The Issue

Dr. Lon White, a medical doctor and researcher with a master's in Public Health, conducted a 30-year prospective study in Hawaii involving over 3,000 Japanese American men in which dietary data were collected and cognitive function observed. Although Dr. White was not originally looking for a direct correlation between tofu and cognitive function, his findings indicate a decrease in cognitive abilities as tofu consumption increases. Additionally, Dr. White conducted 250 autopsies and observed a relationship between low brain weight and tofu consumption. Dr. White plans to publish two articles that will include information on tofu consumption and dementia; one was recently published in the Journal of the American College of Nutrition. Dr. White has also indicated that he is compelled to warn consumers about the possible harmful effects of soy on cognitive function.

The United Soybean Board Response

• In the face of all the research that demonstrates the health-promoting properties of soy, we would be doing a disservice to the public to make any recommendations or generalizations based on one epidemiological study. Dr. White's assertions merely suggest the need for further research.
• Epidemiological studies like Dr. White's do not show cause and effect. While Dr. White tried to control for confounding variables-such as blood pressure, educational background, and other cultural influences, all of which have been linked to diminished cognitive function-it is not possible to eliminte all variables and make a clear connection between tofu consumption and the observed effect on cognitive function. The Japanese population consumes greater quantities of tofu than Americans, and still reports lower incidences of Alzheimer's Disease.
• Epidemiological findings are often refuted by clinical evidence. A classic example is a body of epidemiological studies suggesting that calcium intake may actually increase the risk of osteoporosis and bone fractures. In contrast, human studies conducted by the National Institutes of Health proved that calcium improves bone density and protects against osteoporosis. Calcium has since become universally recognized as a preventive agent for osteoporosis.
• A typical epidemiological study involving a dietary component would generally record the intake of 50 to 100 foods, while Dr. White's study only looked at 26 foods. In addition, Dr. White's method for recording tofu intake was not consistent throughout the study. He created new categories to consolidate the answers given in two different time periods.
• While Dr. White's study cannot easily be replicated, there are several preliminary animal studies that do not support Dr. White's findings on the effect of tofu consumption on cognitive function.
• All too often we make the mistake of overreacting to one particular study and generalizing the findings at the expense of the health and wellness of the general population. One of the most recent examples is the transformation of how we view fats and oils. Consumers have been inundated with the message that "fats are bad." Now health experts are emphasizing the importance of some types of fat, such as the unsaturated fats found in products like soybean oil. It is not in the best interest of the public to draw conclusions from one study --- particularly when there is so much clinical evidence supporting the health-promoting properties of soy.