Heart Disease: The Carbohydrate Connection

When you think of the dietary causes of heart disease, the first thing you may not think of is sugar.  The media has us trained to think of fats, especially saturated fats, which can actually be very good for the heart when from healthy sources. However, it's sugars and carbohydrates that have an especially significant role in causing heart disease.  Why? They cause inflammation in the body!
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Understanding the glycemic (blood sugar) impact of foods is vital:

The glycemic index (GI) is a ranking of carbohydrates on a scale from 0 to 100 according to the extent to which they raise blood sugar levels after eating. Foods with a high GI, are those which are rapidly digested and absorbed and result in marked fluctuations in blood sugar levels. Pure sugar and white bread have a GI of 100. Low-GI foods, by virtue of their slow digestion and absorption, produce gradual rises in blood sugar and insulin levels.  

Even more important is the glycemic load, which takes into account not only the GI of a food, but also portion sizes.  Glycemic Load (GL) is a measure of both the quality (the GI value) and quantity (grams per serving) of a carbohydrate in a meal. 

A food’s glycemic load is determined by multiplying its glycemic index by the amount of carbohydrate the food contains in each serving and dividing by 100.

Using an apple as an example:
​GI value = 38; Carbohydrate per serving = 15g

GL= 38 x 15
          100

The GL of a typical apple is 6

Focusing on the glycemic load of foods is particularly important  to help maintain a steady blood sugar, and everyone can benefit from understanding and monitoring the glycemic load in their diet.
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A Scientific Study:

There was a huge study published in year 2000 on the relationship of glycemic load in one's diet to heart health titled:  A prospective study of dietary glycemic load, carbohydrate intake, and risk of coronary heart disease in US women. This study was a part of the ongoing Nurses’ Health Study.  It was conducted by Simin Liu, et al. (see it here)

Several items were evaluated:
 
1) the relationship of the glycemic load of dietary carbohydrates to the risk of coronary heart disease,
2) if the glycemic index is a better predictor of heart disease than classifying carbohydrates as "simple" or "complex", and 
3) if adiposity (body fat tissue) modifies the relationship of glycemic load to the risk of heart disease.  

The 10 year study was the first of its kind done with human subjects.  A cohort of 75,521 women, ages 38-63, was followed.  The women had no previous diagnoses of cardiovascular diseases, nor diagnoses of diabetes, stroke, angina, or heart attack.  The subjects completed food-frequency questionnaires, for which dietary nutrient intakes were computed, including overall quality of carbohydrate intake.  Over the 10 year study, the researchers documented the subsequent incidents of coronary heart disease, including fatal and non-fatal heart attacks.

Results:
After adjusting for age, smoking status, and other risk variables, the women with the highest glycemic-load scores had a relative risk of 1.57 for coronary heart disease (compared to the women in the lowest group with a score of 1.00).  
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The study concluded that there is a significant relationship between dietary glycemic load and risk of coronary heart disease independent of other known risk factors.

The results also showed that high-glycemic carbohydrates (compared to low-glycemic) are strongly associated with an increased risk of coronary heart disease.  The relative risk for the highest group was 1.98.

Lastly, the researchers found strong evidence that women with a BMI greater than 23 were are greater risk of coronary heart disease.  This is possibly due to the fact that women with higher BMI’s often have insulin resistance, hyperglycemia, and related metabolic disorders which are well recognized risk factors for coronary heart disease.

Dietary Implications:
The researchers in the study doubt the effective use of dietary guidelines that suggest the classification and substitution of “complex” for “simple” carbohydrates. Why? Complex and simple carbs can be either high or low glycemic.  For example, some complex carbohydrates, such as potatoes, have a high glycemic index. Simple sugars found in fruits and vegetables have a low glycemic index.   

A better measure to use in dietary guidelines is the glycemic index, which is more closely tied to risk of coronary heart disease.   They suggest substituting low-glycemic carbohydrates for high-glycemic foods, which can induce high blood glucose responses.   

The low-fat, high-carbohydrate diet, which is so often recommended today, may not prevent heart disease and may actually increase the risk!
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Now....

1.  See the Au Naturale Nutrition Guide to Choosing Healthy Carbs & keep your heart and body healthy!

2.  Click the HERE to print the Chart of Foods by Glycemic Index and Glycemic Load from Mendosa.com.  You'll get a much better picture of which foods are high vs. low GI and GL.​

Glycemic Load of Foods

​References

• Study web link:  http://ajcn.nutrition.org/content/71/6/1455.full.pdf+html
• Liu, S, Wilet, W.C., Stampfer, M.J., Hu, F.B., Franz, M., Sampson, L., Hennekens, C.H., & Manson, J.E. (2000). A prospective study of dietary glycemic load, carbohydrate intake, and risk of coronary heart disease in US women. The American Journal of Clinical Nutrition, Vol. No. 71, pages 1455-1461.
• Glycemic Load, from the Glycemic Index Foundation

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