I assume you all know that we can get vitamin D from sun exposure, am I right?
Now, let's talk about you, woman...
Are you sure that it can benefit you? Do you know how it can benefit YOU, as a woman?
If you're curious, like me, join me on a ride and let's dig the papers together...
We can't start the talk if we don't know the basics, right...?
SO,WHAT IS IT...
Vitamin D is a fat-soluble vitamin. It's produced naturally in human skin exposed to UV rays and occurs in some animal products, such as cod liver oil and smaller amounts in other fatty fish such as herrings, mackerel, sardines and tuna.
You can find it in two major forms: D2 (ergocalciferol) and D3 (cholecalciferol). Both of them appear to be absorbed with equal efficiency. However, there is evidence that D3 may be more efficient at raising levels of 25-hydroxyvitamin* D in your blood(*your body converts vitamin D to a chemical known as 25-hydroxyvitamin D, also called calcidiol.)
WHAT IT DOES
Vitamin D has quite a few important functions. However, let's just exposure perhaps the two most important. These are regulating the absorption of calcium and phosphorus and facilitating normal immune system function.
Getting a sufficient amount of vitamin D is important for normal growth and development of bones and teeth, as well as improved resistance against certain diseases.
WHAT DOES RESEARCH SAY:
There is a quick overview of the studies below, that indicate the benefits of vitamin D:
It may help to reduce your likelihood of developing the flu
It may reduce your risk of multiple sclerosis
It might play an important role in regulating mood and warding off depression
It may decrease your chance of developing heart disease
It may boost weight loss
However, since »Nestology« is all about women's health, we will stop right there and look:
WHAT ARE THE BENEFITS FOR WOMEN
A small study of women(with mean vitamin D blood levels) with primary dysmenorrhea (painful menstrual cramping), found that giving a single high dose (300.000 IU*)of vitamin D3 reduced pain by 41% during the next two menstrual periods.
Whoow, that is a huge dose!
A concern is that high dose vitamin D has been shown to increase the risk of falls and fractures (at least in the elderly) and the dose that they were given was 5.000 IU per day.* (see: Cautions and Concerns)
There is also a study among extremely vitamin D deficient adolescent and young women, which found that high dose supplementation (starting at 200.000 IU, followed by 25.000 IU every two weeks) for four months significantly reduced these symptoms.
A study of women aged 35 to 49 found that those with vitamin D levels above 20ng/mL were 32% less likely to have had uterine fibrosis than those with lower levels.
Furthermore, women who reported getting at least one hour per day of sun exposure were 40% less likely to have had fibroids than women reporting less sun exposure. The risk of fibrosis appeared to continue to decrease as vitamin D levels approached 35 ng/mL.
EARLY MENOPAUSE (i.e. menopause before age 45)
Early menopause is associated with higher risk of cardiovascular disease, osteoporosis and other conditions.
A study of more than 80.000 women found that those who had the highest intakes of vitamin D from foods, had a 17% lower risk of early menopause than the ones with the lowest intakes, after adjusting for age, smoking and other factors. The association was strongest when vitamin D was obtained from dairy foods as opposed to non-diary foods (the reason for this is not clear). Intake of vitamin D from supplements was not associated with a reduced risk. Moreover, a high intake of calcium from supplements (900mg or more per day) was associated with an increased risk of early menopause.
Vitamin D levels in the blood of pregnant women are associated with infant growth. One study found that the birth weight and head circumference of babies rose with increasing vitamin D levels up to 15ng/mL. A level of 15ng/mL or greater in the first trimester was also associated with half the risk of an infant being small for its gestational age. 
There is also a study where they gave pregnant women (!population with high rate of deficiency) large doses of vitamin D and consequently raised their average blood levels to 32 ng/ml. Comparing the results with a group of women that were not given vitamin D, they found out that 44% of those women developed pre-term labour, pre-eclampsia and/or gestational diabetes in contrast to 20% of those women given vitamin D. 
CAUTIONS AND CONCERNS
However, excessive intake of vitamin D as a supplement can potentially result in hypercalcemia (too much calcium in the blood) with symptoms like constipation, confusion, weakness, loss of appetite and painful calcium deposits. Although this is unlikely to occur when daily intake is under 10.000 IU, to avoid hypercalcemia and other potential problems associated with higher levels of vitamin D, keep total intake of vitamin D from supplements and food under established UL.
