Illnesses Linked To Vitamin D Deficiency

In most places around the world you can get vitamin D from the most primary source by simply stepping outside to enjoy some sunshine; the sun helps synthesize vitamin D in the skin to promote the growth of strong bones and cognitive health according to the Mayo Clinic. Vitamin D is an essential need, and just as it is a booster to health, the lack of it can lead to health issues. 

“We see a lot of associations between vitamin D deficiency and poor health outcomes,” says Mary Byrn, PhD, RN, an associate professor at Loyola University in Chicago, who studies vitamin D. “Although these are relationships and we are unable to conclude cause and effect, taking vitamin D supplements or exposing yourself to the sun in a safe manner to increase vitamin D naturally are easy ways to improve your health and try to reduce your risk of multiple diseases,” Dr. Byrn says.

Aside from getting vitamin D through supplements or the sun you can also get it through food, but the options are limited as it is found naturally in very few items, but there are those that have been fortified with vitamin D. 

Depending on the type, wild caught salmon is one of the few food sources of vitamin D. The USDA says that 1 three ounce serving of salmon can provide 12 micrograms of vitamin D which is about 60% of the daily recommended value. 

“Egg yolks offer a small amount of vitamin D, she adds, and fortified milks, cereals, and orange juice can also provide some of your daily requirement,” said dietitian Sarah Gold Anzlovar, RDN.

Bone pain, muscle weakness, fatigue, and mood changes are some of the common symptoms associated with vitamin D deficiency according to the Cleveland Clinic. There are many factors that can influence these symptoms, but if you have not made any changes to your lifestyle recently they may be signs of a deficiency. If any of these apply to you please consider seeing your primary care provider, dietitian or certified medical professional to address your concerns and come up with a plan to correct the problem.

“Because vitamin D isn't found in a lot of foods, and sun exposure may be limited depending on where you live, I recommend everyone get their vitamin D levels checked at their annual checkup,” says Anzlovar. “Then you can evaluate with your healthcare provider whether a supplement or seeking out more vitamin-D-rich foods is necessary.” Know also that some groups, including individuals with dark skin, those with certain underlying health conditions or who are taking certain medications, and those who live in a city far from the equator, may be more prone to having low vitamin D, according to the Cleveland Clinic.

Preliminary research suggests that vitamin D supplements may be helpful in preventing or managing the symptoms of COVID-19. While these studies are still in early stages past research shows that vitamin D may help to protect against respiratory illnesses, such as in one study published in the BMJ examining the impact of vitamin D on respiratory infections including pneumonia, sinusitis, and bronchitis which found that those who took the vitamin were 12% less likely to develop respiratory illness. 

Some researchers believe that although promising it is still too soon to make a connection between vitamin D in COVID-19. “It is still too early to draw a clear link between vitamin D deficiency and COVID-19; however, there was a study that indicated that countries with high prevalence of vitamin D deficiency had higher rates of COVID-19 mortality rates,” says Byrn, referring to an unpublished study by researchers at Northwestern University in Chicago.

However, there still is a possible connection; “We know that vitamin D plays a role in our immune system and our body's ability to fight off infection; we know that there are vitamin D receptors on immune cells and that vitamin D deficiency increases our susceptibility to infection,” says Byrn. “So, it is possible that vitamin D deficiency increases the risk of COVID-19 infection, but we don’t have specific research results that allow us to make a definitive conclusion.”

Studies on vitamin D for flu prevention and mitigation have yielded mixed results. One study published in Nutrients found that vitamin D did not make a difference in boosting the flu shot, while previous studies found school age children who took the vitamin were 42% less likely to get the flu. 

According to Harvard Medical School low levels of vitamin D can lead to low bone calcium and increase the risk of fractures, thus a deficiency may put people at risk for osteoporosis as one of the primary roles of vitamin D is to maintain skeletal health. 

