A study recently published in the journal Archives of Women’s Health found that low prenatal vitamin D levels were significantly associated with higher PPD symptoms among women with high levels of inflammatory markers, such as various cytokines called interleukins.
Post-partum depression (PPD) affects an estimated 10% to 20% of American women. Symptoms of PPD may include severe mood swings, loss of appetite, fatigue, excessive crying, anxiety, irritability and difficulty sleeping. PPD does not only affect the mother, but it often affects those who are close to her, especially the baby. It may lead to less effective parenting, poor bonding, and withdrawal from family and friends.
Numerous studies have shown a clear positive association between inflammation and depression. In addition, research has also demonstrated a strong inverse association between vitamin D status and both inflammation and depression. Therefore, researchers recently hypothesized that an inverse relationship between prenatal vitamin D status and PPD symptoms would exist in pregnant women with high prenatal inflammatory markers.
The researchers analyzed data obtained during pregnancy and postpartum from a previous study to test their hypothesis. The study population included 91 African American women with a first trimester vitamin D measurement, second trimester measure of inflammatory markers and a postpartum assessment of depression.
The researchers evaluated data from African American women, because they have the highest rates of prenatal and postpartum depression compared to other racial groups in the United States. They also have a higher prevalence of vitamin D deficiency compared to other racial groups.
Here is what the researchers found:
- The average vitamin D status was 13.2 ng/ml (33 nmol/l), with 85% of the women considered vitamin D deficient as defined by levels less than or equal to 20 ng/ml (50 nmol/l).
- 97% of the women did not meet the level suggested for pregnant or lactating women of 30 ng/ml.
- There was an inverse association between prenatal vitamin D status and PPD symptoms, which approached significance (p < 0.058). This relationship was significantly modulated by inflammatory markers (p = 0.016).
- Among women with higher levels of inflammatory markers, low vitamin D status was significantly associated with higher PPD symptoms (p < 0.05).
The researchers stated,
“These findings provide the first evidence that low prenatal 25(OH)D and high prenatal inflammation together might predict future postpartum depressive symptomatology in African American women.”
The study possessed a few important strengths to acknowledge. First, it included a relatively large sample population. The researchers also controlled for various confounding factors, allowing them to better isolate the relationship between vitamin D status, inflammation and PPD.
There were also a few key limitations regarding the study. There was a high dropout rate; however, the participants who dropped had similar vitamin D status and prenatal depression scores as those who remained in the study. Furthermore, 74% of the women in the study reported use of a vitamin D supplement (most of whom took 50,000 IU of vitamin D2 taken once per week). A small portion of women were prescribed vitamin D supplements after they had their vitamin D status measured, which may have skewed the results.
The researchers concluded,
“While these results are preliminary and do not establish causation, they are novel and particularly important given the prevalence of low 25(OH)D in this population of African American women. We hope that they may spark interest in further research on this topic including randomized controlled studies.”
Tovey, A. & Cannell, J. New study reports inflammation may modulate the relationship between vitamin D status and post-partum depression. The Vitamin D Council Blog & Newsletter, 2015.
Accortt E., et al. Lower prenatal vitamin D status and postpartum depressive symptomatology in African American women: Preliminary evidence for moderation by inflammatory cytokines. Archives of Women’s Health, 2015.