). Stone agers in the fast lane: Chronic degenerative diseases in evolutionary perspective The American Journal of Medicine, 84 (4), 739-749 DOI: 10.1016/0002-9343(88)90113-1

Cordain, L., et al.  Plant-animal subsistance ratios and macronutrient energy estimations in worldwide hunter-gatherer diets.  American Journal of Clinical Nutrition, 71 (2000): 682-692.

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October 11, 2010 · 7:18 AM

Paleo Diet for Heart Patients With Diabetes and Prediabetes

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 patients—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.

ResearchBlogging.orgPresent 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., Jönsson, T., Granfeldt, Y., Borgstrand, E., Soffman, J., Sjöström, K., & Ahrén, B. (2007). A Palaeolithic diet improves glucose tolerance more than a Mediterranean-like diet in individuals with ischaemic heart disease Diabetologia, 50 (9), 1795-1807 DOI: 10.1007/s00125-007-0716-y

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September 21, 2010 · 2:00 AM

Myth Busted: Alzheimer Dementia NOT Caused By Diabetes

Contrary to popular belief among the experts, type 2 diabetes is not one of the causes of Alzeimer dementia.  They may indeed be associated with each other, but that’s not causation. 

Brain CT scan

An oft-repeated theory from Gary Taubes 2007 masterpiece, Good Calories, Bad Calories, is that many of the chronic diseases of modern civilization, including Alzheimer disease, are caused by abnormal blood sugar and insulin metabolism.  Especially high insulin levels induced by a diet rich in refined carbohydrates.  If that’s the case, you’d expect to see a high prevalence of Alzheimer disease in older type 2 diabetics. 

Dr. Emily Deans (psychiatrist) has been considering this issue recently at her Evolutionary Psychiatry blog.

The brains of Alzheimer patients, under a microscope, are characterized by many senile plaques (aka neuritic plaques) and neurofibrillary tangles.  That’s the gold standard for diagnosis.  Nevertheless, brain biopsies are rarely done to diagnose Alzheimer disease in living patients, and even autopsies after death are rare.  The diagnosis usually is clinical, based on ruling out other illnesses, etc.

Nearly all the studies associating diabetes with Alzheimers disease (and other dementias) are observational or epidimiologic. [The exception is the Honolulu-Asia Aging Study.]  Establishing an association is helpful in generating theories, but establishing causation is the goal.  At least five studies confirm an association.

Neurology this year reported findings of Japanese researchers who examined the brains of 135 people who died between 1998 and 2003.  They lived in Hisayama, a town with an incredibly high autopsy rate of 74%.  These people before death had undergone an oral glucose tolerance test.  Their insulin resistance was calculated on the basis of fasting glucose and fasting insulin (HOMA-IR).  None of them showed signs of dementia at the time of study enrollment in 1988.

What Did They Find?

Twenty-one of the 135 subjects developed Alzheimer-type dementia.  The investigators don’t say if the diagnosis was based on the brain examination, or just a clinical diagnosis without a brain biopsy.  How this got beyond the article reviewers is beyond me.  [If I’m missing something, let me know in the comments section below.]  It must be a clinical diagnosis because if you don’t act demented, it doesn’t matter how many senile plaques and neurofibrillary tangles you have in your brain. 

ResearchBlogging.orgSenile plaques, but not neurofibrillary tangles, were more common  in those with higher levels of blood sugar (as measured two hours after the 75 g oral glucose dose), higher fasting insulin, and higher insulin resistance.  People with the APOE epsilon-4 gene were at even higher risk for developing senile plaques.

The researchers did not report whether the subjects in this study had been previously during life with diabetes or not.  One can only hope those data will be published in another paper.  Why make us wait? 

Average fasting glucose of all subjects was 106 mg/dl (5.9 mmol/l); average two-hour glucose after the oral glucose load was 149 mg/dl (8.3 mmol/l).  By American Association of Clinical Endocrinologists criteria, these are prediabetic levels.  Mysteriously, the authors fail to mention or discuss this.  [I don’t know if AACE criteria apply to Japanese.]  Some of these Japanese subjects probably had diabetes, some had prediabetes, others had normal glucose and insulin metabolism.

