Does or Can Progesterone Metabolize Into Estrogen?

by Lily
(Las Vegas, NV, USA)

Hi Wray,

I've been told by a few medical practitioners that progesterone can be metabolized into estrogen, and therefore they recommend keeping progesterone minimized. Obviously this contradicts with your position on making progesterone dominant, but do you know specifically what they're referring to, or what they may not be understanding? Possibly they're referencing the initial phase of using progesterone cream, where it excites estrogen receptors, but in either case, I like having as much basis and scientific information available, and can't seem to find any papers or information confirming this online. Any insight you have is most appreciated. Thanks so much in advance.

Comments for Does or Can Progesterone Metabolize Into Estrogen?

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Jul 24, 2012
can progesterone metabolize into estrogen?
by: Cheryl


Actually progesterone can be converted into estrogen. Progesterone can be converted into 17-hydroxyprogesterone which can be converted into Androstenedione which is either converted into testosterone or the estrogens.

Jul 25, 2012
Does or Can Progesterone Metabolize Into Estrogen?
by: Wray

Hi Lily Yes it is eventually converted into oestrogen, it's the precursor to all the steroid hormones. Plus cortisol and aldosterone. There are three main groups of steroids, glucocorticoids, mineralocorticoids and androgens…..

Cholesterol → Pregnenolone → Progesterone → Corticosterone → Aldosterone

Cholesterol → Pregnenolone → Progesterone → 17-OH-Progesterone → 11-Deoxycortisol → Cortisol → Cortisone

Cholesterol → Pregnenolone → Progesterone → 17-OH-Progesterone → Androstenedione → Adrenosterone → two further hormones
Cholesterol → Pregnenolone → Progesterone → 17-OH-Progesterone → Androstenedione → Testosterone → DHT
Cholesterol → Pregnenolone → Progesterone → 17-OH-Progesterone → Androstenedione → Testosterone → Oestradiol ⇄ Oestrone → Oestriol (also Oestradiol → Oestriol)

There's a further steroid pathway which doesn't involve progesterone……
Cholesterol → Pregnenolone → 17-OH-Pregnenolone → DHEA → Androstenediol → Testosterone → DHT

Each month women make more testosterone than oestrogen, but most of it is converted to oestradiol by the enzyme aromatase. See the last pathway above under Androgens. So one could argue about keeping progesterone low to prevent testosterone production! Unfortunately the reverse occurs, as this often happens in women with PCOS. One of the major problems in PCOS is anovulation, which leads to low or no progesterone being secreted. This allows the androgens to increase, leading to acne, facial and body hair, scalp hair loss, plus oily skin and hair, some of the symptoms of PCOS. One reason men suffer far more from acne etc than women. Continued below.

Jul 25, 2012
Does or Can Progesterone Metabolize Into Estrogen? Part 2
by: Wray

Hi Lily One thing always seems to be forgotten, all the hormones, neurotransmitters too, affect each other. For instance progesterone influences oestrogen, testosterone, LH, FSH, prolactin, plus the neurotransmitters dopamine, serotonin and GABA. In fact dopamine acts via an 'empty' progesterone receptor. An excess of any of the above hormones will suppress progesterone, PCOS being a prime example, the reverse is also true. To lower oestrogen and testosterone it's essential sufficient SHBG (sex hormone binding globulin) is available. If bound to SHBG they become inactive, but if SHBG is low, more free oestrogen and testosterone are available. It's the free hormone which causes the response, the higher it is the worse the symptoms. Progesterone raises levels of SHBG so binding more of the two hormones, particularly testosterone which has high affinity to it. This of course will mean there is less to convert to the three oestrogens, see here. Progesterone is obviously not bound to SHBG, but to transcortin, also known as corticosteroid-binding globulin. It's regulated by oestrogen, so if oestrogen is high, progesterone will be bound, causing levels to drop, or become unavailable. SHBG is lowered by the sugars, including those found in all grains, legumes, dairy and sweet starchy fruits and vegetables. Fructose, sucrose and glucose (all carbs are converted into glucose), reduce SHBG by 80, 50 and 40% respectively, see here. It's best to avoid all the foods and sugars mentioned, otherwise testosterone rises, and along with it oestrogen. One reason eating or drinking any of the above sugars can cause Acne. So each hormone affects the other, stimulating or inhibiting depending on the level of secretion. But it doesn't end there, secretion itself is dependant on the level of enzymes present and there are many involved. Progesterone affects the enzymes too. For instance balding in men is often attributed to DHT, acne is too. Testosterone is converted to DHT via 5-alpha reductase, progesterone effectively inhibits this, see here, here and here. Another example is aromatase. As men get older their oestrogen levels rise. This is because they secrete more aromatase, this of course converts more testosterone to oestrogen. Continued below.

Jul 25, 2012
Does or Can Progesterone Metabolize Into Estrogen? Part 3
by: Wray

Hi Lily Interestingly progesterone does have a slight inhibitory action on aromatase, see here, here, here, here, here, here and here. What are they not understanding, impossible to say as it's all quite clear. Very few seem to know that the hormones influence each other. Oestrogen and testosterone dominance and why it occurs, does not come into their vocabulary. It's impossible to look at any one thing, be it a hormone, neurotransmitter, an enzyme etc as an isolated, independently acting substance. The body works as a whole, not in parts. These are a few papers on steroidgenesis, see here, here and here. These are a two on progesterone here here. The rest are scattered over our site. The best pages to look at are Menstruation, Oestrogen Dominance, Anxiety, Breast Tenderness, Epilepsy, and Candida. You might also be interested in looking at steroidgenesis in the adrenal glands, as they also make progesterone, see here. Take care Wray

Jan 01, 2016
Ray Peat
by: Anonymous

Wray, interesting response! Have you ever checked out Ray Peat's research and work? click on his articles. I think you might find some interesting thoughts here.

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