Oestradiol (Oestrogen)

What is Oestrogen (Oestradiol)?

Oestrogen is one of the main female sex hormones. Although both men and women produce oestrogen, it is important for the development of female sex characteristics during puberty, regulating the menstrual cycle, and promoting bone health.

Women produce three types of oestrogen across their lifetime:

1. Oestrone is made in adipose tissue and has a major role after menopause.

2. Oestradiol is the most powerful type during the perimenopausal period and is responsible for regulating the menstrual cycle.

3. Oestriol is the least potent form of oestrogen which is important during pregnancy and is produced in large amounts by the placenta.

Oestradiol is mostly secreted by the ovaries in women but can also be produced by the adrenal glands in both sexes and the testes in men.

Why is Oestrogen Important for Women?

Oestrogen has crucial roles in female sexual and reproductive health.

Oestrogen has effects on many different areas of the body, including:

Menstrual cycle regulation: Alongside progesterone, oestrogen regulates the menstrual cycle, peaking around 2 weeks before a period. It then rises again during the second phase of the cycle.

• Breasts: The surge in oestrogen production during puberty causes the breasts to enlarge. It also promotes the development of mammary ducts during pregnancy, preparing the body for breastfeeding following birth.
• Uterus: Oestrogen supports the thickening of the endometrial lining, readying the body for pregnancy.
• Vaginal health: Oestrogen is vital for the increase in the cells that line the vagina and vulva. When oestrogen levels fall, particularly during menopause, the epithelial lining can become thin, causing symptoms like vaginal dryness.
• Bone health: Oestrogen promotes the development of long bones during puberty, and helps maintain bone density during adulthood, protecting against osteoporosis^[1].
• Heart health: Oestrogen protects against heart disease in women^[2]. It increases good or HDL (high-density lipoprotein) cholesterol while lowering bad cholesterol levels.
• Nervous system: Oestrogen can support your mood. Low oestrogen levels can be linked to mood changes in women.
• Pregnancy maintenance: During early pregnancy, oestrogen supports the growing foetus until the placenta takes over. Oestrogen helps the baby’s organs to develop and ensures the placenta functions correctly^[3].

Oestrogen levels naturally decline with age. They tend to peak during the mid to late 20s in women and reduce by 50% by age 50, before dramatically falling after menopause^[4]. The rapid decline in oestrogen is associated with many menopause symptoms, like hot flashes, night sweats, and vaginal dryness. This can lead to some women opting to take oestrogen-containing hormone replacement therapy containing (HRT).

What is a Normal Oestrogen Level?

Defining a ‘normal’ oestrogen level in women is difficult because there are many confounding factors which can influence a normal level, such as:

• Menstrual cycle
• Hormonal contraception
• Hormone replacement therapy (HRT)
• Age

The graph below shows how the average oestrogen level can vary across demographics. In women under 40, oestrogen levels are highest in those in the perimenopause phase, but women who experience irregular periods and those who use hormonal contraception have lower average oestrogen levels.

In the over-40 age group, women who do not take HRT experience a steady decline in oestrogen levels until around 54 before they drop dramatically between 50 and 59.

The graphic below shows oestrogen levels rise and fall twice during a normal menstrual cycle. First, they increase during the follicular phase, peaking at the ovulatory stage before dropping dramatically after an egg has been released from an ovary (ovulation).

Oestrogen levels rise again during the luteal phase before falling at the end of the cycle (around day 28). The second rise in oestrogen occurs alongside increasing progesterone, and the corpus luteum produces both hormones. The corpus luteum is a temporary formation of cells that develop after an egg has been released from the ovary. Its main function is to prepare the uterus for pregnancy. Progesterone levels also decline at the end of the menstrual cycle, if pregnancy doesn’t occur and the cycle begins again.

Causes of High Oestrogen

Oestrogen levels naturally fluctuate throughout the menstrual cycle, and although consistently high oestrogen levels may occur naturally, they are usually caused by:

1. Your body produces too much oestrogen

2. You’re taking too much maybe in the form of hormonal contraception or hormone replacement therapy

3. Your body isn’t breaking oestrogen down normally

Several factors contribute to increased oestrogen levels. They are:

• A high dose of oestradiol containing HRT. Some women may be prescribed high doses of oestradiol to relieve menopause symptoms, but these may increase oestrogen levels to excess levels and can cause the persistence of symptoms^[5].
• Obesity after menopause. Strong scientific evidence shows that being overweight increases oestrogen levels after menopause. Fat cells make oestrogen and it can encourage cells in the breast and womb to keep dividing when they shouldn’t be, leading to cancer^[6].
• Heavy alcohol consumption. Some research shows that excessive alcohol consumption is linked to an increase in oestrogen production. However, this doesn’t mean you’ll reap the benefits because alcohol increases bone loss, the opposite effect of oestrogen^[7]. High oestrogen levels have also been identified in chronic liver disease^[8].
• Ovarian tumours. Some ovarian cancers have been linked to increased circulating oestrogen levels^[9].

What causes high oestrogen levels in men?

