The body produces vitamin D through sunlight. Researchers have now demonstrated an important function of the vitamin in disorders of the female hormone balance. ©

“At the Department of Internal Medicine, we now routinely measure vitamin D levels in the patients concerned. We do this to implement the findings of our study on the effect of vitamin D supplementation,” reports Elisabeth Lerchbaum, a specialist in internal medicine at the Department of Endocrinology and Diabetology at the Medical University of Graz. The disorder involved is “polycystic ovary syndrome” (PCOS), one of the most common hormonal disorders, which is often the cause of menstrual cycle disorders and can even lead to infertility. In Austria, ten to twelve percent of all women are affected. Enlarged ovaries with several small follicles are characteristic of this syndrome. Accordingly, many therapies focus (exclusively) on the aspect of the patient’s unfulfilled wish to have children. However, the consequences for health are more wide-ranging than that. There is evidence of an increase in the risk of cardiovascular disease or type 2 diabetes: the deleterious effect on metabolic parameters such as blood sugar levels and insulin is connected to the higher testosterone level found in the female patients. Vitamin D deficiency is also a frequent side effect and, according to Elisabeth Lerchbaum, it is detected in 80 to 85 percent of patients. In her department, patients with a vitamin D deficiency now receive a medically approved dose of vitamin D in addition to the standard therapy. The physicians keep an eye on how the vitamin D level develops, since the administration of vitamin D had a positive effect on blood sugar levels in the study that was funded by the Austrian Science Fund FWF.

Vitamin D lowers blood sugar levels

In a randomised placebo-controlled study, 180 women with and 150 women without PCOS were administered a vitamin D supplement once a week for a period of six months. All of the women had a vitamin D deficiency at the start of the study. For women with PCOS, the additional intake of the vitamin soon had a positive effect on blood sugar levels: “The fasting blood glucose level is a risk marker for precursors of diabetes. We also simulated the increase in blood glucose after a normal meal using sugar water,” explains the physician. The latter makes even earlier precursors of type 2 diabetes recognizable. This is important because early forms of metabolic problems, such as slightly elevated blood sugar levels or increased insulin levels, often occur in the early stages of PCOS. If this development can be positively influenced, this can reduce the risk of metabolic disease. The researchers were, however, surprised by the fact that the intake of vitamin D had a detrimental effect on blood sugar levels in healthy study participants.

Problems are changing

The problems caused by the disease change over the course of time: women in their early 20s mostly suffer from menstrual cycle disorders or hormone-related problems regarding skin and hair. “There are hardly any complaints beyond that. Later, the inability to have children can become a problem. From the age of 40 onwards, metabolic problems become more important,” Lerchbaum explains. At the Department of Internal Medicine, where Lerchbaum works, the doctors started long ago to include aspects of nutrition, exercise and lifestyle when treating PCOS. They expect this to help prevent the development of metabolic diseases. The more pronounced metabolic problems such as overweight or obesity are, however, and the more often attempts to address this have been made in the past without success, the more difficult it becomes to implement a healthier lifestyle. In addition, a substantial weight loss has a detrimental effect on muscle mass and bone density. Vitamin D could keep both in check, especially in combination with calcium. “Our dosage is safe, inexpensive, has no side effects, is easy to use and supports the success of the treatment at all stages,” emphasises Lerchbaum. This is important for those affected, because the conventional therapies - often hormonal – come with side effects, are time-consuming and involve psychological strain which should not be underestimated. Elisabeth Lerchbaum still sees a great need for more awareness among physicians in private practice regarding the connection between PCOS and metabolic diseases and the significant benefit of preventive measures. She has developed training courses for doctors to address these needs.

Reasonable dosage is important

The aim of the measure is to achieve the optimum vitamin D level. The study has also shown that individual vitamin D levels are related to genetic predisposition - but the methods used to determine them genetically are still too costly to use in clinical practice. On the other hand, there is a lot of potential in this because it could be used to determine the individual optimum and the correct dosage. As far as the latter is concerned, the internist generally advises against taking a supplement without having one’s vitamin D level tested, because that will often lead to overdosage. The FWF study has also revealed that this "extra" supply of vitamin D even tends to have a detrimental effect on metabolic parameters in healthy individuals. To be on the safe side one should have one’s vitamin D level determined, take a targeted dose in the event that a deficiency is found, and then have the vitamin D level checked again after a few months. One thing has been verified, at any rate: in women who suffer from PCOS and who have a vitamin D deficiency, supplementing therapy with correctly dosed vitamin D preparations has a positive effect on blood sugar levels - and is easy to implement. Through long-term observation of the study participants, the research team also intends to find out whether this measure can actually “delay or even prevent” the onset of type 2 diabetes.

Personal details Elisabeth Lerchbaum is an internist at the Clinical Department of Endocrinology and Diabetology at the Medical University of Graz. Her research focuses on endocrinology. The physician, who has been distinguished with many awards, was also named Researcher of the Year at the Medical University of Graz in 2012.


Trummer, V. Schwetz, M. Kollmann, M. Wölfler, J. Münzker, T.R. Pieber, S. Pilz, A.C.Heijboer, B. Obermayer-Pietsch, E. Lerchbaum: Effects of vitamin D supplementation on metabolic and endocrine parameters in PCOS: a randomized-controlled trial, in: European Journal of Nutrition 2018
Trummer, S. Pilz, V. Schwetz, B. Obermayer-Pitsch, E. Lerchbaum: Vitamin D, PCOS and androgens in men: a systematic review, in: Endocrine Connections 2018