Category Archives: Glycemic Index and Load

Paleo Diet and Diabetes: Improved Cardiovascular Risk Factors

Compared to a standard diabetic diet, a Paleolithic diet improves cardiovascular risk factors in type 2 diabetics, according to investigators at Lund University in Sweden.

Researchers compared the effects of a Paleo and a modern diabetic diet in 13 type 2 diabetic adults (10 men) with average hemoglobin A1c’s of 6.6% (under good control, then).  Most were on diabetic pills; none were on insulin.  So this was a small, exploratory, pilot study.  Each of the diabetics followed both diets for three months.

How Did the Diets Differ?

ResearchBlogging.orgCompared to the diabetic diet, the Paleo diet was mainly lower in cereals and dairy products, higher in fruits and vegetables, meat, and eggs.  The Paleo diet was lower in carbohydrates, glycemic load, and glycemic index.  Paleo vegetables were primarily leafy and cruciferous.  Root vegetables were allowed; up to 1 medium potato daily.  The Paleo diet also featured lean meats [why lean?], fish, eggs, and nuts, while forbidding refined fats, sugars, and beans.  Up to one glass of wine daily was allowed.

See the actual report for details of the diabetic diet, which seems to me to be similar to the diabetic diet recommended by most U.S. dietitians.

What Did the Researchers Find?

Compared to the 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).

So What?

The greater improvement in multiple cardiovascular risk factors seen here suggests that the Paleo diet has potential to reduce the higher cardiovascular disease rates we see in diabetics.  Larger studies—more participants—are needed for confirmation.  Ultimately, we need data on hard clinical endpoints such as heart attacks, strokes, and death.

These diabetics had their blood sugars under fairly good control at baseline.  I wouldn’t be surprised if diabetics under poor control—hemoglobin A1c of 9%, for example—would see even greater improvements in risk factors as well as glucose levels while eating Paleo.

I see a fair amount of overlap between this version of the Paleo diet and Dr. Bernstein’s Diabetes Solution diet and the Low-Carb Mediterranean Diet

Steve Parker, M.D.

Reference:  Jönsson, T., Granfeldt, Y., Ahrén, B., Branell, U., Pålsson, G., Hansson, A., Söderström, M., & Lindeberg, S. (2009). Beneficial effects of a Paleolithic diet on cardiovascular risk factors in type 2 diabetes: a randomized cross-over pilot study Cardiovascular Diabetology, 8 (1) DOI: 10.1186/1475-2840-8-35

11 Comments

Filed under coronary heart disease, Glycemic Index and Load, Mediterranean Diet

Sugar-Sweetened Beverages: Bane of Mankind?

Over the last 30 years in the U.S., consumption of sugar-sweetened beverages (SSBs) has increased from3.9% of total calories to 9.2% (in 2001).  In that same time span, the percentage of overweight American adults increased from 47% to 66%.  The obesity percentage rose from15 to 33% of adults. 

[Did the beverages cause the weight gain, or are they just associated?] 

Those are just a few of the many facts shared by the authors of “Sugar-sweetened beverages, obesity, type 2 diabetes mellitus, and cardiovascular disease risk,” published recently in Circulation.  Sugar-sweetened beverages, by the way, include soft drinks, fruit drinks, energy drinks, and vitamin water drinks. 

ResearchBlogging.orgSounds like an interesting article, doesn’t it?  It’s written by some of the brightest lights in nutritional science, including George Bray and Frank Hu.  Unfortunately, the article is a little too boring and technical for most of my readers.  Here are a few tidbits I enjoyed:

  • Fructose (found in similar amounts in sucrose (table sugar) and high fructose corn syrup) may particularly predispose us to deposit fat in and around our internal abdominal organs (“visceral fat,” which some believe to be more unhealthy than fat  in our buttocks or thighs).
  • Fructose may also lead to fat deposits in cells other than fat cells, potentially interfering with cell function.
  • Fructose may adversely affect lipid metabolism (higher triglyceride levels and lower HDL levels, which could promote heart disease).
  • Fructose raises blood pressure and reduces insulin sensitivity.
  • In the liver, fructose is preferentially converted to lipid, causing high triglyceride levels (associated with heart disease and insulin resistance).  [The authors did not mention the common condition of “fatty liver” (aka hepatic steatosis) in this context.]

