18 Remodeling cycle: The four stages of bone remodeling, namely, activation, resorption, reversal, and formation, occur over different time frames, with the formation time taking four to five times longer than the resorption phase.

1. Bone Morphogenetic Proteins (BMPs) Osteoblasts are cells responsible for the secretion and deposition of bone morphogenetic proteins (BMPs) into the extracellular matrix during bone formation.

Bone remodelling relies on the correct function of two principal cells of the bone tissue: the osteoclasts, multinucleated cells that destroy the bone matrix, and the osteoblasts, having osteogenic functions.

Calcitonin is secreted and activates osteoblasts. Osteoblasts secrete osteoid (a composite of collagen, chondroitin sulfate, and osteocalcin). Hydroxyapatite crystals are deposited into the bone matrix. Calcification of bone occurs when calcium and phosphate ions move out of the blood into the bone tissues.

The regulation of bone remodeling is both systemic and local. The major systemic regulators include parathyroid hormone (PTH), calcitriol, and other hormones such as growth hormone, glucocorticoids, thyroid hormones, and sex hormones.

The primary role of osteoblasts is to lay down new bone during skeletal development and remodelling. Through these mechanisms, cells of the osteoblast lineage help retain the homeostatic balance between bone formation and bone resorption.

Definition. Bone remodelling is the continuous metabolic process of bone breakdown (resorption) by specialised cells called osteoclasts, followed by formation of new bone tissue (ossification) by cells called osteoblasts.

Estrogen is critical for skeletal homeostasis and regulates bone remodeling, in part, by modulating the expression of receptor activator of NF-κB ligand (RANKL), an essential cytokine for bone resorption by osteoclasts.

In turn, estrogen plays a main regulatory role in bone metabolism in both women and men, acting on bone remodeling and keeping it within physiological limits. Estradiol acts on the lifespan of osteoblasts, decreasing apoptosis and increasing the functional capacity of individual osteoblasts.

The main effect of estrogen is to inhibit bone remodeling, likely via the osteocyte. Estrogen also inhibits bone resorption, principally by directs effects on osteoclasts, although effects of estrogen on osteoblast/osteocyte and T-cell regulation of osteoclasts likely also play a role.

Estrogen is a sex hormone that is essential to female bone health because it promotes the activity of osteoblasts, which are cells that produce bone. When estrogen levels drop during menopause, the osteoblasts aren’t able to effectively produce bone.

When estrogen levels drop, many women lose bone density. Teens and young women who often miss their periods usually have low estrogen levels. As a result, their bones may not be as strong. For midlife women, the drop in estrogen that happens with menopause can lead to rapid bone loss.

Estrogen is the key regulator of bone metabolism in both men and women. Menopause and the accompanying loss of ovarian estrogens are associated with declines in bone mineral density (BMD): 10-year cumulative loss was 9.1% at the femoral neck and 10.6%, lumbar spine. Estradiol concentrations also predict fractures.

Loss of androgens in males retards bone development as observed in hypogonadal men [17]. Similarly, in postmenopausal women, estrogen level falls off and can lead to loss of bone mineral density and osteoporosis.

Estrogen is important to new bone production because it supports osteoblasts, which are bone-producing cells. Without estrogen, osteoblasts can’t produce enough new bone, and eventually, osteoclasts (bone-absorbing cells) overpower them. That’s why post-menopausal women are at a high risk for osteoporosis.

What are the symptoms of low estrogen?

• painful sex due to a lack of vaginal lubrication.
• an increase in urinary tract infection (UTIs) due to a thinning of the urethra.
• irregular or absent periods.
• shifts in mood.
• hot flashes.
• breast tenderness.
• headaches or accentuation of pre-existing migraines.
• depression.

If you are experiencing unexplained depression, anxiety, or fatigue, or even hot flashes, weight gain, and bone loss, then you may be an ideal candidate for hormone replacement therapy. This specialized therapy will address these symptoms and help you start feeling like yourself.

Food

1. Soybeans and the products produced from them, such as tofu and miso, are a great source of phytoestrogens . Phytoestrogens mimic estrogen in the body by binding to estrogen receptors.
2. Flax seeds also contain high amounts of phytoestrogens.
3. Sesame seeds are another dietary source of phytoestrogens.

When women have low levels of progesterone, they may experience abnormal uterine bleeding, an irregular menstrual cycle, frequent miscarriages, pain during pregnancy, reduced sex drive and/​or weight gain.

This article will show you 12 natural ways to balance your hormones.

1. Eat Enough Protein at Every Meal.
2. Engage in Regular Exercise.
3. Avoid Sugar and Refined Carbs.
4. Learn to Manage Stress.
5. Consume Healthy Fats.
6. Avoid Overeating and Undereating.
7. Drink Green Tea.
8. Eat Fatty Fish Often.

Signs or symptoms of a hormonal imbalance

• weight gain.
• a hump of fat between the shoulders.
• unexplained, and sometimes sudden, weight loss.
• fatigue.
• muscle weakness.
• muscle aches, tenderness, and stiffness.
• pain, stiffness, or swelling in your joints.
• increased or decreased heart rate.

Low estrogen levels can impact many aspects of a woman’s overall health and wellbeing, including her physical, emotional, and sexual health. They may also increase a woman’s risk of serious conditions, including heart disease, osteoporosis (softening of bone tissue), and obesity.

What is high or low estrogen levels? When estrogen is too high or too low you may get menstrual cycle changes, dry skin, hot flashes, trouble sleeping, night sweats, vaginal thinning and dryness, low sex drive, mood swings, weight gain, PMS, breast lumps, fatigue, depression and anxiety.

The main side effects of taking oestrogen include:

• bloating.
• breast tenderness or swelling.
• swelling in other parts of the body.
• feeling sick.
• leg cramps.
• headaches.
• indigestion.
• vaginal bleeding.

Exercise regularly. Research suggests that exercise can help to reduce high estrogen levels. Premenopausal women who engage in aerobic exercise for five hours a week or more saw their estrogen levels drop by nearly 19%. Cardio exercise helps the body break estrogen down and flush away any excess.

Eating certain foods may reduce the body’s levels of estrogen, including:

1. cruciferous vegetables, such as broccoli, cabbage, cauliflower, and kale.
2. mushrooms.
3. red grapes.
4. flaxseeds.
5. whole grains.

High levels of estrogen may put you at higher risk of blood clots and stroke. Estrogen dominance may also increase your chances of thyroid dysfunction. This can cause symptoms such as fatigue and weight changes.

Men and postmenopausal women excrete similar amounts of estrogen in feces, but during the menstrual cycle much higher concentrations are found. Calculations reveal that fecal excretion of these estrogens represents about 5-10% of total excretion of estrogens in urine and feces.