Role of Vitamin D in Female Health

2 Jan, 13

Role of Vitamin D in Women's Health

Vitamin D and Women's Health

Vitamin D is a secosteroid molecule, which, in its active 125-di-hydroxylated form (Calcitriol), influences hormone activities in humans.¹ Its role in skeletal growth, development and calcium metabolism is very well known.² However, the presence of vitamin D receptors on most cells and tissues in the body relate to its effects on numerous disease states and disorders.¹ Besides osteomalacia, osteoporosis and rickets, it is also implicated in the aetiology of other conditions, including cardiovascular disease, cancer and diabetes mellitus. ²

Vitamin D also plays an important role in women's health with its deficiency-related health implications,which are prominent from childhood through adulthood and even after menopause. Studies suggest its important role in pre-eclampsia, polycystic ovary syndrome (PCOS), gestational diabetes mellitus (GDM), etc.

This article provides an insight into the importance of vitamin D in women's health.

Vitamin D Deficiency and Metabolic Risk Factors in PCOS Patients2

Aim

To investigate

The prevalence of vitamin D deficiency in PCOS women.
The relationship between vitamin D status and metabolic risk factors.

Materials and Methods

This was an observational study.
N=52 women randomized as below:
- PCOS group, n=25 PCOS women.
- Control group, n=27 control women.
Serum 25-(OH)D concentrations <25 nmol/l- severe vitamin D deficiency.

Results

44.0% subjects in the PCOS group and 11.2% in control group were severe vitamin D deficient. (P=0.047).
Among PCOS subjects, 25-(OH)D levels negatively correlated to the following:
- Body mass index (BMI) (P=0.033)
- C-reactive protein (P=0.027)
- Free androgen index (P=0.025)
Among PCOS subjects, 25-(OH)D levels positively correlated to the following:
- Quantitative insulin sensitivity check index (P=0.035)
- High-density lipoprotein cholesterol (HDL-C) (P=0.033)
- Sex hormone-binding globulin (P=0.038)

The association of vitamin D deficiency with the quantitative insulin sensitivity check index and HDL-C was independent of the BMI and the waist-to-hip ratio.

Conclusion

Vitamin D deficiency is highly prevalent in PCOS women.
Vitamin D status in PCOS correlates with insulin sensitivity, HDL-C, and C-reactive protein.
Vitamin D deficiency is associated with multiple metabolic risk factors in PCOS women.

Vitamin D and Pelvic Floor Disorders in Women3

Aim

To estimate the prevalence of vitamin D deficiency in women with pelvic floor disorders (PFDs) and to evaluate possible associations between vitamin D levels and PFDs.

Materials and Methods

This was a cross-sectional analysis carried out using 2005-2006 National Health and Nutrition Examination Survey data.
N=1,881 non-pregnant women, older than 20 years of age, with data on both PFDs and vitamin D measurements.
Vitamin D levels lower than 30ng/mL was considered insufficient.
The prevalence of demographic factors, PFDs and vitamin D levels were determined.
Association between vitamin D levels and PFDs with control for known risk factors was evaluated.

Results

23% of women reported one or more PFDs.
For women reporting at least one PFD and for those with urinary incontinence, mean vitamin D levels were significantly lower, irrespective of age.
With increasing vitamin D levels in all women aged 20 years or older and in the subset of women 50 years and older, the risks of one or more PFDs decreased significantly.
In women 50 years and older, vitamin D levels >30 ng/mL significantly reduced the likelihood of urinary incontinence.

Conclusion

Higher vitamin D levels are associated with a decreased risk of PFDs in women.
Treatment of vitamin D insufficiency and deficiency in both premenopausal and postmenopausal women could improve pelvic muscle strength, with a possible reduction in the prevalence of PFDs, including urinary incontinence.

Calcium and Vitamin D Intake and the Risk of Incident Premenstrual Syndrome (PMS)4

Aim

To evaluate these relationships between vitamin D, calcium and PMS.

Materials and Methods

This was a case-control study.
Women aged 27 to 44 years and free from PMS at baseline in 1991, were further randomized as below:
- Group 1, n=1,057 women who developed PMS over 10 years of follow-up.
- Group 2, n=1,968 women reporting no diagnosis of PMS and no or minimal menstrual symptoms.
Using a food frequency questionnaire, intake of calcium and vitamin D was measured in 1991,1995 and 1999.

Results

After adjustment for age, parity, smoking status and other risk factors, women in the highest quintile of total vitamin D intake (median=706 lU/day) had a relative risk of 0.59 compared with those in the lowest quintile (median=112 lU/day) (P=0.01).
The intake of calcium from food sources was inversely related to PMS; compared with women with a low intake (median=529mg/day), participants with the highest intake (median=1,283mg/day) had a relative risk of 0.70 (P=0.02).
The intake of skim or low-fat milk was associated with a lower risk (P<0.001).

Conclusion

A high intake of calcium and vitamin D may reduce the risk of PMS.
Large-scale clinical trials addressing this issue are warranted.
Given that calcium and vitamin D may also reduce the risk of osteoporosis and some cancers, these nutrients may be recommended even for younger women.

