Many foods you eat contain soybeans, a complete protein. Tofu, textured vegetable protein, infant formula, cheese and other dairy substitutes can be made from soy. The main isoflavones in soy include genistein, daidzein and glycitein. These are phytoestrogens: estrogens that come from plants. Estrogen is a hormone that controls reproductive processes in females. Many of the studies conducted on soy and the brain have been done on rodents, or as in vitro studies on cells in the lab.
Improves Memory
A chemical synthesized from soy improves memory in older people. A study by Japanese researchers appearing in the November 2010 "Journal of Clinical Biochemistry and Nutrition" found evidence that the chemical phosphatidylserine boosted recall on memory tests. Human experimental subjects age 50 to 69 improved their scores on verbal tests over a placebo group after taking the chemical for three months. Phosphatidylserine comes from combining the lecithin in soy with the amino acid L-serine.
Disrupts Hormones
If you eat soy while pregnant, or give your baby soy formula, you should be cautious, say researchers. Phytoestrogens in plants such as soy might interfere with your child's brain development. Research conducted at Drake University in Des Moines, Iowa, found genistein adversely affected spatial learning in rats. According to an article in "Hormones and Behavior" in March 2010 by Evan R. Ball and colleagues, the phytoestrogen genistein affected rats' ability to navigate a water maze. Developmental problems occurred in male offspring exposed to genistein maternally before birth, and after birth through their mother's milk.
Reduces Inflammation
Including soy in your diet might protect against the onset of dementia. Genistein reduces inflammation of cells in your brain, say researchers Marcelina Malinowska and colleagues. Experiments in mice show genistein can slow the progression of some degenerative brain diseases. Investigation of brain cells known as astrocytes and microglial found them to be less inflamed in the mice following several months of eating the genistein. This study has implications for the treatment of brain diseases in human populations.
Protects Cells
Soy can protect your brain cells from oxygen deprivation, especially if you have a stroke. During a stroke, brain cells can die from lack of oxygen because the blood supply is cut off. When tested on cell cultures and also in mice, the chemicals genistein and daidzein were found to be protective. The study, published in "Neuroscience" in January 2009, showed that these phytoestrogens helped prevent cell death.
References
- "Journal of Clinical Biochemistry and Nutrition"; Soybean-Derived Phosphatidylserine Improves Memory Function of the Elderly Japanese Subjects with Memory Complaints; Akito Kato-Kataoka, Masashi Sakai, Rika Ebina, Chiaki Nonaka, Tsuguyoshi Asano and Takashi Miyamori; November, 2010
- "Hormones and Behavior"; Effects of Genistein in the Maternal Diet on Reproductive Development and Spatial Learning in Male Rats; Evan R. Ball,1 Mary Kay Caniglia,2 Jenna L. Wilcox,3 Karla A. Overton,3 Marra J. Burr,1,3 Brady D. Wolfe,1 Brian J. Sanders,3,4 Amy B. Wisniewski,5 and Craige C. Wrenn; March, 2010
- "PLos One"; Genistein Improves Neuropathology and Corrects Behaviour in a Mouse Model of Neurodegenerative Metabolic Disease; Marcelina Malinowska, Fiona L. Wilkinson, Kia J. Langford-Smith, Alex Langford-Smith, Jillian R. Brown, Brett E. Crawford, Marie T. Vanier, Grzegorz Grynkiewicz, Rob F. Wynn, J. Ed Wraith, Grzegorz Wegrzyn and Brian W. Bigger; December, 2010
- "Neuroscience"; Soy Phytoestrogens Are Neuroprotective Against Stroke-Like Injury In Vitro; Derek A. Schreihofer and Lori Redmond; January, 2009
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