Excess soy consumption has long been associated with ADD/ADHD, depression, anxiety, dementia and other mental health issues.1 Now it appears it can aggravate seizures as well. Cara J. Westmark, PhD, and her team at the Waisman Center for Developmental Disabilities at the University of Wisconsin, Madison, pull no punches when they title an article in the Journal of Alzheimer’s Disease “Soy Exacerbates Seizures in Mouse Models of Neurological Disease” and warn, “These results have important implications for individuals on soy-based diets.”2
The average American, of course, would not describe his or her diet as “soy based,” but soy ingredients are found in more than 60 percent of packaged and processed foods and nearly 100 percent of fast foods.3 The plant-based diet fad has furthermore encouraged many health-conscious Americans to substitute soy products for both meat and dairy. Although animal products would appear to be “soy free,” most commercial and health-food store eggs, milk and flesh foods contain residual isoflavones from soy-based feeds.4
Infants on soy formula—currently about 25 percent of bottled fed babies according to the American Academy of Pediatrics—are on soy-based diets because they rarely receive anything else to eat, a fact that has led the Israeli Health Ministry, French Food Agency, German Institute of Risk Assessment and British Dietetic Association to warn parents and pediatricians that soy formula could jeopardize brain and body development and should be used only as a last resort.5,6
Another captive population is prisoners. The Weston A. Price Foundation is currently suing the state of Illinois on behalf of prisoners who have suffered devastating damage to their digestive tracts and thyroids due to a high soy diet averaging 100g of soy products per day, with a phytoestrogen content of around 100mg.7
The level of seizures occur among today’s Illinois prison population is unknown. However, a 1978 study in JAMA reported seizure disorders at 1.9 percent among prisoners in Illinois, three times the level found in the general population.8 Although prisoners in the 1970s may have been spared the extremely high 100 grams of soy protein served up today, they most likely endured economy fare such as hamburger and other rations extended with soy grits, textured soy protein and soy flour. Whether soy on the menu might have caused such a high percentage of seizures is unknown. Prisoners, after all, may well have suffered for years from neurological damage that led to violent tendencies, crime and incarceration. Whether they were already seizure-prone individuals or not, the research of Westmark et al suggests their high soy diet could only have made matters worse.
Those who think seizures are rare and only happen to other people, need to think again. According to Dr. Westmark, one out of ten Americans will experience a seizure during their lifetimes.9 According to the Mayo Clinic, seizures may result from many disorders affecting the brain. Best known is epilepsy, a disease characterized by seizures, but seizures can signify metabolic disturbances such as hypoglycemia or dangerously high or low levels of sodium, calcium, magnesium or water. Seizures can also be triggered by brain injury, infections such as meningitis, tumors, lupus, stroke and high fevers.10 In many cases, the cause of seizures is unknown, and the underlying molecular mechanism(s) that initiate and propagate seizures are not well understood.”11
Patients with Alzheimer’s disease, Fragile X syndrome, Down syndrome, and autism are particularly susceptible to seizures,12 and the focus of much research at the Waisman Center of Developmental Disabilities has been on the myriad ways drugs, diet and genetic manipulation can affect amyloid beta levels, seizure threshold and behavioral phenotypes.13 In an editorial entitled “Concocting the Right Diet for Brain Health” published last December in Translational Medicine, Dr. Westmark expressed concern about the risks of soy: “The prevailing view is soy is healthy, but much remains to be learned regarding its effects on brain development and function.” She furthermore warned:
“There is a paucity of studies on the effects of phytoestrogens on fetal and early childhood development; yet, twenty-five percent of infant formulas are based on soy protein. Considering body weight, these infants are getting 6-11 times the dose of phytoestrogens necessary to exert hormone-like effects in adults. There are epigenetic changes associated with a soy-based diet in monkeys suggesting the potential to greatly alter gene expression. We have observed significantly elevated seizure rates in mouse models of Alzheimer’s disease, Fragile X syndrome and Down syndrome when juvenile mice are fed a soy- based diet. Our data suggests that soy-based infant formulas may lower seizure threshold particularly in babies genetically predisposed to developmental disorders. Thus, understanding the negative effects of soy phytoestrogens and modulating intake during pregnancy and infancy could prevent neurological damage during critical periods of sensory development.”14
What’s most surprising about this research is that the mice fed a casein-based refined diet showed “decreased amyloid beta and attenuated seizure rates.” Casein is a fractionated milk protein that is high in the amino acid methionine and seriously deficient in cysteine. It has such a poor nutritional profile that the soy industry has found it a reliable “control” to use in studies where the intent is to make soy look good. Indeed Japanese research at the Faculty of Agriculture, Shizuoka University in Japan, has shown that casein will significantly raise total cholesterol levels and lower HDL levels compared to other proteins.15,16 Consequently most studies used to support the FDA’s 1999 soy/heart disease health claim are deeply flawed because of the routine use of casein as the control.17 In the case of the research done at the Waisman Center, the rats fed a chow comprised of casein, sugar and cornstarch came out on top, and the data clearly indicated “soy isoflavones are associated with decreased seizure threshold.” Indeed soy-restricted diets reduced seizures in multiple lines of mice bred for diseases in which they would be prone to seizures.
