Just when you thought your diet was as healthy as you could make it by avoiding pesticides, saturated fat, sugars, etc, along comes news about more problems with the Standard American Diet (SAD) in the form of advanced glycation end products or AGEs.
Simply stated, AGEs are reactions between carbohydrates (sugars and starches) and either proteins, or fats primarily at high temperatures. They can occur in foods (called exogenous) or made in the body as part of normal metabolism (called endogenous). The destructive effects of AGEs are associated with their ability to promote oxidative stress and inflammation by attaching or sticking to things like cell receptors or linking with proteins either in foods or in the body. This process alters the protein structure and function in either case.
This process of grabbing an electron from another atom or molecule is known as oxidation, and the condition that results from excessive oxidation in the body is called oxidative stress. Oxidative stress thus is a killer condition. Sooner or later, oxidative stress will result in tissue damage, accelerate aging and degenerative disease, and is likely to be involved in the development of cancer, heart disease, Alzheimer’s disease, and diabetes complications.
Previously, no one thought that AGEs were a healthy hazard since they were thought to be poorly absorbed or destroyed in the strong acidic environment of the stomach. However, recently, studies in animals and humans are showing that about 10% of ingested AGEs are absorbed, and about two-thirds of them are deposited in tissues, where they exert significant proinflammatory and oxidative effects.
AGEs are best known in the context of diabetes mellitus (DM), both types 1 and 2. Type 2 DM patients have considerably higher blood levels of AGEs than do healthy control subjects.
A fairly recent study found that in type 2 DM patients, a high AGE meal produced a more pronounced impairment of heart vessel function that did an otherwise identical low AGE meal. The difference in the AGE content in the meals was obtained by varying the cooking temperature and time. (American Journal of Clinical Nutrition 2007;85:1236-43).
A study in 2010 fed healthy volunteers two types of diets – one a low AGE steamed diet and the other a high AGE diet with foods based on high temperature cooking and tested their effects on glucose and lipid metabolism as well as oxidative stress.
In comparison with the steamed diet, 1 month of consuming the high-heat treated diet significantly lowered insulin sensitivity and blood levels of omega-3 fatty acids, and vitamins A and E.
In other words, cooking methods influenced an increased risk of diabetes and heart disease. (American Journal of Clinical Nutrition 2010, 91:1220-6)
A recent study found high levels of AGEs in infants. In the infant study, during the first year of life, after switching from breast milk onto commercial formulas, the infants’ AGEs had doubled to levels seen in people with diabetes, and many had elevated insulin levels. Formulas that are processed under high heat can contain 100 times more AGEs than human breast milk. (Diabetes Care October 2010, 33:2232-2237).
So, what to do? Probably not surprising is this simple guide to reducing the amount of AGEs in your diet:
- Processed foods (boxed and frozen meals)
- Full-fat dairy foods such as aged cheeses
- High-fat spreads (butter, cream cheese, margarine, mayonnaise
- Fried/oven-fried/broiled foods, especially meat
- Highly processed and refined oils
- Dry-heat processed crackers, chips, and cookies
- Fish (except fried or breaded)
- Fruit (sparingly)
- Low-fat dairy
- Whole grains/legumes (unless prepared with added fats)
Try to use more poached and stewed cooking methods, e.g. broiled chicken (AGE 5,828 kU) and broiled beef (AGE 5,963 kU) when stewed had 1,124 kU and 2,230 kU, repectively. A hard boiled egg has about 1/100th of the AGE content as a fried egg.
The use of marinating meats with lemon juice or vinegar limited AGE formation. Interestingly, these cooking methods have long been utilized in Mediterranean and Asian cuisines for centuries.
Eating whole foods and few processed foods is the simple message to avoid eating these potentially harmful compounds that can be detrimental to our health.