A recent research on the diet containing low levels of AGEs (advanced glycation end products) having a potential of improving insulin sensitivity in overweight individuals was published in the ‘American Journal of Nutrition’ by Barbora de Courten et al., on March 30th 2016. A diet based intervention was carried out which exhibited the potential of reducing the risks of diabetes and cardiovascular diseases in healthy overweight subjects.
According to the trial, two different types of diets — one containing high amount of AGEs and the other with low levels of AGEs — were given to healthy but overweight individuals. The consumption of low AGEs containing diet reduced blood glucose levels by increasing insulin sensitivity. The rate of diabetes and cardiovascular disease causing common indicators — oxidant stress and inflammation — were also reduced. The trial was further authenticated and registered by the leading U.S. National Institutes of Health, ‘ClinicalTrials.gov’.
Insulin sensitivity is a measure of how effectively insulin levels are managed in the body to reduce elevated blood glucose levels. Type II diabetes develops when the body fails at using insulin for reduction of blood glucose levels. People with low insulin sensitivity gradually develop insulin resistance. Such individuals require large amounts of insulin, either formed in their own pancreas or from injections, to keep blood glucose levels stable.
What Are Low AGEs?
Advanced glycation is a non-enzymatic reaction between reducing sugars and free amino groups of proteins, lipids, or nucleic acids naturally occurring in the body. AGEs are highly oxidative compounds and the end products formed as a result of such reactions include derivatives known as CML and MG. These substances are produced as a part of normal metabolism of the human body but overly increased levels of AGEs in tissues and circulation become alarming. AGEs also exist in foods; thermal processing including heat treatments while baking, roasting, frying and grilling increase the amount of these toxic compounds in food products.
Modern heat-processed foods containing high number of ‘advanced glycation end products’, also known as glycotoxins, have been positively linked with the risks of developing certain chronic conditions, like diabetes type II and cardiovascular diseases by increasing oxidative stress and chronic inflammation. These glycotoxins upon consumption of AGEs-rich diet bind with cell surface receptors or cross-link with body proteins, altering their structure and function. High levels of two important derivatives, ‘CML’ and ‘MG’, secreted in blood and urine, indicate high dietary AGEs consumption. These derivatives are also considered a leading cause of metabolic disorders.
It is estimated that about 70 percent of the U.S. diet consists of processed foods as stated by Melanie Warner, a former The New York Times business reporter, “Nobody set out to dominate the American diet, to make everything we’re eating so highly processed and so highly technical — it was a gradual revolution.” Warner, who is also the author of the book ‘Pandora’s Lunchbox’, continued, “It basically started 100 years ago.”
American Diabetes Association reported that approximately 30 million Americans are diabetic and $322 billion is spent on diabetes in America per year. It was also estimated that diabetics had 1.8 times higher chances of having heart complications than non-diabetics.
A randomized cross-over diet based trial involving 20 participants — 6 women and 14 men — with a mean 6 SD body mass index was carried out. The subjects consumed diets containing high or low AGEs content alternately for two weeks. All the participants consumed both types of diets; AGEs-rich and AGEs-low with the time gap of four weeks in between. Laboratory tests were also performed at the starting and ending of each intervention to assess insulin sensitivity. These include hyperinsulinemiceuglycemic clamp and an intravenous glucose tolerance test. Plasma and urinary samples were also drawn to check the important AGEs associated indicators (CML, CEL, and MG-H1) with the help of mass spectrometry.
The low levels of CML, CEL, and MG-H1 in the urine after consuming low AGEs diet confirmed rise in insulin sensitivity by 1.3mg/kg/min. Whereas, high-AGE diet showed a decrease in insulin sensitivity by 0.8mg/kg/min. The findings suggest that a diet containing low levels of AGEs can serve as an effective strategy to manage insulin levels and thus has a scope of reducing risks of diabetes and cardiovascular disease in overweight individuals.
‘Thermal processing’ is done to increase shelf life, sterility, flavor and color of the processed foods. Techniques like cooking, grilling and roasting of food lead to increased production of AGEs derivatives like NV-carboxymethyl lysine (CML) and methylglyoxal-derived hydroimadazolidines (MG-H1s), more than from boiling and steaming.
Foods that are high in lipids, like meat, contain high amounts of the derivative ‘CEL’. Highly processed foods like meat products, such as bacon; cheese, tinned vegetables, savoury snacks, such as fries, crisps etc., contain high amounts of AGEs. Moreover, common foods such as heated milk, baked breads, biscuits and cookies, toasted breakfast cereals, grilled steak, brewed beer, and roasted coffee beans possess high amount of AGEs due to heat processing. A research work suggested that dry heat promotes an increased production of AGEs related derivatives by 100 folds as compared to uncooked foods.