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Why Do Women Need Vitamin D, And How Much?

Among many aspects of our well-being, Vitamin D plays a vital role. But just how much Vitamin D do you need, and why do you need it in the first place? We’ll shed light on the answers to these questions, plus the nuanced considerations surrounding Vitamin D intake. 

From bone health to immune function, upping your Vitamin D game could do wonders for your health, and we’ll delve into the practical ways to ensure you’re getting enough. Let’s get started and demystify this powerhouse vitamin.

What is Vitamin D?

Vitamin D, often dubbed the “sunshine vitamin,” is a fat-soluble nutrient that plays a pivotal role in maintaining optimal health, especially bone health. It achieves this primarily by helping our body retain and absorb calcium and phosphorus

“Vitamin D also acts like a hormone, with vitamin D receptors found in the bone, gut, brain, breast, nerve, and other tissues,” says Monique Piderit, registered dietitian and PhD candidate.

Vitamin D isn’t a singular entity but rather a family of compounds, with the two primary forms being Vitamin D2 (ergocalciferol) and Vitamin D3 (cholecalciferol). While both forms of Vitamin D can be found in supplement form, they naturally occur in different ways.

“Vitamin D3 is the pre-vitamin form found naturally in foods like salmon, pilchards, and egg yolks,” Piderit says. Vitamin D3 is also produced by our skin when exposed to the sun’s ultraviolet-B (UVB) rays, which is our primary natural source of Vitamin D. 

Vitamin D2, on the other hand, is mostly sourced from plant-based foods and fortified products. 

The conversion of both forms of Vitamin D into their active, usable state occurs in the liver and kidneys, where they are transformed into calcidiol and calcitriol, respectively. These active forms are instrumental in carrying out the myriad functions that make Vitamin D an indispensable nutrient for overall health. 

Benefits of Getting Enough Vitamin D

An adequate Vitamin D intake is associated with a ton of health benefits. Some Vitamin D benefits are:

  • Bone health and muscle strength. Vitamin D aids in the absorption of calcium and phosphorus, essential minerals for bone mineralization. According to one meta-analysis, oral Vitamin D supplementation is associated with a reduced risk of fractures and osteoporosis. Another study highlights the positive impact of Vitamin D on muscle strength and balance in older adults, emphasizing its role in preventing falls and fractures. 
  • Reduced cardiovascular risk. Low Vitamin D levels have been linked to increased risk of heart diseases such as hypertension, heart failure, and stroke. However, it’s unclear whether Vitamin D deficiency contributes to causing heart disease or simply indicates poor health when you have a chronic condition.
  • Increased immune function. People who do not have adequate Vitamin D levels might be at increased risk of infections and autoimmune diseases, such as rheumatoid arthritis, multiple sclerosis, type 1 diabetes, and inflammatory bowel disease.
  • Cognitive health. Vitamin D could support your brain as you age. One observational study found that low Vitamin D levels were associated with a higher risk of dementia. Other research suggests adequate Vitamin D intake could more generally support cognitive health and mitigate risk for several neurodegenerative disorders.
  • Regulating mood. It only makes sense that getting enough of the “sunshine vitamin” could make you happier. A systematic review and meta-analysis found that Vitamin D supplementation can reduce negative emotions–patients with major depressive disorder and individuals with Vitamin D deficiency were most likely to benefit from supplementation. 
  • Supporting skin and hair. Some research suggests that adequate Vitamin D levels are associated with reduced acne, psoriasis, and hair loss, and could help treat other skin conditions like atopic dermatitis.
  • Supporting healthy pregnancy. Taking a Vitamin D supplement while pregnant could help you achieve better maternal and infant health outcomes, though you should consult your doctor before deciding to implement one into your prenatal routine. Research shows Vitamin D supplementation during pregnancy may improve fetal growth and reduce the risks for small-for-gestational-age, preeclampsia, preterm birth, and gestational diabetes, and that mothers with sufficient Vitamin D levels have offspring with less enamel defects.  

How Much Vitamin D You Need

Vitamin D is measured in IU, or international units. According to the Food and Nutrition Board of the Institute of Medicine, the Recommended Dietary Allowance (RDA) of Vitamin D is 600 IU for everyone between the ages of 1 and 70. 

