Skip to content

Surprising Side Effects of Not Getting Enough Vitamin D, Says Science

You probably wouldn't have associated these outcomes with vitamin D deficiency.
FACT CHECKED BY Kiersten Hickman

There are many health benefits of taking a vitamin D supplement. From supporting your immune system and helping fight off infectious diseases (such as COVID-19) to improving mental health, the vitamin is not one to leave out in your diet.

Below, we pinpoint four surprising side effects you likely wouldn't have thought could occur from having insufficient vitamin D levels. Then, be sure to check out The One Vitamin Doctors Are Urging Everyone to Take Right Now.

It may cause respiratory complications.

Curly woman feeling bad and suffering from strong cough while having flu

You may not think it, but vitamin D and respiratory issues are connected. In fact, vitamin D deficiency has been linked to an increased risk of upper respiratory tract infections. Inadequate levels have also been associated with asthma-related events. According to a 2014 study that tracked more than 21,000 adults with asthma, those with the condition and a deficiency were 25% more likely to experience an acute asthma attack and more in need of seeing a specialist on a regular basis. If you're prone to respiratory infections or you have asthma, taking a supplement could help you prevent illness and reduce the severity of an asthma attack.

Higher risk of UTIs.


We all know that vitamin D helps prevent a viral infection such as the common cold, however, what likely isn't as obvious is the vitamin's ability to prevent an infection that can occur down south. According to a study published in the BMJ Archives of Disease in Childhood, vitamin D deficiency was a risk factor for urinary tract infection in children—especially girls. The same can even be said for adult women. A 2013 study found that women who had recurrent UTIs had lower levels than those who didn't.

Get even more healthy tips straight to your inbox by signing up for our newsletter!

Increased risk of preterm birth.

Mother in pink lace dress holding her 1 week old little baby

Preterm birth, which is a birth that occurs before the 37th week of pregnancy, could be prevented. A study that examined more than 2,000 pregnant women with higher levels of 25-hydroxy vitamin D (an indicator of our bodies' vitamin D stores) had a lower risk of giving birth prematurely. Researchers theorize that vitamin D could reduce bacterial infection in the placenta, which is what causes preterm birth in some instances.

Next, check out What Your Diet Should Look Like If You Have Gestational Diabetes, According to an RD.

You may experience an increased risk of heart disease.

Portrait Of A Mature Man Having Heart Attack

Perhaps the most shocking side effect of them all? There may be an association between vitamin D deficiency and heart disease. One study published in 2009 found that participants with very low levels of the vitamin were nearly three times as likely to die of heart failure. What's more? They were also five times as likely to die of sudden cardiac death. However, further evidence is needed to confirm that there's a direct link.

For more, be sure to check out These Are the Two Best Diets For Heart Health, According to Doctors.

Cheyenne Buckingham
Cheyenne Buckingham is the former news editor of Eat This, Not That! Read more about Cheyenne