Some of the authors conclusions:

  • SSBs are the largest contributor to added-sugar intake in the U.S.
  • SSBs contribute to weight gain.
  • SSBs may cause type 2 diabetes and cardiovascular disease—separate from their effect on obesity—via high glycemic load and increased fructose metabolism, in turn leading to insulin resistance, inflammation, pancreas beta cell impairment, high blood pressure, visceral fat build-up, and adverse effects on blood lipids.

I especially like their final sentence:

For these reasons and because they have little nutritional value, intake of SSBs should be limited, and SSBs should be replaced by healthy alternatives such as water.

Steve Parker, M.D.

Reference: Malik, V., Popkin, B., Bray, G., Despres, J., & Hu, F. (2010). Sugar-Sweetened Beverages, Obesity, Type 2 Diabetes Mellitus, and Cardiovascular Disease Risk Circulation, 121 (11), 1356-1364 DOI: 10.1161/CIRCULATIONAHA.109.876185

1 Comment

Filed under Carbohydrate, Causes of Diabetes, coronary heart disease, Glycemic Index and Load, Overweight and Obesity

Low-Carb Mediterranean Diet Improves Glucose Control and Heart Risk Factors in Overweight Diabetics

In overweight type 2 diabetics, a low-carbohydrate Mediterranean diet improved HDL cholesterol levels and glucose control better than either the standard Mediterranean diet or American Diabetes Association diet, according to Israeli researchers reporting earlier this year.

Background

Prior studies suggest that diets rich in monounsaturated fatty acids (olive oil, for example) elevate HDL cholesterol and reduce LDL cholestrol and triglycerides in type 2 diabetics.

Low-carb diets improve blood sugar levels and reduce excess body weight in type 2 diabetics, leading to the ADA’s allowance in 2008 of a low-carbohydrate diet as an alternative to standard diabetic diets.

Many—probably most—type 2 diabetics have insulin resistance:  the body’s cells that can remove sugar from the bloodstream are not very sensitive to the effect of insulin driving sugar into those cells.  They “resist” insulin’s effect.  Consumption of monounsaturated fatty acids  improves insulin sensitivity.  In other words, insulin is better able to push blood sugar into cells, removing it from the bloodstream.

Previous studies have shown that both low-carb diets and the Mediterranean diet reduce after-meal elevations in blood sugar, which likely lowers levels of triglycerides and LDL cholesterol.

How Was the Study Done?

The goal was to compare effects of three diets in overweight type 2 diabetics in Israel over the course of one year.  Study participants totalled 259.  Average age was 56, average weight 86 kg (189 lb), average hemoglobin A1c 8.3%, and average fasting plasma glucose (sugar) was 10.3 mmol/L (185 mg/dl).  [Many diabetics in the U.S. fit this profile.]  People taking insulin were excluded from the study, as were those with proliferative diabetic retinopathy—no reasons given. 

Participants were randomly assigned to one of three diets, so there were about 85 in each group.  [Over the course of one year, people dropped out of the study for various reasons, leaving each group with about 60 subjects.] 

Here are the diets:

  • 2003 ADA (American Diabetes Association) diet:  50-55% of total caloric intake from carbohydrate (mixed glycemic index carbs), 30%  from fat, 20% from protein
  • Traditional Mediterranean (TM):  50-55% low-glycemic-index carbs, 30% fat—high in monounsaturated fat, 15-20% protein
  • Low-carb Mediterranean (LCM) :  35% low-glycemic-index carbs, 45% fat—high in monounsaturated fat, 15-20% protein

Patients were followed-up by the same dietitian every two weeks for one year.  All were advised to do aerobic exercise for 30-45 minutes at least three days a week.

Olive oil is traditionally the predominant form of fat in the Mediterranean diet and is a particularly rich source of monounsaturated fat.  At no point in this report was olive oil mentioned, nor any other source of monounsaturated fat.  Until I hear otherwise, I will assume that olive oil was the major source of monounsaturated fat in the TM and LCM diets. 

 All diets were designed to provide 20 calories per kilogram of body weight. 

In all three diets, saturated fat provided 7% of total calories.  Monounsaturated fatty acids provided 23% of total calories in the LCM, and  10% in the other two diets.  Polyunsaturated fatty acids provided 15% of calories in the LCM, and 12% in the other two diets.  The ADA diet provided 15 grams of fiber, the TM had 30 g, and the LCM had 45 g.

