How Much Vitamin D Do Women Need per Day?

15 Micrograms (mcg) or 600 International Units (IU)

Medically reviewed by Suzanne Fisher, RDMedically reviewed by Suzanne Fisher, RD

Vitamin D is a fat-soluble vitamin from the sun, food, or dietary supplements. For women, vitamin D is critical, helping to maintain strong bones and support healthy pregnancies.

Maintaining adequate vitamin D levels is essential for health. All vitamin D sources must go through a series of chemical reactions in the body before use. So, the source of vitamin D does not necessarily matter as long as you are getting enough.

The following article covers vitamin D, its benefits, how much you should consume, and more.

Takeaway

Gender identity is how an individual experiences gender internally. Sex reflects biology (chromosomal makeup, hormones, and/or anatomy). Gender identity can be the same or different from one’s assigned sex at birth. It speaks to one’s sense of self and may not be outwardly visible.

How Much Vitamin D per Day Do Women Need?

The Recommended Dietary Allowance (RDA) for vitamin D is the following for women:

• Ages one to 70 years: 15 micrograms (mcg) (600 International Units (IU)).

• Older than 70: 20 mcg (800 IU).

• During pregnancy and lactation: 15 mcg (600 IU).

Fat enhances vitamin D absorption. Consume vitamin D with food sources of fat such as oil, dairy, nuts, or seeds. Moreover, many fortified food sources of vitamin D, like dairy products, already naturally contain fat.

Most women do not consume the RDA for vitamin D. Still, they can meet their vitamin D needs through sun exposure and a combination of foods.

Explainer

In the United States, the Food and Drug Administration (FDA) does not regulate supplements like prescription drugs. This means some supplement products may not contain what the label says. When choosing a supplement, look for third-party tested products and consult a healthcare provider, registered dietitian nutritionist (RDN or RD), or pharmacist.

What Influences Vitamin D Requirements?

Multiple factors influence vitamin D absorption and requirements, including the following.

Sunlight Exposure

Exposure to sunlight is essential for the body to produce vitamin D. About 80% of vitamin D in the body comes from the sun.

Balancing the risk of ultraviolet (UV) exposure with the need for vitamin D is tricky. However, research shows that protecting skin from UV rays with sunscreen does not meaningfully impact vitamin D levels.

A person's vitamin D concentrations tend to change depending on the season. Vitamin D levels dip in seasons with less light, like winter. This is due to the sun’s decreased strength and limited direct skin exposure to sunlight.

Individuals who spend significant amounts of time indoors may require more vitamin D from other sources. Similarly, people who always cover their bodies when outside experience a greater risk of vitamin D deficiency.

Age and Life Stage

Getting enough vitamin D is essential at all stages of life.

Vitamin D is necessary for infants. Although breast milk contains some vitamin D, it is not enough to meet the RDA of 10 mcg (400 IU).

Breastfed infants should receive supplemental vitamin D. Infant formulas contain sufficient vitamin D, so supplementation is unnecessary.

Older adults have higher vitamin D requirements. The body’s ability to produce vitamin D from sunlight decreases with age. Additionally, older adults may be likelier to spend more time indoors.

Less exposure to sunlight contributes to a higher demand for other sources of vitamin D. Aging does not affect the gut’s ability to absorb vitamin D.

Skin Tone

Melanin is a pigment that gives skin its color. Melanin also filters UV light and protects skin against sun damage. Higher melanin levels cause darker skin pigments.

People with skin with more melanin typically need more sunlight to get enough vitamin D. They can have a more challenging time getting enough of it during winter months or in lower light. Conversely, skin with less melanin gets vitamin D from the sun more easily.

Be sure to speak with your healthcare provider about your unique vitamin D needs and how to ensure that you get enough to stay healthy.

Geographic Location

Many geographical factors affect vitamin D production from the sun.

Vitamin D production increases at higher altitudes because of greater UV exposure. Conversely, smog, cloud cover, and thicker ozone layers limit the amount of UV radiation that reaches the skin.

Locations further from the equator at higher altitudes experience less sunlight in the winter and more in the summer. This contributes to seasonal differences in vitamin D status.

Other Factors

Health conditions that affect nutrient absorption impact vitamin D requirements. Some instances that require additional consideration for vitamin D include the following:

• Gastric procedures: Certain gastric procedures, like gastric bypass, affect the upper small intestine, where vitamin D is absorbed.

• Gastrointestinal conditions: Vitamin D is a fat-soluble nutrient, so conditions that affect fat absorption also impact the body’s ability to absorb vitamin D. Certain conditions, such as celiac disease and inflammatory bowel diseases like Crohn’s and ulcerative colitis, impact fat absorption and increase the risk of vitamin D deficiency.

• People affected by obesity: Vitamin D is stored in fat (adipose) tissue. People affected by obesity tend to have lower levels of circulating vitamin D.

