Need for vitamin D supplementation uninfluenced by polycystic ovary syndrome, notes research

19 Nov 2019 --- In a bid to resolve the controversy around the role of vitamin D intake and women with reproductive disorders, a study conducted by the Finnish University of Oulu has concluded that polycystic ovary syndrome (PCOS) is associated with higher vitamin D levels when adjusting for confounding factors. Moreover, the cohort study found that vitamin D levels had no correlation with substantial positive health effects in the alleviation of metabolic syndrome or cardiovascular diseases (CVD)-related risk factors.

“Women with PCOS seem not to be in the special need of vitamin D, as they have similar or even higher vitamin D levels as controls,” Dr. Johanna Lumme, one of the study authors, tells NutritionInsight.

Previously, studies of vitamin D levels in PCOS have mostly included small clinical samples, while studies on large, unselected populations have been lacking. Moreover, previous scientific literature pointed to a connection between vitamin D and PCOS.

The study hypothesized that women with PCOS in the population-based cohort would have lower vitamin D levels compared with the non-PCOS controls. While this was not found to be the case, women with PCOS did show the accumulation of several metabolic risk factors, namely obesity, homeostatic model assessment of insulin resistance and high-sensitivity C-reactive protein. 

Moreover, studies from this cohort report a higher rate of Type 2 diabetes, hypertension and dyslipidemia in affected women. Nevertheless, the results revealed that, despite these metabolic derangements, women with PCOS have an adequate vitamin D status compared with the controls.

Prior studies have shown PCOS to be a risk factor for vitamin D insufficiency, high body mass index and metabolic syndrome. The research team found that the major reflector of vitamin D reserves in the women with PCOS was still in a normal range, although the levels were almost at the cut-off level.

Health recommendations
As one of the most common female hormonal conditions affecting women in childbearing years, PCOS showed no greater propensity to vitamin D insufficiency than the control groups, the study found. This female hormonal condition is the most common endocrine disorder in women of reproductive age. It is commonly related to obesity, impaired glucose metabolism and insulin resistance, and is one of the main causes of anovulatory infertility.

Dr. Lumme advises to take nutritional intake, fortification and supplementation with vitamin D tablets into particular consideration. She points to the fact that obesity is known to decrease vitamin D levels, making for one more reason to campaign against obesity. 

“We also recommend that women measure their vitamin D level to ensure that the concentration is at least on the sufficient level,” she says. 

Research parameters
The study population was drawn from the Northern Finland Birth Cohort 1966, which includes all live births that occurred in 1966 in northern Finland. Initial data collection occurred at the 24th week of gestation and participants were then examined at birth, with further examinations at the ages of one, 14, 31 and 46. This study utilized the data from the two latter examinations. 

PCOS showed no greater propensity to vitamin D insufficiency than the control groups.With this database, the study referred to one of its key strengths being the largest study to date assessing vitamin D levels in women with PCOS using a population-based setting. The participation rate in the cohort is particularly high, with over 4,000 survey participants with the same ethnic and genetic background. In addition, the narrow age range of the present population controlled the factor that vitamin D levels are affected by age.

Given this study’s data collection was performed before the general vitamin D fortification of dairy products in Finland, Dr. Lumme notes that the study does not reflect the current situation of vitamin D levels in the studied population. 

To continue this research, Dr. Lumme explains that she and her research team aim to study secular changes in vitamin D levels in the population. “Also, studies for theory of vitamin D receptor polymorphism and possible vitamin D resistance among PCOS women is worth studying,” she adds. 

The true power of vitamin D
Vitamin D is known for boasting a wide range of health benefits, such as slowing diabetes progression and melanoma growth as well as battling cancer. Research from the Trinity College Dublin demonstrates that vitamin D deficiency is prevalent in older adult populations living at Northern latitudes and highlights the importance of public health strategies throughout midlife and older age to achieve optimal vitamin D status. 

However, researchers agree that patients should be wary of viewing supplementation as an immediate fix. In the field of breast cancer, one expert says that herbal supplementation “does more good than harm,” while a British Medical Journal study found that vitamin D supplementation alone was not associated with preventing all causes of death as vitamin D is no “silver bullet” for longevity. Earlier this year, a mouse study found that some types of vitamin D supplementation may be less effective in people with obesity. Instead, it may be more effective to treat vitamin D deficiency in obese individuals with calcidiol.

By Anni Schleicher