Adherence to the assigned diet was assessed with a “food frequency questionnaire” administered at six months.

What Did the Researchers Find?

Average reported energy intake was similar in all three groups: 2,222 calories per day.

Monounsaturated fat intake differences were statistically significant: 14.6, 12.8, and 12.6% for the LCM, TM, and ADA diets, respectively.  Polyunsaturated fat intake differences were statistically significant: 12.9, 11.5, and 11.2% for the LCM, TM, and ADA diets, respectively.

Percentage of energy from carbs was highest for the ADA diet (45.4%), intermediate for the TM diet (45.2%), and lowest for the LCM diet (41.9%).

At the end of 12 months, all three groups lost about the same amount of weight (8-9 kg or 18-20 lb), body mass index, and waist circumference.

Hemoglobin A1c fell in all three groups, but was significantly greater for the LCM group than for the ADA diet (6.3% absolute value vs 6.7%).

Triglycerides fell in all three groups, but was significantly greater for the LCM diet compared to the ADA diet.

The LCM group achieved a significant increase (12%) in HDL cholesterol compared to the ADA diet, but not different from the TM group.

LDL cholesterol fell in all three groups, and the LCM group’s drop (25%) was clearly superior to that of the ADA diet (14%) but about the same as the TM diet (21%).

Conclusions of the Investigators

We found that an intensive community-based dietary intervention reduced cardiovascular risk factors in overweight patients with [type 2 diabetes] for all three diets.  The LCM group had improved cardiovascular risk factors compared to either the ADA or the TM groups.

Only the LCM improved HDL levels and was superior to both the ADA and TM in improving glycaemic control.

It would appear that the low carbohydrate Mediterranean diet should be recommended for overweight diabetic patients.

My Comments

There’s no way the average diabetic could replicate this low-carb Mediterranean diet without working closely with a dietitian or nutritionist.

Any superiority of this low-carb Mediterranean diet may have as much to do with the increased monounsaturated fat intake as with the reduced carb consumption.  Monounsaturated fatty acid consumption is thought to improve insulin sensitivity. 

NutritionData’s Nutrient Search Tool can give you a list of foods high in monounsaturated fat.

The Mediterranean diet and low-carb diets independently have been shown to lower after-meal glucose levels, which probably lowers LDL cholesterol and triglycerides.

I’m disappointed the dietitians were not able to achieve a lower level of carbohydrate consumption in the low-carb Mediterranean diet group.  I suspect if they had, improvements in glucose control and lipids would have been even better.  But proof awaits another day.

We saw last year an article in the Annals of Internal Medicine that showed a dramatic reduction in the need for glucose-lowering drugs in type 2 diabetics following a different low-carb Mediterranean diet over four years, compared to a low-fat American Heart Association diet.  These two studies convince me a low-carb Mediterranean diet has real life-preserving and life-enhancing potential. 

Diabetics looking for a low-carb Mediterranean diet today have several options:

If you’re aware of any other low-carb, explicitly Mediterranean-style diets, please share in the Comments section.

Steve Parker, M.D. 

References: 

Elhayany, A., Lustman, A., Abel, R., Attal-Singer, J., and Vinker, S.  A low carbohydrate Mediterranean diet improves cardiovascular risk factors and diabetes control among overweight patients with type 2 dabetes mellitus:  a 1-year prospective randomized intervention studyDiabetes, Obesity and Metabolism, 12 (2010): 204-209.

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

2 Comments

Filed under Carbohydrate, coronary heart disease, Fat in Diet, Glycemic Index and Load, Mediterranean Diet, olive oil

Eat the Right Carbs to Alleviate Diabetes and Heart Disease

Harvard’s Dr. Frank Hu in 2007 called for a paradigm shift in dietary prevention of heart disease, de-emphasizing the original diet-heart hypothesis and noting instead that “. . . reducing dietary GL [glycemic load] should be made a top public health priority.”  Jim Mann at the University of Otago (Dunedin, New Zealand) authored a 2007 review of carbohydrates and effects on heart disease and diabetes.  Here are highlights from the article summary in the European Journal of Clinical Nutrition:

The nature of carbohydrate is of considerable importance when recommending diets intended to reduce the risk of type II diabetes and cardiovascular disease and in the treatment of patients who already have established diseases. Intact fruits, vegetables, legumes and whole grains are the most appropriate sources of carbohydrate. Most are rich in [fiber] and other potentially cardioprotective components.  Many of these foods, especially those that are high in dietary fibre, will reduce total and low-density lipoprotein cholesterol and help to improve glycaemic control in those with diabetes.

