Sugar and Your Arteries: Stiff and Tight!

June 24, 2009

Sugar and Your Arteries: Stiff and Tight! 

Competency # 10 Glycemic Index and #11 Sugar                  ReferenceLavi et al Jr of the Am Card Assoc 2009;53:2283 

 This is a very important study and extremely important for us to understand.  A group from Tel Aviv conducted a brilliant, clean and simple study looking at what happens to your arteries after eating a “high glycemic” food versus a “low glycemic” food.  They used water as a placebo, pure glucose as a standard, corn flakes as a high glycemic food and a high fiber, whole grain cereal as a low glycemic meal.  

As we have stated before, most boxed cereals that have been made from a grain that is ground up into flour, made into paste, baked into flakes, and then put in a box.   They tend to have a glycemic index of 70-85 or so.  That means they put glucose into your blood at 70-85% of the speed of pure glucose.  The same grain, not ground up but served with its fiber coat still intact will often have a glycemic index in the 38-45 range.  That means whole grains, with a glycemic index of 35 can be significantly changed by grinding them up and displacing the fiber.  Their GI rises from 35 to 80.  

Is that a problem?  Emphatically yes, says this study. What was discovered in the study was that “flow-mediated dilation” (FMD) and percent endothelial independent nitroglycerin-mediated dilation (%NTG) were directly and statistically significantly affected by the glycemic index.  (Whew, try those terms with crackers in your mouth.)  These calculations are scientifically valid ways of measuring how your artery stretches in response to a pulse of blood.  

If your artery is nice and stretchy, the pulse passes by without much effort or damage.  If the artery is stiff, you get a much higher peak of pressure, a little hammer blow, if you will.   Pure glucose and cornflakes made for a 5% worse change in flow stretchiness.  That’s called endothelial dysfunction.  That means the lining of your arteries don’t work as well as you would want them to.  High glycemic foods damage your arteries. 

 Does this cause a problem?  Not in the short term (hours or days).  In fact, the effect lasts just 1-2 hours, and then it’s gone.  But the habit and pattern of eating processed high glycemic foods with snacks and sugared sodas all day long mean that 4-5 times a day we give our blood sugar a boost, and our arteries a hit.  That’s how it begins.  We damage our arteries, then we flood our blood with fats, and plaque starts to build.  It’s the lifelong habit and pattern.  It’s our culture. The good news is right there in front of us.  The effect lasts two hours.  You can make it go away in two hours.  Start eating differently and you can change your FMD and %NTG in one meal.  Ha! 

 WWW: What will work for me.  I’m getting better at avoiding sugar.  I’ve looked at many snack bars and found more than three types of sugar listed in the ingredients.  As a consequence, I’ve chosen to eat other foods instead.  And I remember Miss Brennaman in third grade pounding into my stubborn little head the difference between “of” and “from”.  Made “OF” whole grains means you can see the chunks.  Made “FROM” means it’s been ground up and no good.  I’m going for the “MADE OF”.   Imagine your nice stretchy arteries!

Column written by Dr. John E Whitcomb, MD, Brookfield Longevity, Brookfield, WI. (262-784-5300)