Egg Nutrition Center Blog

Advances in Protein Research

Is it just me or is there growing interest in understanding the importance of the long overlooked macronutrient protein? Protein has always seemed like the Cinderella of diet planning. Carbohydrates and fats always commanded much more attention in dietary guidance, including protein as only afterthought.

As the baby boomer generation enters their senior years there seems to be a growing concern about keeping healthy through diet and exercise. Baby boomers are seeing that the high carbohydrate/low fat meals they were advised to prepare left them perpetually hungry and often at risk of cardiovascular disease related to the unattractive spare tire around their abdomen.  It’s time to ask why have the last 20 years seen an epic growth of obesity, metabolic syndrome and little change in the cardiovascular disease rates despite this supposedly healthy dietary advice?

Enter the shocking success of the Atkins/South Beach diets that found followers experienced more sustained relief from hunger and improved cardiovascular risk factors resulting from a reduction in carbohydrates and an increase in both fat and protein intake. People who previously sacrificed their favorite full fat meat, cheese and chicken dishes found that they could eat these foods again if they gave up white rice, bagels and pasta and surprisingly, were rewarded with increased high density lipoprotein levels along with reduced triglycerides and body weight garnering praise from their physician.

Now the scientific community appears to be catching up with the success of the higher protein intake. Two published studies1,2 looked at the effect of high protein intake on diabetes control.  In the Why WAIT (Weight Achievement and Intensive Treatment) Program, developed at the Joslin Diabetes Center for diabetes weight management in clinical practice, a high protein-low carbohydrate (30% protein [1.5–2 g/kg] and 40% carbohydrates) energy–restricted diet was tried within a multidisciplinary diabetes weight management program for 12 weeks. The authors conclude that an intake of 1.0-1.5 gm/kg of protein is appropriate for diabetics, helping to improve many health risk factors including a lower HbA1c in addition to a reducing total serum cholesterol, LDL cholesterol, triglycerides, blood pressure and markers of inflammation. The researchers reported diabetic patients were less hungry after meals, which contributes to their lower calorie intake and subsequent reduced body weight while maintaining muscle mass. The authors do however make the point that a higher protein intake may be contra- indicated in patients with diabetes accompanied by chronic kidney disease.

More recently, a study published in Advances in Nutrition 3 suggests the brain’s control of appetite is greatly affected by protein intake. From both animal and human research the authors conclude that after protein consumption, peptide hormones are released from the gastrointestinal tract that communicates information about the peripheral energy status to the brain. These hormones control food intake by acting on brain regions involved in energy homeostasis such as the brainstem and the hypothalamus.  High-protein diets lead to greater activation than a normal-protein diet in the regions of the brain responsible for satiety. These areas are triggered particularly by leucine, a branched chain amino acid that influences the reward and motivation aspects of eating behavior and plays an important role in the reduced hedonic response associated with a high-protein intake.

1         Hamdy, O. Issues in Nutritional Treatment of Type 2 Diabetes Mellitus and Obesity, Current Diabetes Reports, April 2011, 11(2):75-6.

2         Hamdy, O. and Norton E.S. Protein Content in Diabetes Nutrition Plan, Current Diabetes Reports, April 2011, 11(2):111-9.

3         Journel, M. et. al. Brain Responses to High Protein Diets, Advances in Nutrition, 2012, 3:322-9.

Author: Marcia Greenblum, MS, RD