Frequent consumption of low glycaemic index foods has been reported to confer similar benefits, but it is not clear whether such benefits are independent of the dietary fibre content of these foods or the fact that low glycaemic index foods tend to have intact plant cell walls.

A wide range of carbohydrate intake is acceptable, provided the nature of carbohydrate is appropriate. Failure to emphasize the need for carbohydrate to be derived principally from whole grain cereals, fruits, vegetables and legumes may result in increased lipoprotein-mediated risk of cardiovascular disease, especially in overweight and obese individuals who are insulin resistant.

Why does this matter to me and readers of this blog?  Dietary carbohydrates are a major determinant of blood sugar levels, tending to elevate them.  Chronically high blood sugar levels are associated with increased complication rates from diabetes.  People with diabetes are prone to develop heart disease, namely coronary artery disease, which causes heart attacks, weakness of the heart muscle, and premature death. 

Steve Parker, M.D.

References: 

Mann, J.  Dietary carbohydrate: relationship to cardiovascular disease and disorders of carbohydrate metabolismEuropean Journal of Clinical Nutrition, 61 (2007): Supplement 1: S100-11.

Hu, Frank.  Diet and cardiovascular disease prevention: The need for a paradigm shift.  Journal of the American College of Cardiology, 50 (2007): 22-24.

4 Comments

Filed under Carbohydrate, coronary heart disease, Fiber, Fruits, Glycemic Index and Load, Grains, legumes, Vegetables

Low-Glycemic Index Eating Improves Control of Diabetes

Lowering glycemic index (GI) led to improved contol of blood sugar, better insulin sensitivity, and weight loss in people with type 2 diabetes given group education sessions, according to researchers at Pennsylvania State University.

As background, the scientists note that:

GI may play a role in preventing or treating type 2 diabetes by decreasing the risk for obesity or by altering metabolic endpoints.  Improvements in glycaemic control were observed in people with diabetes in a recent meta-analysis.  A lower-GI diet was shown to decrease postprandial glucose [blood sugar after meals] and insulin responses and improve serum lipid concentrations.  Lower-GL [glycemic load] diets were associated with decreased risk for type 2 diabetes, decreased levels of C-reactive protein and inflammation, and weight loss.

Ninety-nine test subjects completed the study that enrolled adults 40 to 70  years old who had diabetes at least one year but were not taking insulin shots.  Average body mass index was 33, so they were obese.  Average weights were 84.5 kg (186 lb) for women and 108.7 kg (239 lb) for men.  Average baseline hemoglobin A1c was estimated at 7%, so these folks were under good glucose control.  Baseline carbohydrate intake was 45% of total energy, a bit lower than the general population. 

The 9-week intervention involved nine weekly group education sessions—lasting 1.5 to 2 hours—focusing on selection of lower-GI (vs higher-GI) foods instead of restricting carbohydrates.  Also covered were monitoring of portion sizes to control carb consumption, carb counting to control carb distribution and intake, and self-monitoring of food intake. 

Results

Although weight loss was not a goal, weights fell by 1-2 kg (2-4 pounds).  Men lost more than women.  Overall diet glycemic index fell by 2-3 points (a modest amount).  Comparing values before and after intervention, fasting glucose and postprandial glucose fell significantly, and insulin sensitivity improved.  Although not measured, the authors estimate hemoglobin A1c levels would have fallen an absolute 0.3%, based on measured glucose levels.  Percentage of calories from carbohydrate did not change. 

Comments

This is one of the few studies to try low-glycemic index behavioral intervention in adults with type 2 diabetes.  Results are encouraging. 

The researchers and I wonder if results would have been even more dramatic if the test subjects hadn’t been so well controlled before intervention or if they had dropped their glycemic index even lower.  Probably so.  Many people with type 2 diabetes have hemoglobin A1c’s well over 7%.

The researchers attribute the weight loss to portion control and simple self-monitoring of consumption. 

For people with diabetes, this study supports selection of lower-glycemic index instead of higher-GI.  In fact, we’d see less diabetes, heart disease, breast cancer, and gallbladder disease if all women—diabetic or not—ate lower-GI

Steve Parker, M.D.

