Impact of Vitamin D status on age at menopause: A prospective cohort study

Abstract

Calcium levels, closely tied to Vitamin D, significantly impact female health. However, the link between Vitamin D and menopause, its onset, and symptom severity remains unclear. This study aimed to examine the impact of Vitamin D supplementation on the age at menopause, menopausal symptoms, hormonal levels, and bone density in women. A 2-year prospective study of 100 menopausal women, grouped by Vitamin D levels (<20 ng/mL and >30 ng/mL), analyzed menopausal age, symptoms, hormone levels, and bone density. The results show that the women with vitamin D levels below 20 ng/mL had later menopause, more severe symptoms, lower estrogen, higher follicle-stimulating hormone, poorer bone density, and reduced quality of life than those with levels above 30 ng/mL, with all differences statistically significant (P < 0.05). Finally, I concluded that the vitamin D deficiency in menopausal women is linked to delayed menopause, severe symptoms, and poor hormonal and bone health. Adequate levels may support better menopausal health.

INTRODUCTION

Vitamin D is vital for calcium balance, and its deficiency has been linked to early menopause.[1] Some studies show a moderate link between Vitamin D and menopausal stages,[2] while others suggest that deficiency worsens both physical and mental symptoms.[3] A 2019 study found that low Vitamin D levels were linked to more severe menopausal symptoms, including sexual dysfunction and chronic pain.[4] Vitamin D is closely linked to symptom severity in menopause, particularly bone loss, as declining estrogen worsens both Vitamin D levels and bone health.[5,6] Mei et al.[7] also noted that Vitamin D impacts skeletal, cardiovascular, and emotional well-being during this stage.

While some studies suggest Vitamin D supplements may benefit vaginal health in menopausal women by easing dryness and altering pH,[8] others report no clear link to menopause onset.[9] One cross-sectional study also associated Vitamin D deficiency in postmenopausal women with obesity and metabolic syndrome.[10] The clinical trials highlight Vitamin D’s role in metabolic health, notably improving blood sugar control in postmenopausal women with type 2 diabetes.[11] Its deficiency is widespread and strongly linked to osteoporosis,[12] while even moderate supplementation can enhance Vitamin D status and related biomarkers.[13]

Although the link between Vitamin D and menopause onset remains unclear,[14] its benefits for bone and metabolic health during menopause are well-supported.[14] Some evidence suggests that Vitamin D may ease symptoms rather than affect the timing of menopause.[15] This study explores the relationship between Vitamin D levels and menopausal age, accounting for factors such as location, physical activity, and diet.

METHODS

Study design and setting

This study aimed to explore how Vitamin D supplementation might influence the timing of menopause. Conducted in urban teaching hospitals and outpatient clinics, the research included 100 women aged 45–55 years, separated into two groups depend on Vitamin D levels: 50 with Vitamin D deficiency (serum 25-hydroxyvitamin D <20 ng/mL) and 50 with normal levels (serum 25-hydroxyvitamin D >30 ng/mL). The participants were matched by age, ethnicity, and socioeconomic status to reduce the bias. With biannual follow-ups over 2 years, the study monitored Vitamin D levels and menopausal status to determine their relationship.

Participants

Women with irregular periods for at least 12 months, indicating menopausal transition, were included. Those with conditions affecting Vitamin D metabolism, on hormonal therapy, or taking high-dose Vitamin D supplements were excluded. The participants were referred by healthcare providers and gave informed consent. Baseline data were collected through interviews and standardized questionnaires.

Data collection

The 2-year study included biannual assessments to examine how Vitamin D affects menopause onset. Data collected covered:

Demographics and lifestyle (age, ethnicity, diet, activity, and smoking) to control confounders.

Medical history and menopausal status, confirmed by menstrual cessation of 12+ months.

Vitamin D levels via blood tests, along with sun exposure.

Hormone tests for estrogen and follicle-stimulating hormone (FSH) to assess reproductive aging.

Menopausal symptom questionnaires compared by Vitamin D status.

All the data were securely stored in an anonymized online database for the analysis.

Vitamin D assessment

Vitamin D was measured by serum 25-hydroxyvitamin D every 6 months using immunoassay, classifying levels as deficient (<20 ng/mL) or normal (>30 ng/mL). FSH, estrogen, and inflammation markers were also tested. The main outcome was age at natural menopause (12 months without menstruation). The secondary outcomes included symptoms, hormone levels, bone density (dual-energy X-ray absorptiometry), and quality of life (QoL) (SF-36).

