Today’s product designers are seeking trans-fatty-acid-free (per serving) alternatives for all types of food formulations. Often, the answer means a move to fats high in saturated fatty acids. Because both trans fatty acids and saturated fatty acids are associated with elevated heart disease risk factors, product designers face a fatty-acid dilemma.
There is general agreement that trans fatty acids should be removed from the food supply to address the health concerns, but it is not clear which fats should be used as replacements. Further, emerging research suggests this will not get any clearer in the near future.
Saturates not so bad after all
While it is assumed that reintroduction of saturated fat might be deleterious, recent research suggests that the role of saturated fatty acids needs to be re-examined. “Current dietary intake recommendations of macronutrients have targeted total fat, cholesterol and saturated fat as the principle means to improve human health,” says Bruce German, professor, Department of Food Science & Technology, University of California-Davis. “Such recommendations have been translated into a long-term agricultural objective of eliminating these components from human foods. However, many authorities are questioning if it is possible that evolution found benefits to saturated fatty acids that current nutrition recommendations do not consider.”
Nutrition research in the 1980s revealed significant differences in how humans metabolized individual fatty acids, and scientists at that time speculated that some saturated fatty acids were “better” than others. Some scientists believe that saturated fatty acids cannot be considered as a single group, because in the human body, each saturated fatty acid has a specific function depending on its chain length. However, because nobody is eating individual fatty acids, but rather a mix of fatty acids as only one component of complex foods, other scientists say saturated fatty acid metabolism and impact on blood cholesterol levels must be considered in terms of daily intake.
“For example, the label of a bar of chocolate may state a high percentage of your recommended intake, or daily value (DV), of saturated fats,” says John Radcliffe, professor, Department of Nutrition & Food Science, Texas Woman’s University, Houston. “Much of that is provided by stearic acid, which does not raise blood cholesterol levels as do most other saturated fatty acids. However, even though chocolate contains high amounts of stearic acid, it is still important to adhere to the recommended daily intake of saturated fat. This is 10% of a person’s energy intake, or approximately 17 to 25 grams per day for most adults, regardless of the source.”
Stearic acid is typically found in animal fats such as beef tallow and lard. “Researchers originally speculated that stearic acid was rapidly converted to oleic acid (an 18-carbon monounsaturated fatty acid) in the body, making it ‘healthy,’” says Gerald McNeill, director of R&D, Loders Croklaan, Channahon, IL. “However, recent research has not supported that theory, and it has been repeatedly shown that stearic acid is not converted to oleic acid. And, although stearic acid has been shown to not cause an increase in low-density lipoprotein cholesterol (LDL, or “bad” cholesterol) when consumed, it was also shown not to increase high-density lipoprotein cholesterol (HDL, or “good” cholesterol). That is not good.
“It should be noted that the only other fatty acids that do not increase HDL are trans,” McNeill continues. “The other saturated fatty acids, such as palmitic acid, increase HDL, but they also increase LDL. So, there is really no net difference among the different kinds of saturated fatty acids. In fact, because all saturated fats do both good and bad things, they are not as ‘harmful’ to humans as was once believed.”
And remember, humans do not consume individual fatty acids. They are complex blends delivered via a food matrix. Other food components such as fiber and plant sterols impact absorption and cholesterol levels.
“Given the lack of difference in the healthfulness of different kinds of saturated fatty acids, it does not make much sense to give a special status to one kind of saturated fat,” says McNeill. “The result could be an undesirable, unforeseen consequence. After all, look what happened the last time a fatty acid got a special label status.” Think trans.