It is breast cancer awareness month but let's focus on prevention and breast health. Creating health means we must consider what we put in and on our body every day. Some chemicals we know are toxic, parabens for example.  Some chemicals cause a lot of confusion. I want to focus on a chemical (hormone) which seems to be shrouded in terminology confusion.
The hormone I'm talking about is "progesterone" and understanding the difference between the synthetic or artificially Progestin and our natural progesterone, can make a huge difference in your breast health.
I hear this question from my patients continuously, "What is the difference between progesterone and Progestin and is one better than the other?"
Our bodies make progesterone. Pharmaceutical companies make a synthetic hormone version called Progestin. The generic names include: medroxyprogesterone, levonorgestrel, megestrol, norethindrone. Brand names include: Depo-Provera, Mirena, Next Choice, Plan B, Plan B One-Step First Progesterone MC10, Menopause Formula Progesterone, Prometrium, Provera, Prempro, Activella and others. 
Natural progesterone is the happy hormone. It acts much like Prozac in your body. It helps you feel calm, helps you sleep, it improves thyroid function, metabolism, is anti-inflammatory, helps your heart and helps your hair grow. With too little natural progesterone we get symptoms such as belly-centric weight gain, chronic constipation, low libido, cravings, fatigue and depression and irritability during menstruation and perimenopause and menopause. [12-16]
C.W. Randolph, M.D., co-founder of the Natural Hormone Institute, says that women with low progesterone may experience these symptoms and others such as lumpy breasts that are painful to the touch, severe premenstrual symptoms of bloating, moodiness, pain or especially severe hot flashes during menopause. Because these symptoms can be attributed to many causes, progesterone deficiency is often overlooked and misunderstood.
Progesterone plays a vital role in building strong bones and in controlling blood sugar levels. In fact, studies have shown after a large meal progesterone levels are known to drop. Studies also confirm progesterone can impair insulin sensitivity in fat and muscle. What we know for sure is too much progesterone or too little progesterone can affect blood sugar regulation. [3-5]
Where do we make progesterone in our bodies? It is estimated that 90 percent of our endogenous progesterone is made from the release of an egg from the ovaries. Once an egg matures it grows an outside lining called the corpus leteum. This lining releases most of a woman's progesterone. Pregnancy is the other "natural" state when women make a lot of progesterone. A little progesterone is also made in our adrenal glands. Ovulating women will normally produce about 20 mg of progesterone per day for about 8-10 days of a monthly. Generally speaking women who have regular menstrual cycle each month normally make enough natural progesterone. [3-7]
Let's discuss a few important facts on the artificial version, Progestin.
Progestin is commonly found in hormone replacement therapy (HRT) also known as hormone therapy (HT) and hormonal birth control (pills, the ring, the shot and hormonal IUD). Many of these prescriptions also contain various estrogens which I will not address in this article.
• The synthetic molecule structure of Progestin IS similar but NOT identical to progesterone.
• Progestin's can bind to some receptors in the body but NOT all.
• Progestin's has 165 drugs (569 brand and generic names) which have moderate drug interaction. A few of the most common drug interactions are with Proxac, Ambien, fish oils, Synthyroid and Xanax. 
• Progestin has nine disease interactions including breast malignancy (breast cancer), liver disease, thromboembolism, depression, fluid retention, glucose intolerance, thyroid function tests hyperlipidemia, weight gain. 
• Oral doses of hormones are processed in the liver, many of which will be excreted and unused.
The bottom line is Progestin does not provide many of the natural benefits of our natural, endogenous progesterone. Women who use hormonal birth control do not ovulate, therefore do not release an egg to develop a corpus leteum. In this way, hormonal birth control blocks the production of most of our natural progesterone. Artificial Progestins, found in many types of birth control (and HRT) is NOT the same endogenous form of progesterone made by our body. Optimal progesterone levels come through balanced, regular menstrual cycles which produce an egg, a corpus leteum and natural progesterone.
Progestin and the other generic and brand names above, are a man-made chemical which various pharmaceutical companies patent under their own product names. Progestins are all made by pharmaceutical companies because they cannot patent natural human progesterone.
Progestin's has numerous side effects. Let's consider the effects of Progestin on insulin resistance. Some studies claim artificial hormones do not effect carbohydrate metabolism in women without diabetes. However, few of those studies compared the same types of birth control. [4-6] Many studies have shown, progesterone excess creates insulin problems and the opposite is true, progesterone deficiency creates insulin problems. Balance is the key. Unfortunately, dosing hormones with a herd mentality of one two sizes fits all is inherently problematic. Women's bodies vary and do not all need the same doses of hormones.
Interlaced is the fact that diabetes aka. insulin resistance is on the rise. Could years of Progestin usage be blocking some of the positive effects progesterone has on insulin levels? Is progesterone deficiency playing a role in insulin resistance? [4-6] Studies suggests it does but the jury is still out. For those taking Progestin pills daily, e.g., birth control or HRT, considerations should focus on the body's normally have peaks and valleys of natural progesterone. Progesterone rises sharply before ovulation and stays high until a few days before your period. Artificial Progestin's are not prescribed the same way the body cycles.
