５０、A recent study shows that people living on the continent of North America suffer 9 times more chronic fatigue and 31 times more chronic depression than do people living on the continent of Asia. Interestingly, Asians, on average, eat 20 grams of soy per day, whereas North Americans eat virtually none. It turns out that soy contains phytochemicals called isoflavones, which have been found to possess disease-preventing properties. Thus, North Americans should consider eating soy on a regular basis as a way of preventing fatigue and depression.