As with all good research papers, the authors compare their findings with similar published studies.  They found one autopsy study that tended to agree with their findings (Honolulu) and three others that don’t (see references below).  In fact, one of the three indicated that diabetes seems to protect against the abnormal brain tissue characteristic of Alzheimer disease.

Botton Line

Type 2 diabetes doesn’t seem to be a cause of Alzheimer disease, if autopsy findings and clinical features are the diagnostic criteria for the disease. 

If we assume that type 2 diabetics have higher than normal blood sugar levels and higher insulin levels for several years, then hyperglycemia and hyperinsulinemia don’t cause or contribute to Alzheimer dementia.  Myth busted.  [I hope that’s not copyrighted by the “Myth Busters” TV show.]

Type 2 diabetes is, however, linked with impaired cognitive performance, at least according to many of the scientific articles I read in preparation for this post.  So type 2 diabetics aren’t in the clear yet.  It’s entirely possible that high blood sugar and /or insulin levels cause or contribute to that.  [Any volunteers to do the literature review?  Best search term may be “mild cognitive impairment.”]

Type 2 diabetes is associated with Alzheimer disease, but we have no proof that diabetes is a cause of Alzheimers.  Nor do we have evidence that high blood sugar and insulin levels cause Alzheimer disease. 

Alzheimer disease is a major scourge on our society.  I’d love to think that carbohydrate-restricted eating would help keep blood sugar and insulin levels lower and thereby lessen the devastation of the disease.  Maybe it does, but I’d like to see more convincing evidence.  It’ll be years before we have a definitive answer. 

Steve Parker, M.D.

References:
Matsuzaki T, Sasaki K, Tanizaki Y, Hata J, Fujimi K, Matsui Y, Sekita A, Suzuki SO, Kanba S, Kiyohara Y, & Iwaki T (2010). Insulin resistance is associated with the pathology of Alzheimer disease: the Hisayama study. Neurology, 75 (9), 764-70 PMID: 20739649

Heitner, J.,  et al. “Diabetics do not have increased Alzheimer-type pathology compared with age-matched control subjects: a retrospective postmortem immunocytochemical and histofluorescent study.” Neurology, 49 (1997): 1306-1311.  Autopsy study, No. of subjects not in abstract. They looked for senile plaques and neurofibrillary tangles, etc. The title says it all.

Beeri,  M.S., et al. “Type 2 diabetes is NEGATIVELY [emphasis added] associated with Alzheimer’s disease neuropathology.” J. Gerontol A. Biol Sci. Med. Sci. 60 (2005): 471-475.  385 autopsies. The title again says it all.

Arvanitakis, Z., et al. “Diabetes is related to cerebral infarction but NOT [emphasis added] to Alzheimers disease pathology in older persons.”  Neurology, 67 (2006): 1960-1965. Autopsy study of 233 Catholic clergy, about 50:50 women:men.

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September 1, 2010 · 2:00 AM

Are Refined Carbs Worse for Your Heart Than Saturated Fat?

To reduce coronary heart disease, we need to focus on reducing consumption of refined carbohydrates rather than fat and cholesterol, according to Dr. Frank Hu.

Dr. Hu is not a wild-eyed, bomb-throwing radical. He’s a Harvard professor of nutrition and epidemiology with both M.D. and Ph.D. degrees.  High-glycemic-index carbs in particular are the bad boys, he writes in an editorial published in the American Journal of Clinical Nutrition earlier this year.

Additional details are at my April 26, 2010, post at the Self/NutritionData Heart Health Blog.

Steve Parker, M.D.

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August 23, 2010 · 5:22 AM

2002 Atkins Diet at a Glance

Dr. Robert C. Atkins is the modern popularizer of low-carb dieting.  He was neither the first nor only low-carb advocate of the 20th century, but certainly the most influential in modern history in terms of followers.  His Dr. Atkins Diet Revolution was published in 1972 and sold millions of copies. 

