Food Prep May Be as Important as Ingredients Themselves
TUESDAY, April 24 (HealthDay News) -- The methods used to produce or cook food may have as much impact on your health as the actual food, U.S. researchers report.
Grilled, fried or broiled animal products such as meats and cheeses contain a class of toxins called "advanced glycation end products" (AGEs), which have been linked to inflammation, insulin resistance, diabetes, vascular and kidney disease, and Alzheimer's disease, say a team from the Mount Sinai School of Medicine in New York City.
AGEs are also produced when food products are sterilized and pasteurized.
In a new study, the Mount Sinai researchers found that healthy people can have elevated levels of AGEs in their blood and that levels tend to be higher in older adults than in younger adults.
The study of 172 healthy men and women, ages 18-45 and ages 60-80, found that AGE levels were 35 percent higher in participants age 64 and older than in those younger than age 45.
Overall, the higher the participants' consumption of foods rich in AGEs, the higher their blood levels of AGEs and the higher their levels of C-reactive protein and other biomarkers of inflammation.
The major factor determining blood levels of AGEs is the amount of AGEs in the diet, not the amount of dietary calories, Sugar or fat, the researchers said.
They were also surprised to discover that young, healthy people could have very high levels of AGEs -- concentrations that were in the same range as those of people with diabetes. This suggests that early and prolonged exposure to AGEs could accelerate the onset of diseases, the researchers said.
The study was published in the April issue of the Journal of Gerontology: Medical Sciences.
"AGEs are quite deceptive, since they also give our food desirable tastes and smells," senior author Dr. Helen Vlassara, professor of medicine and geriatrics, and director of the Division of Experimental Diabetes and Aging at Mount Sinai, said in a prepared statement.
"So, consuming high amounts of grilled, broiled or fried food means consuming significant amounts of AGEs, and AGEs in excess are toxic. People should be given information about AGE intake and be advised to consider their intake in the same way they would think about their trans fats and salt intake. They should be warned about their AGE levels the way they are about their cholesterol levels or cigarette smoking," Vlassara said.
Books and programs on food combining have been on and off the best-seller lists for years. They should be in the fiction section. The authors claim that eating protein and carbohydrates, or fat and carbohydrates together causes problems because they require different enzymes for digestion, and either acid or alkaline conditions. They give you elaborate lists of foods that you can or cannot eat at the same meal. If any of this were true, the human race would be extinct. Few foods are "pure" protein, carbohydrate or fat. Your digestive system has evolved to deal with mixed foods, and the enzymes secreted by your pancreas can digest them all in any combination.
Your stomach is strongly acidic, no matter what food you eat. Stomach acid is much stronger than lemon juice, tomatoes or any other acid food. Nothing you eat escapes this acid "soup" while it is in your stomach, so it makes no difference whether you combine acid and alkaline foods.
These authors tell you that the undigested food will ferment and putrify, causing you to accumulate toxins in your intestines. This just doesn't happen. Your intestines do a very efficient job of breaking down carbohydrates, fats and proteins into their building blocks, which are then absorbed into your bloodstream. As long as you are not constantly constipated, your colon does an excellent job of removing the waste products of digestion. If you have a problem with constipation, the answer lies not which foods you combine, but in adding fiber and water to your diet.
They even claim that the undigested food makes you fat, which is impossible. To be stored as fat, a food must be broken down into its building blocks and pass from the intestines into the bloodstream. Any undigested food would be excreted, making you thinner, not fatter.
People who lose weight following these nonsensical rules do so simply because they are forced to limit their food choices and therefore consume fewer calories.
Do not confuse these ridiculous diets with serious "combination" recommendations that are made in two special situations:
Diabetics and others who are concerned about sharp rises in blood Sugar are advised to eat fruits and root vegetables only in combination with other foods. Fruits and root vegetables contain lots of Sugar or quickly digested starches which can cause blood sugar to rise after eating. However, a healthy Diet does not eliminate these foods because they also contain lots of vitamins, minerals and other phytochemicals that your body uses to keep you healthy and prevent diseases. When you eat these foods WITH other foods, particularly proteins or fats, they are digested more slowly. Diabetics should include a variety of fruits and root vegetables in their diet, but eat them with meals, not alone.
Strict Vegetarians who eat no animal products are often advised to COMBINE beans and grains so they will get complete proteins. This is true, but you do not need to eat the foods together at the same meal. The proteins found in meat and dairy products contain all nine essential amino acids (the ones your body needs and cannot make), and so they are called complete proteins. Most plant sources of protein, such as beans and grains, contain only two to seven of the essential amino acids, so you must eat a variety of these foods to assure that you get them all. However, you can do this over the course of the day or week. Amino acids circulate constantly in your bloodstream and are used as needed. You do not need to eat the foods simultaneously to supply your body with the different amino acids you need.
Researchers at the University of Warwick have found that the standard British cooking habit of boiling vegetables severely damages the anticancer properties of many Brassica vegetables such as broccoli, Brussel sprouts, cauliflower and green cabbage.
Past studies have shown that consumption of Brassica vegetables decreases the risk of cancer. This is because of the high concentration in Brassicas of substances known as glucosinolates which are metabolized to cancer preventive substances known as isothiocyanates. However before this research it was not known how the glucosinolates and isothiocyanates were influenced by storage and cooking of Brassica vegetables.
The researchers, Prof Paul Thornalley from Warwick Medical School at the University of Warwick and Dr Lijiang Song from the University of Warwick's Department of Chemistry bought Brassica vegetables, (broccoli, Brussel sprouts, cauliflower and green cabbage) from a local store and transported them to the laboratory within 30 minutes of purchasing. The effect of cooking on the glucosinolate content of vegetables was then studied by investigating the effects of cooking by boiling, steaming, microwave cooking and stir-fry.
Boiling appeared to have a serious impact on the retention of those important glucosinolate within the vegetables. The loss of total glucosinolate content after boiling for 30 minutes was: broccoli 77%, Brussel sprouts 58%, cauliflower 75% and green cabbage 65%.
The effects of other cooking methods were investigated: steaming for 0-20 min, microwave cooking for 0-3 min and stir-fry cooking for 0-5 min. All three methods gave no significant loss of total glucosinolate analyte contents over these cooking periods.
Domestic storage of the vegetables at ambient temperature and in a domestic refrigerator showed no significant difference with only minor loss of glucosinolate levels over 7 days.
However the researchers found that storage of fresh vegetables at much lower temperatures such as -85 °C (much higher than for storage in a refrigerator at 4-8 °C) may cause significant loss of glucosinolates up to 33% by fracture of vegetable material during thawing.
The researchers found that preparation of Brassica vegetables had caused only minor reductions in glucosinolate except when they were shredded finely which showed a marked decline of glucosinolate levels with a loss of up to 75% over 6 hours after shredding.
Professor Thornalley said: "If you want to get the maximum benefit from your five portions-a-day vegetable consumption, if you are cooking your vegetables boiling is out. You need to consider stir frying steaming or micro-waving them."