Actually, research is not fickle. Research results from one study are not considered conclusive by the scientific community. Remember, good research requires multiple studies to validate techniques and theories. It requires considerable discussion by researchers about the interpretation of data. Only then can research data be considered reliable enough for making appropriate food choice recommendations.
Nutritionists agree with each other more than they disagree.
However, the greatest disagreement comes from single study results presented at professional meetings and then presented to the public as if they were accepted by scientific peers. The field of health and nutrition is so large that few individuals have the time to read all of the literature pertaining to their area of study. Therefore their conclusions may be only one possible interpretation of data. The reports on the association between tofu consumption and brain aging in Japanese men in Hawaii is a good example of this. This data does justify refraining from taking concentrated soy isoflavone supplements until more research is done.