To test the hypothesis that soy isoflavones promoted the seizures, the researchers determined to feed some of the mice chows that were supplemented with genistein and/or daidzein, the two isoflavones found in the highest quantity in soy.
After just three days of treatment with the standard soy protein chow, the group of specially bred “Alzheimer’s disease” mice responded with “wild running” and audiogenic seizures. 18
In plain English, audiogenic seizures are seizures brought on by the sound of an alarm. “Wild running” refers to an out-of-control style of running that progresses to loss of the righting reflex, tonic hind limb extension and other signs of seizure, often followed by death. “Righting reflexes” bring the body into a normal position in space and resist forces acting to displace it. They allow the animal to orient itself and regain its balance. Mice that do not die from the seizures regain the righting reflex and appear normal within a few minutes.
The researchers identified daidzein as a component of soy protein that elicited a strong wild running phenotype in wild type mice -- i.e. normal mice as found in nature. Three days of eating chow spiked with daidzein induced plenty of wild running, but no statistically significant increase in seizures. As yet, the researchers have not identified other components found in soy protein that work in tandem with the daidzein to trigger the progression into seizures and death. As for the Alzheimer’s mice, soy protein increased seizures but daidzein did not, though there was a strong trend for increased wild running in the females.19
Interestingly enough, daidzein but not genistein led to increased “wild running.” The non soy chows enhanced with genistein or the combination of genistein and daidzein, failed to provoke seizures in the wild type or Alzheimer’s disease mice. Indeed the genistein may have counteracted that,20 a finding that will surely lead the soy industry to put a positive spin on the study with a headline such as “soy genistein stops seizures.”
To understand the mechanism underlying the activity of the soy isoflavone daidzein, the researchers performed in vitro experiments in which they “assessed dendritic AβPP expression in primary, cultured, wild type neurons treated with daidzein or genistein” and “found altered AβPP expression.” They concluded both the in vivo and in vitro findings “have important implications for individuals on soy-based dies as well as for the rodent model.”21
It is also extremely interesting that daidzein alone appears to have caused the seizures and increased Aß processing. According to neurosurgeon and excitotoxin expert Russell Blaylock, MD, “this is a mechanism unrelated to excito-toxicity” though it is possible “daidzein may trigger excitotoxicity indirectly--say by activating microglia.”22 Much research shows seizures are generated by MSG and other excitotoxins, which are widely found in modern soy products. Glutamate, for example, is created as a byproduct of the industrial processing methods used to manufacture soy protein isolate and other fractionated protein products. In addition, food manufacturers often add MSG -- often hiding under the alias “natural flavoring” -- to improve taste and smell.23 However, this would also be true of manufacturing methods used to produce acceptable tasting casein products.
