Doctors Just Revealed 5 Fascinating Vitamin D Facts You Probably Didn’t Know

Updated: Jan. 18, 2024

As much as there is for you to love about vitamin D, there's also still plenty for you to learn...and this supernutrient might even be serving you in ways you've never imagined.

Vitamin D‘s been having a moment, and it’s no wonder. The quintessential list of vitamin D benefits often includes strengthening bones and teeth, supporting immunity, promoting brain and nerve health, and even possibly making hair shinier.

Even so, with all the hype it gets, there are plenty of surprising vitamin D facts that are valuable for your awareness. Read on to discover some under-the-radar vitamin D wins, plus a few heads-ups, to supplement wiser.

How long does it take vitamin D to work? Dietitians Explain Just How Long It Takes Vitamin D to Work in Your Body

1. Vitamin D deficiency is related to sexual health and function.

Couple Smiling And Enjoying Date With Lunch On Building RooftopAleksandarGeorgiev/Getty Images

Research from the past few years suggests low vitamin D levels may affect performance in the bedroom for both men and women.

For men, vitamin D can boost fertility by increasing sperm motility. According to research published in The World Journal of Men’s Health in May 2019, vitamin D improves testicular function, which produces sperm and essential sex hormones, like testosterone.

For women, several studies have found an association between vitamin D deficiency and sexual dysfunction (like a 2019 study published in the peer-reviewed Journal of Urology). Symptoms include low sex drive, lack of arousal, and pain during sex.

If you wouldn’t mind boosting your libido, you’re not alone—plenty of data have noted that pandemic stress has taken a toll on how romantic many of us feel. You may find it reassuring to learn that one step toward getting back that loving feeling may be as simple as making sure you’re consuming enough vitamin D.

Want vitamin D on your plate on your next dinner date? Read 6 Easy Ways to Eat More Vitamin D-Rich Foods.

2. Too much vitamin D can cause kidney stones.

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Yes, there is such thing as overdoing it with vitamin D supplements. Excess vitamin D intake (specifically from supplements) can have unwanted side effects…the worst of which include kidney stones. Dr. John Poothullil, MD, FRCP, author of Your Health Is At Risk: How to Navigate Information Chaos to Prevent Lifestyle Diseases, tells The Healthy: “Vitamin D increases how much calcium is absorbed by the gut. However, too much vitamin D is dangerous because it can cause high calcium levels, leading to kidney stones.” Dr. Poothullil says other side effects of excess vitamin D include nausea, vomiting, muscle weakness, and confusion.

If you supplement with vitamin D, pay close attention to the dosage to ensure you’re not reaching toxic levels. Dr. Poothullil recommends a daily amount of 800 international units (IU). However, for people in northern climates or who don’t get outdoors much, a 1,000 to 2,000 IU supplement can be beneficial. Before taking vitamin D supplements of any strength, we recommend you talk to your healthcare provider.

3. Vitamin D levels impact your urologic health.

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Urologic health relates to the body parts involved in sexual health (commonly the prostate and testicles in men) and producing, storing, and eliminating urine (bladder, kidneys, urinary tract for men and women).

A growing body of research shows vitamin D deficiency is associated with several urologic problems in adults, such as:

  • Overactive bladder: If you often rush to the toilet or wake to pee at night, you could have an overactive bladder. Fortunately, upping your vitamin D levels can help end nighttime bathroom visits because vitamin D helps strengthen muscles that allow urine out of the bladder, according to a 2021 study published in the International Urogynecology Journal.
  • Bladder cancer: Vitamin D deficiency may have more severe health consequences than frequent urination. A 2019 study showed low vitamin D levels were associated with a higher risk of bladder cancer.
  • Urinary tract infections (UTIs): Getting enough vitamin D can help prevent recurring UTIs, according to a 2019 study that showed low vitamin D levels are associated with an increased risk of UTIs in both adults and children.
  • Prostate gland enlargement: According to research published in The Canadian Journal of Urology, there’s a correlation between not regularly getting your daily dose of vitamin D and a higher risk of prostate gland enlargement, resulting in various uncomfortable urinary symptoms.

4. Aging affects your skin’s ability to produce Vitamin D.

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We’re all too well aware that our skin loses its smooth, supple complexion as we age. What you may not know is aging skin also loses its ability to produce vitamin D. It’s rather widely understood that our system produces vitamin D when our skin is exposed to sunlight. However, getting outside and soaking up rays won’t have the same effect as you age, according to a study published in Endocrinology and Metabolism Clinics of North America.

How much sun exposure does your skin need to produce enough vitamin D? Dr. Joan Salge Blake, EdD, RDN, LDN, FAND, explains, “Research suggests that up to 30 minutes of sun exposure, particularly between 10 a.m. and 2 p.m. (either daily or at least twice a week) to the face, arms, hands, and legs without sunscreen may lead to sufficient vitamin D synthesis depending on where you live and the intensity of the sun.”

Looking for just the right vitamin D supplement for you? The 4 Best Vitamin D Supplements Depending on Your Specific Needs, from Registered Dietitians.

5. Not all women require the same amount of vitamin D.

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Certain women may need more or less vitamin D than the daily recommendation of 800 IU. For example, a 2016 study found pregnant women who gave birth in winter, have low vitamin D levels in early pregnancy, or gain more weight than average during pregnancy may need higher doses of vitamin D than other pregnant women.

Vitamin D is a critical nutrient during pregnancy for both mother and baby. Deficiency increases the risk of congenital rickets and bone fractures in babies and preeclampsia in mothers. If you’re a mom-to-be, speak with your doctor about finding a quality prenatal vitamin that includes vitamin D.

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