The Difference Between Synthetic and Bioidentical Hormones

By guest author, Mark Stengler, Naturopathic Doctor

Known as “The Natural Physician” to his patients, readers and audiences across North America, Mark Stengler is a licensed naturopathic physician, author and lecturer with expertise in nutrition, herbal therapy, vitamin therapy, homeopathy, natural hormone replacement and integrated medicine.

The term “bioidentical hormones” refers to hormones that are exactly the same in structure and function as those produced by the human body. Substances derived from plant or animal tissues are modified (on a molecular level) in a laboratory until they precisely match the natural human hormones.

Synthetic hormones, in contrast, are not identical in structure and function to those produced by the human endocrine system. For example, birth control pills are composed of chemically synthesized hormones, usually estrogen and progestin (a type of synthetic progesterone), that are molecularly different from natural human hormones. Actually, the concept of a “natural” source can be confusing. The synthetic estrogen-replacement drug Premarin is derived from a natural source, the urine of a pregnant horse, but the drug contains estrogens found naturally only in horses and not in humans.

Synthetic estrogen-replacement drugs increase the risk of several potentially fatal diseases, especially when combined with progestin. In 2002, a large-scale study called the Women’s Health Initiative revealed that postmenopausal women who used synthetic estrogen and progestin had a significantly increased risk of breast cancer, coronary artery disease, stroke and blood clots. In response to this alarming news, many doctors immediately recommended that patients stop synthetic HRT. Interestingly, statistics for the year that followed showed a drop of 7 percent in breast cancer overall and a decline of 12 percent in estrogen receptor–positive breast cancers (which are more likely to occur when estrogen levels are high) among women ages 50 to 69.

No comprehensive studies have yet explored whether bioidentical hormones are safer than synthetic ones. However, anecdotal evidence indicates that serious side effects from bioidentical HRT are uncommon. Hormones work by attaching to cell receptors (molecules on a cell’s surface that allow other substances to affect cell activity). Because these cell receptors are designed to interact with the body’s natural hormones, bioidentical hormones provide the best fit. Synthetic hormones do not fit as well and therefore may be more likely to cause problems at a cellular level. Evidence: Premarin has been shown in test tube studies to damage cell DNA, according to a study published in 2001 in Chemical Research Toxicology.

Unfortunately, many medical doctors are uninformed about bioidentical HRT, perhaps because bioidentical hormones are not marketed or promoted by the pharmaceutical industry. (To be patented, a pharmaceutical product must not duplicate any substance found in nature, so bioidentical hormones do not yield the large profits that many drugs do.)

To learn more about bioidentical hormone replacement, speak with a Pharmaca pharmacist today.