Reference:  Gutschall, Melissa, et al.  A randomized behavioural trial targeting glycaemic index improves dietary, weight and metabolic outcomes in patients with type 2 diabetes.  Public Health and Nutrition, 12(2009): 1,846-1,854.

2 Comments

Filed under Carbohydrate, Glycemic Index and Load

Top 10 Diabetes Superfoods

The American Diabetes Association has published a list of  Top 10 Diabetes Superfoods.  They share a low glycemic index and provide key nutrients, according to the ADA.  Click the link for details.  Here they are in no particular order:

  • beans
  • dark green leafy vegetables
  • citrus fruit
  • sweet potatoes
  • berries
  • tomatoes
  • fish high in omega-3 fatty acids
  • whole grains
  • nuts
  • fat-free milk and yogurt

Regular readers here know I have no problem generally with regular or high-fat versions of dairy products.  An exception would be for people trying to lose weight while still eating lots of carbohydrates; the low- and no-fat versions could have lower calorie counts, which might help with weight management.

But compare non-fat and whole milk versions of yogurt in the USDA nutrient database.  One cup of non-fat fruit variety yogurt has 233 calories, compared to 149 calories in plain whole milk yogurt.  The “non-fat” version  reduced the fat from 8 to 2.6 g (not zero g) and replaced it with sugars (47 g versus 11 g). 

Unfortunately, your typical supermarket yogurts are low-fat yet loaded with sugar or high fructose corn syrup that impede weight loss.

Nevertheless, this superfoods list may give us some guidance in design of a Diabetic Mediterranean Diet.  Except for “fat-free,” everything else on the list is a component of the traditional healthy Mediterranean diet.  “Fat-free” is a modern invention and not necessarily an improvement.

Steve Parker, M.D.

2 Comments

Filed under Dairy Products, Fish, Fruits, Glycemic Index and Load, Grains, Health Benefits, legumes, Mediterranean Diet, nuts, Vegetables

Low-Carb Ketogenic Diet Beats Low-Glycemic Index Diet in Overweight Type 2 Diabetes

42-15653241

Avoid the needle with a low-carb ketogenic diet

Duke University (U.S.) researchers demonstrated better improvement and reversal of type 2 diabetes with an Atkins-style diet, compared to a low-glycemic index reduced-calorie diet.

Methodology

Ninety-seven overweight and obese adults, 78% women and 40% black, were randomly assigned to either:

  • a very low-carb ketogenic diet (Atkins induction phase, as in Atkins Diabetes Revolution) or
  • a low glycemic-index index calorie-restricted diet (The GI Diet by Rick Gallop). 

Thirty-eight were in the Atkins group; 46 in the low-glycemic index (low-GI) group.  Seventeen dropped out of each group before the end of the 24-week study.  Average weight was 234.3 pounds (106.5 kg); average body mass index was 37.  The Atkins group averaged 13% of total calories from carbohydrate; the low-GI cohort averaged 44%. 

Results

Both groups lost weight and had improvements in hemoglobin A1c, fasting insulin, and fasting glucose. 

The Atkins group lowered their hemoglobin A1c by 1.5% (absolute drop, not relative) versus 0.5% in the other group. 

The Atkins group lost 11.1 kg versus 6.9 kg in the other group. 

The Atkins group increased HDL cholesterol by5.6 mg/dl versus no change in the other group. 

All the aforementioned comparisons were statistically significant. 

Diabetes medications were stopped or reduced in 95% of the Atkins group versus 62% of the low-GI group.

Total and LDL cholesterol levels were unchanged in both groups. 

Triglycerides fell significantly only in the Atkins group.

My Comments

You may be interested to know that this study was funded by the Robert C. Atkins Foundation.

One strength of this study is that it lasted for 24 months.  Many similar studies last only eight to 12 weeks.  A drawback is that, with all the drop-outs,  the number of participants is low. 

The GI Diet performed pretty well, too, all things considered.  Sixty-two percent reduction or elimination of diabetes drugs—not bad.  For a six-year-old book, it’s still selling fairly well at Amazon.com.  That may be why they chose it as the comparison diet.

