An interview with Dr. David Zava
A common question is whether it’s OK to use progesterone cream while taking contraceptive pills or patches. Dr. Lee’s response was always, “Probably, but we need more information to be sure.” Here is an interview with Dr. Lee’s friend and colleague, Dr. David Zava, with an update on this topic.
Dr. Zava: Let's answer this question by first looking at what the synthetic hormones in birth control pills and patches do in a woman' s body. Overall, they drop your estradiol [an estrogen], progesterone and testosterone levels, they interfere with cortisol levels and they increase the risk of insulin resistance. Women on birth control pills tend to gain wait around the waist, which is a hallmark of insulin resistance.
About 95 percent of the natural hormones found in the blood are inactivated by serum hormone binding globulin (SHBG). This is one of your body’s control mechanisms for maintaining hormone balance. Think of SHBG as a sponge that soaks up excess hormones. The synthetics found in birth control pills aren't soaked up by SHBG so there is no real regulation of them.
Let’s take ethinyl estradiol, a synthetic estrogen, as an example. Unlike your natural hormones, it doesn’t' t bind to SHBG, so it remains available to the tissues. At the same time, it causes the liver to produce huge amounts of SHBG. That means ethinyl estradiol is freely available but the natural hormones, which do bind to SHBG, are very unavailable.
Contraceptive chemicals “shuts down” your own hormones
In women, SHBG particularly soaks up testosterone, so women on birth control pills tend to have very low testosterone levels. Low testosterone can mean low libido, slow metabolism and weight gain, vaginal dryness and bone loss. If you're taking birth control pills you're probably missing out on the benefits of normal testosterone levels.
Synthetic hormones are also going to the brain and shutting down gonadotrophins, specifically the LH and FSH that regulate the menstrual cycle, so women taking birth control pills aren't making their own estrogen, progesterone or testosterone, and they aren't ovulating. If you suppress that part of the brain long enough it will shut down because you're not asking it for anything. If you go off the birth control, it may take awhile to kick back in and in some women it never comes back. Meanwhile, your body is accustomed to making all this SHBG, so even if you do start making your own hormones the SHBG is soaking up every bit of them.
Women who go off birth control pills can be extremely hormone deficient for weeks or months, sometimes years.
Synthetic hormones have an identity crisis
A synthetic hormone is very schizophrenic. It doesn't know which receptor it belongs to. Take medroxyprogesterone acetate (MPA) for example, a progestin [synthetic progesterone]. Yes it hits the progesterone receptors and acts something like progesterone, but it also hits glucocorticoid receptors and acts like a cortisol, which suppresses your adrenals. So I frequently see women on birth control with low cortisol. It has some cortisol activity but it's not consistent. This is why women on birth control pills can get so tired and depressed. MPA also has some androgen [male hormone] activity as well as some anti-androgen activity. Pretty soon the body doesn't know what it wants or needs because its hormone balancing systems aren't working.
Your own natural hormones are very specific. Testosterone doesn't see estrogen receptors or cortisol receptors, it only sees testosterone receptors. Estradiol doesn't see progesterone or testosterone receptors. Mother Nature made these hormones very unique for the receptors that they bind to and they don't bother with much else—within physiologic ranges. If you start taking high doses of natural hormones it's a different story, you'll get side effects and hormone imbalance. MPA on the other hand will bind to all of them. It's a mess and it's why you get all the side effects. It's just awful. It doesn't happen to every woman, but when it happens it's horrible.
Now we can get back to the question of whether you can use progesterone cream when you're taking birth control pills. The progestin in the birth control pills goes to the brain and shuts down ovulation. No ovulation, no pregnancy. Meanwhile, the progesterone cream can help counter some of the side effects of the synthetic hormones. I've seen many women who are having side effects from birth control use progesterone cream and feel much better.
Dr. David Zava is the CEO of ZRT Labs and the co-author of What Your Doctor May Not Tell You About Breast Cancer.