In terms of seizure control, it would seem useful to optimize the daidzein to genistein ratio in soy feeds and soy foods, but that’s easier said than done. Isoflavone content varies greatly from one batch of soybeans to another, much to the dismay of the soy industry, which finds it cannot reliably either minimize risks or maximize alleged benefits. Predicting isoflavone content remains elusive because the levels are influenced by many factors, including crop year, geographical location, number of daylight hours, temperature, humidity, rain, fertilizers, types of pathogens and the plant’s response to attack or disease.24
The significance of research on diet and seizures cannot be overstated. Westmark et al provide sobering figures: Seizures occur along with Alzheimer’s disease in 10 to 22 percent of patients; Fragile X Syndrome, 18 to 23 percent; Down syndrome, 8 percent; autism, 21 to 38 percent; and traumatic brain injury, 53 percent.”25
Expanding on Dr. Westmark’s warning in Translational Medicine about the risks of high soy diets during pregnancy, infancy and early childhood, the current study includes this warning:
“High exposure to estrogenic compounds during fetal and early childhood development through soy-based food products could disrupt the function of the natural steroid hormones and contribute to the high incidence of seizures associated with many childhood, neurological disorders including autism and FXS (Fragile X Syndrome). Understanding the role of soy constituents, such as daidzein, on AβPP (amyloid-β protein precursor) synthesis and metabolism and modulation of intake during pregnancy and infancy could reduce seizure incidence and prevent neurological damage.”26
Westmark et al furthermore report work in progress in which the data -- as yet unpublished -- point to higher incidence of febrile seizures in autistic children fed soy-based formula.27
The current study states more research is needed and concludes with, “Thus, a clearer understanding of the environmental factors, such as soy, that modulate synaptic AβPP levels may provide a dietary intervention to reduce Aβ levels and seizures.”27
What to do in the meantime? Those smart enough to value their brain health will say “better safe than sorry” and cut way back on soy!
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Thanks to Sylvia Onusic PhD for research assistance.
1. Daniel, Kaayla T. The Whole Soy Story: The Dark Side of America’s Favorite Health Food (Washington DC, New Trends, 2005) 251-258, 307-308, 355, 371-372.
2. Westmark CJ, Westmark PR, Malter JS. Soy-based diet exacerbates seizures in mouse models of neurological disease. J Alzeimers Dis. 2012 Oct 3. [Epub ahead of print]
3. Daniel 287-292.
4. Daniel, Kaayla T. The Soy-ling of America: Second Hand Soy in Animal Feeds
5. For more information about the Israeli, French and German warnings:
6. Daniel, Kaayla T. The Whole Soy Story, 353-354.
7. For more information about the lawsuit:
8. Lambert NK, Young QD. Increased prevalence of seizure disorders among prisoners. JAMA, 1978; 239 (25); 2674-2675. doi:10.1001/jama.1978.03280520046016.
9. Westmark et al.
11. Westmark et al.
12. Westmark et al.
14. Westmark, Cara J. Editorial: Concocting the right diet for brain health. Translational Medicine, 2011, 1:3. http://dx.doi.org/10.4172/2161-1025.1000106e
15. Sugiyama K, Ohkawa S, Muramatsu K. Relationship between amino acid composition of diet and plasma cholesterol level in growing rats fed a high cholesterol diet. J Nutri Vitaminol (Tokyo), 1986, 2, 4, 413-433.
16. Sugiyama K, Muramatsu K.J Significance of the amino acid composition of dietary protein in the regulation of plasma cholesterol. Nutr Sci Vitaminol (Tokyo). 1990, 36 Suppl 2:S105-10.
17. The Weston A. Price’s submitted a 65-page petition to the FDA, asking the agency to retract the 1999 soy/heart health claim, written by Kaayla T. Daniel, PhD, and signed by Kilmer S. McCully MD, Mary G. Enig, PhD, Galen D. Knight PhD and Sally Fallon Morell, president of the Weston A. Price Foundation. It is available online at: www.westonaprice.org/soy-alert/soy-heart-health-claim.
18. Westmark et al.
19. Westmark et al.
20. Westmark et al.
21. Westmark et al.
22. Email from Russell Blaylock, MD, to Kaayla T. Daniel, PhD, October 7, 2012.
23. Daniel, The Whole Soy Story, 128.
24. Daniel, The Whole Soy Story, 295-299.
25. Westmark et al.
27. Westmark et al.