The diet with fewer carbohydrates—Atkins induction—was most effective for  improving control of blood sugars.  So effective, in fact, that the researchers sound a note of warning:

For example, participants taking from 40 to 90 units of insulin before the study were able to eliminate their insulin use, while also improving glycemic control.  Because this effect occurs immediately upon implementing the dietary changes, individuals with type 2 diabetes who are unable to adjust their own medication or self-monitor their blood glucose should not make these dietary changes unless under close medical supervision.  

[Not all insulin users were able to stop it.]

Overall, lipids were improved or unchanged in the Atkins group, despite the lack of limits on saturated fat intake.  A common criticism of the Atkins diet is that it has too much saturated fat, leading to higher total and LDL cholesterol levels, which might raise long-term cardiovascular risks.  Not so, here. 

When you reduce carbohydrate intake, the percentages of fat and protein in the diet also change.  In this Atkins diet, protein provided 28% of daily calories, and fat 59%.  In the low-GI diet, protein provided 20% of daily calories, fat 36%.  The beneficial effects of the Atkins diet probably reflect the low carbohydrate consumption rather than high protein and fat. 

The Atkins induction-phase diet was clearly superior to the low-glycemic index diet in this overweight diabetic sample, without restricting calories.

Steve Parker, M.D.

Reference:  Westman, Eric, et al.  The effect of a low-carbohydrate, ketogenic diet versus a low-glycemic index diet on glycemic control in type 2 diabetes mellitusNutrition & Metabolism 2008, 5:36   doi:10.1186/1743-7075-5-36

Additional Reading

Samaha, F., et al.  A low-carbohydrate as compared with a low-fat diet in severe obesity.  New England Journal of Medicine, 348 (2003): 2,074-2,081.

Boden, G., et al.  Effect of a low-carbohydrate diet on appetite, blood glucose levels, and insulin resistance in obese patients with type 2 diabetes.  Annals of Internal Medicine, 142 (2005): 403-411.

Vernon, M., et al.  Clinical experience of a  carbohydrate-restricted diet: Effect on diabetes mellitus.  Metabolic Syndrome and Related Disorders, 1 (2003): 233-238.

Yancy, W., et al.  A pilot trial of a low-carbohydrate ketogenic diet in patients with type 2 diabetes.  Metabolic Syndrome and Related Disorders, 1 (2003): 239-244.

3 Comments

Filed under Carbohydrate, Glycemic Index and Load, ketogenic diet, Overweight and Obesity

Dental Problems and Systemic Chronic Disease: A Carbohydrate Connection?

Perfect health on a carnivorous, low-carb diet

Perfect health on a carnivorous, low-carb diet

Dentists are considering a return to an old theory that dietary carbohydrates first cause dental diseases, then certain systemic chronic diseases, according to a review in the June 1, 2009, Journal of Dental Research

We’ve known for years that some dental and systemic diseases are associated with each other, both for individuals and populations.  For example, gingivitis and periodontal disease are associated with type 2 diabetes and coronary heart disease.  The exact nature of that association is not clear.  In the 1990s it seemed that infections – chlamydia, for example – might be the unifying link, but this has not been supported by subsequent research.     

The article is written by Dr. Philippe P. Hujoel, who has been active in dental research for decades and is affiliated with the University of Washington (Seattle).  He is no bomb-throwing, crazed, radical. 

The “old theory” to which I referred is the Cleave-Yudkin idea from the 1960s and ’70s that excessive intake of fermentable carbohydrates, in the absence of good dental care, leads both to certain dental diseases – caries (cavities), periodontal disease, certain oral cancers, and leukoplakia – and to some common systemic chronic non-communicable diseases such as coronary heart disease, type 2 diabetes, some cancers, and dementia.  In other words, dietary carbohydrates cause both dental and systemic diseases – not all cases of those diseases, of course, but some.   

Dr. Hujoel does not define “fermentable” carbohydrates in the article.  My American Heritage Dictionary defines fermentation as:

  1. the anaerobic conversion of sugar to carbon dioxide and alcohol by yeast
  2. any of a group of chemical reactions induced by living or nonliving ferments that split complex organic compunds into relatively simple substances

As reported in David Mendosa’s blog at MyDiabetesCentral.com, Dr. Hujoel said, “Non-fermentable carbohydrates are fibers.”  Dr. Hujoel also shared some personal tidbits there. 

