Abdel Omran, the famous medical professor who coined the term ‘epidemiological transition’ has named the last stage of ‘change over’ as the ‘age of degenerative and man made diseases’. These wordings are totally explicit that it wouldn’t be difficult for many of us to link the cause of various diseases and catastrophes to what we have done and what we are currently doing. Let us look deeper into the technology of refrigeration and its effect on our health. It is one of the technological advances which has made our lives so better that we don’t even like to think that its negative sides do exist for real.
Before going into the modern aspects of changes in food with refrigeration let us first see what Ayurveda has to tell regarding intake of cold foods. Ayurveda strictly disregards the use of cold and dry foods. It also states not to take food which has been reheated. Intake of such foods will harm the body due to the formation of metabolic toxins (āma). These toxins then lead to health deterioration and diseases.
Refrigerators have revolutionized kitchens around the globe and have modified our pattern of food intake to such an extent that it is almost irreversible. Let us try to find out what all are the changes brought to the food through refrigeration and reheating. Refrigeration causes loss of essential nutrients which won’t be evident to our sense organs. Undoubtedly, refrigerators change the color, flavor and texture of the food and we can assume that such changes will definitely bring about changes in the quality of the food. Tests reveal that antioxidants in melons were destroyed due to refrigeration and that the starch in potato breaks down during refrigeration. Such examples hint at a possible change in the basic structural and functional qualities of food.
Refrigeration always slows down microbial growth, but it is never fully stopped. And hence if those of us using refrigerators don’t store the food items clean, there is an increased chance of food contamination. Refrigerators are often treated as junkyards of each day's left over food. In that case, the food generally stays out in normal room temperature for about 4 hours or more continuously before it is refrigerated. But according to the food safety rule depicted as ‘4-40-140’ rule, food should not be kept for continuous 4 hours in a temperature range between 40 and 140 Fahrenheit. This is approximately between 5 and 60 degree Celsius and within this range maximum microbial growth occurs. So if we are to refrigerate and use the same food over and over, it might be just demonized food we are storing for the coming days. Moreover, when we keep the fridge opened for long periods, the temperature in it drops and we might be initiating more microbial activity which can lead to food poisoning.
There is a more dangerous part which is usually a corollary to refrigeration, that is reheating. Most of the studies point towards release of toxins during reheating which may be detrimental to our health. To start with our staple food, rice. Uncooked rice contains spores of bacteria called Bacillus cereus which can withstand the whole cooking process. There is a possibility for it to release toxins during reheating and this can easily cause food poisoning. Many of us have noticed rice becoming rubbery once it is reheated. This is because when rice is cooked the starch in it gets gelatinized (starch particles getting swollen up due to absorption of water) making it more digestible. The same rice when cooled the swollen starch expels water and forms tighter bonding causing the rice to feel rubbery. This process is called ‘retrogradation’. Retrograded starch is less digestible.
Protein foods are rich in nitrogen and so on reheating it gets oxidized producing toxins. Methods to cook protein foods should be generally chosen with caution as increased temperature may cause more formation of advanced glycation end products (AGE) which are deemed carcinogenic. Reheating proteins have also shown to change the protein composition affecting its digestibility.
Green vegetables like spinach are rich in nitrate. Reheating them is usually considered a bad idea because of the formation of nitrite, generally deemed as carcinogenic. And since such foods are rich in iron, reheating induces more oxidation and thereby release of more free radicals. Accumulation of free radicals causes myriad disease ranging from diabetes to cancer.
We are all better aware about the issues reheated oils cause. It may seem irrelevant here. But just think, aren’t we reheating oil while we are reheating food? Yes we are, because we use a lot of oil to cook food. So the issues with reheated oils also come along when we use reheated food. Reheating vegetable oils cause release of aldehydes and hydroperoxides which are toxic chemicals linked with cancer causation. Another chemical named HNE (4-hydroxy-trans-2-nonenal) is also released which disturbs the normal functioning of DNA, RNA and proteins. Reheating also increases the trans fatty acids in oils which is noxious to the cholesterol levels. There are more deleterious issues with reheated oil like free radical release, antioxidant reduction, polymerisation etc.
All these scientific statements haven't been proved beyond doubt. But there are few facts regarding the spike in lifestyle diseases that need full attention. Till liberalization of Indian economy in the 1990s, refrigerators were a luxury to the common Indian citizen due to oppressive taxation. Post liberalization situation changed and now one in every three Indian owns a refrigerator. That said, the toll the various lifestyle diseases take on our society seems very much connected to technological advancements like refrigerators. Taking hypertension for example, prevalence of hypertension in the mid 1950s was at 1.2-4%. Between 1960 and 1990 prevalence increased from 5% to somewhere between 12-15%. It currently stands at 29.8%. So is the case of all the lifestyle diseases. Refrigeration alone can’t be held culpable, but it surely has played its part.
I too have a fridge at home and so I certainly know how difficult it is to say adieu to our leftover caretaker. We can easily wait for the modern, so called ‘science based’ hypotheses to be proved true for justifying our delay in choosing a healthy lifestyle or we can believe and act according to a science which is very much a part of our culture and which has stood the test of time.