How vitamin D illuminates women’s health

Women, take note – the topic of vitamin D is hotly debated and has spiked the interest of people wanting to keep themselves healthy.  Obtaining sufficient vitamin D whether from food sources, the sun or supplements, is important for everyone but for women there are many reasons why the “sunshine vitamin” is one not to be deficient in.  

What is vitamin D?

Vitamin D is a fat-soluble vitamin that acts as a hormone.  It is known as the sunshine vitamin because it can be made in the skin with exposure to ultraviolet light.  Because vitamin D can be made in the body, it is essential in the diet only when exposure to sunlight is limited or the body’s ability to synthesize it is reduced.  Whether vitamin D is obtained from food sources or the sun, it is inactive until it is modified by biochemical reactions in the both the liver and the kidneys.

Vitamin D has many important functions in the body including:

·      Mineralization of bones and teeth

·      Absorption of calcium and phosphorus

·      Cell differentiation

·      Immunity

·      Blood pressure regulation

Causes of vitamin D deficiency in women

Women appear to have lower vitamin D levels than men for several reasons:

·      Women tend to have more body fat than men.  Being obese or having more body fat is an important factor in lowering vitamin D levels because fat cells absorb vitamin D and keep it from circulating throughout the bloodstream.

·      Women tend to spend less time outdoors than men with adequate exposure to the sun.  Women may also be more likely to use sunscreen blocking UV light for making vitamin D in addition to wearing hats or clothing with long sleeves or pants.

·      As we age, whether a woman or man, less vitamin D is absorbed from dietary sources and our bodies produce less vitamin D in their skin from the sun. 

·      If a woman lives above the 42nd parallel – from Chicago or Boston north – the months of November through February do not produce sufficient vitamin D even on a sunny day. 

Testing for vitamin D status

Vitamin D status is checked with a blood test called a 25(OH)D blood test.  This can be done at a doctor’s office and it will show whether a person is getting enough vitamin D or not and if they need to take a supplement or not. 

Depending on what organization you trust more on the results of this test and what your physician recommends, the ranges of vitamin D status vary as to whether a person is considered deficient, insufficient or sufficient in their vitamin D status:

If you go by the Vitamin D Council, they recommend the following:

Deficient – 0-30 ng/ml

Insufficient – 31-39 ng/ml

Sufficient – 40-80 ng/ml

Toxic - >150 ng/ml

The Endocrine Society follows and recommends these ranges:

Deficient – 0-20 ng/ml

Insufficient – 21-29 ng/ml

Sufficient – 30-100 ng/ml

What does a vitamin D deficiency mean for a woman?

Vitamin D is just as critical for women as it is for men. Numerous studies are proving vitamin D provides many benefits specifically related to enhancing a woman’s health.

If a woman is deficient in vitamin D, it can affect her health in many ways:

·      Breast cancer – Studies have shown women with sufficient vitamin D levels had a 45% decreased risk of breast cancer.  Other studies have found that women diagnosed with breast cancer had, on average, lower blood levels of 25(OH)D.

·      Ovarian cancer – The impact of vitamin D on ovarian cancer has not been as well studies but it is reported to have a protective effect.  A recent study found that sufficient vitamin D status appears to delay progression of ovarian cancer.

·      Cardiovascular disease – A growing number of studies point to vitamin D deficiency as a risk factor for heart attacks, congestive heart failure, peripheral arterial disease, and strokes.  Even though more large scale studies are required, a recent 2016 study suggest that daily vitamin D supplementation may reduce cardiovascular risk factors.

·      Depression – There have been studies suggesting that supplements of vitamin D may improve mild depression.  At this point, treatment with high dose supplements of vitamin D for depressive symptoms is considered experimental and should only be used with medical supervision.

·      Lupus – Lupus is a chronic autoimmune disease that can affect almost any organ system in the body with multiple symptoms. About 9 out of 10 adults with lupus are women ages 15 to 45.  Vitamin D has been found to have effects on immune function and inflammation with studies suggesting a relationship of vitamin D to autoimmune conditions. This may suggest a possible connection of low vitamin D status and lupus. 

·      Osteoporosis – Postmenopausal women are at a higher risk of the brittle bone disease of osteoporosis.  In order for calcium to be absorbed and deposited into bone, there must be sufficient vitamin D for this to happen.  Women who have had a low calcium intake over the years along with insufficient vitamin D, are more likely to develop osteoporosis as they age.  Women obtaining adequate vitamin D along with calcium throughout their lifetime appear to have a reduced risk of osteoporosis.

·      Fertility – For women trying to conceive, it appears that vitamin D may be linked to better fertility, as well as a healthy pregnancy. Although the data for vitamin D and fertility is not conclusive, several studies have found that vitamin D blood levels of 30 ng/mL or higher are associated with higher pregnancy rates. Two studies found that among populations of mostly Caucasian and non-Hispanic white women, those with a normal vitamin D level were four times more likely to get pregnant through IVF compared to those who had a low vitamin D level. A meta-analysis investigated whether vitamin D blood levels are associated with live birth rates in women undergoing fertility treatments. It found that women with a level greater than 30 ng/mL had higher live birth rates than women with lower vitamin D levels.

Recommendations and sources of vitamin D

The current Institute of Medicine Guidelines for vitamin D is as follows:

·      Infants 0-12 months – 400 IU (International Units)

·      Children 1-13 years  - 600 IU

·      Adolescents 14-18    - 600 IU

·      Adults 19-70 years   - 600 IU

·      Adults 71 or older    - 800 IU

·      Pregnancy                - 600 IU

·      Breastfeeding          -  600 IU

Best sources of vitamin D include the following:

·      Sunlight – Between 10-20 minutes of sun exposure on arms and legs or face 3 times weekly between 10 am to 3 pm.

·      Best food sources: Salmon, sardines, tuna, egg yolks, vitamin D fortified orange juice, vitamin D fortified milk, and vitamin D fortified yogurt

·      Vitamin D supplements

It’s best to consult with your physician on the amount to take if using a vitamin D supplement. Generally, most adults can safely take up to 2000 IU of vitamin D3 a day for maintenance.  In the meantime, get adequate sun exposure, increase food sources of vitamin D and always discuss with your physician of the need for a vitamin D supplement.