In the context of excessive carbohydrate intake, the article frequently mentions sugar, refined carbs, and high-glycemic-index carbs.  Dental effects of excessive carb intake can appear within weeks or months, whereas the sysemtic effects may take decades. 

Hujoel compares and contrasts Ancel Keys’ Diet-Heart/Lipid Hypothesis with the Cleave-Yudkin Carbohydrate Theory.  In Dr. Hujoel’s view, the latest research data favor the Carbohydrate Theory as an explanation of many cases of the aforementioned dental and systemic chronic diseases.  If correct, the theory has important implications for prevention of dental and systemic diseases: namely, dietary carbohydrate restriction.

Adherents of the paleo diet and low-carb diets will love this article; it supports their choices.

I agree with Dr. Hujoel that we need a long-term prospective trial of serious low-carb eating versus the standard American high-carb diet.  Take 20,000 people, randomize them to one of the two diets, follow their dental and systemic health over 15-30 years, then compare the two groups.  Problem is, I’m not sure it can be done.  It’s hard enough for most people to follow a low-carb diet for four months.  And I’m asking for 30 years?!   

Dr. Hujoel writes:

Possibly, when it comes to fermentable carbohydrates, teeth would then become to the medical and dental professionals what they have always been for paleoanthropologists: “extremely informative about age, sex, diet, health.”

Dr. Hujoel mentioned a review of six studies that showed a 30% reduction in gingivitis score by following a diet moderately reduced in carbs.  He mentions the aphorism: “no carbohydrates, no caries.”  Anyone prone to dental caries or ongoing periodontal disease should do further research to see if switching to low-carb eating might improve the situation. 

Don’t be surprised if your dentist isn’t very familiar with the concept.  Has he ever mentioned it to you?

Steve Parker, M.D.,

Author of The Advanced Mediterranean Diet

Reference:  Hujoel, P.  Dietary carbohydrates and dental-systemic diseasesJournal of Dental Research, 88 (2009): 490-502.

Mendosa, David.  Our dental alarm bell.  MyDiabetesCentral.com, July 12, 2009.

2 Comments

Filed under Carbohydrate, Causes of Diabetes, coronary heart disease, Glycemic Index and Load

Glycemic Load Linked to Breast Cancer Risk

Who knew?

Who knew?

Swedish researchers report that  a high dietary glycemic load is tied to a woman’s risk of developing breast cancer.  This adds to a growing body of evidence that high glycemic index and load may be harmful.  Prior studies relate them to higher rates of diabetes and heart disease. 

Click here for my review of glycemic index and load.  NutritionData.com also has a good review of glycemic index.

Steve Parker, M.D.

References:

Reuters Health.  “Glycemic load” of diet tied to breast cancer risk.  MedlinePlus, July 10, 2009.

Parker, Steve.  Glycemic index and chronic disease risk (mostly in women).  Advanced Mediterranean Diet Blog, April 19, 2009.

Comments Off on Glycemic Load Linked to Breast Cancer Risk

Filed under Glycemic Index and Load

Low-Glycemic-Index Eating Had No Effect on Control of Mild Type 2 Diabetes

Caprese salad

Caprese salad

A Canadian study last year found no overall effect on type 2 diabetes control by using a low-glycemic-index diet and lower-carbohydrate diet, although the low-glycemic-index diet did reduce post-meal glucose levels and C-reactive protein.

Background

For many years, a high-fat, low-carbohydrate diet was recommended for type 2 diabetics.  Then in 1979 the American Diabetes Association recommended a high-carb, low-fat diet.  Later, the ADA allowed more fat, mostly monounsaturated. 

The experts are still debating how much and what kind of carbohydrate people with diabetes should eat.  Recent years have seen a trend towards lower carbohydrate intake and lower-glycemic-index eating.  Much of the supportive evidence we have is based on short-term studies – six to 12 weeks. 

A Cochrane review in 2004 concluded that there was no high-quality data on the effectiveness of dietary treatment of diabetes.

The authors of the Canadian study at hand wrote:

Although almost everyone would agree that diet is the cornerstone of diabetes therapy, there is marked disagreement about what kind of dietary advice is best, particularly with respect to dietary carbohydrate.

We can put a man on the moon, but still aren’t sure what’s the best diet for people with diabetes despite years of experience and experimentation.

The Canadian researchers aimed to compare the effects of altered glycemic index and amount of carbohydrate on hemoglobin A1c, blood glucose, lipids, and C-reactive protein in men and women with type 2 diabetes.

