When we eat refined carbohydrates or "sugars", our blood glucose content (glycemia) rapidly increases. Glucose is immediately captured by the hormone insulin to be transported inside the cells of muscles and liver. But why this rush? Why is it so urgent to keep glucose away from the blood?
Glucose in the blood, as well as in the cells if not used for energy, is highly damaging.
The damage of glucose derives from both being pro-inflammatory and by creating advanced glycation-end products (AGEs). These are conjugation (coupling) molecules between glucose or an oxidative molecule (free radical) and a protein, a fat or a nucleic acid (which from DNA). Such coupling alters the structure and function of proteins (and enzymes) and produce highly oxidation molecules that produce further oxidative stress and inflammation.
AGEs are produced normally in the body by the process of metabolism but when they reach elevated levels they become very harmful. For this reason they are considered glycotoxins (toxins derived from glucose) and an important factor in aging and in the development or worsening of many degenerative diseases such as diabetes, atherosclerosis, chronic renal failure, Alzheimer’s disease.
When there is a high level of glucose or oxidative species (free radicals) in the cell, the production of AGEs is more elevated. We increase the level of AGEs by intaking different types of food and by several cooking processes. AGEs are indeed naturally present in animal-derived food. The highest levels are found in beef then cheeses, high-fat spreads, including butter, cream cheese, margarine (who still eats this??), and mayonnaise, followed by poultry, pork, fish, and eggs.
Grains, legumes, breads, vegetables, fruits, and milk show the lowest amount of AGE, unless prepared with added fats.
Type of cooking changes the levels of AGEs. Poaching, steaming, boiling (low temperature and high water) cooking adds ½ to 1/4 of AGEs compared to broiling, roasting and grilling. However, marinating in vinegar or lemon juice limits the extent of AGE formation in BBQ and broiling.
A low intake of such AGEs has been linked to longer lifespan and avoidance of chronic diseases. People who consume lower-meat meals prepared with moist heat (soups and stews) in a diet rich in plant foods could consume half the daily intake seen in people who consume a diet rich in grilled or roasted meats, fats, and highly processed food. A reduction of AGE by 50% is accompanied by reduced oxidative stress and longer life span.
Diets that are higher in protein and fat and lower in carbohydrate may substantially raise AGE intake and production and thus contribute to health problems over the long term.
Also high levels of stress and a lack of sleep also contribute to AGE development.
Moreover, a sedentary lifestyle (less burning of glucose) is one of the major contributors to high AGE levels, whereas regular exercise and physical activity helps reduce the amount of AGEs in our body.
Thus, reduced levels of AGEs can be achieved by:
- increasing the consumption of fish, legumes, vegetables, fruits, and whole grains
- reducing intake of solid fats, fatty meats, full-fat dairy products, and highly processed foods,
- steaming and boiling instead of broiling and roasting or bbqing
- practicing regular physical exercise
JAIME URIBARRI, MD, SANDRA WOODRUFF, RD, SUSAN GOODMAN, RD, WEIJING CAI, MD, XUE CHEN, MD, RENATA PYZIK, MA, MS, ANGIE YONG, MPH, GARY E. STRIKER, MD, and HELEN VLASSARA, MD, 2010. Advanced Glycation End Products in Foods and a Practical Guide to Their Reduction in the Diet, J Am Diet Assoc. 110(6): 911–16.e12.