Sir Isaac Newton wrote in 1676: “If I have seen further, it is by standing on the shoulders of giants.”  Twentieth century giants for Dr. Atkins include Frank Evans, Blake Donaldson (the original paleo diet guru?), Per Hansen, Alfred Pennington, and John Yudkin.  Most of these were physicians, by the way.  William Banting preceeded them, in the 19th century.

Dr. Atkins New Diet Revolution, published in 2002, was a huge seller then and maintains a respectable sales volume even now.  My impression is that Atkins Nutritionals, Inc., has replaced it with The New Atkins for a New You, which I reviewed last spring.  Enough people still follow DANDR that I need to stay familiar with it.  Here’s my brief summary of the phases.

Induction or Phase 1

  • Limit carbs to 20 g of “net carbs” daily for a minimum of two weeks.
  • “Net carbs” is the total carb count in grams, minus the fiber grams.
  • 3 cups of salad greens daily with olive oil/vingar or lemon juice OR 2 cups of salad greens and one cup of non-starchy cooked vegetables (e.g., broccoli or zucchini).
  • May also eat 3–4 ounces of aged cheese, a handful of olives, and half an avocado daily.

Ongoing Weight Loss (OWL) or Phase 2

  • Deliberate slowing of weight loss.
  • Gradually add back nutrient-rich carbs.
  • Increase net carbs weekly by just 5 g, by eating more veggies, nuts, seeds, even berries (this is where the “carb ladder” comes into play, adding carb groups in a specific order).
  • Some dieters can even add small amounts of beans and fruits other than berries, until weight loss stalls.  At that point, you drop back 5 g net carbs, to your Critical Carbohydrate Level for Losing (CCLL).

Pre-maintenance or Phase 3

  • Begins 5 or 10 pounds before reaching your weight goal.
  • Weight loss slows even more, taking at least 2 months to lose that last 10 pounds.
  • Can now add some starchy veggies like sweet potatoes, peas, whole grains.
  • If weight loss stops before goal, drop back down by 5-10 g net carbs, to your revised CCLL.

Lifetime Maintenance or Phase 4

  • Starts when you’ve been at goal weight for one month.
  • No more junk food, ever.
  • Stay vigilant for excessive carbs.  You may never be able to go back to whole grains or higher-carb fruits and vegetables.

Steve Parker, M.D.

PS: Gary Taubes reviews the history of low-carb diets in his masterpiece, Good Calories, Bad Calories.

Sir Isaac Newton
Head and shoulders portrait of man in black with shoulder-length gray hair, a large sharp nose, and an abstracted gaze

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August 18, 2010 · 7:53 AM

Whole Grains Lower Blood Pressure: So What?

The American Journal of Clinical Nutrition earlier this month published a research report on whole grain consumption and various cardiovascular disease risk factors.  U.K. investigators compared the effects of refined grains versus whole grains in healthy middle-aged adults.  The strongest finding was that three servings a day of whole grains—wheat and oats in this instance—reduced systolic blood pressure by 5 mmHg. 

The investigators suggest this BP lowering may be responsible for the reduced risk of heart attack and stroke associated with whole grain consumption in observational studies.

Additional details are at my Self/NutritionData Heart Health Blog post of August 17, 2010.  The researchers noted a three or four percent reduction in LDL cholesterol (“bad cholesterol”) in study participants eating refined grains, yet , mysteriously, had nothing to say about that.

Steve Parker, M.D.

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August 16, 2010 · 2:42 PM

High Carbohydrate Eating Increases Risk of Diabetes

ResearchBlogging.orgThe American Journal of Clinical Nutrition reported earlier this month that high consumption of carbohydrates, high-glycemic-index eating, and high-glycemic-load eating increases the risk of developing diabetes.  High fiber consumption, on the other hand, seems to protect against diabetes. 

The article abstract doesn’t mention type 1 versus type 2 diabetes, but it’s probably type 2, the most common kind.