Statistical analysis

Vitamin D’s effects on menopause and health were evaluated using the t-tests for continuous data and Chi-square (χ²) tests for the categorical variables. SPSS, Version 25.0 (Armonk, NY: IBM Corp) was used, with significance at P < 0.05. Results were summarized by means and frequencies to ensure accuracy.

RESULTS

Age (continuous data) was analyzed using the independent t-tests, whereas categorical data (socioeconomic status, diet, physical activity, and smoking) were examined with χ² tests at P < 0.05. Table 1 shows no significant demographic or lifestyle differences between the groups.

Table 1.

Comparison of demographic and lifestyle factors between Vitamin D-deficient and healthy groups (n=50)

Variable	Deficient group	Normal group	P
Age (years), mean±SD	50.0±3.5	49.0±3.2	0.25
Socioeconomic status
Low	19	16	0.45
Middle	17	19
High	14	15
Dietary habits
High-fat	20	20	0.36
Balanced	11	13
High-sugar	19	17
Physical activity levels
Sedentary	20	19	0.44
Moderate	16	15
Active	14	16
Smoking status
Smoker	24	22	0.49
Nonsmoker	26	28

SD: Standard deviation

Independent t-tests compared age at menopause, estrogen, and FSH levels, with significance at P < 0.05. All the variables differed significantly between the groups: The Vitamin D-deficient group had later menopause, lower estrogen, and higher FSH, reflecting reduced ovarian function. The normal group showed the opposite pattern, suggesting better ovarian health and earlier menopause. These findings suggest that Vitamin D may influence hormonal regulation and reproductive aging as shown in Table 2 and Figure 1.

Table 2.

Comparison of age at menopause, estrogen levels, and follicle-stimulating hormone levels between Vitamin D deficient and healthy people

Variable	Deficient group	Normal group	Statistical test	P
Age at menopause (years)	50.18±1.84 (49.66–50.70)	46.81±1.38 (46.42–47.20)	Independent t-test	<0.01
Estrogen levels (pg/mL)	39.22±4.33 (37.99–40.45)	70.86±9.72 (68.10–73.62)	Independent t-test	<0.01
FSH levels (mIU/mL)	69.76±8.74 (67.28–72.24)	33.62±6.91 (31.66–35.58)	Independent t-test	<0.01

FSH: Follicle-stimulating hormone

Figure 1.

Comparison of age at menopause, estrogen level, and follicle-stimulating hormone Level between Vitamin D deficient and healthy people. FSH: Follicle-stimulating hormone, SD: Standard deviation

Independent t-tests compared menopausal symptom severity and QoL scores, with significance at P < 0.05 [Table 3]. Women with Vitamin D deficiency reported more severe symptoms and lower QoL, while those with normal levels experienced milder symptoms and higher SF-36 scores. These results suggest that preventing Vitamin D deficiency may help reduce menopausal symptoms and improve QoL during menopause [Figure 2].

Table 3.

Comparison of menopausal symptom severity and quality of life scores between the Vitamin D deficient and healthy groups

Variable	Deficient group	Normal group	Statistical test	P
Severity of menopausal symptoms (1–10)	8.04±1.09 (7.73–8.35)	3.62±1.35 (3.24–4.00)	Independent t-test	<0.01
QoL scores	70.08±12.45 (66.54–73.62)	84.38±11.35 (81.15–87.61)	Independent t-test	<0.01

QoL: Quality of life

Figure 2.

Comparison of menopausal symptom severity and quality of life scores between participants with and without Vitamin D deficiency. SD: Standard deviation

Independent t-tests compared bone mineral density (BMD) and C-reactive protein (CRP) levels, with significance at P < 0.05 [Table 4]. The Vitamin D-deficient group had significantly lower BMD, increasing osteoporosis risk, and higher CRP levels, indicating greater systemic inflammation linked to health risks such as cardiovascular disease and metabolic syndrome. In contrast, the normal group showed better bone health and lower inflammation, supporting Vitamin D’s role in maintaining bone density and reducing inflammation [Figure 3].

Table 4.

Comparison of bone mineral density and C-reactive protein levels between Vitamin D-deficient and healthy groups

Variable	Deficient group (n=50)	Normal group (n=50)	Statistical test	P
BMD (g/cm2)	0.86±0.10 (0.83–0.89)	0.89±0.13 (0.85–0.93)	Independent t-test	<0.044
CRP levels (mg/L)	4.44±2.76 (3.64–5.24)	3.56±1.15 (3.16–3.96)	Independent t-test	0.038

CRP: C-reactive protein, BMD: Bone mineral density

Figure 3.