 Armas, et al, Vitamin D2 is much less effective than vitamin D3 in humans, The Journal of Clinical Endocrinologz & Metabolism, 2004; 89(1):5387-5391
 Trang, et al, Evidence that vitamin D3 increases serum »%-hydroxyvitamin-D more efficiently than vitamin D2, American Journal of Clinical Nutrition, 1998;68:854-8
 Mitsuyoshi Urashima, Takaaki Segawa, Minoru Okazaki, Mana Kurihara, Yasuyuki Wada, Hiroyuki Ida; Randomized trial of vitamin D supplementation to prevent seasonal influenza A in schoolchildren, The American Journal of Clinical Nutrition, Volume 91, Issue 5, 1 May 2010, Pages 1255–1260, https://doi.org/10.3945/ajcn.2009.29094
 Munger KL, Levin LI, Hollis BW, Howard NS, Ascherio A. Serum 25-Hydroxyvitamin D Levels and Risk of Multiple Sclerosis. JAMA. 2006;296(23):2832–2838. doi:10.1001/jama.296.23.2832
 Jorde, R. , Sneve, M. , Figenschau, Y. , Svartberg, J. and Waterloo, K. (2008), Effects of vitamin D supplementation on symptoms of depression in overweight and obese subjects: randomized double blind trial. Journal of Internal Medicine, 264: 599-609. doi:10.1111/j.1365-2796.2008.02008.x
 Wang, T. J., Pencina, M. J., Booth, S. L., Jacques, P. F., Ingelsson, E., Lanier, K., Benjamin, E. J., D'Agostino, R. B., Wolf, M., … Vasan, R. S. (2008). Vitamin D deficiency and risk of cardiovascular disease. Circulation, 117(4), 503-11. doi: 10.1161/CIRCULATIONAHA.107.706127
 Major, G., Alarie, F., Doré, J., & Tremblay, A. (2008). Calcium plus vitamin D supplementation and fat mass loss in female very low-calcium consumers: Potential link with a calcium-specific appetite control. British Journal of Nutrition, 101(5), 659-663. doi:10.1017/S0007114508030808
 Lasco A, Catalano A, Benvenga S. Improvement of Primary Dysmenorrhea Caused by a Single Oral Dose of Vitamin D: Results of a Randomized, Double-blind, Placebo-Controlled Study. Arch Intern Med. 2012;172(4):366–367. doi:10.1001/archinternmed.2011.715
 Tartagni, Massimo et al.«Vitamin D Supplementation for Premenstrual Syndrome-Related Mood Disorders in Adolescents with Severe Hypovitaminosis D«Journal of Pediatric and Adolescent Gynecology , Volume 29 , Issue 4 , 357 – 361. doi:10.1016/j.jpag.2015.12.006
 Baird, Donna et al.« Vitamin D and the Risk of Uterine Fibroids« Epidemiology. 24(3):447–453, May 2013,doi.: 10.1097/EDE.0b013e31828acca0
 Sprini, D., Rini, G. B., Di Stefano, L., Cianferotti, L., & Napoli, N. (2014). Correlation between osteoporosis and cardiovascular disease. Clinical cases in mineral and bone metabolism : the official journal of the Italian Society of Osteoporosis, Mineral Metabolism, and Skeletal Diseases, 11(2), 117-9.
 Purdue-Smithe, A. C., Whitcomb, B. W., Szegda, K. L., Boutot, M. E., Manson, J. E., Hankinson, S. E., Rosner, B. A., Troy, L. M., Michels, K. B., … Bertone-Johnson, E. R. (2017). Vitamin D and calcium intake and risk of early menopause. The American journal of clinical nutrition, 105(6), 1493-1501.
 Alison D. Gernand, Hyagriv N. Simhan, Mark A. Klebanoff, Lisa M. Bodnar; Maternal Serum 25-Hydroxyvitamin D and Measures of Newborn and Placental Weight in a U.S. Multicenter Cohort Study, The Gernand, Alison D.: »Maternal Serum 25-Hydroxyvitamin D and Measures of Newborn and Placental Weight in a U.S. Multicenter Cohort Study«.Journal of Clinical Endocrinology & Metabolism, Volume 98, Issue 1, 1 January 2013, Pages 398–404, https://doi.org/10.1210/jc.2012-3275
 Sabok, Aanchal et al.« Supplementation of vitamin D in pregnancy and its correlation with feto‐maternal outcome«.Clinical Endocrinology. Vol.83, Issue 4 doi.: https://doi.org/10.1111/cen.12751