Question: Is it true that I'll be more likely to develop Alzheimer's disease if I eat tofu?
Tofu study is
harmful, not tofu
Answer: A well-publicized study that hit Hawaii like a storm some months ago suggested that by eating tofu in midlife, you'll be more likely to develop cognitive problems, including Alzheimer's disease, in old age.
The study created unnecessary fear and all but put tofu manufacturers out of business.
This study was conducted in Hawaii, at the Pacific Health Institute. It used 3,700 Japanese American men and 500 of their wives as test subjects. All were residents of Hawaii. What the researchers found was that the men and women who ate tofu two or more times a week in their middle years were more likely to experience mental decline in their later years, compared to those who seldom ate tofu.
There were several problems with the study.
One was that it didn't take into account other lifestyle factors which may be linked to mental decline in old age. For example, the overall dietary habits of the test subjects weren't considered. The 4,200 individuals used in the study were randomly picked from all walks of life. It's a proven fact that people who are better off economically tend to eat more nutritiously than those lower on the economic ladder. Inadequate diet, especially in childhood, is a proven risk factor in healthy neurological function later in life.
If it turns out that the consumption of tofu is not randomly distributed across the Japanese population in Hawaii, but is concentrated more in certain groups of people who also have other risk factors, then the disparity in mental functioning observed by the study could be related to something besides tofu consumption.
Another problem with the study is that only Japanese people were tested.
Such a study would be more useful and more reliable if it cut across the racial spectrum.
And there are other problems concerning the test groups used.
There were just two groups, one that ate tofu twice a week or more in their middle years, and one that seldom ate tofu in midlife. It's unclear what percent of each group developed cognitive problems, which makes it difficult to determine if the numbers are significant enough to even matter statistically.
Also, were other risk factors considered, such as drug use, smoking, heart disease and family history? All of these factors would influence the outcome of the study.
I find it interesting that the study's own scientists found that a history of stroke is a better predictor of cognitive problems than the amount of tofu one eats.
Why then did the tofu findings get so much press?
If a high tofu intake is linked to brain atrophy in old age, as the study suggests, how can these researchers explain the low rate of cognitive problems and Alzheimer's in Japan, where tofu is a dietary staple?
This was a preliminary study and so far is alone in its conclusion, whereas there are numerous other studies that show soy products, including tofu, help protect against heart disease and some cancers.
In fact the FDA recently allowed soy product manufacturers to state that their product helps protect against heart disease.
In my mind, the benefits of eating tofu outweigh the negative implications of this one flawed study.
Stephenie Karony is a certified health
and fitness instructor, a personal trainer and the author of
"Body Shaping with Free Weights." Send questions to her at
P.O. Box 262, Wailuku Hi. Her column appears on Wednesdays.