Tag Archives: Frank Hu

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

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

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

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.

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