Hues of brown are prized for flavour and eye appeal in the cooking world. Searing meat locks in juices and lends to a deep brown crust, rich in robust flavour. Crisp, brown skin covering turkey is a mark of perfection at holiday meals. The golden peaks of a meringue pie add a hint of caramel delight.
AGEs in food
Behind browning and flavouring of foods, such as the ones above, are advanced glycated end products (AGEs), the final products of Maillard Browning. Grilling, baking, frying, roasting, and searing – high temperature, dry heat cooking methods – cause attachment of sugar molecules to amino acids of proteins or fats through a process called glycation. Oxidized fat, that is, fat heated or exposed to light and air during storage, is more prone to glycation.
Flavour, colour, and odor is a pleasant indicator of AGEs in cooked food; however, even raw food contains varying amounts of AGEs. Animal-based food – meat, poultry, cheese, and butter – have the highest AGEs; high-temperature, dry-heat cooking accelerates the formation of AGEs. Fruits and vegetables have the least AGEs. When cooked, AGEs in fruit and vegetables also increase, yet not to a level even close to that in meat.
AGEs in the body
AGEs in food, either derived from cooking or inherent before cooking, are absorbed when eaten. Metabolic reactions within the body additionally form AGEs as blood sugar attaches to proteins, fats, and even genetic material (i.e. DNA). These newly formed glycated compounds change structurally and functionally; “normal” function is lost. Where once lipids (fats) existed in cell membranes to tightly regulate what enters and exits the cell, the membrane becomes more permeable. In addition, proteins such as those with hormonal, enzymatic, structural, signalling, and immune functions become impaired when changed into AGEs. This spells bad news for health.
The summation of exogenous or endogenous AGEs make up the overall amount of AGEs in the body. Normally, kidneys clear AGEs from blood, then eliminate breakdown products in urine. Because metabolically derived AGEs form slowly in small amounts over weeks or months, kidneys keep up with clearance. However, after a high-AGE meal, high levels of AGEs exceed clearance capacity. Impaired kidney function can further contribute to incomplete AGE clearance. Excess AGEs then return to circulation and deposit in tissue.
AGEs depositing in tissue cause oxidative stress and inflammation – processes that are linked to nearly every aspect of chronic disease and aging. Arthritis, cardiovascular disease, dementia, diabetes, kidney disease, osteoporosis, wrinkles and skin sagging, vision issues, and delayed wound healing are linked to AGEs in the body.
AGEs produced from metabolic processes contribute a normal level of AGEs – a level below the clearance capacity of the kidneys. People with high blood sugar, such as people with diabetes, have higher levels of AGEs since glycation of proteins, fats, and genetic material (i.e. DNS) increases with higher blood sugar. It’s unsurprising, then, that people with diabetes are at higher risk of cardiovascular disease, kidney disease, and retinopathy. Inflammation and oxidative stress are at the foundations of these diseases.
Diets high in AGEs are the number one cause of high AGEs in the body. Moreover, preparation methods of food are more impacting than the type and amount of food one chooses (eating healthy portion sizes is still advisable since overeating causes oxidative stress, leading to degenerative diseases).
First and foremost, smokers should seek a cessation program for support. Cigarettes are high in AGEs, not to mention toxins, both of which accelerate aging through oxidative stress. To lower AGEs coming from food start by choosing foods that are naturally low in AGEs, then use cooking methods that reduce formation of AGEs, and, finally, add ingredients that inhibit formation of AGEs or mitigate the effects.
Foods rich in protein and fat, particularly of animal origin, are highest in AGE. That is not to say vegan or vegetarian diet should become a mainstay diet. No. This information can be used to make informed choices that can include meat – even high AGE meat – sometimes. Highly processed, commercially prepared foods are almost always high in AGEs – another reason to include more whole, homemade foods in your diet. Refer to A Guide to Low-AGE Foods.
Prepare foods using moist, low heat spread over long cooking times as in boiling, stewing, poaching, steaming, and cooking en papillote (in parchment paper or foil stacks). Dutch ovens, pressure cookers, and slow cooker crock pots are ideal for low-AGE cooking. Keep broths on hand to add flavour and moisture when braising, stewing, poaching, and simmering. Hot temperature cooking such as sautéing or stir-frying is better than roasting, grilling, searing, broiling, and frying because heat is transferred for only a short time.
As most passionate chefs know, searing meat before braising or roasting seals flavour and juices and browns the sides, nicely. I get it. I do it too, not that I’m a red-seal chef or anything like that. To lower AGEs, consider searing roasts on a lower temperature for a shorter time. Overall, keep high AGE foods and cooking methods to a minimal. Consider having 2 or more vegetarian meals a week. Have more fish and poultry than red-blooded meats.