The observational reseach was done in the Netherlands, but I bet the findings apply to other populations as well.  Australian researchers had established years ago that high-glycemic-index and high-glycemic-load eating is associated with onset of diabetes, at least in women. 

Is high carbohydrate consumption putting too much strain on the pancreas, which produces the insulin needed to process the carbs?

Steve Parker, M.D.

Reference:  Sluijs I, van der Schouw YT, van der A DL, Spijkerman AM, Hu FB, Grobbee DE, & Beulens JW (2010). Carbohydrate quantity and quality and risk of type 2 diabetes in the European Prospective Investigation into Cancer and Nutrition-Netherlands (EPIC-NL) study. The American journal of clinical nutrition PMID: 20685945

1,2,3

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August 13, 2010 · 8:16 AM

Is a Low-Carb Diet Safe For Obese Adolescents?

High-protein, low-carbohydrate diets are safe and effective for severely obese adolescent, according to University of Colorado researchers.

Childhood obesity in the U.S. tripled from the early 1980s to 2000, ending with a 17% obesity rate.  Overweight and obesity together describe 32% of U.S. children.  Some experts believe this generation of kids will be the first in U.S. history to suffer a decline in life expectancy, related to obesity.

Colorado researchers wondered if a low-carb, high-protein diet is a reasonable treatment option.  Why high protein?  It’s an effort to preserve lean body mass (e.g., muscle). 

ResearchBlogging.orgThey randomized 46 adoloscents (age 12–18) to either a high-protein, low-carb diet (HPLC diet) or a calorie-restricted low-fat diet to be followed for 13 weeks.  HPLC dieters could eat unlimited calories as long as they attempted to keep carb consumption to 20 g/day or less.  Low-fat dieters were to choose lean protein sources, aiming daily for 2 to 2.5 grams of protein per kilogram of ideal body weight.  Study participants underwent blood analysis and body compositon analysis by dual x-ray absorptiometry.  These kids weighed an average of 108 kg (238 lb) and average body mass index was 39. 

Analysis of food diaries showed the following:

  • Average caloric intake was 1300-1450/day, toward the lower end for the HPLC dieters
  • Energy composition of the HPLC diet: 32% from protien, 11% from carb, 57% from fat
  • Energy compositon of the LF diet: 21% from protein, 51% from carb, 29% from fat
  • Average daily carb consumption for the HPLCers ended up closer to 40 g (still very low) 

Findings

Both groups lost weight, with the HPLC dieters trending to greater weight loss, but not to a statistically significant degree.  They did, however, show a greater drop in body mass index Z-score, however.  Study authors didn’t bother to explain “body mass index Z-scores,” assuming I would know what that meant.  Average weight in the HPLC group dropped 13 kg (29 lb) compared to 7 kg (15 lb) in the low-fat group.

Total and LDL cholesterol fell in both groups, and insulin resistance improved.  Neither diet had much effect on HDL cholesterol.

As usual, triglycerides fell dramatically in the HPLC dieters.

Nearly 40% of the kids—about the same number in both groups—dropped out before finishing the 13 weeks.

The HPLC group did not see any particular preservation of lean body mass, and actually seemed to lose a bit more than the low-fat group.

There were no serious adverse effects in either group. 

Surprisingly, satiety and hunger scores were the same in both groups.  [Low-carb, ketogenic diets have a reputation for satiation and hunger suppression.]

My Comments

This is a small short-term study with a large drop-out rate; we must consider it a pilot study.  That’s why I’m not as enthusiastic about it as the researchers.  Nevertheless, it does indeed suggest that high-protein, low-carb diets are indeed safe and effective in obese adolescents.  It’s a start.   

Steve Parker, M.D.

Reference: Krebs, N., Gao, D., Gralla, J., Collins, J., & Johnson, S. (2010). Efficacy and Safety of a High Protein, Low Carbohydrate Diet for Weight Loss in Severely Obese Adolescents The Journal of Pediatrics, 157 (2), 252-258 DOI: 10.1016/j.jpeds.2010.02.010

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