In a recent study, researchers determine the composition of previous meals affects the glycemic response after subsequent meals.
Previous studies on the correlation between glycemic index, glycemic load, and chronic disease risk remain inconclusive and ambiguous. The glycemic response refers to the response that foods could have on blood sugar levels following their consumption. The glycemic index is a relative score of different carbohydrates that are found in a food which may affect blood glucose levels. Glycemic load measures both the quality and the amount of carbohydrate in a certain food.
The inconsistencies in past study results may be due to many things, including how the data was collected and outstanding physiological factors. It is possible that the glycemic index values of a certain food are influenced by the food that you have already previously eaten. One way that researchers may explore this issue in a different light is to study the second meal’s effect on the glycemic response. Since it is known that raised blood glucose could be a potential risk factor for many chronic diseases (including cardiovascular disease, cancer, respiratory diseases, diabetes, and many others), it is therefore important that we understand how the glycemic response is affected by the nutrients in our meals.
A US study by Huicui Meng and colleagues recently published in the American Journal of Clinical Nutrition tackled this issue. The objective of their study was to assess the effect of the nutrients found in a previous meal to determine their effects on the glycemic response after a subsequent test food. The study involved 20 healthy participants who had to complete six different test sessions within a 12-week period. The participants received a high carbohydrate, high fat, or high protein meal followed by white bread and a glucose drink. Blood was sampled throughout the testing period and the fat content was also determined.
They found that when the participants consumed breakfast that was high in protein before they had the white bread, there was a rise in their glucose levels along with a decrease in glycemic index and glycemic load. However, breakfasts that contained high carbohydrates or high fat had the opposite outcomes.
Therefore, their results showed that the nutrient composition of a meal can really affect the glycemic response of future meals. This is coined the “second meal effect”. They note that future studies will need to determine whether these effects could influence the known GI or GL scores of certain foods, which may influence the interpretation of the association between these foods and chronic disease risk.
Written by Ingrid Qemo, BSc
Meng, H., Matthan, N.R., Ausman, L.M., Lichtenstein, A.H. 2017. Effect of prior meal macronutrient composition on postprandial glycemic responses and glycemic index and glycemic load value determinations. Am. J. Clin. Nutr. doi: 10.3945/ajcn.117.162727.