• People with alcohol use disorder: Regular, excessive alcohol use—for women, eight or more drinks per week or four or more on any day—may reduce vitamin D levels.

• Tobacco use: Tobacco use can lower vitamin D levels, particularly among minority populations.

Health Benefits of Vitamin D for Women

Research on the importance of vitamin D continues to evolve, with more evidence supporting its essential role in female health. Maintaining adequate vitamin D levels benefits bone health, immune function, pregnancy outcomes, and mood.

Bone Health

Bones are constantly remodeling. Under normal conditions, the bone breakdown rate equals the bone-building rate. However, over time and with changes that occur with aging, bone breakdown can overtake bone building.

Setting yourself up for bone health at each life stage is vital. Women reach peak bone mass around the age of 30. Vitamin D is essential for supporting the accumulation of bone mass.

Hormonal changes during menopause affect bone health. Significant bone remodeling occurs post-menopause, requiring adequate vitamin D levels to prevent bone loss.

Vitamin D and calcium work together to support bone health. Calcium is the main mineral in bones, and vitamin D is required for adequate calcium absorption.

Research yields mixed results on vitamin D supplements' benefits for bone health. Instead, more studies support taking vitamin D and calcium together for healthy bones. According to one meta-analysis, supplementing with vitamin D and calcium reduces the risk of total and hip fractures by 15% and 30%, respectively.

Despite vitamin D's influential role in bone health, it remains unclear if vitamin D in amounts greater than the RDA benefits bone health and protects against fractures. Current guidelines encourage meeting the RDA through food or supplements to support bone health.

Immune Function

More and more research supports the role of vitamin D in immune health. Vitamin D influences immune function in myriad ways. Vitamin D receptors line immune cells, helping to regulate inflammation and the body’s immune response.

Vitamin D supports the body’s innate immune system, helping to defend it against harmful organisms (pathogens).

Vitamin D also plays a role in the autoimmune response. Autoimmune conditions are when the body attacks itself. Autoimmune diseases are characterized by overactive T and B immune cells. Vitamin D limits the activity of T and B cells, reducing an autoimmune response.

Additionally, emerging research suggests a role for vitamin D in supporting a healthy gut microbiome.

Maintaining adequate vitamin D levels supports immune health and function. Low vitamin D levels increase susceptibility to infections and illnesses. Moreover, insufficient vitamin D status is associated with a greater risk of autoimmune diseases, such as Hashimoto’s disease.

Mood Regulation

Vitamin D is involved in numerous brain processes. Brain and nerve cells (neurons) have vitamin D receptors. Additionally, vitamin D influences the release of mood-related neurotransmitters like serotonin and dopamine.

A link exists between low levels of vitamin D and depression. However, research shows mixed results on the benefits of vitamin D supplementation for reducing depression symptoms.

One meta-analysis observed improved depression symptoms in people affected by major depressive disorder major depressive disorder (MDD). However, another analysis found no improvement in symptoms among people with low levels of depression and sufficient vitamin D.

Notably, vitamin D influences pregnancy and postpartum depression. Lower vitamin D concentrations are associated with an increased risk of pregnancy and postpartum depression.

Still, additional research is necessary to determine the effects of vitamin D supplements on mood, particularly among people without MDD and with adequate vitamin D levels.

Pregnancy

Some reports indicate that 40% of pregnant individuals are vitamin D deficient. Low levels of vitamin D are associated with pregnancy complications. So, ensuring adequate vitamin D concentrations during pregnancy may improve pregnancy outcomes.

Research shows a link between low vitamin D and miscarriages. However, it is unclear whether supplementing with vitamin D protects against miscarriages.

Vitamin D influences the success of in vitro fertilization (IVF). According to one analysis, people with sufficient vitamin D levels experience greater success with IVF. Still, more studies are necessary.

Multiple studies have shown that adequate vitamin D levels reduce the risk of preeclampsia. Some evidence also indicates vitamin D supplementation lowers the risk of severe postpartum bleeding, but more research is necessary.

Aside from benefits to the mother, maintaining sufficient vitamin D reduces the risk of a low birth weight. However, additional research is warranted to understand if vitamin D lowers the risk of a baby born preterm (at less than 37 weeks).

How Do I Know My Vitamin D Status?

A vitamin D blood test measures 25-hydroxyvitamin D (calcidiol), the circulating form of vitamin D. Calcidiol reflects vitamin D from sun exposure, supplements, and food.

The Food and Nutrition Board at the National Academies of Sciences, Engineering, and Medicine defines vitamin D status for adults based on the following values of  25-hydroxyvitamin D:

• Deficient: less than 12 nanograms per milliliter (ng/mL)

• Inadequate: 12 to 20 ng/mL

• Adequate: 20 to 50 ng/mL

A vitamin D deficiency causes rickets in children and soft bones (osteomalacia) in adults. There is no consensus on a standard or optimal vitamin D level. Still, insufficient vitamin D negatively affects bone and overall health.