Evidence also implicates Progestin's in breast cancer development. Progestin has been shown to proliferate the growth of a protein called Rank-L. This protein is abundant in breast tissue. Data showed that the RANKL system controls the incidence and onset of Progestin-driven breast cancer. 
The hormone terminology is confusing and women, rightfully, often don't know what to believe today. Compounding the issue is yet another option I haven't yet discussed, "bio-identical" progesterone.
Physiologically speaking bio-identical is a marketing term. A more accurate description is "bio-mimicking." Plant-derived progesterone has been shown to be bio-mimicking and proven helpful with underlying deficiencies. Many brands, usually made from Mexican Wild Yam are available in cream form over-the-counter and have decades of use worldwide. Many doctors including the famous Dr. John Lee wrote books about the thousands of female patients for which he prescribed natural Mexican yam derived progesterone cream with incredible success. 
Prometrium is the FDA-approved oral drug made from a (unidentified) plant source and is considered more similar to our natural progesterone than Progestin. Unfortunately, oral dosages have to be metabolized in the liver which can be an additional burden to the liver. This pill has a peanut oil base, beware if you have peanut allergies. Dosed in either 100mg or 200mg pills this dose is quite a bit higher than what the body would typically make through menstrual cycles. The inactive ingredients for Prometrium capsules 200mg include: peanut oil NF, gelatin NF, glycerin USP, lecithin NF, titanium dioxide USP, D&C Yellow No. 10, and FD&C Yellow No. 6. Same ingredients in the 100 mg capsules except you also get Red (dye) No. 40. You be the judge if everything in a Prometrium pill would also be produced in the human body. 
Consider your breast health this month. Get educated about what you are putting in and on your body. You can change the expression of your genes and your health. Creating breast health is your choice and you do have options. To learn more about natural hormone balancing check out some of my other blogs and books.
1. J Appl Toxicol. 2008 Jul;28(5):561-78. doi: 10.1002/jat.1358. Paraben esters: review of recent studies of endocrine toxicity, absorption, esterase and human exposure, and discussion of potential human health risks. Darbre PD1, Harvey PW.http://www.ncbi.nlm.nih.gov/pubmed/18484575
4. Steroidal contraceptives: effect on carbohydrate metabolism in women without diabetes mellitus.http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD006133.pub5/abstract
5. Potential role of estradiol and progesterone in insulin resistance through constitutive androstane receptor. http://jme.endocrinology-journals.org/content/47/2/229.full
6. Progesterone inhibits glucose uptake by affecting diverse steps of insulin signaling in 3T3-L1 adipocytes. http://ajpendo.physiology.org/content/298/4/E881
7. Longitudinal Study of Insulin Resistance and Sex Hormones over the Menstrual Cycle: The BioCycle Study.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2999972/
8. Osteoclast differentiation factor RANKL controls development of progestin-driven mammary cancer. http://www.ncbi.nlm.nih.gov/pubmed/20881962?dopt=Abstract
9. Once a Month: Understanding and Treating PMS, Katharina Dalton, MD; Hunter House, Inc., Alameda, CA; 1999.
10. "Progesterone Levels During Pregnancy," Alan E. Beer, MD; Finch University of Health Science, Chicago Medical School, Chicago, IL; 2001.
11. "Mood Biochemistry of Women at Midlife," Phyllis J. Bronson, PhD, Journal of Orthomolecular Medicine, Vol.16, No.3; 2001.
12. Natural Progesterone: The Multiple Roles of a Remarkable Hormone, John R. Lee, MD; BLL Publishing, Sebastopol, CA; 1993.
13. Heavy Menstrual Flow & Anemia Self Help Book, Third Edition, Susan M. Lark, MD; Celestial Arts; Berkeley, CA; 1999.
14. Mitchell Fleisher, MD, Nellysford, VA, speaking at 9th Annual International Congress of BioEnergetic Medicine, in Orlando, Florida; May 20 to 22, 2005.
15. "A Review of Current Research on the Effects of Progesterone," Diane Boomsma, RPh, FIACP, and Jim Paoletti, RPh, FIACP, in the International Journal of Pharmaceutical Compounding, Vol.6, No. 4, 2002.
16. Common Sense Guide to a Healthy Heart, John R. Lee, MD; Hormones, Etc., Inc.; 1999.
17. "Comparison of Regimens Containing Oral Micronized Progesterone or Medroxyprogesterone Acetate on Quality of Life in Postmenopausal Women: A Cross-Sectional Survey," Lorraine A. Fitzpatrick, Cindy Pace, BS, and Brinda Witta, PhD, in the Journal of Women's Health & Gender Based Medicine, Vol.9, No.4; 2000.
18. www.accessdata.fda.gov/drugsatfda.../label Download Prometrium on the FDA.gov website.