Quoted from The Hundred-Year Lie:

Jay S. Cohen, professor of medicine at the University of California at San Diego, makes a case in his book Over Dose for the scientifically proven benefits of natural hormones derived from vegetables. “I know several women who had miserable times with drug company hormones, yet have done very well with natural hormones,” writes Cohen.

He cites four medical studies that support his natural-is-better contention. Here they are, by date of publication:

  • 1989: A study in the journal Obstetrics and Gynecology, in which the study authors demonstrate how natural progesterone taken orally “can produce excellent blood levels without the unwanted effects (such as fluid retention, breast tenderness, weight gain and depression) of the synthetics.”
  • 1995: A study in the journal Infertility and Reproductive Medicine Clinics of North America, in which scientists tout a “natural regimen” for its “little breakthrough bleeding” compared to synthetics.
  • 1997: A study in the journal International Journal of Fertility and Women’s Medicine, in which the study authors reveal having found that “naturally occurring estrogens lower blood pressure, or have no effect on blood pressure,” while synthetic estrogens and progestins elevate blood pressure.
  • 1999: In the journal Fertility and Sterility, the study authors conclude, “In addition to the decreased potential for adverse effects [with natural hormones], there are clear advantages in convenience, cost, compliance, and quality of life.”

Fitzgerald, Randall (2006-06-22). The Hundred-Year Lie: How to Protect Yourself from the Chemicals That Are Destroying Your Health (pp. 198-199). Plume. Kindle Edition.