Potato based diet doesn't disturb blood sugar control in Diabetes
Researchers
have found for the first time in a rigorously controlled clinical trial that
people with Diabetes don't need to avoid potatoes. It is said that potatoes
with high glycemic index should be avoided by diabetics as they may adversely
affect blood sugar. But the study indicates that glycemic index is not an
accurate surrogate for an individual's glycemic response (GR) to a food
consumed as part of an evening meal.
The findings show that participants had a better 'nocturnal' glycemic response
when they ate a mixed meal with skinless white potatoes compared to an
isoenergetic and macronutrient-matched mixed meal that included a low GI
carbohydrate food -- basmati rice.
The study has been published in Clinical Nutrition.
People
with type 2 Diabetes (T2D) are frequently told to avoid eating potatoes, and
other high Glycemic Index (GI) foods, because of the longstanding perception
that these foods make it difficult to control blood sugar levels. This is
especially problematic during the night when blood sugar tends to spike -- a
phenomenon that has been associated with cardiovascular disease and endothelial
dysfunction.
In the study the participants were provided the same breakfast and lunch, but
they were randomly assigned to one of four dinners, each including either
skinless white potatoes (test meal) prepared in three different ways (boiled,
roasted, boiled then cooled then reheated) or basmati rice (control meal).
Participants repeated the experiment, with a 9-day break in between each trial,
to cycle through all test meals and the control. In addition to having blood
samples collected regularly (both immediately after the meal and again every 30
minutes, for 2 hours), participants also wore a continuous glucose monitor
overnight to track changes in blood sugar levels while sleeping.
There were no differences between meals in glucose response following the
dinner that contained any of the potato dishes or basmati rice. Moreover,
participants' overnight GR was more favorable after eating the evening meal
that included any of the high GI potato side dishes compared to low GI basmati
rice.
"These
findings are contrary to that of observational research and traditional dietary
guidance that has led some to believe potatoes are not an appropriate food
choice for people with T2D," added Devlin. "Our study shows high GI
foods, like potatoes, can be consumed as part of a healthy evening meal without
negatively affecting GR -- and while delivering key nutrients in relatively few
calories, which is essential for people with T2D."
"Despite its frequent use among nutrition researchers, GI is not an
appropriate tool for understanding how a meal impacts glycemic control; it is a
very specific measurement for foods consumed in isolation, typically conducted
under controlled laboratory conditions," says Dr. Brooke Devlin, PhD, the
primary investigator, at Australian Catholic University in Melbourne.
"It's rare that people eat foods in isolation, and findings from this
study demonstrate how other factors, such as the time of day or food pairings,
need to be considered when investigating the GR of mixed meals in individuals
with T2D."
This study followed a rigorous methodology by using a randomized crossover design and measuring glucose levels both immediately post-meal and overnight to obtain a better picture of the potatoes' impact on GR. However, the researchers noted a few limitations: study participants' baseline GR was assessed for only one evening meal, the dinner provided was larger than what is typically recommended for people with T2D (but in line with Australian eating patterns, at 40 percent of an individual's total energy intake), and the potatoes' impact on long-term glycemic control was not assessed.
Despite
such limitations, the researchers concluded that "potatoes are a vegetable
that is sustainable, affordable and nutrient-dense, and thus, they can play an
important role in modern diets irrespective of metabolic health status.