June 5, 2012
Overall Memory Skills Not Improved By Soy Consumption
Connie K. Ho for redOrbit.com
Tofu. Bean paste. These are just a few of the products that include soybean which is thought to have health benefits in the area of memory development. However, a new study has found that soy protein may not preserve overall thinking skills in middle-aged and older women who are over the age of 45; however, soy may be able to improve memory skills linked to facial recognition.
The results are published in a recent edition of Neurology, the medical journal of the American Academy of Neurology. Researchers at the University of Southern California (USC) Keck School of Medicine and the Stanford School of Medicine found no major difference in the results of those who took soy protein supplements and those who did not. Soy and soy-based products have isoflavones, which are estrogen-like compounds thought to be able to improve memory and boost overall brain function. The hippocampus, the region of the brain that manages memory, has many estrogen beta receptors and isoflavones can activate these receptors.
"There were no large effects on overall cognition one way or another," noted the study's lead author Dr. Victor Henderson, a professor of health research and policy and of neurology and neurological sciences at Stanford, in a prepared statement.
In the experiment, 313 healthy postmenopausal women between the ages of 45 and 92 took 25 grams of soy protein or a milk-protein matched placebo on a daily basis. This amount of soy protein is comparable to the dosage found in traditional Asian diets. Participants were then given exams that tested their memory abilities over a period of two and a half years.
"Soy is a staple of many traditional Asian diets and has been thought possibly to improve cognition in postmenopausal women," explained Henderson, who also serves as a Fellow with the American Academy of Neurology, in the statement. "Our study found long-term use of soy protein neither improved nor impaired overall cognition."
The study showed that there was no major change in test scores between those who took milk protein supplements and those who were given soy protein. However, there was a small amount of improvement in visual memory identified in the soy protein group as opposed to the milk protein group. The soy protein group showed an increase in test scores of facial recognition by approximately 13 percent.
Regarding this issue, Henderson stated that this could be important but that "the finding needs to be replicated in future studies." Henderson and co-authors stated in the paper that women should not strive for a high-soy diet or take soy protein supplements in hopes of boosting memory ability. Likewise, Henderson believes that women should not feel discouraged to eat soy due to the results of the study.
"I don't think they should be disappointed at all," remarked Henderson in the statement. "They should be pleased that there aren't negative effects on overall cognitive function and that there are potential gains in aspects of memory. If a woman enjoys eating soy and if there may be other health benefits, she should keep doing what she's doing."
The project by Henderson and his colleagues was the longest and largest done on soy use. The results align with previous studies that have been done, including an experiment of a 12-month trial by Dutch women where daily soy intake did not produce “significant effect on cognitive endpoints." This particular study was published in the Journal of the American Medical Association in 2004.