Oestrogen is one of the two key female sex hormones, but outside of its involvement in the menstrual cycle, few of us know much about it.

That’s a problem, because oestrogen isn’t just an integral chemical messenger within our reproductive system, it’s also hugely health-protective and can impact everything from our immune system to our bone health.

But when we talk about oestrogen, it’s important to understand exactly what we’re talking about. Oestrogen isn’t exactly a hormone – it’s the term used to describe a trio of hormones – known as oestradiol, oestriol and oestrone – which each play a role at different phases of the female life cycle.

To find out more, we spoke to Colleen Fogarty-Draper, PhD RD and Holland & Barrett’s women’s health advisor. Here’s what she had to say. 

Oestradiol

When we talk about oestrogen in the context of the menstrual cycle, we’re primarily talking about oestradiol. “Oestradiol helps to mature and maintain the reproductive system,” Fogarty-Draper explains. “The strongest of the three types of oestrogen, it’s the main one made by the female body, and produced in the ovaries.”

Fluctuations in oestradiol that occur during the luteal phase can contribute to PMS symptoms, such as mood shifts and breast tenderness.

Oestriol

Oestriol levels remain low for most of our lives, until we get pregnant. It’s at that point where it starts to be made in much higher amounts by the placenta, with levels increasing throughout pregnancy and reaching their highest just before birth.

“It helps the uterus to grow and stay healthy and, when needed, it prepares the body for childbirth and breastfeeding,” Fogarty-Draper says.

Oestrone

While oestradiol levels drop during menopause, the body still produces oestrogen – just in the form of oestrone instead.

“Oestrone is the major oestrogen for post-menopausal women, and it’s produced by the adrenal glands and fatty tissue,” Fogarty-Draper explains. “Low levels can worsen fatigue, osteoporosis and hot flushes and can lead to low mood and low libido.” 

No matter what the dominant form of oestrogen in your body is, paying attention to fluctuations in your oestrogen levels is incredibly important.

Having too high or too low levels of oestrogen can lead to numerous uncomfortable symptoms, ranging from disrupted periods and low sex drive to changes in your mood and sleep patterns. For more information, check out our guides to the signs of low and high oestrogen and what you can do about it.

“It is also the ratio of oestrogen to other hormones – progesterone in particular – that can affect your symptoms,” Fogarty-Draper explains.

It’s for this reason that focusing on your hormonal balance is so important: while you can’t stop your hormones from fluctuating (that’s a normal and healthy part of the menstrual cycle), having disproportionate amounts of one hormone compared to the others can cause wide-reaching issues.

“If you think you have a hormone imbalance, talk to one of the H&B Women’s Health Coaches for wellness and lifestyle recommendations and your GP to find out if there are medical solutions that make sense for you,” Fogarty-Draper adds.

“Track your symptoms and diet and lifestyle habits in a digital app or in a way that you can share with your coach and GP. That way, you will ensure they can help you as much as possible.”

Colleen Fogarty-Draper is one of a team of experts behind Holland & Barrett’s new women’s health campaign, which is bringing free, expert-backed women’s health advice to high streets across the UK. 

Images: Getty