Soyfoods and Brain Health

The U.S. Soybean Export Council (USSEC) tracks trends that may represent global market opportunities for U.S.-grown soy. As evolving consumer priorities elevate health, wellness and nutrition considerations, soyfoods may gain additional traction globally. Research on soyfoods and depression is an emerging area of interest.

Scientists have been motivated to study the effects of soyfoods on depression because soybeans are a rich source of isoflavones. Isoflavones are naturally occurring compounds. They are different from the hormone estrogen, but they do share some properties in common.

Currently, 73 percent of global consumers rate mental health and depression as having a moderate or severe impact on their everyday life.  Everyone experiences mood fluctuations –the normal emotional ups and downs of everyday life. But globally, more than 264 million people suffer from depression that goes beyond a bout of the blues.

Depression is a mood disorder that causes a persistent feeling of sadness and loss of interest. When depression is long-lasting with moderate or severe intensity, it may become a serious health condition. Its effects cause people to suffer greatly and function poorly at work, school and at home.

Researching the role of diet in decreasing risk of depression: Despite the fact that there are effective treatments available for mental disorders, between 76 percent and 85 percent of people in low-income and middle-income countries receive no treatment for their disorder.  Women are more likely to be affected by depression than men, which suggests there may be a hormonal component to depression. It is known that depression results from a complex interaction of social, psychological and biological factors.

Food is one factor that may affect the odds of having depression. A group of academics suggests that “diet is as important to psychiatry as it is to cardiology, endocrinology and gastroenterology.”

Two recent analyses suggest that a healthy dietary pattern may decrease the risk of depression, whereas a western-style diet may increase risk of this disease.  Much of the research showing that soyfoods reduce risk of depression has been conducted in postmenopausal women.

Examining the anti-depressive effects of soybean isoflavones: A logical question to ask is whether soy is protective against depression, given that it alleviates hot flashes and night sweats.  After all, poor sleeping habits can lead to depression and there is a link between menopausal symptoms and depression. While that is an interesting hypothesis, research indicates the anti-depressive effects of soy are unrelated to its effect on hot flashes. For example, a Japanese study found that isoflavones in soybeans alleviated depression in postmenopausal women without affecting hot flashes.

One intriguing study to evaluate the anti-depressive effects of isoflavones involved women suffering from depression living in the Dominican Republic who were enrolled into one of four groups.  One group received isoflavones alone, two groups received common drugs (fluoxetine or sertraline) used to treat depression, and one group received isoflavones plus one of the drugs. Isoflavones on their own performed as well as the established drugs, and the combination treatment performed better than each of the other three groups.

How much soy is enough? Studies have used a variety of different amounts of soy, but generally two servings per day of the traditional soyfoods appear sufficient to alleviate depression. A serving is a cup of soymilk or a half cup of tofu or edamame.

While it isn’t possible to say for certain that soy will benefit people with depression, it is a nutritious, high-protein food, so there are plenty of reasons to add it to the diet. Soyfoods from U.S.-grown soybeans provide high-quality protein, healthy fat and a variety of vitamins and minerals.

EDITOR’S TAKE:

This type of health-related research is very intriguing. Could we be on the cusp of a remarkable breakthrough in the treatment of depression or other mental conditions? There seems to be some evidence that should cause the soy industry to continue investing in this line of research. Other commodity groups, such as cranberries or other fruits and vegetables, might consider pursuing research that examines and answers the questions about precisely what health benefits could be derived from that particular commodity. And, let’s be honest, health benefits would accelerate consumer demand and profitability if they can be substantiated. It seems to be worth the investment to determine the answer.