Authored by: Emer O’Driscoll, Senior Women’s Health Dietitian at Blackrock Health, Women’s Health Centre

Bone health refers to the maintenance of strong, dense and healthy bone tissue. It involves preventing premature bone mass loss and reducing the risk of osteopenia and osteoporosis. Nutrition and lifestyle play important roles in building bone and preventing bone loss across the woman’s lifespan. Healthcare professionals play an important role in identifying women at risk of poor bone health, promoting early intervention, providing education on modifiable lifestyle factors, and facilitating appropriate assessment, referral and management to help prevent and manage osteopenia and osteoporosis.

Bone Health Across the Lifecycle of the Woman

• Childhood and Adolescence (Age 0-20): This is a critical period to lay down bone mass. From age 17-20 years, 90% of peak bone mass (PBM) is achieved (1).
• Early Adulthood (20s-30s): Bone strength continues to develop. The aim is to keep bones strong through dietary intake and exercise and prevent future osteoporosis.
• Perimenopause and menopause (40s-50s): Due to the falling levels of oestrogen bone loss can accelerate at this stage.
• Post menopause and older age (60s+): The focus shifts to reducing bone loss and preventing fractures through nutritional support and strength training (2).

Key Nutrients for Bone Density

Calcium

Dietary calcium is preferred over supplements for the general population due to better absorption and lower risk of arterial calcification (3). Dietitians generally recommend a balanced, calcium rich diet for bone health rather than relying solely on supplements (4).

Requirements (5,6,7):

Dietary sources:

• Dairy Products: Milk, yoghurt, and cheese are the predominant dietary source of calcium.
• Marine: Sardines and tinned salmon with bones.
• Plant-Based: Fortified cereals and breads, fortified plant-based drinks, dark green leafy vegetables, nuts, sesame seeds, dried figs and beans. Plant-based sources of calcium are generally less bioavailable than those from animal sources (8).

1200mg of calcium is roughly equivalent to 5 servings from the “Milk, Yoghurt, and Cheese” shelf of the Food Pyramid (9). Most postmenopausal women in Ireland currently average only 2–3 servings, representing a significant bone health gap. It is also important to remember that calcium absorption is heavily dependent on Vitamin D status (5,10).

Vitamin D

Vitamin D is essential for calcium absorption (11) and also plays a vital role in muscle protein synthesis, which indirectly protects bone via fall prevention (12).

Requirements: Irish health guidelines recommend that all individuals in Ireland aged 12-64 years should take:

• 15µg (600 IU) daily supplement, particularly from Halloween to St Patrick’s Day (5). This is due to Ireland’s northern latitude, where in winter months the sun isn’t strong enough to synthesise the vitamin in our skin.
• For those 65 years+, an all-year-round 15µg daily supplement is recommended as the skin’s ability to synthesise vitamin D significantly decreases with age (8).

Dietary sources:

• Oily fish such as salmon, mackerel, anchovies, sardines, herring and trout.
• Egg yolks.
• Fortified milks and cereals.

Protein

Provided there is adequate calcium intake, a protein-rich diet has been found to be beneficial for bone health (13) and bone mineral density (BMD) appears to be positively associated with dietary protein intakes (14).

Requirements:

Dietary sources (16):

• Dairy: Milk, yoghurt, and cheese.
• Animal Protein: Lean red meat, poultry, fish and eggs.
• Plant-Based: Beans, lentils, chickpeas, tofu, and nuts/seeds.

Attention to the ‘Bone Health Gap’ in Young Women

Despite the foundational role of nutrition in skeletal longevity, a significant bone health gap is emerging among young women in Ireland, driven by suboptimal intakes of calcium, vitamin D and protein during the critical years of PBM accrual.

• Calcium Gaps: The National Adult Nutrition Survey (NANS) suggests that approximately 13-20% of adult women (aged 18-64) fail to meet the EAR for calcium (17). Newer analysis in NANS II 2024 suggests in women of childbearing age (18-50 years) the gap is widening showing up to 35% inadequacy (18). A concerning trend shows that the inadequacy is much higher among teenagers, with 75%+ of teenage girls (9–18 years) failing to meet their calcium EAR (19).
• Vitamin D Gaps: A large-scale analysis of Irish adults demonstrated that younger adults (aged 18–39 years) exhibited the highest rates of vitamin D deficiency. During the winter months, the prevalence of inadequacy (<50nmol/L) climbed to over 70%. This suggests that lifestyle factors, such as increased indoor time and lower dietary fortification, are leaving the youngest segment of the adult female population entering their peak bone-building years with critically low skeletal reserves (20).
• Protein Gaps: Up to 20% of young women may be failing to meet the EAR for protein, frequently a byproduct of restrictive eating patterns (21). In teenagers (13-18 years) there is a gap in protein quality and timing. For bone health, the body needs a steady supply of amino acids throughout the day to stimulate Insulin-like Growth Factor 1 (IGF-1) (22).

