8 Ways To Naturally Boost Your Vitamin D (And Why It Is Important To Reproductive Health)

Thanks to COVID-19, the spotlight is once again on Vitamin D – which you need for to support your immune system, mood, bones and muscles. Vitamin D not just a vitamin, it’s also a hormone – essential for fertility, with a lowered status associated with impaired fertility levels, PCOS and Endometriosis.

But recent research has shown that whilst many conditions are associated with Vitamin D (25-OH) deficiency, supplementation doesn’t necessarily solve the problem – which ultimately is a deficiency in sunlight and a likely deficiency in magnesium (more on that below).

How does Vitamin D metabolism work?

When sunlight hits your skin, three metabolic reactions occur:

  1. A cholesterol precursor is turned into inactive Cholecalciferol (pre-formed Vitamin D) by UV-B under the skin.
  2.  It is then stored as inactive Calcidiol (25-OH Vitamin D) in your liver; then..
  3. Converted into its active form of Calcitrol (aka 1,25-OH Vitamin D) in the kidneys.

Factors that impact your Vitamin D

For some however, utilising the benefits of sunshine (and reaching adequate Vitamin D levels) may be impacted by:

  • A magnesium deficiency – which is imperative to all three steps of Vitamin D metabolism (as per above).
  • Other cofactor deficiencies – such as Vitamin K, boron and zinc.
  • Darker skin – as melanin lowers the skins ability to make Vitamin D in response to sunlight exposure. 
  • Genetic variations in the VDR gene – that may impact Vitamin D utilisation.
  • Poor liver & gut health – including bile & pancreatic insufficiency, bacterial imbalances, chronic GI disorders such as Chrone’s and Coeliac disease; Gilberts Syndrome and gastrectomy.
  • A low fat diet-  as Vitamin D requires fat for optimum absorption. 
  • Obesity >30 BMI – as the Vitamin D is distributed into a larger volume of weight which drives serum levels down.
  • Chronic inflammation – as found in inflammatory diseases such as endometriosis.
  • Wearing sunglasses all day – UV-B exposure stimulates D3 metabolite synthesis in the eyes.
  • Your age – as the older you get, the less you can absorb/metabolise.
  • The time of year you have it taken – your levels are always going to be lower in the colder months with more skin coverage. 

The best way to test your Vitamin D levels

Before you go ahead with testing, it is imperative to first check your magnesium levels, as it’s required for every step of Vitamin D activation in your body (in fact, the standard test for Vitamin D could actually be the perfect blood test to assess your magnesium status!).

Most practitioners will measure inactive 25-OH vitamin D (Calcidiol – your vitamin D stores) in the blood because it’s found in higher concentrations and stays much longer in your body (in comparison to the activated 1,25-OH Vitamin D). When you’re looking at your blood results you want your levels to be greater than 100 nmol/L.

Some clinicians also measure activated 1,25-OH vitamin D (Calcitrol) levels in the blood, which is regulated by parathyroid hormone. This test is mainly carried out in cases where production may be disturbed (e.g. kidney disease, vitamin D-resistant rickets, sarcoidosis, tuberculosis, rheumatoid arthritis, biliary cirrhosis, inflammatory bowel disease and lymphoproliferative diseases; anticonvulsants). In fact, Calcitrol levels go up, not down, when you’re deficient in Vitamin D.

Vitamin D and reproductive health

Vitamin D deficiency is correlated with a number of female reproductive complaints including infertility, endometriosis, uterine fibroids and PCOS. It is also imperative to monitor levels and avoid deficiency when trying to get pregnant or when you are pregnant.

In Endometriosis, Vitamin D may assist with its immune modulating effects and may reduce dysmenorrhoea (period pain) by interrupting the production of inflammatory molecules like prostaglandins.

Hypovitaminosis (low) of vitamin D is has also been links to an increased risk of uterine fibroids, with D3 supplementation actually reducing fibroid size in “in vivo” animal models.

In women with PCOS, Vitamin D supplementation has been shown to improve overall fertility, pregnancy rates and regular menstruation cycles, as well as metabolic markers (such as insulin, triglycerides and cholesterol) in those that are overweight.

For fertility, Vitamin D is also required in the development of the corpus luteum – a gland which is formed within an ovary at the site of the follicle (or ‘sac’) that has matured and released its egg during ovulation.

How to naturally boost your Vitamin D levels

So if you’ve tested and you’re running low on D, and or have any of the risk factors listed above, you are going to need more sunshine and potenitally some supplemental D3 to compensate (but only if your levels are substantially less than 100 nmol/L). Easy natural ways to increase your levels of vitamin D include:

  • Extra magnesium! Eat a diet rich in magnesium foods (such as nuts, seeds, avocados, dar leafy greens, legumes and dark chocolate). Reduce your stress (as that’s when magnesium gets dumped into the urine by the kidneys). Take 600mg of magnesium glycinate (in split doses) a day and work optimising your digestion.
  • Leaving your sunscreen and sunglasses off in the early morning sun. Get sunlight exposure as much as possible during the day, but not to the extent where you risk skin damage.
  • If you need to supplement, take a low dose D3 combined with K2 (as they work synergistically to support one another’s effects). Vitamin D supplementation is not recommended long term or in high doses – should always be regularly retested at the same lab (as per above).
  • Eat Vitamin D rich foods such as mushrooms, egg yolks, sprouted seeds, wild fatty small fish & and cod liver oil.
  • Work on your gut health to strengthen the microbiome, pancreatic function, bile flow and resolve any bacterial issues (like SIBO).
  • Naturally stimulate your bile flow by supporting your liver and gallbladder by staying hydrated, eating bitter foods, drinking dandelion (root) tea and celery juice. Useful supplements include phosphatidylcholine, glycine, taurine, milk thistle, magnesium and betaine hydrochloride.
  • Treat underlying inflammation with herbs & supplements like curcumin, cod liver oil, ginger, resveratrol, green tea and antioxidants generally.
  • Address and treat underlying hyperparathyroidism if present.


📷  Graphic from Harvard Health website