A vitamin D deficiency may be linked to a higher risk of depression, which may come as no surprise for those familiar with seasonal affective disorder. One study published in the Journal of Diabetes Research found those with type 2 diabetes taking a vitamin D supplement experienced improved moods, with a significant decrease in depression, anxiety and improvements in mental health after 6 months of treatment. 

“Low vitamin D may play a role [in depression], and it would be good to advocate and ask your provider to check your vitamin D level to see if a deficiency could be contributing to your symptoms,” advises Byrn.

A review published in the Journal of Clinical Endocrinology and Metabolism found that those with a vitamin D deficiency may be twice as likely to be diagnosed with schizophrenia; but it was noted that randomized and controlled trials are needed to determine if treatment for low levels of vitamin D may help to prevent schizophrenia. 

According to a study published in the journal Neurology moderate to severe vitamin D deficiency in elderhood is associated with a doubled risk for some forms of dementia which includes Alzheimer’s disease. In this study those with low levels had a 53% increased risk of developing all cause dementia, while those with a severe deficiency had a 125% increased risk, and those with lower levels were about 70% more likely to develop Alzheimer’s disease specifically, and those who were severely deficient were over 120% more likely. It was noted that this study was not able to prove a direct cause and effect relationship, but it was theorized that vitamin D may help to clear plaques in the brain that are linked to dementia.

The connection between low levels of vitamin D and diabetes is more clear. A study published in Biochemical Journal found that when there is a deficiency many cellular processes within the body begin to break down which sets the stage for the onset of diseases such as diabetes. 

“Again we see a relationship between vitamin D deficiency and diabetes,” says Byrn. Just why there’s a link is still unknown, but researchers have hypotheses. “Some researchers believe the link is related to the role of vitamin D in insulin sensitivity and resistance; however, randomized controlled trials don’t all support evidence that increasing vitamin D levels through vitamin D supplements results in improvements in insulin sensitivity,” says Byrn. Previous research points to these mixed results.“Another possibility of the link is related to the role of vitamin D in inflammation, because people with type 2 diabetes also have higher chronic inflammation,” notes Byrn.

The journal Clinical Cancer Research published a study finding a link between low blood levels of vitamin D and aggressive prostate cancer in European American and African American men, with the connections seeming to be especially strong in Africian American men suggesting that low levels in this population were more likely to test positive for the cancer than other men with normal levels of vitamin D. However, it was noted that the study could not prove low levels led to prostate cancer, only that there may be an association. 

The Journal of Sexual Medicine published a study finding that men with severe erectile dysfunction had significantly lower levels of vitamin D than men with mild erectile dysfunction. It was theorized that a deficiency may contribute to ED by impeding the artery's ability to dilate to cause endothelial dysfunction which is also a marker for heart disease. 

A study published in the Journal of the American College of Cardiology suggests that low levels of vitamin D are linked to arterial stiffness in healthy people, and when the arteries do not function properly the penis may not be able to get enough blood supply contributing to ED. 

Studies have established an association between low vitamin D blood levels and heart disease as well as the related conditions, but it has not been clearly established whether supplementation can reduce the risks. A review published in Circulation Research cites bodies of evidence pointing towards vitamin D levels as a potential culprit for health issues related to heart disease including atherosclerosis, diabetes, stroke, and high blood pressure. 

Breast Cancer: Basic and Clinical Research published a study finding that “most of the vitamin D studies support the inverse association between vitamin D level and breast cancer risk.”  Another study published in Breast Cancer Research found that when exposed to high concentrations of vitamin D, breast cancer cells reduced in severity. 

Vitamin D may help to reduce your risks for a range of health problems. The easiest way to get vitamin D is to go outside more and enjoy some time in the sun. In addition to this essential vitamin you can also reduce the risks of disease by living a healthy lifestyle which includes maintaining a healthy weight, being physically active, keeping stress levels in check, getting enough sleep, and following a healthy diet.