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The Bitterness of Sweet

You already know that processed, refined sugary foods (as opposed to fruits) are associated with weight gain (1), as well as diabetes, heart disease, and stroke (2,3).

But high processed sugar intake also has a negative impact on cognitive function in both children (4) and older people. And now we see a new study about the relationship between sugar and Alzherimer’s disease.

First, a brief detour into ScienceLand:

The glycemic index (GI) ranks carbohydrates according to how much they raise blood sugar levels after you eat them. Foods with a high GI are quickly digested and cause large fluctuations in blood sugar levels. Low-GI foods, on the other hand, are digested more slowly. This means blood levels of glucose and insulin rise slowly and stay more stable.

While, the glycemic index measures how much a given food affects blood glucose, glycemic load takes into account the total amount of food that is eaten. In other words, one potato is associated with a certain glycemic index, and three potatoes triples the glycemic load.

What’s the big deal about low-glycemic-load diets? Twenty-five years of data has shown that there is greater weight loss associated with low glycemic-load diets (5,6).

Even when there is equal weight loss among different diets, low-glycemic-load diets are much better at preventing diabetes, heart disease, and stroke (2).

Last week, there was a study published concerning nearly 3,000 elderly people whose intake of high- and low-glycemic load diets were compared over a period of twelve years (7). At the end of that time, it was found that those people who ate a higher glycemic-load diet had a significantly increased risk of developing dementia and Alzheimer’s disease.

Once again, the evidence is overwhelming: enjoy real food that doesn’t come in a box or a wrapper.* You’ll start out in life healthier and smarter – and you’ll end up that way, too.

* Except for dark chocolate, of course. A little bit never killed anyone.


(1)Mozaffarian D et al 2011. Changes in diet and lifestyle and long-term weight gain in women and men. N Engl J Med 2011; 364:2392-404.

(2) Gross LS. Increased consumption of refined carbohydrates and the epidemic of type 2 diabetes in the United States; an ecologic assessment. Am J Clin Nutr 2004; 79(5):774-9.

(3) Augustin LSA et al. Glycemic index, glycemic load and glycemic response: an international scientific consensus summit from the International Carbohydrate Quality Consortium (ICQC). Nutr, Metab & Cardiovasc Dis 2015; 25:795-815).

(4) Cohen JFW et al. Associations of Prenatal and Child Sugar Intake With Child Cognition. Am J Prev Med 2018; 54(6):727.

(5) Ebbeling CB et al. Effects of a low-glycemic load vs low fat diet in obese young adults: a randomized trial. JAMA 2007; 2092-102.

(6) Wolever TMS et al. The glycemic index: methodology and clinical implications. Am J Clin Nutr 1991; 54:846-54.

 (7) Gentreau M, Chuy V, Féart C, et al. Refined carbohydrate-rich diet is associated with long-term risk of dementia and Alzheimer’s disease in apolipoprotein E ε4 allele carriers [published online ahead of print, 2020 Jun 7]. Alzheimers Dement. 2020;10.1002/alz.12114. doi:10.1002/alz.12114