Which snack substitution would lower the glycemic index for a patient having 4 oz of whole milk and 6 graham crackers?

The correct choice, which involves substituting 3 graham crackers with 1 tablespoon of peanut butter, effectively lowers the glycemic index due to the nature of the foods involved. Graham crackers are refined carbohydrates that have a higher glycemic index, meaning they can cause a more rapid increase in blood sugar levels. In contrast, peanut butter is a source of healthy fats and protein, which can slow the absorption of carbohydrates and result in a more gradual increase in blood sugar. The addition of protein and fat from the peanut butter changes the overall macronutrient profile of the snack, making it a more balanced and glycemic-friendly option.

In terms of the other choices, substituting 6 graham crackers with 2 oz of low-fat yogurt could provide some benefits, but yogurt might still have a relatively moderate glycemic index depending on its sugar content. Choosing 1 whole banana instead of the 4 oz of milk may not lower the glycemic index significantly, as bananas contain natural sugars and can have a higher glycemic index than whole milk. Lastly, substituting 6 graham crackers with 1 oz of cheese adds protein and fat, which can help with satiety, but cheese itself is not typically a direct carbohydrate substitute, hence its