Dietary trans fat linked to worse memory, FDA bans partially hydrogenated oils

Higher consumption of dietary trans fatty acids (dTFA), commonly used in processed foods to improve taste, texture and durability, has been linked to worsened memory function in men 45 years old and younger, according to a University of California, San Diego School of Medicine study published online on June 17 in PLOS ONE.

Researchers evaluated data from 1,018 men and women who were asked to complete a dietary survey and memory test involving word recall. On average, men aged 45 and younger recalled 86 words; however, for each additional gram of trans fats consumed daily, performance dropped by 0.76 words. This translates to an expected 12 fewer words recalled by young men with dTFA intake levels matching the highest observed in the study, compared to otherwise similar men consuming no trans fats.

"Trans fats were most strongly linked to worse memory in men during their high productivity years," said Beatrice A. Golomb, MD, PhD, lead author and professor of medicine at UC San Diego School of Medicine. "Trans fat consumption has previously shown adverse associations to behavior and mood--other pillars of brain function. However, to our knowledge a relation to memory or cognition had not been shown."

After adjusting for age, exercise, education, ethnicity and mood, the link between higher dTFA and poorer memory was maintained in men 45 and younger.

The study focused predominantly on men because of a small number of women in this age group. However, including women in the analysis did not change the finding, said Golomb. An association of dTFA to word memory was not observed in older populations. Golomb said this is likely due to dietary effects showing more clearly in younger adults. Insults and injuries to the brain accrue with age and add variability to memory scores that can swamp ability to detect diet effects.

Trans fatty acids have been linked to negative effects on lipid profiles, metabolic function, insulin resistance, inflammation and cardiac and general health. In 2013, the United States Food and Drug Administration issued a preliminary determination that trans fats were no longer generally recognized as safe. According to the Centers for Disease Control, reducing dTFA consumption could prevent 10,000 to 20,000 heart attacks and 3,000 to 7,000 coronary heart disease deaths per year in the U.S.

"As I tell patients, while trans fats increase the shelf life of foods, they reduce the shelf life of people," said Golomb.

Meanwhile, the FDA announced yesterday:

Based on a thorough review of the scientific evidence, the U.S. Food and Drug Administration today finalized its determination that partially hydrogenated oils (PHOs), the primary dietary source of artificial trans fat in processed foods, are not “generally recognized as safe” or GRAS for use in human food. Food manufacturers will have three years to remove PHOs from products. 

“The FDA’s action on this major source of artificial trans fat demonstrates the agency’s commitment to the heart health of all Americans," said FDA's Acting Commissioner Stephen Ostroff, M.D. "This action is expected to reduce coronary heart disease and prevent thousands of fatal heart attacks every year.”

This determination will significantly reduce the use of PHOs, the major source of artificial trans fats, in the food supply. In 2013, the FDA made a tentative determination that PHOs could no longer be considered GRAS and is finalizing that determination after considering public comments.

Since 2006, manufacturers have been required to include trans fat content information on the Nutrition Facts label of foods. Between 2003 and 2012, the FDA estimates that consumer trans fat consumption decreased about 78 percent and that the labeling rule and industry reformulation of foods were key factors in informing healthier consumer choices and reducing trans fat in foods. While trans fat intake has significantly decreased, the current intake remains a public health concern. The Institute of Medicine recommends that consumption of trans fat be as low as possible while consuming a nutritionally-adequate diet. 

“Studies show that diet and nutrition play a key role in preventing chronic health problems, such as cardiovascular disease and today’s action goes hand in hand with other FDA initiatives to improve the health of Americans, including updating the nutrition facts label,” said Susan Mayne, Ph.D., director of the FDA’s Center for Food Safety and Applied Nutrition. “This determination is based on extensive research into the effects of PHOs, as well as input from all stakeholders received during the public comment period.”

The FDA has set a compliance period of three years. This will allow companies to either reformulate products without PHOs and/or petition the FDA to permit specific uses of PHOs. Following the compliance period, no PHOs can be added to human food unless they are otherwise approved by the FDA.

The FDA encourages consumers seeking to reduce trans fat intake to check a food’s ingredient list for partially hydrogenated oils to determine whether or not a product contains PHOs. Currently, foods are allowed to be labeled as having “0” grams trans fat if they contain less than 0.5 grams of trans fat per serving, including PHOs, the primary dietary source of artificial trans fat in processed foods.