What Are the Risks of These Gaps?

As bone loss is clinically asymptomatic, women may be unaware of the skeletal cost of their dietary choices. As dietitians our input is therefore essential to ensure that any necessary dietary restrictions are monitored and education is provided to mitigate long-term risks of osteoporosis and osteopenia.

While osteoporosis is primarily associated with postmenopausal women, recent Irish data highlights a significant burden of osteopenia across younger cohorts (23).

Adolescents and young women with restrictive eating patterns can experience bone mass declines of 3–5% per year (24). Inadequate intake of calcium and Vitamin D during a female’s reproductive years reduces the attainment of PBM, increasing the risk of osteoporosis in later life (25).

The Growing Impact of Nutrition Misinformation

The landscape of Irish public health is increasingly challenged by nutrition misinformation across digital platforms. Recent research conducted by DCU highlighted that approximately 87% of young adults source nutrition and health advice directly from TikTok. Only 2.1% of these videos aligned with established public health guidelines (26).

There are many false claims on social media to go dairy-free for ‘skin health’, ‘hormonal balance’ or because ‘dairy leaches calcium from bones making blood acidic’. However, there appears to be no direct evidence of osteoporosis progression, fragility fractures or altered bone strength with the acid load originating from a balanced diet (13).

The Importance of Educating Young Women in Ireland

The most compelling reason for early education is the finite window of bone development. Up to 90% of PBM is acquired by age 18.

Ireland also presents a unique set of challenges that make education vital for young women here:

• Vitamin D Deficiency: Due to our northern latitude, Irish women cannot synthesise Vitamin D from sunlight in winter. Without education on supplementation and fortified foods, calcium absorption is severely compromised.
• Dietary Trends: As discussed, recent IUNA data shows concerning calcium gaps in Irish females. There is a growing trend of casual dairy avoidance which removes the most bioavailable source of calcium from their diets. Cultural pressures regarding body image in Ireland can lead to restrictive dieting and low energy availability. This can lead to functional hypothalamic amenorrhoea, which delays bone accrual and can result in bone loss in young women.
• Economic and Social Burden: The National Osteoporosis Society and the HSE highlight that hip fractures are a major cause of morbidity in Ireland. By educating young women now, we are performing primary prevention.

In conclusion, with 75% of teenage girls in Ireland not meeting their calcium EAR and with 90% of our PBM laid down age 17-20 years and our Irish winter vitamin D shortfall, it is clear that attaining PBM early in life is key. As dietitians we have a responsibility to educate and advocate the importance of nutrition for bone health early in life for women.