For those die-hard grillers out there, this article is not a kill-joy to your BBQ-ing happiness. Summer BBQs with friends and family add much enjoyment to life. To minimize AGEs on the BBQ by up to 50% marinate meat and poultry in an acidic marinade before grilling. Ensure your marinate has either wine, lemon juice, vinegar, or tomato juice – something acidic to reduce AGE formation. Mix any of these acids with meager amounts of oil and plenty of herbs and spices. Avoid sugar-laden marinades, which will char meat easily and create AGEs. Cook steaks rare to medium-rare for the lowest AGE formation.
Lastly, oxidative stress and inflammation produced by AGEs once logged in tissues can be counteracted with antioxidant-rich foods. Phytochemicals, often associated with colourful fruits and vegetables and whole grains have immense capacity to stop oxidative effects of AGEs and toxins. Sprouting and fermentation activate phytochemicals in seeds, vegetables, grains, and legumes, such that resulting effects are more potent, thus more health promoting. Balance high AGE foods with raw vegetables and fruits.
Of course, the most important strategy for lowering AGEs is to reduce the amounts entering the body through food. Exercise will help by controlling blood sugar, but, ultimately, one must reduce external sources.
If you’d like to learn more about aging well and reducing risk of chronic disease or if you’d like more guidance on A.G.E-less eating, I’d love to present to a group of health-conscious individuals or help you one-on-one. Contact me.
Guide to Low-AGE Foods
Protein:pulses < eggs < poultry < pork < beef
Even foods typically referred to as proteins have sugars. All meat and poultry, for example, have small amounts of sugar, just enough to crosslink with amino acids of protein or fats when applying heat. Lean meat has less AGEs, but even lean meat cooked at high temperatures and dry heat forms high AGEs.
Cheese:cheddar cheese (21% M.F.) < cheddar cheese (30% M.F. or higher) < cottage cheese < Parmesan cheese < processed cheese slices
AGEs form in cheese due to dehydration, heating milk for pasteurization, and long storage for aging. Cheese that are low-fat, less processed, and are aged for shorter times minimize AGE formation.
Fats and oils:cold-pressed, unrefined oils < avocado < pumpkin seeds (raw) < sunflower seeds (raw) < sunflower seeds (roasted) < almonds, raw < butter
Raw nuts and seeds, avocados, and unrefined oils are stored at cool temperatures in containers that block light are best. Avoid purchasing oils in bulk. Once opened oils oxidize faster, leading to more AGEs. Use oils that are appropriate for the cooking temperature. For example, use cold-pressed avocado oil for high temperature cooking rather than extra-virgin olive oil.
Grains:rice, cooked <oatmeal, cooked < bread < bread, toasted < cracker < Graham cracker < biscuit < rice cakes < crisp rice cereal < biscotti
Boiling or steaming grains forms the lowest AGEs. Crackers, chips, snack foods, breakfast cereals, cookies, and biscuits have higher AGEs because grains are baked or fried to remove moisture and add crispiness. Steel-cut oats or large-flaked oats make for a filling porridge.
Milk products:milk, non-fat < yogurt < milk, whole < ice cream < condensed milk < powdered milk < hot chocolate from packet
The high water content in milk products, protect against AGE formation in milk and yogurt. Choose low-fat milk products without added sugar, and AGEs will remain low. Removing water content in milk products increases AGEs as in condensed milk, powdered milk, hot chocolate from packet.
Vegetables and fruits:apples, raw < tomatoes, raw < apples, baked < plums, dried < sweet potatoes, baked < pepper and mushrooms, grilled < French-fried potatoes
Starchy and non-starchy vegetables are low in AGEs. Grilling, roasting, and dehydrating fruits and vegetables will increase AGEs around 10 times, but the resulting AGE level is not even close to the level of AGEs in raw meat and poultry. Eat fruits and vegetables raw most often.
Bagchi D, Swaroop A, editors. Food Toxicology. 1 edition. Boca Raton: CRC Press; 2016.
MD HV, Woodruff S, MD GES. Dr. Vlassara’s AGE-Less Diet: How a Chemical in the Foods We Eat Promotes Disease, Obesity, and Aging and the Steps We Can Take to Stop It. 1 edition. Garden City Park, NY: Square One; 2016.
Stipanuk M. Biochemical, Physiological & Molecular Aspects of Human Nutrition. 2 edition. Philadelphia, Pa.: Saunders; 2006. 960 p.