There are several reasons why oestradiol levels may rise in men:

• Increasing age
• Increased body weight
• Chronic stress
• Testosterone replacement therapy

Symptoms of High Oestrogen

Causes of Low Oestrogen

Hormone imbalances are common, and low oestrogen levels can cause several symptoms, including lighter or non-existent periods. The treatment for low oestrogen will depend on the underlying cause.

Because the ovaries are mainly responsible for producing oestrogen, any condition that affects them can cause low oestrogen levels. Some of the causes include:

Perimenopause

The most common cause of declining oestrogen levels is menopause. The body naturally transitions to menopause in your 40s, although this can vary from woman to woman. During this transition period, oestrogen levels can fluctuate from high to low, causing some of the common menopause symptoms. After the menopause, oestrogen levels are very low^[10].

Surgical removal of the ovaries

Women who have had their ovaries surgically removed will experience menopause and an abrupt start to menopause-related symptoms because of the lack of oestrogen.

Overexercising

Young women who regularly exercise are at a greater risk of developing relative energy deficiency in sports (RED-S). RED-S is a condition characterised by a lack of energy intake which does not compensate for the level of physical activity (energy expenditure)^[11].

Alongside a myriad of symptoms, RED-S can cause a hormonal imbalance that suppresses oestrogen levels, leading to missed or in the most severe cases, absent periods (amenorrhoea). RED-S can affect the person’s menstruation and reproductive health, but can also affect their general health and wellbeing.

Eating disorders

Anorexia and bulimia are examples of eating disorders that can affect a person’s physical and mental wellbeing^[12]. Unhealthy eating practices can also affect fertility, lowering oestrogen levels in women and androgens in men^[13].

Pituitary gland dysfunction

Conditions such as hyperprolactinemia, where a person has increased levels of the hormone prolactin, can cause low oestrogen levels in women. That’s because prolactin reduces the production of other pituitary hormones, follicle-stimulating hormone (FSH) and luteinising hormone (LH), which act on the ovaries to release oestrogen. A lack of FSH directly affects the secretion of oestrogen from the ovaries^[14].

Causes of low oestrogen in men
Low oestrogen levels in men are not usually a cause for concern. However, hormone imbalances may be caused by hypogonadism, a condition where the testes produce little or no hormones, including testosterone and oestrogen.

Hypogonadism in men can be caused by:

• Testicular injury, tumour, or infection
• Genetic conditions
• Alcohol abuse
• Chemotherapy or radiation treatment
• Disorders of the hypothalamus or pituitary gland
• High prolactin levels
• Medications^[15]

Symptoms of low oestrogen

Managing Your Oestrogen Levels

Depending on the cause of a hormonal imbalance, there are several things you can do to help manage your oestrogen levels.

Hormone replacement therapy (HRT)

Low oestrogen levels are commonly associated with perimenopause or menopause, so hormone replacement therapy may be an effective way to manage the symptoms. You should discuss HRT with your doctor who will help you decide if it is the right treatment for you.

HRT is available in different preparations and forms, including patches, gels, and tablets. Which type is suitable for you will depend on your blood test results. Your GP will discuss the options with you and which one will be most suitable.

Avoid RED-S

RED-S is defined by low energy availability because of an ongoing calorie deficit, if left untreated it can cause irreparable damage to the body. There are many characteristic warning signs for RED-S in women, the main one being the absence of periods which is a sign of hormone imbalance.

RED-S can be avoided by taking adequate care of your nutrition and balancing it with training and recovery. It is important to pay close attention to your carbohydrate intake when training and your recovery nutrition. You can do this by:

• Eating consistent meals and snacks to support your energy intake
• Avoid skipping meals or leaving long periods between meals
• Make sure your energy intake matches your energy expenditure

Lifestyle changes

Lifestyle changes can help manage your oestrogen levels. Some of these may help to ‘normalise’ your levels and help you avoid things like hormone replacement therapy. They include:

• Weight loss if you are overweight or obese
• Lowering your alcohol intake
• Exercise can regulate oestrogen levels in postmenopausal women^[16]
• Following a Mediterranean Diet can have positive effects on oestrogen regulation^[17]

Phytoestrogens

Phytoestrogens are natural oestrogen-like compounds found in plants and some dairy products. They work by binding to oestrogen receptors and have weak oestrogenic effects in menopausal women.

There are four types of phytoestrogens:

• Isoflavones: Soybeans
• Stilbene: Grapes and peanuts
• Coumestan: split peas and alfalfa
• Lignan: Flaxseeds

The most commonly studied phytoestrogens are isoflavones and soybeans are the most important source. You’ll need to eat 40 to 70 mg/day to achieve any health effects from phytoestrogens. In the Western world, the average consumption is around 2 mg/day^[18].

Other foods that contain phytoestrogens are:

• Garlic
• Celery
• Carrots
• Wheat
• Sweet potatoes
• Apples
• Pomegranates
• Rice

Phytoestrogens may protect against cardiovascular disease and improve heart health, by reducing total cholesterol, blood pressure, and C-reactive protein levels.

Written by Leanne Edermaniger

Based in the UK, Leanne specialises in writing about health, medicine, nutrition, and fitness.

She has over 5 years of experience in writing about health and lifestyle and has a BSc (hons) Biomedical Science and an MSc Science, Communication and Society.