/oss/taxonomy/term/1336/all en /oss/article/cancer-controversial-science-diets-drugs-food-health-news-supplements/green-tea-extracts-and-liver-disease <p>I think we are safe in saying that green tea doesn’t make taste buds frolic. So why do people drink it? The same reason for which the Chinese have been consuming it for millennia. Its supposed health benefits. Green tea doesn’t contain the flavourful compounds that form when tea leaves are allowed to ferment. During fermentation enzymes are released that convert the naturally occurring polyphenols in the leaves to a host of tasty compounds. Instead of being fermented, green tea is made by steaming or drying fresh tea leaves in order to prevent oxidation of the polyphenols.</p> Sat, 23 Aug 2014 13:06:03 +0000 Joe Schwarcz PhD 2184 at /oss /oss/article/food-health-quackery-quirky-science-you-asked/you-asked-there-any-food-or-beverage-leads-negative-calorie-balance <div>Easy answer. No. There is nothing that can be consumed that causes a greater expenditure of calories than it provides. But advertisers have given the idea a shot. But it wasn’t long before the idea was shot down. There’s no doubt that soft drink producers are in a quandary. Their product is coming under increasing nutritional scrutiny and it is not faring well. Schools are eliminating the sales of soft drinks and the public is becoming increasingly wary of consuming sugar-laden beverages with “empty calories.” Replacing sugar with artificial sweeteners does not seem to be the answer to the marketing woes, mainly because of the common (generally unjustified) perception that these substances are mired in unresolved safety issues. So if empty calories or zero calories don’t boost sales, how about “negative calories?” A beverage that causes more calories to be “burned” than it supplies certainly sounds attractive. And back in 2006 the Coca Cola Company claimed it had come up with just such a product in “Enviga,” a green tea-based drink.   At the time Dr. Rhona Applebaum, chief scientist for Coke claimed that “Enviga increases calorie burning and represents the perfect partnership of science and nature.” Well, let’s take a look at this “perfect partnership.” First, a bit about the terminology. Calories cannot be “burned,” they are not things, they are a unit of measure. Simply stated, a food calorie is the amount of heat needed to raise the temperature of a kilogram of water by one degree Celsius. Where then does the expression “burn calories” originate?  When a substance burns, it releases heat.  If a piece of pie is said to contain say 300 calories, then combusting it in a closed chamber, called a calorimeter, will produce enough energy to heat 300 kg of water by one degree.   Our body can also “burn” that piece of cake, meaning that 300 calories worth of energy is released as a series of chemical reactions decompose, or “metabolize,” the cake’s fats, carbohydrates and proteins. The products of these reactions are eventually exhaled in our breath or excreted in the urine and feces, while the energy produced is used to maintain our body temperature and supply the power needed for the proper functioning of our organs and muscles. If we do not “spend” all the calories that are potentially available, there is no need for the body to completely “burn” the food components, and the remnants are stored. Weight gain ensues!   Of course, should we then engage in some activity, the stored supplies can be called upon to undergo the reactions needed to produce the required energy, and weight is lost. Obviously then, to lose weight, more calories must be expended than are provided by the ingested food. Three servings of Enviga contained only 15 calories but according to Coca Cola stimulated the body’s metabolism to produce an extra 60-100 calories per day. These calories, given off in the form of heat, are produced when stored nutrients are converted to substances that are released from the body. The implication was that drinking 3 servings of Enviga a day leads to weight loss, although the company was careful not to make that claim.   Let’s have a look look at the science behind the hype.</div> <p><a href="http://blogs.mcgill.ca/oss/2013/12/13/you-asked-is-there-any-food-or-beverage-that-leads-to-a-negative-calorie-balance">Read more</a></p> Fri, 13 Dec 2013 22:41:58 +0000 Joe Schwarcz PhD 2045 at /oss