The well-publicized push to eliminate transfats from Americans' diets has led the food industry to pursue alternatives to transfatty acids. One of these alternatives is "interesterified" fats.
In considering these new kinds of fats, it is useful to keep in mind why transfats were invented in the first place. A few decades ago, when it became apparent that diets high in saturated fats were unhealthy, the food industry was faced with the problem of how to avoid using these saturated fats, but still create fat-containing foods that a) were solid at room temperature, and b) didn't spoil. Without such substances, many baked goods and the stuff that fills Oreo cookies (for instance) would be impossible. Man-made transfats seemed to fill the bill. Accordingly, the public health gurus, in the 1960s and 1970, urged the food industry to substitute the more "healthful" transfats for saturated fats. The food industry did so, only to be castigated today (by the same gurus - the very same individuals in some cases) for using transfats in the first place, now that evidence has accumulated that these fatty acids may not be any less dangerous that saturated fats.
As a result, the food industry is engaging in a major effort to find a new form of fat that doesn't spoil and that is not a liquid. The latest candidate is interesterified fats. These fats are produced by taking a type of saturated fatty acid that is considered relatively safe (stearic acid, present in chocolate), and combining it with vegetable oils (which contain unsaturated fat). The combination produces a type of fat that has the stability and solidity of saturated fats, but (it is hoped) the health profile of unsaturated fats. Indeed, interesterified fats are showing up in foods already. The Food and Drug Administration recently ruled that food companies can label products containing these new fats as "high stearate" or "stearic rich" fats, or as "interesterified fats," thus avoiding the politically negative buzz word, "hydrogenated," which is associated with transfats.
DrRich Comments:
Here's the problem. We have no idea what the long-term health consequences will be of long-term use of interesterified fats. It took 30 years to figure out that transfats were not healthy, and it is likely to take just as long with interesterified fats - or any other fat we can invent that does not exist in nature. A recent study out of Malaysia and Brandeis University appears to show that interesterified fats can worsen LDL and HDL levels, and increase blood glucose levels. So perhaps these new substances are not the final answer.
But any new species of man-made fat will have the same generic problem - we won't know for decades what the true health impact will be, even though we need to decide today whether to manufacture, sell and consume them. The fact is, if we're going to eat processed, long-shelf-life fat-containing foods at all, we need to use either saturated fats - or transfats, interesterified fats, or some other variety of man-made stuff. The safest thing to do, obviously, is to eat only fresh, non-processed foods for the next 20 - 30 years until the science sorts itself out. Another approach, less safe but possibly more practical, is to limit our intake of processed foods to reasonable levels, and increase our intake of fresh foods as much as we can.
Sources:
Sundram K, Karupaiah T, Hayes K. Stearic acid-rich interesterified fat and trans-rich fat raise the LDL/HDL ratio and plasma glucose relative to palm olein in humans. Nutr Metab 2007; doi:10.1186/1743-7075-4-3. Available at: http://www.nutritionandmetabolism.com.
Runestad, Todd. How to live without trans fats. Functional Foods and Nutraceuticals. December, 2004. Available at: http://www.ffnmag.com/NH/ASP/strArticleID/609/strSite/FFNSite/articleDisplay.asp
