Sunday, August 5, 2012


There is a well ingrained perception that nuts are rich sources of energy as they contain high levels of fat which is logical. Obviously those watching calorie content in their diet will naturally shun these food components as much as possible. Nutrition labeling regulations provide for information including fat content in a product, saturated fat, trans fats and calories derived from them. Most of these data are generated by multiplying the carbohydrate, protein and fat content in a product by the appropriate factors laid down under universally accepted nutrition norms. Thus knowing the proximate composition of a product enables calculation of gross energy supposed to be available to the body. New findings that the entire fat content in some of the tree nuts like Almonds, when consumed, is not absorbed by the body are indeed surprising and will probably be welcomed by diet watchers all over the world. It is interesting to learn about the logic of this new revelation as reported by a  a credible scientific group recently based on laboratory studies. 

Scientists are starting to discover that the standard way of measuring calories, established more than 100 years ago, may not be terribly accurate when it comes to higher fat, high-fiber foods like nuts. But when it comes to almonds, the count may be off by a whole lot. Food scientists at the U.S. Department of Agriculture recently published a new study that finds almonds have about 20 percent fewer calories than previously documented. That's off by a lot more than an earlier British study showing pistachios have about 5 percent fewer calories than we thought, says USDA researcher David Baer, who worked on both studies. "We were surprised," he says. Baer and his colleagues compared the feces (poop, if you prefer) of people eating a controlled diet with almonds to ones who were eating a diet without any nuts. What they found was that "when people are consuming nuts, the amount of fat in the feces goes up," Bear says. "And that suggests that we're not absorbing all the fat or calories that's in the nut." In essence, the fat in the feces shows there's a disconnect between the gross energy found in an almond and the energy our bodies actually absorb.

Why 20% of the fat consumed via Almond is excreted from the GI tract is a matter of conjecture as of now. It is possible that the masticating efficiency in human beings may not be adequate to expose the fat contained in Almond cells to digestive juices which are supposed to hydrolyze it into fatty acids before absorption across the intestine. If this is so the fat absorption factor should be highly variable depending on how any given food is eaten by different individuals. It is true that efficiency of absorption can be high when food is eaten slowly, chewed and masticated thoroughly before swallowing. Especially in the case of oil seed nuts, extraction of fat is indeed a difficult process and the oil seed processing industry employs high pressure presses after breaking the fat cells to get almost 90% of the theoretical oil content. It is the pre-pressing step involving thermal treatment that breaks the fat cells, enabling the mechanical presses to recover the oil efficiently. In the human system fat release is largely dependent on the efficiency of mastication which will determine the amount of fat absorbed eventually across the GI tract. In the light of above findings, calorie content as being declared needs to be confirmed by actual in vivo testing but on the practical side the existing system of calculated calories based on proximate composition, followed universally will still serve the purpose of diet formulations and nutrient labeling.    


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