Not getting enough vitamin D over time causes decreased bone mass and density (osteoporosis). More than 53 million people in the United States are at risk for osteoporosis, which increases the chance of fractures.

To prevent low vitamin D, prioritize vitamin D-rich foods, supplement as warranted, and spend time outdoors. Blood tests enable you to check vitamin D status and adjust your routine accordingly, whether that includes adding or changing a supplement dosage.

Sources of Vitamin D

There are three ways to get vitamin D: sun, food, and supplements.

Sunlight

Sunlight is the best source of vitamin D. However, protecting skin from sun damage is essential to reduce the risk of skin cancer (melanoma). 

The best time to get sun for vitamin D production is between 10:30 a.m. and 1:30 p.m. During this time, the sun’s rays are at a narrower angle, allowing for more sunlight to reach the skin. However, this is also the peak time for potential sun damage, especially during the summer months. Using sunscreen with a sun protection factor (SPF) is key.

Research shows that sunscreen with an SPF of up to 30 minimally affects vitamin D levels. UV radiation can penetrate the skin and be converted into vitamin D despite sunscreen. Therefore, regularly spending time in the sun with sunscreen still permits vitamin D absorption.

Food Sources

Natural food sources of vitamin D include the following:

• Rainbow trout: 540 IU per 3-ounce (oz) serving (90% of the daily value (DV))

• Atlantic salmon: 447 IU per 3-oz serving (75% of DV)

• Raw, white mushrooms exposed to ultraviolet light: 367 IU per 1/2 cup serving (61% of DV).

• Eggs: 50 IU per whole egg (8% of DV).

Many food products have vitamin D added. Fortified food sources of vitamin D include the following:

• 2% milk: 111 IU per 1 cup serving (19% of DV).

• Soy milk: 119 IU per 1 cup serving (20% of DV).

Supplements

There are two forms of vitamin D: D2 (ergocalciferol) and D3 (cholecalciferol). Vitamin D2 is plant-based. Vitamin D3 is often obtained from animal sources but can also be produced from lichen.

Both D2 and D3 are well absorbed by the body and are converted to 25-hydroxyvitamin D. However, some research suggests that vitamin D3 increases serum vitamin D levels more effectively. Still, both forms of supplemental vitamin D are effective.

There is no consensus on the ideal dosage of vitamin D. In the absence of a deficiency, the Institute of Medicine recommends supplementing with vitamin D in the amount necessary to meet the RDA of 600 IU daily.

So, if you eat two eggs and drink a glass of milk daily, supplementing with 400 IU of vitamin D should be sufficient.

However, other organizations disagree. The Endocrine Society recommends adults take 1,500 to 2,000 IU of vitamin D daily to keep vitamin D levels above 30 ng/mL.

The effects of vitamin D supplementation depend on dosage, duration, and baseline vitamin status. Working with a registered dietitian can help determine the appropriate dosage.

Safety Considerations

Avoid vitamin D if you're allergic to it or its components (parts). Seek immediate medical attention if you have a severe allergic reaction (itching, hives, shortness of breath).

Vitamin D is toxic in excessive amounts. Vitamin D toxicity is possible from supplements, not food or sun exposure.

Too much vitamin D increases calcium absorption in the digestive tract, contributing to high calcium (hypercalcemia). In severe cases, vitamin D toxicity causes kidney failure, calcification of soft tissue throughout the body, heart issues, and even death.

Because of the health effects associated with excessive intake, the tolerable upper limit for vitamin D is 4,000 IU daily for women ages 9 and older and those who are pregnant and lactating.

Be mindful of vitamin D when using the following medications:

• Orlistat: The weight-loss drug Orlistat reduces fat and vitamin D absorption.

• Steroids: Corticosteroids (such as prednisone) affect vitamin D metabolism, causing lower vitamin D levels.

• Statins: Cholesterol is essential for the body's production of vitamin D. Statins, which lower cholesterol, may also reduce vitamin D levels. Conversely, taking high doses of supplemental vitamin D may lower the effectiveness of statins.

• Thiazide diuretics: Thiazide diuretics reduce calcium's removal from the body. Taking vitamin D supplements with thiazide diuretics can increase calcium absorption, causing hypercalcemia.

Takeaway

Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian nutritionist (RD or RDN), pharmacist, or healthcare provider. No supplement is intended to treat, cure, or prevent disease.

Summary

Vitamin D confers multiple health benefits for women, such as supporting bone strength and reducing pregnancy complications.

Although few foods naturally contain vitamin D, the RDA of 600 IU can be reached through a combination of different foods (including fortified ones), supplements, and sun exposure.

Maintaining sufficient nutrient levels is essential for reaping the benefits of vitamin D.

Read the original article on Verywell Health.