Large sample, prospective, randomized controlled studies on treatment are scarce.

在治疗上还缺少大样本、前瞻性随机对照性研究。

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Many people enthusiastically tried the so-called Feingold Diet, but the enthusiasm waned as the years went on and "some very well-done randomized controlled studies" questioned Feingold's theory, says Deborah Pearson, Ph.

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These are the kinds of big, randomized, controlled studies that the U.S. Food and Drug Administration requires before a new drug is approved.

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That research, however, typically didn't involve randomized, controlled studies.

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