Matzot, White Potatoes and the Glycemic Index
The following article is by Tzipora Wolff, MD., Staff Physician at Bishvilaych Women’s Well Health Center.
With Pesach fast approaching and thoughts of a week long diet consisting in great part of matzot and potatoes, an article discussing healthy dietary carbohydrates seems appropriate and timely.
Carbohydrates have been traditionally classified as simple (ie.sugars) or complex ( ie.starches) on the basis of the number of sugar molecules in their chemical structures. It had been assumed that complex carbohydrates cause smaller rises in blood glucose than simple carbohydrates.
A growing body of scientific data, however, contradicts this notion. These data demonstrate that digestion of carbohydrates, particularly starch, is not a rate-limiting event and is often quite rapid because of the presence of sufficient ability to digest starch (called “amylolysis”) in the intestine 8. As an example, the rise in blood sugar after eating a potato and white bread are similar to the response pure glucose ( or candy), indicating that complex carbohydrates may not differ from simple sugars in their effect on blood glucose level.
This discovery has led to the development of the glycemic index (GI), a measure of the relative impact of carbohydrate-containing foods on blood sugar. A particular food’s GI is determined by evaluating the incremental rises of blood glucose after ingestion of a food that contains 50 g of carbohydrate compared with the same amount of carbohydrate from a reference food, usually white bread or glucose.
The GI of a food depends upon the rapidity of digestion and absorption of its dietary carbohydrates. Typically, foods with a low degree of starch gelatinization, such as pasta, and those containing a high level of viscous soluble fiber, such as whole-grain barley, oats, and rye, have slower rates of digestion and lower GI values.
The consumption of low GI foods as part of a healthy diet has numerous health benefits including lower rates of weight gain, risks of heart disease and diabetes, and even decreased risk of some cancers.
One argument against the glycemic index (GI) concept is that it does not explain the entire picture, since the blood glucose response is influenced by the quantity of carbohydrate consumed as well as the quality (the latter reflected in the GI).
To address this concern, the concept of glycemic load (GL) was introduced. Defined as the product of the GI value of a food and its carbohydrate content, GL incorporates both the quality and quantity of carbohydrate consumed. In general, carbohydrate-rich foods with low fiber content have high GI and GL values; examples include potatoes, refined cereal products, and many sugar-sweetened beverages. In contrast, whole grains, fruits, and vegetables with high fiber content provide low to very low GLs per serving.
The following are examples of glycemic index values for commonly eaten foods on Pesach:
Matzoh (one board): N/A
Whole wheat matzoh: N/A
White potato: N/A
Sweet potato: N/A
Quinoa: N/A
In general, there are several ways to achieve a lower dietary GL:
- Replace carbohydrate with protein
- Replace carbohydrate with fat
- Substitute a low-GI carbohydrate for a high-GI carbohydrate
So for example, if sweet potatoes could be substituted for potatoes and whole wheat matzot for matzoh at most meals, the overall glycemic load would be decreased and the overall impact would be a healthier Pesach diet for you and your family. Similarly, if a larger portion of protein (ie. Fish or chicken) is eaten along with a smaller portion of matzoh or potatoes, the glycemic load for that particular meal will be decreased. The addition of vegetables (with the exception of white potatoes, of course) to the meal similarly lowers the overall glycemic load.
May this information about healthy dietary carbohydrates contribute to a happy, healthy and kosher Pesach for all.