If anyone needs yet another reason to change from a diet high in refined carbohydrates, they just got it.  A study just reported in a July 2007 issue of the American Journal of Clinical Nutrition found that a diet higher in refined carbohydrates (high glycemic index foods) significantly increased the risk of developing age-related macular degeneration.

Macular degeneration is the number one cause of blindness in this country in people age 60 and up, a statistic of particular importance to baby boomers.  Estimates from this study were that 100,000 cases of blindness from AMD could be avoided if people would make this one easy change – stop eating refined sugar and flour and the foods and drinks made with them.

Several studies conducted over the last two years are showing a number of benefits of lower carbohydrate diets.  Here is the list of other benefits seen in studies done over the last couple of years.

Lower glycemic index diets -

1. Help with weight loss.
2. Lower cardiovascular risks
3. Lower triglycerides significantly
4. Lower blood pressure.
5. Lower C reactive protein, a marker for inflammation in the body.
   (By the way, high CRP’s are a risk factor for macular degeneration.)
6. Help prevent non-alcoholic fatty liver.
7. Lower risk of getting Type II diabetes
8. Lower risk of ovarian and pancreatic cancer
9. Help maintain higher resting energy expenditure, a measure of baseline metabolism, and double the decrease in insulin resistance compared to low fat diets.
10. Help adherence to diets by increasing satiety (feeling more satisfied and less hungry.)

The following abstract from a study in the on-line journal Nutrition and Metabolism summarizes the research this way:

“Because of its effect on insulin, carbohydrate restriction is one of the obvious dietary choices for weight reduction and diabetes.” . . .

The authors discussed what has been uppermost in the minds of people researching low carb diets.  Because low carb diets are often higher in fat, many people have feared that these diets might increase cardiovascular risk.   The conclusion of these authors based on the majority study results?  “Many literature reports have shown that they (higher fat, low carb diets) are actually protective even in the absence of weight loss,” and “clearly confirm that carbohydrate restriction leads to an improvement in atherogenic lipid states” even when saturated fat intake is higher and no weight is actually lost.  “In distinction, low fat diets seem to require weight loss for effective improvement in atherogenic dyslipidemia.”

There is a slow and steady stream of research pointing to benefits of eating diets lower in carbohydrate, especially carbohydrates that induce a larger and quicker elevation in blood glucose.  The research is very encouraging not only for disease prevention, but even for those trying to improve their outlook with existing Type II diabetes.  For example, one recent study showed that for people with Type II diabetes consuming a diet that was comprised of only 22% carbohydrate versus a diet of 50-60% carbohydrate (the level conventionally recommended), was “significantly superior” for both weight management and glycemic control.

So whether you are trying to prevent disease or control dysglycemic disease, lower carbohydrate intake seems to be the best way to do it.  These lower carb diets replace sugary foods and refined flours with plenty of vegetables (like broccoli and leafy greens,) and some beans and legumes, but are moderate to low in fruit and whole grains.  In addition our typical recommendation would include avoiding gluten containing grains as well.  Over the years I have personally witnessed the benefits of this type of diet in my patients literally thousands of times.  It great to see all of the studies finally confirming anecdotal evidence that many professionals have realized for years.

References:

Chiu CJ, Taylor A, et al, "Association between dietary glycemic index and age-related macular degeneration in nondiabetic participants in the Age-Related Eye Disease Study," J Clin Nutr 07; 86(1): 180-188.

Hu J.  Diet and Cardiovascular Disease Prevention: The Need for a Paradigm Shift

Am Coll Cardiol.2007; 50: 22-24

Pereira MA, Swain J, Goldfine AB, et al.: Effects of alow–glycemic-load diet on resting energy expenditure and heart diseaserisk factors during weight loss. JAMA 292: 2482–2490, 2004.

Augustin L, et al. Dietary glycemic index, glycemic load and ovarian cancer risk: a case–control study in ItalyAnnals of Oncology 14:78-84, 2003

Fuchs C, et al. J of the Natl Ca Inst Sept 2004

Willet W, et al. Glycemic index, glycemic load, and risk of type 2 diabetes.Am J of Clin Nutr 2002 Jul;76(1):274S-80S.

Ma, Y. American Journal of Epidemiology, Feb. 15, 2005; vol 161: pp 359-367. Glycemic Index. News release, University of Massachusetts Medical School.

Feinman R, Volek J.  Low carbohydrate diets improve atherogenic dyslipidemia even in the absence of weight loss.  Nutr Metab (Lond). 2006; 3: 24.

Nielson J, Joenssen E. Low-carbohydrate diet in type 2 diabetes. Stable improvement of bodyweight and glycemic control during 22 months follow-up Nutr Metab (Lond). 2006; 3: 22.