Methodology

162 subjects with mild diabetes, 35-75 years old, managed by diet alone, were randomly assigned to one of three diet groups:

  1. high-carb, high-glycemic-index (“high-GI“): 47% of calories from carb, 31% of cals from fat, glycemic index 63
  2. high-carb, low-glycemic-index (“low-GI“): 52% of cals from carb, 27% of cals from fat, glycemic index 55
  3. low-carb, high-monounsaturated fat (“low-CHO“): 39% of cals from carb, 40% of cals from fat, glycemic index 59

Average body mass index was 31 (mildly obese); average weight 83 kg (183 lb).  The study lasted one year, a major strength of the study.

Results One Year Later

Hemoglobin A1c rose from 6.1% to 6.3%, with no difference between the various diet groups.  There were no differences in insulin levels, whether fasting or two hours after an oral glucose tolerance test.  Blood sugar levels after a glucose tolerance test were 7% lower with the low-GI diet compared to the other diet groups.  No difference in LDL cholesterol levels.  Little effect on triglycerides and HDL cholesterol.  No differences in weight.  C-reactive protein in the high-GI group fell from3.34 mg/L to 2.75.  C-reactive protein in the low-GI group fell from 2.64 to 1.95.  [All these C-reactive protein readings are in the normal range.]        

Comments

Nearly all the people with diabetes I encounter are very different from this study cohort: they are on drug therapy for diabetes.  So the results here don’t  necessarily apply to the more typical cases of moderate or severe diabetes that require one or more glucose-control drugs. 

Low-carb diet advocates can justifiably argue that the carb intake was still too high, and that’s why their numbers weren’t better.  Vernon and Eberstein in their book, Atkins Diabetes Revolution, note that many people with type 2 diabetes will have to limit carboydrates (“net carbs”) to 40-60 grams a day.  In the study at hand, the low-carb diet aimed for 39% of calories from carbohydrates.  On a 2000-calorie diet, that’s 195 grams – a far cry from 60 grams.      

Low-Gi advocates also can justifiably argue that the glycemic index was not low enough to make a difference.  The researchers admit that the test diet reductions in carb intake and glycemic index were “modest.”  Perhaps they thought that more drastic reductions were unsustainable.

Attempts to control diabetes with low-carb or low-glycemic-index eating should make more dramatic changes.

The low-glycemic-index diet lowered two-hour glucose levels on the glucose tolerance tests.  The authors state that this parameter is a better indicator of heart disease risk – lower in this case – than are fasting glucose levels.  Findings suggests improvements in insulin resistance and/or pancreas beta cell function.  This finding may have no real-world clinical significance: remember that hemoglobin A1c levels were the same across all groups. 

The changes in C-reactive protein just don’t seem clinically significant to me (nor to an editorialist in the same journal issue).

The aforementioned editorialist, Dr. Xavier Pi-Sunyer, had an interesting comment:

This finding suggests that we must be careful about disrupting subjects’ or patients’ diets with radical , doctrinaire changes that may actually be counterproductive.  Furthermore, the diets had carbohydrate contents that varied from 39% to 52% of energy intake, and yet this variability had no effect on the subjects’ HbA1c.  This finding confirms previous reports that the proportion of carbohydrate in the diet is not very important in determining the concentration of fasting blood glucose and that variations of 10% to 15% of total calories make little difference to overall control in patients with early type 2 diabetes.

I would emphasize “. . . in patients with early type 2 diabetes.”

A Mediterranean-style diet, then, could be just as effective as, if not better than, all the other “diabetic diets” out there.

Steve Parker, M.D.

References:  Wolever, Thomas, et al.  The Canadian Trial of Carbohydrates in Diabetes (CCD), a 1-y controlled trial of low-glycemic-index dietary carbohydrate in type 2 diabetes: no effect on glycated hemoglobin but reduction in C-reactive proteinAmerican Journal of Clinical Nutrition, 87 (2008); 114-125.

Additional Resource:  Michael R. Eades, M.D.  Making worthless data confess.  The Blog of Michael R. Eades, December 13, 2008.  Accessed July 10, 2009.  [Highly critical analysis from a leading low-carb, high-protein advocate.]

2 Comments

Filed under Carbohydrate, Glycemic Index and Load