In a new study, researchers from Weill Cornell Medical College in New York City, NY, found that the order in which different types of food are consumed has a significant impact on post-meal glucose and insulin levels in obese people. Writing in the journal Diabetes Care, the authors suggest their findings may have dietary implications for diabetic and other high-risk patients.
For people with type 2 diabetes, it is important to maintain normal glucose levels after eating, because if their blood sugar level spikes then they are at increased risk of complications, including hardening of the arteries and heart disease, which can eventually lead to death.
Some previous studies had found that eating vegetables or protein before carbohydrates could be an effective way to lower post-meal glucose levels. The researchers behind the new study wanted to see whether this association applied to a typical Western diet, with meals consisting of a mix of vegetables, protein carbohydrates and fat.
In the study, 11 patients with obesity and type 2 diabetes who were taking metformin - a drug that helps control glucose levels - ate the same meals in different orders 1 week apart, so that the researchers could observe how their glucose levels were affected.
The set meal consisted of ciabatta bread, orange juice, chicken breast, lettuce and tomato salad with low-fat dressing and steamed broccoli with butter.
Glucose and insulin levels lower when carbohydrates were eaten last
The researchers first took the patients' glucose levels in the morning, 12 hours after they last ate. On the first day of the study, the participants were told to consume the carbohydrates in their meal (ciabatta bread and orange juice) first, and to follow this 15 minutes later by the protein, vegetables and fat in the meal. The participants' glucose levels were checked 30, 60 and 120 minutes after eating.
The experiment was then repeated 1 week later, except this time the food order was reversed - the protein, vegetables and fat were eaten first, with the carbohydrates consumed 15 minutes later.
When the vegetables and protein were eaten before the carbohydrates, the researchers found that glucose levels were 29%, 37% and 17% lower at the 30, 60 and 120-minute checks, compared with when carbohydrates were consumed first. Also, insulin was found to be significantly lower when the participants ate vegetables and protein first.
"Based on this finding, instead of saying 'don't eat that' to their patients, clinicians might instead say, 'eat this before that,'" says senior author Dr. Louis Aronne, the Sanford I. Weill Professor of Metabolic Research and a professor of clinical medicine at Weill Cornell Medical College.
Dr. Aronne acknowledges that follow-up work is required - the findings are from a pilot study with a very small sample group - but says that "based on this finding, patients with type 2 might be able to make a simple change to lower their blood sugar throughout the day, decrease how much insulin they need to take, and potentially have a long-lasting, positive impact on their health."
"Carbohydrates raise blood sugar, but if you tell someone not to eat them - or to drastically cut back - it's hard for them to comply. This study points to an easier way that patients might lower their blood sugar and insulin levels," Dr. Aronne concludes.