References

1. NIH Consensus Development Panel on Osteoporosis Prevention, Diagnosis, and Therapy. Osteoporosis prevention, diagnosis, and therapy. JAMA. 2001 Feb 14;285(6):785-95.
2. Irish Osteoporosis Society. Nutrition and bone health. Dublin: Irish Osteoporosis Society 2021. Available from: https://www.irishosteoporosis.ie/information-support/nutrition-and-bone-health/
3. Anderson, J. J., et al. (2016). “Calcium Intake From Diet and Supplements and the Risk of Coronary Artery Calcification and its Progression Among Older Adults: 10-Year Follow-up of the Multi-Ethnic Study of Atherosclerosis (MESA).” Journal of the American Heart Association.
4. Marra MV, Boyar AP. Position of the Academy of Nutrition and Dietetics: micronutrient supplementation. J Acad Nutr Diet. 2018 Nov;118(11):2162-73.
5. Food Safety Authority of Ireland. Scientific recommendations for food-based dietary guidelines for 5 to 65 year olds in Ireland. Dublin: FSAI; 2023. Report No.: ISBN 978-1-910348-61-1.
6. Department of Health. Healthy eating guidelines, food pyramid and health promotion materials. Dublin: Government of Ireland; 2022. Available from: https://www.gov.ie/en/publication/70605-healthy-eating-guidelines-food-pyramid-and-health-promotion-materials/
7. Irish Osteoporosis Society. Calcium and Vitamin D Factsheet. Dublin. Available from: https://www.irishosteoporosis.ie/wp-content/uploads/2021/04/IOS-fact-sheet-calcium-and-Vitamin-D.pdf
8. Food Safety Authority of Ireland. Scientific recommendations for food-based dietary guidelines for older adults in Ireland. Dublin: FSAI; 2021. Available from: https://www.fsai.ie/publications/scientific-recommendations-for-food-based-dietary-guidelines-for-older-adults-in-ireland
9. National Dairy Council, Irish Nutrition and Dietetic Institute. Nutrition and you: a guide for older adults (65+ years). Dublin: NDC; 2021. Available from: https://issuu.com/thenationaldairycouncil/docs/final_ndc_nutrition_you_older_adults_65_yrs
10. Food Safety Authority of Ireland. Vitamin D: scientific recommendations for food-based dietary guidelines for older adults in Ireland. Dublin: FSAI; 2020. Available from: https://www.fsai.ie/publications/vitamin-d-older-adults-report
11. Christakos S. Vitamin D: a critical regulator of intestinal physiology. JBMR Plus. 2021 Oct 25;5(12):e10554.
12. Ling Y, Xu F, Xia X, Dai D, Xiong A, Sun R, Qiu L, Xie Z. Vitamin D supplementation reduces the risk of fall in the vitamin D deficient elderly: An updated meta-analysis. Clin Nutr. 2021 Nov;40(11):5531-5537.
13. R. Rizzoli, E. Biver, J.-P. Bonjour, V. Coxam, D. Goltzman, J. A. Kanis, J. Lappe, L. Rejnmark, S. Sahni, C. Weaver, H. Weiler, J.-Y. Reginster. Benefits and safety of dietary protein for bone health—an expert consensus paper endorsed by the European Society for Clinical and Economical Aspects of Osteopororosis, Osteoarthritis, and Musculoskeletal Diseases and by the International Osteoporos. Osteoporosis International, 2018.
14. Darling, A. L., et al. (2009). “Dietary protein and bone health: a systematic review and meta-analysis.” The American Journal of Clinical Nutrition, 90(6), pp. 1674–1692.
15. HSE, Healthy Ireland. Healthy eating for older adults. Dublin: Health Service Executive; 2024. Available from: https://assets.gov.ie/static/documents/healthy-eating-for-older-adults.pdf
16. National Dairy Council, Cappagh Hospital Foundation. Mind your bones: nutrition. Dublin: NDC. Available from: https://www.mindyourbones.ie/nutrition.html
17. Irish Universities Nutrition Alliance. National adult nutrition survey: summary report. Dublin: IUNA; 2011. Available from: https://www.iuna.net/publications
18. Irish Universities Nutrition Alliance. National adult nutrition survey II (NANS II): summary report on nutrient intakes and food consumption patterns. Dublin: IUNA; 2024. Available from: https://www.iuna.net/publications
19. Cashman, K.D., Kehoe, L., Kearney, J., McNulty, B., Walton, J. and Flynn, A. (2022) ‘Adequacy of calcium and vitamin D nutritional status in a nationally representative sample of Irish teenagers aged 13–18 years’, European Journal of Nutrition, 61(8), pp. 4001–4014.
20. Scully, H., Laird, E., & Healy, M. (2020). “Large variations in vitamin D levels depending on Dublin postcode.” Trinity College Dublin / MISA. (Further expanded in Scully, H. (2023) “Vitamin D in the Irish Population: an analysis of prevalence and determinants”).
21. Irish Universities Nutrition Alliance. National adult nutrition survey: report on nutrient intakes and food consumption patterns. Dublin: IUNA; 2021. Available from: https://www.iuna.net/publications
22. Irish Universities Nutrition Alliance. National teens’ food survey II: summary report. Dublin: IUNA; 2021. Available from: https://www.iuna.net/publications
23. Irish Osteoporosis Society. Osteoporosis: clinical guidelines for health professionals. 2021 [updated 2024]. Available from: https://www.irishosteoporosis.ie/information-support/healthcare-professionals/
24. Donaldson AA, Gordon CM. Skeletal complications of eating disorders. Metabolism. 2015 Sep;64(9):943-51.
25. Leonard UM, Kiely ME. Can micronutrient requirements be met by diets from sustainable sources: outcomes of dietary modelling studies using diet optimization. Ann Med. 2024;56(1):2343272.
26. O’Connor C, DCU School of Health and Human Performance, MyFitnessPal. The impact of social media on nutrition and health behaviours in Gen Z: a national survey. Dublin: Dublin City University; 2024. Available from: https://www.dcu.ie/news/2024/jan/dcu-and-myfitnesspal-survey-reveals-gen-z-nutrition-trends