Bone Health in Perimenopause — Protecting Against Osteoporosis

Bone is a living tissue in a constant state of remodeling — old bone is broken down (resorption) by cells called osteoclasts, and new bone is built (formation) by osteoblasts. Estrogen is the master regulator of this balance in women. It restrains osteoclast activity, promotes osteoblast survival, and ensures that bone formation keeps pace with bone breakdown.

During perimenopause, as estrogen levels become erratic and eventually decline, osteoclast activity increases while osteoblast function diminishes. The balance tips decisively toward net bone loss. This isn't a gradual, linear process — it accelerates dramatically in the years immediately surrounding the final menstrual period. The most rapid bone loss occurs in the 2-3 years before and 3-5 years after menopause, with women losing 2-3% of bone density per year during this window.

Over the full menopausal transition, women can lose 10-20% of their total bone density — with the spine and hip being particularly affected. This is why osteoporosis predominantly affects women: by age 60, roughly 30% of women have osteopenia (low bone density) and about 15% have osteoporosis, compared to much lower rates in men of the same age.

The clinical significance is that the bone you enter perimenopause with is the bone you'll draw from for the rest of your life. Building and preserving bone density during perimenopause — through exercise, nutrition, and potentially hormone therapy — is one of the most impactful long-term health investments a woman in midlife can make.

The standard recommendation from the U.S. Preventive Services Task Force (USPSTF) is that all women should be screened with a DEXA scan at age 65, or earlier if they have risk factors for osteoporosis. However, many experts — including NAMS and the International Society for Clinical Densitometry — argue that this threshold is too late for meaningful prevention and that screening should be considered during the perimenopausal or early postmenopausal period for women with risk factors.

Risk factors that warrant earlier screening include: family history of osteoporosis or hip fracture (especially in a parent), early menopause (before age 45), prolonged amenorrhea (loss of periods for reasons other than pregnancy), low body weight or small frame, smoking, excessive alcohol use, long-term corticosteroid use, celiac disease or inflammatory bowel disease (which impair calcium absorption), history of eating disorders, and prior fragility fractures.

A DEXA scan is a quick, painless, low-radiation test that measures bone mineral density at the spine and hip. Results are reported as T-scores: a T-score above -1.0 is normal, between -1.0 and -2.5 indicates osteopenia, and below -2.5 indicates osteoporosis. Importantly, a single DEXA provides a snapshot; serial scans (typically every 2 years) track the rate of bone loss, which is often more clinically useful than a single measurement.

If you're in perimenopause and have any of the risk factors listed above, proactively request a DEXA scan. Knowing your baseline bone density gives you and your provider the information needed to make proactive decisions about exercise, supplementation, and hormone therapy.

The type of exercise matters enormously for bone health. Bone responds to mechanical loading — the physical stress placed on it by gravity, impact, and muscle contraction. The principle of bone adaptation (Wolff's law) states that bone remodels itself to become stronger in response to the forces placed upon it. This means that the most effective exercises for bone are those that stress the skeleton.

Weight-bearing impact exercises — activities performed on your feet where you're working against gravity — are the most effective for bone density. These include brisk walking, jogging, hiking, stair climbing, dancing, and jumping. Higher-impact activities produce more bone stimulus; studies show that even brief bouts of jumping (10-20 jumps per day) can meaningfully improve hip bone density in premenopausal and early postmenopausal women.

Resistance training (strength training) is equally important. Muscle contractions pull on bones at their attachment points, stimulating bone formation at those sites. Exercises that load the spine (squats, deadlifts, overhead press) and hips (lunges, step-ups) are particularly valuable since these are the most fracture-prone sites. Progressive overload — gradually increasing the weight or resistance — is key; your bones need increasing stimulus to continue adapting.

Swimming and cycling, while excellent for cardiovascular health, do not significantly improve bone density because they don't provide weight-bearing or impact forces. If these are your primary activities, consider adding 2-3 sessions per week of resistance training or impact exercise.

Balance and proprioception training (yoga, tai chi, single-leg exercises) don't directly build bone but are critically important for fall prevention — since fractures result from both weak bones and falls, preventing falls is equally important.