Comparison of bone mineral density and C-reactive protein levels between Vitamin D-deficient and healthy groups. SD: Standard deviation, CRP: C-reactive protein

DISCUSSION

This 2-year prospective study of 100 women compared those with Vitamin D deficiency (<20 ng/mL) to those with normal levels (>30 ng/mL). Data on demographics, health, hormones, and menopausal symptoms showed that the deficient group experienced later menopause, lower estrogen, higher FSH, more severe symptoms, reduced QoL, lower bone density, and increased inflammation. These findings indicate that Vitamin D influences hormonal balance, reproductive aging, symptom severity, bone health, and menopause timing.

A review emphasized Vitamin D’s role in immune and hormonal regulation, especially estrogen production in postmenopausal women, matching the findings of lower estrogen in Vitamin D-deficient women. Studies from China and elsewhere show that Vitamin D[3] correlates positively with estradiol and reduces FSH levels.[16,17] Women with low Vitamin D also had lower estradiol during their cycles.[18] These results suggest that Vitamin D may enhance ovarian function and delay menopause. Deficiency is linked to worse menopausal symptoms and poorer QoL, indicating that adequate Vitamin D might ease symptoms and boost well-being.

Arslanca et al.[19] reported that each unit drop in serum Vitamin D raised hot flash risk by 5.9%. Other studies highlight that Vitamin D deficiency, especially in perimenopausal women, increases morbidity and negatively affects QoL, stressing early diagnosis.[20] Vitale et al.[21] found that Vitamin D combined with isoflavones and calcium significantly improved menopausal symptoms and QoL, including mood and sexual health. Similarly, Maylyan et al.[22] showed that Vitamin D plus hormone therapy effectively eased symptoms such as mood swings and hot flashes.

Vitamin D deficiency is linked to lower BMD and higher CRP levels, reflecting poorer bone health and increased inflammation. Women with normal Vitamin D levels show better bone status and less inflammation. Studies, including those on systemic lupus erythematosus[23] and elderly populations,[24] confirm this connection. Mendelian randomization research also supports the role of Vitamin D deficiency in raising CRP, impacting cardiovascular and metabolic health.[25] The present study observed significantly higher CRP levels in Vitamin D-deficient women, indicating increased inflammation. However, CRP alone provides a limited view of immune changes during menopause. Recent research suggests that Vitamin D deficiency in postmenopausal women is associated with broader immune dysregulation, including altered lymphocyte populations and diminished natural killer cell function.[3] Animal studies show that limited Vitamin D increases inflammation in periovarian fat, implying that elevated CRP may not fully capture the broader inflammatory impact.[26] Clinical research also links low Vitamin D to decreased estrogen and greater inflammation in postmenopausal women.[27] These findings support the idea that the raised CRP levels in this study may reflect deeper immune and hormonal disruptions associated with Vitamin D deficiency during menopause.

Studies on Vitamin D and calcium supplementation in menopausal women show mixed results. The Women’s Health Initiative reported minimal effects on sleep, mental health, and fatigue, suggesting limited impact on overall QoL.[28] These outcomes may depend on dosage and lifestyle, highlighting the need for further research. However, other trials show clear benefits: A 2-year study found that Vitamin D and calcium improved bone health, preserved muscle strength, and slowed bone aging in postmenopausal women,[29] supporting their role in osteoporosis prevention and better physical well-being.

Vitamin D plays a key role in immune regulation, helping to counteract menopause-related inflammation and immune decline, which are worsened by reduced estrogen levels.[3] Maintaining sufficient Vitamin D supports immune balance and lowers inflammation. Research also shows benefits for urogenital health, with improvements in vaginal and urinary function during menopause.[30] In addition, Vitamin D helps preserve BMD and lowers fracture risk.

CONCLUSION

This study demonstrated a clear link between Vitamin D status and key menopausal outcomes. Women with Vitamin D deficiency experienced later menopause, lower estrogen, higher FSH levels, more severe symptoms, poorer QoL, reduced BMD, and heightened inflammation. Ensuring sufficient Vitamin D may support hormonal balance, protect bone health, and improve overall well-being during menopause. Future research should prioritize intervention trials to further explore the potential benefits of Vitamin D supplementation.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.