It’s quite common for people to not meet the minimum requirement for this vitamin. One analysis found that Vitamin D deficiency is prevalent in the United States, especially in non-Hispanic Black Americans, women, individuals aged 20–29, and during winter.

Further research has shown that confounding factors such as skin pigmentation, latitude of residence, obesity, and others make standardizing and simplifying Vitamin D recommendations difficult. Vitamin D can be a bit of a black box–while we can track how much we’re getting from food and supplements, determining the amount being created from our exposure to the sun can be more difficult. If you want to know your body’s current Vitamin D levels, you can ask your doctor for a blood test. 

How to Get More Vitamin D

Now that you know how crucial this vitamin is for your well-being, you’re probably wondering “where can I get Vitamin D”? The answer is that boosting Vitamin D levels involves a strategic interplay between sunlight exposure, dietary choices, and, in some cases, supplementation. 

Sunlight Exposure

The skin, a natural Vitamin D factory, produces the vitamin when exposed to ultraviolet B (UVB) rays. To capitalize on this, you can spend time outdoors during peak sunlight hours, typically between 10 am and 3 pm. Exposing large areas of skin, such as arms and legs, for around 5 to 30 minutes, depending on factors like skin pigmentation, latitude, and the season, can contribute significantly to Vitamin D synthesis.

However, this advice comes with a caveat. While sunlight is a natural source of Vitamin D, concerns about skin damage and skin cancer risk necessitate a balanced approach. Sunscreen use, though essential for skin protection, can hinder Vitamin D synthesis. Striking a balance between safe sun exposure and skin protection is crucial.

“While there is no consensus as to how much sun to get, it is safe and sensible to get about 15 minutes of sunlight three times per week on exposed legs and arms with no sunscreen,” Piedrit says.

Dietary Sources

Fortifying your diet with Vitamin D food sources enhances the chances of meeting recommended levels. Fatty fish, such as salmon, mackerel, and trout, are excellent sources of Vitamin D. Additionally, cod liver oil, egg yolks, and beef liver contribute to dietary intake.

For individuals with dietary restrictions or preferences, fortified foods and beverages offer alternative sources. Milk, orange juice, yogurt, and breakfast cereals often undergo fortification to provide additional Vitamin D. These options can be particularly valuable for those who may struggle to meet their nutritional needs through natural food sources alone.


When sunlight exposure and dietary sources fall short, Vitamin D supplements may be a practical solution. 

“Vitamin D supplements are available in both forms (D3 and D2). However, high doses of vitamin D2 seem to not be as potent as vitamin D3,” Piderit says. “Studies have also shown that taking smaller but more frequent daily doses is more effective in increasing blood vitamin D levels compared to taking much larger weekly or monthly doses.”

Supplemental doses should be determined in consultation with healthcare professionals, as individual needs vary. Regular monitoring of serum Vitamin D levels helps in adjusting supplementation to achieve and maintain optimal concentrations.

Vitamin D Toxicity

While Vitamin D is essential for various physiological functions, it is possible to consume too much of it. Vitamin D toxicity, though rare, can occur when an excessive amount of this fat-soluble vitamin accumulates in the body, leading to adverse health effects. It usually occurs after months of taking extra large doses of Vitamin D via supplements, and is unlikely to be caused by sun exposure or eating a diversified diet.

“Excess vitamin D causes increased calcium levels in the blood, which deposit in soft tissues like the lungs, kidneys, and heart,” Piedrit says.

Signs and symptoms of Vitamin D toxicity primarily revolve around hypercalcemia, with manifestations including headache, irritability, metallic taste, pancreatitis, dehydration, nausea, and vomiting. These symptoms underscore the importance of monitoring Vitamin D levels regularly, especially when supplementation is involved. The maximum suggested daily intake level of vitamin D is 4,000 IU. 

As you can see, more is not always better, and an informed, balanced approach is key to reaping the benefits of Vitamin D without falling into the pitfalls of toxicity. Consult your healthcare provider before you start taking a supplement and make sure you understand the daily dose. 

Take advantage of the sunshine vitamin

From bolstering bone health to potentially weaving a shield against diseases, getting enough Vitamin D is clearly an important part of maintaining a strong and healthy body. Empowered with this new information, you’ll be able to make the best decisions for your body (alongside your doctor) when it comes to sun exposure, food choices, and supplements.