For perimenopausal and postmenopausal women, the recommended daily calcium intake is 1,000-1,200 mg (from food and supplements combined). Food sources are preferred over supplements when possible — dairy products, fortified plant milks, canned sardines and salmon (with bones), tofu made with calcium sulfate, broccoli, kale, and almonds are all good sources. If your dietary intake is insufficient, a calcium supplement can fill the gap, but avoid taking more than 500-600 mg in a single dose (absorption decreases with larger doses).

Vitamin D is essential for calcium absorption and bone metabolism. Without adequate vitamin D, your body absorbs only 10-15% of dietary calcium, compared to 30-40% with sufficient levels. The recommended intake for women over 50 is 600-800 IU daily, but many experts recommend 1,000-2,000 IU daily, and some women need more to achieve optimal blood levels (generally defined as 25-hydroxyvitamin D above 30 ng/mL).

Vitamin D deficiency is remarkably common, particularly in women who live at higher latitudes, have darker skin, spend limited time outdoors, or are overweight (vitamin D is fat-soluble and gets sequestered in adipose tissue). A simple blood test can measure your level, and supplementation should be guided by this result. Vitamin D3 (cholecalciferol) is more effective at raising blood levels than D2 (ergocalciferol).

Other nutrients that support bone health include magnesium (involved in vitamin D activation and bone mineralization), vitamin K2 (helps direct calcium to bones rather than arteries), and protein (essential for the collagen matrix that gives bones their flexibility and resilience). A nutrient-dense diet that includes adequate protein, fruits, and vegetables provides most of these supporting nutrients.

Yes, hormone therapy (HT) is one of the most effective interventions for preventing bone loss during and after the menopausal transition. Estrogen directly suppresses the increased osteoclast activity that drives perimenopausal and postmenopausal bone loss, and multiple large studies — including the Women's Health Initiative — have demonstrated that HT reduces hip fracture risk by approximately 34% and vertebral fracture risk by a similar magnitude.

The bone-protective effects of estrogen are dose-dependent and present across all formulations — oral, transdermal, and low-dose. Even low-dose estrogen therapy provides meaningful bone protection for many women. The Mirena IUD (levonorgestrel-releasing intrauterine system) alone does not protect bones — it's the systemic estrogen component of HT that matters.

The timing of HT initiation is important. Starting estrogen during perimenopause or early postmenopause (within 10 years of the final menstrual period) provides the most benefit, both for bone protection and overall cardiovascular safety. This aligns with the "window of opportunity" hypothesis that guides current HT prescribing.

However, bone protection is typically not the sole reason to prescribe HT — it's one of several benefits weighed against individual risks. If you're taking HT for vasomotor symptoms, sleep, or quality of life, the bone-protective effect is a significant added benefit. If bone health is your primary concern and you don't have other indications for HT, there are alternative medications specifically designed for osteoporosis prevention and treatment (bisphosphonates, denosumab, raloxifene) that your provider may recommend instead.

Several common lifestyle factors accelerate bone loss during perimenopause, and addressing them can make a meaningful difference in long-term bone health. Smoking is one of the most significant — it directly inhibits osteoblast function, reduces calcium absorption, accelerates estrogen metabolism (leading to lower estrogen levels), and is associated with earlier menopause. Women who smoke have measurably lower bone density than non-smokers and a substantially higher fracture risk.

Excessive alcohol consumption (more than 2 drinks per day) impairs bone formation, interferes with calcium and vitamin D metabolism, and increases fall risk. Moderate alcohol intake (up to 1 drink per day) does not appear to harm bone density and may even have a slight protective effect in some studies, though this shouldn't be taken as a recommendation to drink.

Sedentary behavior is a major and modifiable risk factor. Bone density responds to loading — if you're not regularly putting mechanical stress on your skeleton through weight-bearing activity and resistance training, you're losing an essential stimulus for bone maintenance.

Excessive caffeine intake (more than 3-4 cups of coffee daily) may modestly increase calcium excretion, though the effect is small if dietary calcium is adequate. Very restrictive diets — particularly those that eliminate dairy without replacing calcium from other sources, or that are very low in protein — can compromise bone health. Eating disorders, even those in remission, carry long-lasting effects on bone density.

Certain medications can accelerate bone loss, including long-term corticosteroids (even inhaled at high doses), proton pump inhibitors, some anticonvulsants, and aromatase inhibitors. If you're on any of these medications, discuss bone monitoring with your provider.