Wednesday, November 18, 2015

Can some foods cause cancer? Depends on severity of heat exposure

Contrary to the saying that food is medicine and medicine is food attributed to Socrates, foods can also be the poison if not properly cared for during preparation if some scientists are to be believed. All natural foods found edible are considered safe when consumed in moderate quantities that can meet body's neeeds of calories, proteins, fat and other essential nutrients but improper storage and handling can cause deterioration in quality and some time even adverse consequences. It is true that the wonders brought about by food scientists in the form of preservation technologies which laid the foundation of modern food industry have enabled mankind to avoid food poisoning and other undesirable consequences of spoiled foods to a great extent. Stray cases of food poisoning that occur from time to time are due to negligence and improper processing and packing. Also responsible is the recklessness on the part of processing industry in introducing chemical substances which turn out to be dangerous in the long run. Artificial colors, synthetic sweeteners, many food preservatives and appearance enhancers, artifacts generated during processing, leached substances from packaging materials etc are examples of unsafe process aids causing health damages to varying extent. These examples may be far and few but it is a reality that such dangers do exist about which consumers must be aware.

It was only recently that some researchers highlighted the dangers of vegetable oils when used for frying and recommended not using some vegetable oils for high temperature applications. The generation of toxic aldehydes in frying oils poses a real danger and the preliminary findings of the above group is being taken seriously by the safety authorities world over to generate adequate data on this issue to lay down guidelines for frying processes. The irony is that there is an inverse relationship between taste and flavor and extent of heating. Higher the temperature tastier are the products. Imagine the chaotic situation that exists to day with all types of oils being used for frying at temperatures varying from 160 to 210 C and duration of heating varying from a few minutes to hours together. Is it humanly possible to have any control on frying operations in millions of households and small industries? Therefore it makes eminent sense to declare on the packs of those oils that they are not suitable for frying for long duration and temperatures beyond 160 C.

A similar situation is emerging with regard to toasting and roasting processes vis a vis some materials like potato and bread. Here the contentious issue is formation of a toxic substance called Acrylamide, a reaction products between proteins and carbohydrates. This chemical was detected in 2002 by Swedish workers in two of the most popular products viz French Fries and Potato Chips and raised alarms regarding its wide occurrence in a variety of products heated to temperatures beyond 120 C Though till to date Acrylamide has not been implicated in cancer in humans, the possibility does exist because of conclusive data obtained in animal studies implicating this chemical as a carcinogen. What is known is that Acrylamide has toxic effects on reproductive system and nervous system in humans at levels of 500 micro gram per kg body weight..World wide policy makers are uncertain about the safe limit of Acrylamide that can be permitted in human foods. However there is a standard for potable water which should not contain more than 0.1 micro gram per liter. Naturally logic says that food consumed also should not have levels beyond that but still such limits have not yet been prescribed in any country or by the WHO of the United Nations.

Recent recommendation by the British food authorities that foods like bread and potato should be subjected to less severe heating to prevent formation of Acrylamide has pushed the problem in the public realm and cannot be ignored easily. After all Acrylamide formation is possible only if the food contains both Aspargine containing proteins and sugars such as Glucose and Fructose. However it is not clear whether consumers will listen to this advisory seriously because of the traditional practices of making tasty potato crisps and toasts from bread with dark hues. According to common sense, human beings have been consuming potato crisps and bread toasts for hundreds of years, apparently with no harm! But a raw material like potato to day is vastly different from what was consumed by our predecessors as most potatoes are cold stored and the concentration of glucose in them reach alarming levels which can increase the levels of Acrylamide during frying. According to most recent studies, Acrylamide formation can be as high as 3000 ug per kg of potato chips, an alarming level considered from any angle. 

Whether there is any universal agreement on the Acrylamide content of different commercial foods marketed to day, it is a fact that exposure to this toxin is significantly higher to day than it was 50 years ago. Some of the commercial products like potato chips, cookies and crackers, coffee, bread, breakfast cereal, and French Fries contribute significant amounts of Acrylamide in the diets of populations in the Western countries. For example more than 25% of Acrylamide exposure in US comes from French Fries while another 25% is ingested through Bread. Other foods like baked goods, potato chips etc contribute the rest. It is difficult to believe that a popular brand of Potato chips available in many countries is reported to have Acrylamide levels between 250 ug and 470 ug per kg. There is a brand of sweet Potato chips under the name Route 11 which contains a whopping 2760 ug of Acrylamide per kg! Even dark roast coffee and Cocoa can contain Acrylamide as high as 100 ug per kg. While Coffee may not pose much of a hazard since only insignificant levels are leached into brewed coffee, cocoa based beverages can have high levels of the toxin. 

Now that safety experts are seized of this challenging safety issue, what needs to be done is bothering the authorities to no end. While commercial processors can be restrained from making products with Acrylamide beyond a certain level, how is it possible to discourage house hold consumers from making over heated products causing generation of Acrylamide in their kitchens? Advisories like using fresh potatoes only for making crisps, chips and fries or eating lightly toasted bread or low temperatures for preparing foods containing proteins and sugars may serve the purpose to a very limited extent as consumers tend to forget then in their desire to prepare tasty foods. Acrylamide busting additives though are being developed, how far it is practical to use them in the kitchens of restaurants and house holds is a million dollar question. 

There is some apprehension among some people that Acrylamide alarm might have been overstated and these chemicals might not be as harmful as it is made out to be. The reason for this is that Acrylamide formed while preparing a particular food, considered to be a complex cocktail of organic chemicals, may not be in a position to be absorbed by the body during its travel through the GI tract and therefore it could get excreted without much harm. This may be a wild conjecture and needs further studies before coming to any concrete conclusion. Until such time it is wise to be cautious while preparing foods, especially at home, not to go for high temperatures and long cooking time           . 


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