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Lack of vitamin D is linked to PCOS, a common cause of involuntary female infertility

Lack of vitamin D is linked to PCOS, a common cause of involuntary female infertilityPCOS or polycystic ovary syndrome is a hormone imbalance and the most common cause of involuntary female infertility. The disease brings on symptoms such as tiredness, sugar cravings, overweight, hirsutism, and an increased risk of type 2 diabetes. It turns out that women with PCOS also have lower levels of vitamin D in their blood and that can affect the development of the disease. Therefore, all women with PCOS should have their vitamin D levels checked and take supplements if necessary, according to a study from Saudi Arabia. In terms of PCOS prevention, it is also relevant to take a vitamin D supplement if you avoid the sun, wear full-body clothing, or live at northern latitudes.

PCOS (polycystic ovary syndrome) is a hormonal imbalance that affects women of childbearing age. The disease is characterized by fluid-filled sacs in one or both ovaries, ovary dysfunctions, and irregular periods. All of this makes it difficult for a woman to conceive.
The overproduction of male sex hormones (androgens) may result in acne and typical male traits such as increased hair growth (hirsutism) and a deeper voice.
One of the contributing factors in PCOS is insulin resistance that reduces the glucose uptake in cells. This may result in cravings, and you are easily tempted to consume too many calories that are stored in the form of abdominal fat. Around 50 percent of women suffering from PCOS are overweight and their BMI is above 25. Insulin resistance and unstable blood sugar levels also burden the liver, causing it to produce too many lipids and too much cholesterol. PCOS sufferers are therefore at increased risk of developing a host of different diseases such as type 2 diabetes, cardiovascular disease, and uterine cancer.
An estimate 6-12 percent of women worldwide suffer from PCOS. Danish women have a higher-than-average rate.

Vitamin D prevents PCOS in several ways

The sun during the summer period is our main source of vitamin D. We get very limited quantities of vitamin D from dietary sources such as oily fish, liver, and dairy products. There is widespread vitamin D deficiency in the world due to factors such as spending too much time indoors, having dark skin, and not getting enough sunshine during the winter period at northern latitudes.
An increasing number of scientists associate this vitamin D deficiency with the growing PCOS incidence. Vitamin D is a steroid hormone that affects metabolic processes in most of our cells and organs, including the pancreas, brain, bones, intestines, kidneys, and immune cells.
Vitamin D controls the pancreatic production and secretion of insulin. Women with PCOS and low vitamin D levels often have elevated blood sugar levels, insulin resistance, and elevated cholesterol and blood lipid levels. All of these things are caused by a disrupted blood sugar metabolism and that is something scientists want to look into in future studies. It also appears that lack of vitamin D aggravates the different symptoms linked to PCOS. A meta-analysis has shown that vitamin D supplementation can improve insulin resistance and levels of cholesterol and other blood lipids.

Blood levels of vitamin D

  • Blood levels of vitamin D are categorized as deficiency (below 30 nmol/L), insufficiency (30-50 nmol/L), and sufficiency (higher than 50 nmol/L).
  • Several experts believe that the optimal level is around 60-100 nmol/L

 Women with PCOS should check their vitamin D and take supplements if needed

The new study was carried out at the King Saud University of Riyadh, the capitol of Saudi Arabia. Although there is plenty of sunshine in this country vitamin D deficiency is quite common among the women due to the fact that they spend a lot of time indoors, have dark skin, and cover themselves completely with clothing. Thirty-one women with PCOS and 75 healthy controls took part in the study. They were asked to answer different questions about diet and lifestyle. Their height, weight, and waist circumference were measured and their BMI was calculated. Blood samples were taken to measure levels of vitamin D, TSH (thyroid-stimulating hormone), long-term blood sugar (HbA1c), and cholesterol.
It turned out that vitamin D levels in the blood were lower in women with PCOS compared with healthy women. This difference was not related to BMI or other measurable variables. The scientists therefore suggest that all patients with PCOS have their vitamin D levels measured with a blood sample. In case they are deficient they should be advised to take a supplement to prevent the symptoms from getting worse. The new study is published in Frontiers in Nutrition.

Vitamin D supplements and individual requirements

The Danish Veterinary and Food Administration has published new guidelines concerning vitamin D and recommends 5-10 micrograms daily for white adults during the entire winter period (from October to April). The guidelines recommend 10 micrograms per day all year for people with dark skin or those who cover themselves in clothing or do not get enough sunshine for other reasons. The official recommendations are meant to ensure enough vitamin D for normal calcium metabolism and to prevent rickets. However, these recommendations do not take into account that most of the body’s cells depend on vitamin D to carry out an array of metabolic processes. More and more scientists point to the fact that we may need much more vitamin D to cover these unaddressed needs.
Supplements with 20-80 micrograms of vitamin D are available on the market. The required dose depends on many factors such as the amount of sun exposure, age, skin type, BMI, and chronic diseases. EU’s Scientific Committee on Food has established a safe upper intake level of 100 micrograms per day for adults, including pregnant and breastfeeding women.
Vitamin D is lipid-soluble and is absorbed and utilized best in the body when you take capsules with vitamin D mixed with oil. We also need magnesium to help us convert vitamin D into its biologically active form.

Useful advice on how to prevent and treat PCOS

  • Eat healthy main meals that stabilize the blood sugar
  • Make sure to get plenty of protein and health fats
  • Lower your intake of carbohydrates – especially the refined ones
  • Eat many different vegetables (including compact ones)
  • Try to avoid weight gain
  • Exercise and stay physically active


Iman Abdullah Bindayel. Low Vitamin D level in Saudi Women with Polycystic Ovary Syndrome. Frontiers in Nutrition. 12 April 2021

Andrea Rosanoff et al. Essential Nutrient Interactions: Does Low or Suboptimal Magnesium Interact with Vitamin D and/or Calcium status. Advances in Nutrition 2016

Pernille Lund. Sådan får du styr på dit blodsukker og din vægt. Ny Videnskab. 2013

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