PCOS, Calcium & Bone Health: Should You Rely on Supplements or Food?

If you’re living with PCOS and experiencing irregular cycles or long gaps between periods, you’re not just dealing with hormones that affect your skin, weight or energy, you may also be at risk of weakened bones.

That’s because women with PCOS often experience long stretches of low oestrogen, especially when ovulation is absent or delayed. Oestrogen plays a key role in maintaining bone strength and without enough of it, your bone density may gradually decline, even if you’re still young.

So how can you support your bones naturally? And do you really need a calcium supplement, or is there a better way?

In this blog, we’ll explore the connection between PCOS, bone health, and calcium, and why a food-first approach with vitamin D, K2 and other nutrients may be a safer and more effective strategy for long-term hormone and bone support.

Why Bone Health Matters in PCOS

Bone health isn’t just a concern during menopause. In women with PCOS, especially those with irregular or absent periods, lower oestrogen levels can affect bone mineral density earlier in life.

Research shows that missed ovulation and long cycles may lead to reduced oestrogen exposure, which affects the body’s ability to build and maintain strong bones.

Oestrogen helps prevent bone loss by slowing the breakdown of old bone tissue. Without regular ovulation and the normal hormonal cycle, this protective effect may be reduced, increasing your long-term risk of osteopenia or osteoporosis, particularly if other risk factors (like vitamin D deficiency or under-eating) are present.

Why Relying on Calcium Supplements Isn’t Always the Answer

When it comes to bone health, calcium often gets all the attention. But more isn’t always better, and calcium supplements aren’t risk-free.

What’s the problem with calcium supplements?

• High-dose calcium supplements can interfere with the absorption of iron and magnesium

• Without enough vitamin K2 or magnesium, calcium can build up in arteries rather than bones

• Excess calcium may increase the risk of kidney stones or vascular calcification in some women

In PCOS, where inflammation and insulin resistance are already concerns, overloading the body with calcium supplements, without balancing co-factors, may do more harm than good.

A Better Approach: Whole Food Calcium + Key Co-Factors

Instead of relying on isolated supplements, supporting your bones through whole foods provides a more balanced and absorbable source of nutrients. Plus, food sources of calcium come with magnesium, protein and other bone-supportive compounds that work together to protect your skeletal health.

Best calcium-rich foods for PCOS:

• Plain Greek yoghurt (high in calcium and protein)

• Hard cheese like cheddar or parmesan

• Tofu (especially if set with calcium)

• Kale, bok choy, broccoli (plant-based sources with additional benefits for hormones and gut health)

• Fortified plant milks (e.g. almond, oat or soya milk fortified with calcium and vitamin D)

Tip: Pair calcium-rich foods with meals that include fat and vitamin D (like oily fish or egg yolk) to boost absorption.

Don’t Forget Vitamin D It’s Essential for More Than Bones

Vitamin D deficiency is extremely common in women with PCOS, and it doesn’t just affect bones.

Low levels of vitamin D have been linked to:

• Insulin resistance

• Irregular cycles

• Fertility challenges

• Mood swings and fatigue

Vitamin D is also essential for absorbing calcium from food and helping it reach the bones where it’s needed. Studies show that vitamin D supplementation (with or without calcium) can improve insulin sensitivity, support follicle development, and help regulate cycles in women with PCOS.

Best ways to get vitamin D:

• Sunlight exposure: 15–20 minutes a few times a week on bare skin (difficult in the UK!)

• Oily fish: salmon, sardines, mackerel

• Egg yolks

• Supplementation (if deficient): usually 800–2,000 IU/day with K2 and magnesium

Why Vitamin K2 Matters for Bone and Hormone Health

Vitamin K2 is often overlooked, but it’s crucial for directing calcium to the bones (and keeping it out of soft tissues like arteries). Without it, calcium can end up in the wrong place, increasing health risks rather than improving them.

Best food sources of vitamin K2:

• Natto (a fermented soy food)

• Egg yolk

• Soft cheeses like brie or gouda

• Butter from grass-fed cows

Unlike vitamin K1 (found in leafy greens), vitamin K2 is harder to get in a standard diet, so it’s worth paying attention to if you’re trying to build strong bones.

Supporting Bone Health with a PCOS-Focused Plan

When it comes to protecting your bones in PCOS, the best approach is simple, sustainable, and realistic. NHS recommendations are on this link. Here’s what I recommend:

What to include daily:

Nutrient	Food Sources	Daily Target
Calcium	Yoghurt, cheese, kale, tofu, fortified milk	1,000 - 1,200 mg
Vitamin D	Sun, oily fish, eggs, supplement if needed	800 - 2,000 IU
Vitamin K2	eggs, soft cheeses	No RNI (90 - 180 mcg)
Magnesium	Nuts, seeds, greens, dark chocolate	300 - 400 mg
Protein	Dairy, legumes, oily fish	1.4-1.6 g/kg

Should You Supplement?

Supplements may be helpful if your diet is limited or your vitamin D levels are low, test don't guess, but they should be used carefully and only when needed.

• Choose a combined vitamin D3 + K2 formula if supplementing

• Use calcium citrate rather than carbonate for better absorption

• Avoid high-dose calcium unless recommended after blood work

• Always balance with magnesium and dietary intake

Summary: Bone Health Support for Women with PCOS

• Low oestrogen from missed or irregular periods in PCOS can affect bone density

• Calcium supplements aren’t always the best answer, focus on whole food sources

• Vitamin D and K2 are just as important for healthy bones and hormone balance

• A food-first, nutrient-dense approach can help protect bone health long-term

Want to learn more?

If you’re feeling stuck with PCOS symptoms and unsure where to turn next, I can help. My 12-week PCOS Hormone Shift Method is designed to take the guesswork out of hormone support, with gut health at its core.

You’ll get simple, achievable steps each week, with the option to explore testing and ongoing guidance to keep you on track.

Start with a free discovery call or download your free Hormone Snapshot to get started.

Book Your Free Call

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Updated in June 2025 to reflect new PCOS research and nutrition strategies.

Disclaimer

This blog is for general information and educational purposes only. It is not intended to provide medical advice, diagnose health conditions, or replace personalised care from a qualified healthcare professional.As a BANT-registered nutritionist, I offer nutrition and lifestyle support to help manage and improve health outcomes, but I do not diagnose or treat medical conditions. Always consult your GP or healthcare provider before making changes to your diet, lifestyle, or supplements, especially if you have a medical condition, take prescription medication, or are pregnant or breastfeeding.Individual needs can vary, and what works for one person may not be appropriate for another. All information is evidence-based to the best of my ability at the time of writing, but research and guidance can evolve. If you're looking for tailored support, please get in touch to book a 1:1 consultation.