Maternal Vitamin D Deficiency Increases the Risk of Pre-Eclampsia5

Aim

To assess the effect of maternal 25-(OH)D concentration on the risk of pre-eclampsia and to check vitamin D status in new-boms of pre-eclamptic mothers

Materials and Methods

This was a nested case-control study.
Pregnant women were followed from less than 16 weeks' gestation to delivery and grouped as follows:
- Group 1, n=55 nulliparous pregnant women with singleton pregnancies who developed pre-eclampsia.
- Group 2, n=219 nulliparous pregnant women with singleton pregnancies who did not develop pre-eclampsia.
Women's banked sera were newly measured for 25-(OH)D.
Outcome measure: pre-eclampsia (new-onset gestational hypertension and proteinuria for the first time after 20 weeks' gestation).

Results

Adjusted serum 25-(OH)D concentrations in early pregnancy were lower in women who subsequently developed pre-eclampsia compared with controls (P=0.01).
Monotonic dose-response relation was seen between serum 25-(OH)D concentrations at less than 22 weeks and risk of pre-eclampsia.
The risk of pre-eclampsia doubled for every 50nmol/l decline in 25-(OH)D concentration.
Newborns of pre-eclamptic mothers were twice likely to have 25-(OH)D <37.5 nmol/l as compared to the control newborns.

Conclusion

Maternal vitamin D deficiency may be an independent risk factor for pre-eclampsia.
For preventing pre-eclampsia and promoting neonatal well-being, vitamin D supplementation in early pregnancy should be explored.

Maternal Plasma 25-(OH)D Concentrations and the Risk for GDM6

Aim

To determine the association between maternal plasma 25-[OH]D concentrations in early pregnancy and the risk for GDM

Materials and Methods

This was a nested case-control study.
N=171 pregnant women were randomized as below:
- Group 1, n=57 incident GDM-ascertained pregnant women.
- Group 2, n=114 women who were not diagnosed with GDM.
Controls were frequency matched to cases for the estimated season of conception of the pregnancy index (i.e., spring, summer, autumn, winter).

Results

At an average of 16 weeks of gestation, maternal plasma 25-[OH]D concentrations were significantly low in women who developed GDM than controls (P<0.001), and remained significant (P-0.018)) even after the adjustment for maternal age, race, family history of diabetes, and prepregnancy BMI.
Approximately 33% of GDM cases, compared with 14% of controls (P<0.001), had maternal plasma 25-[OH]D concentrations consistent with a pre-specified diagnosis of vitamin D deficiency (<20 ng/ml).
After adjustment for the above-mentioned covariates, vitamin D deficiency was associated with a 2.66-fold increased GDM risk.
Each 5 ng/ml decrease in 25-[OH]D concentrations was related to a 1.29-fold increase in GDM risk.
The findings did not change substantially after adjustment for season and physical activity.

Conclusion

Maternal vitamin D deficiency in early pregnancy is significantly associated with an elevated risk for GDM.
Treating vitamin D deficiency in pregnancy, via supplementation or lifestyle measures, can contribute to the prevention of GDM.

Vitamin D Inadequacy Among Postmenopausal Women7

Aim

To review the prevalence of vitamin D inadequacy among postmenopausal women with and without osteoporosis and/or other musculoskeletal diseases.

Materials and Methods

This was a systematic review.
Publications in the past 10 years reporting prevalence for vitamin D inadequacy, which reported serum 25-(OH)D values below various levels, were reviewed.

Results

In postmenopausal women, the prevalence of 25-(OH)D levels <20 ng/ml ranged from 1.6% to 86%.
In osteoporotic populations, the prevalence of 25-(OH)D levels <12 ng/ml ranged from 12.5% to 76%.
The prevalence rates reached 50% to 70% in patients with a history of fracture(s).
The most common factors associated with inadequate vitamin D levels were as follows:
- Limited sun exposure
- Lack of dietary vitamin D intake
- Winter time
- Increasing age (over 70 years)

Conclusion

The prevalence of inadequate vitamin D levels appears to be high in postmenopausal women, especially in those with osteoporosis and a history of fracture.
Vitamin D supplementation might offer scope for prevention of falls and fracture, especially in elderly and osteoporotic populations.

Key Points

Vitamin D deficiency in PCOS women is associated with multiple metabolic risk factors.
Maternal vitamin D deficiency may be an independent risk factor for pre-eclampsia.
Vitamin D insufficiency and deficiency are associated with a risk of PFDs in women and its treatment may reduce the risk.
Maternal vitamin D deficiency in early pregnancy is associated with increased risk for GDM, and supplementation or lifestyle measures can help to prevent it.
A high intake of calcium and vitamin D may reduce the risk of premenstrual syndrome.
Calcium and vitamin D may be recommended for younger women as it reduces the risk of osteoporosis and some cancers.
Inadequate vitamin D levels appear to be high in postmenopausal women and vitamin D supplementation may help in the prevention of falls and fracture.

References

1. Alternative Medicine Review 2008; 13(2):153-164.
2. Metabolism. 2011; 60(10):1475-81.
3. Obstet Gynecol 2010; 115:795-803.
4. Arch Intern Med. 2005; 165:1246-1252.
5. J Clin Endocrinol Metab 2007; 92:3517-3522.
6. Plops ONE. 2008; 3(11):e3753.
7. Q J Med 2005; 98:667-676.