Vitamin D is an important vitamin that has numerous roles in the body. Some research has explored whether taking vitamin D3 supplements may affect progesterone levels in women. This article reviews the current evidence on the potential effects of vitamin D3 on progesterone.
What is vitamin D3?
Vitamin D refers to a group of fat-soluble vitamins that are important for bone health and have many other functions in the body. There are two main forms of vitamin D:
- Vitamin D2 (ergocalciferol): found in some foods and often used to fortify foods like milk and cereals
- Vitamin D3 (cholecalciferol): made by your skin when exposed to sunlight and also found in some animal-based foods
Vitamin D3 supplements are very common and are usually derived from lanolin in sheep’s wool. Both D2 and D3 are converted to the active form of vitamin D, known as calcitriol, in your body. However, vitamin D3 may be more effective at raising vitamin D levels compared to D2 (1).
What is progesterone and what does it do?
Progesterone is a hormone involved in the female menstrual cycle and pregnancy. It is produced mainly by the corpus luteum in the ovaries after ovulation. Progesterone levels rise significantly after ovulation and stay elevated during the luteal phase of the menstrual cycle.
Some of progesterone’s main roles include:
- Thickening the endometrium to prepare for implantation of a fertilized egg
- Supporting early pregnancy
- Balancing the effects of estrogen
If conception does not occur, progesterone levels will drop, leading to menstruation. Abnormal progesterone levels can cause issues like irregular periods, infertility, and problems during pregnancy.
Does vitamin D affect progesterone levels?
Some research has examined if vitamin D levels or supplementation may influence progesterone levels, with mixed results.
Human studies
Several small studies in women have found associations between vitamin D levels and progesterone:
- A study in 40 women found that progesterone levels during the third trimester of pregnancy were significantly lower in women with the lowest vitamin D levels (2).
- Another study in 96 pregnant women found that those with sufficient vitamin D levels (over 30 ng/mL) had significantly higher progesterone levels during the first trimester compared to women with insufficient or deficient levels (3).
- One study followed 222 women undergoing frozen embryo transfers. Higher vitamin D levels were linked to significantly increased clinical pregnancy rates. The researchers speculated this may be due to improved endometrial receptivity from higher progesterone levels (4).
- However, two other studies found no significant associations between vitamin D levels and progesterone in groups of pregnant women (5, 6).
Overall, the human research is limited but indicates vitamin D levels may potentially play a role in progesterone production, especially during pregnancy.
Animal and cell studies
Some cell and animal studies provide insight into the possible effects of vitamin D on progesterone:
- One lab study found that calcitriol, the active form of vitamin D, increased progesterone production in cultured human ovarian cells (7).
- Another study found that vitamin D deficiency in rats led to reduced progesterone levels, while vitamin D supplementation increased progesterone. Rats deprived of vitamin D could not achieve normal progesterone levels (8).
- Treating vitamin D deficient female rats with vitamin D supplements increased progesterone levels and restored normal reproductive functioning (9).
Overall, these controlled studies in cells and animals indicate that vitamin D has the potential to directly stimulate progesterone production.
Does vitamin D3 supplementation affect progesterone?
Only a handful of studies have looked specifically at the effects of vitamin D3 supplements on progesterone levels:
- A study in 164 women with polycystic ovary syndrome (PCOS) found that giving 50,000 IU per week of vitamin D3 for 24 weeks resulted in significantly increased progesterone levels compared to placebo (10).
- In 120 women with PCOS, those who took vitamin D3 supplements (50,000 IU per 2 weeks) for 3 months had significantly elevated progesterone levels after treatment compared to baseline (11).
- One study in women undergoing IVF treatments found that starting vitamin D3 supplements (2000 IU per day) 3 months prior to starting IVF resulted in significantly higher progesterone levels during treatment compared to women not taking vitamin D3 (12).
- However, two other studies in women with infertility or PCOS found no significant changes in progesterone after 3–5 months of vitamin D3 supplementation (13, 14).
Overall, some controlled studies suggest vitamin D3 supplementation may increase progesterone levels in certain groups of women, like those with PCOS or infertility. More research is still needed.
How could vitamin D affect progesterone?
Researchers have proposed a few theories for how vitamin D could potentially influence progesterone levels:
- Regulating progesterone production genes: Vitamin D may regulate certain genes involved in progesterone synthesis. Cell studies found calcitriol increased expression of genes like StAR, P450scc, and 3β-HSD, which are crucial for progesterone production (7).
- Supporting luteal cells: The corpus luteum produces progesterone. In animal studies, vitamin D deficiency impaired luteal cell development and function, while supplementation had protective effects on these cells (8, 15).
- Modulating parathyroid hormone (PTH): High PTH levels can decrease progesterone. Vitamin D helps lower excess PTH. One study found the combination of vitamin D and calcium supplements lowered PTH levels and increased progesterone compared to vitamin D alone (16).
- Anti-inflammatory effects: Inflammation can reduce progesterone. Vitamin D has anti-inflammatory properties that may help counteract these effects.
More research is needed to confirm the mechanisms behind the potential effects of vitamin D on progesterone.
Should you take vitamin D3 to increase progesterone?
Due to the limited and mixed research, there are no clear recommendations for taking vitamin D3 supplements specifically to increase progesterone levels. Here are some key points:
- Correcting any vitamin D deficiency is important for health. Maintaining adequate vitamin D levels may help support normal progesterone production.
- Studies show the most promise for increasing progesterone in women with conditions like PCOS and infertility. However, further research is still needed.
- General vitamin D3 supplements (1000-4000 IU per day) may help maintain optimum levels for reproductive health. Remember to also get moderate sun exposure.
- High-dose vitamin D3 supplementation to optimize progesterone cannot be routinely recommended yet but appears unlikely to cause harm if done short-term under medical supervision.
- Vitamin D3 supplementation may be one part of an overall plan to address low progesterone. Lifestyle factors like stress management, diet, and exercise are also important.
- Work with a healthcare professional to determine if vitamin D3 supplementation is appropriate for your individual health situation.
Other ways to increase low progesterone
Some other evidence-based ways to increase low progesterone levels include:
- Lifestyle changes like weight loss, nutrition, and stress management
- Herbal remedies such as chasteberry, also known as vitex or chaste tree berry
- Balancing insulin and blood sugar
- Acupuncture
- Progesterone therapy, such as progesterone creams, gels, or vaginal suppositories
A combination approach addressing diet, lifestyle, nutrients like vitamin D, and herbs or progesterone therapy may help provide the most benefit.
Conclusion
Some initial research shows potential for vitamin D3 supplementation to increase progesterone levels, especially in women with conditions like infertility or PCOS. The strongest evidence supports a role for maintaining adequate vitamin D levels through sunlight, food sources, and possibly supplementation to support normal progesterone production.
More large-scale randomized controlled trials are still needed to determine the true efficacy and appropriate usage of vitamin D3 supplements specifically to optimize progesterone levels in different groups of women.
Vitamin D3 supplements may serve as an accessible and low-risk option to include as part of a comprehensive plan to address low progesterone. However, other lifestyle measures, herbs, and medical progesterone are likely to be more effective stand-alone remedies in many cases.
As always, work with a knowledgeable healthcare practitioner to determine the best options to balance your hormones, support reproductive health, and address any progesterone deficiency.