Progesterone vs Progestin. What’s the difference?

What is the difference between progesterone and progestin?

Both progesterone and progestin belong to a class of hormones called progestogens, although progestin is a synthetic progestogen and progesterone is a natural progestogen.  This article will explore each substance and how it works in our bodies.

Progesterone: the human hormone

Progesterone is the hormone produced by your body to balance oestrogen.  As we age, it is the first sex hormone to decline, beginning its downward journey when women are in their mid to late 30s.  Progesterone is the hormone that prepares for and maintains a pregnancy and high levels of progesterone will stop further ovulation.  When levels drop during the monthly cycle, it prompts menstruation.

Progesterone has all sorts of benefits for the female body.  It keeps the menstrual cycle regular and maintains bone density.  It increases the production of GABA, a naturally occurring amino acid that regulates nervous activity in the brain, resulting in more stable moods and better sleep.  Research also suggests that it makes your brain feel sharper, reduces muscular aches and pains, maintains good cholesterol, gives you glowing skin and can even improve your libido.  Irregular menstrual cycles, irregular bleeding, migraines, mood swings and even miscarriage can all be caused by low levels of progesterone.

As progesterone balances oestrogen, its decline can lead to oestrogen dominance, where hard-to-shift stomach fat, sleep disturbance and low mood may all be present.  At this point, supplementation with progesterone may help.  This helps with the management of symptoms and also protects the endometrium.  When a doctor judges it to be necessary, progesterone can be used during the second half of the menstrual cycle and then on a daily basis.  Hormones such as oestrogen, testosterone, DHEA, pregnenolone or melatonin are often used in combination with progesterone.

Progesterone is a natural substance in the body, however, the bio-identical progesterone used in medications is sourced from natural ingredients, such as wild yams and then synthesised in a laboratory to make it fully bio-identical.

Progestin: the synthetic hormone

So, if progesterone is so good, why do we have progestins and what is the difference?  Researchers developing the first HRT medications noticed the important work of progesterone.  As developing a new medication is an expensive process (think millions), they didn’t want to work with a molecule that was created by nature.  Natural molecules cannot be patented and therefore do not give a good return on investment.  The scientists decided to slightly change the progesterone molecule so that it could fulfil part of the role of natural (bio-identical) progesterone and enhance some of its features.  Synthetic progestin was the result and it was designed to bind to progesterone receptors in the body and create similar effects as progesterone.

Progestin can change the lining of the uterus and stop the lining from building up, which prevents pregnancy and balances oestrogen dominance.  Many progestins are licensed for use in the UK, including brands of the Pill, the Mirena Coil and HRT.  These have proven life-changing for so many women over the years but for some, there has been an associated cost.  An increased risk of breast cancer and side effects such as weight gain, nausea, tiredness, bloating, mood swings and aches and pains have all been linked to progestins.

You can make informed choices when you are fully informed about risks and benefits.  If you don’t want to take a synthetic progestin, there are alternatives.  Bio-identical progesterones are licensed for use in the UK (such as Utrogestan and Crinone) or used in compounded products.