ALBANY, Ga.—Packed full of nutrients, peanuts and peanut butter factor into the daily diet of millions of Americans and are featured in a host of protein-rich foods and snacks. New research published in the British Journal of Nutrition also tips its hat to the tasty legume after it found eating peanuts or peanut butter at breakfast can control blood sugar throughout most of the day, even after eating a high-carbohydrate lunch.
Researchers at Purdue University and the Federal University of Vicosa in Brazil conducted a randomized cross-over clinical trial to examine the acute and second-meal effects of peanuts on glycemic response and appetite in obese women with type 2 diabetes risk. They found peanuts and peanut butter caused a significant reduction in the desire to eat for up to 12 hours and a significant increase in the secretion of the hormone PYY that promotes satiety and feelings of fullness.
During three phases of the study, 1.5 ounces of peanuts, 3 tablespoons of peanut butter, or no peanuts or peanut butter were consumed with a breakfast consisting of orange juice and cream of wheat followed by a lunch consisting of white bread and strawberry jam. Blood samples and appetite ratings were taken over a series of three hours following breakfast and again after lunch to assess glucose control and satiety; participants were also asked to keep a food diary for the remainder of the day after leaving the testing site.
Results showed peanut butter or peanuts included with breakfast promotes secretion of the appetite-suppressing hormone peptide YY (PYY). Participants who consumed peanut butter or peanuts with breakfast reported a lower desire to eat for up to eight to 12 hours later and maintained lower blood sugar following a high-carbohydrate lunch compared to participants that did not include peanut butter or peanuts.
Peanut butter had a slightly stronger effect, possibly because the cell walls of the peanut are ruptured during processing and may help slow the rate that carbohydrates are absorbed from the gut, resulting in a lower glycemic response in the blood.
The researchers suggest that it is the synergy of components in peanuts, including the high protein, high fiber and healthy oils that help to maintain blood sugar control, as well as contribute to feelings of fullness.
"Combined with findings from other work, this new research provides additional reasons to start your day with peanut butter and include a snack of peanuts in the late afternoon if you want to control your appetite and blood sugar too," said Pat Kearney, MEd, RD, program director for The Peanut Institute.