The primary source of vitamin D is accessible by stepping outside and into the sunlight. The sun helps synthesize vitamin D in the skin, which then promotes better cognitive health and the growth of strong bones. These are just 2 of the positive effects of vitamin D.
But just as vitamin D is beneficial to your health, a lack of it may lead to illness.
Science recognizes many associations between vitamin D deficiency and poor health outcomes. Taking vitamin D supplements and safely enjoying sunny days outdoors to increase your vitamin D naturally are effective ways to improve your health. It also helps reduce the risk of multiple diseases.
Food is not the best source of vitamin D, although some foods are fortified with vitamin D, like milk. Salmon, egg yolks, fortified cereal and orange juice can be good sources of vitamin D.
Let’s take a deeper look at several illnesses that result from a vitamin D deficiency.
Common symptoms of vitamin D deficiency
Symptoms of vitamin D deficiency include bone pain, muscle weakness, fatigue, and mood changes. Many health problems may result in similar symptoms, but they may also point to a vitamin D deficiency. If this sounds familiar, consider talking to your doctor.
Let’s take a deeper dive into some of the health problems that result from a vitamin D deficiency.
Vitamin D deficiency and osteoporosis
A primary role of vitamin D is to promote healthy bones. Low levels of vitamin D lead to low bone calcium stores, increasing the risk of fractures. A vitamin D deficiency may put people at risk for osteoporosis, which happens when new bone doesn’t generate at the same pace as the loss of old bone. Vitamin D plays a key role in bone health including osteoporosis: low vitamin D levels decrease calcium absorption, and calcium absorption is important for bone health.
If you don’t have osteoporosis, you may not need to supplement with vitamin D. A study published in August 2019 in the Journal of the American Medical Association found that among healthy people, supplementing with vitamin D didn’t improve bone health.
Vitamin D deficiency and depression
If you know about seasonal affective disorder (SAD), you may also know that vitamin D deficiency may be linked to a higher risk of depression.
Vitamin D status is connected to your mood. There is research evidence that shows a relationship between mood and vitamin D levels, where deficient vitamin D levels are related to depression.
One study published in April 2017 in the Journal of Diabetes Research, found that vitamin D supplementation helped improve the mood of women with type 2 diabetes. All the women in the small study were given a high dose of vitamin D (50,000 IU weekly) for six months. The researchers found a significant decrease in depression and anxiety.
If you have symptoms of depression like irritability, feelings of emptiness or hopelessness, thoughts of suicide, or appetite changes, consider contacting your doctor to discuss a possible vitamin D deficiency.
Vitamin D and respiratory illnesses
There has been a lot of preliminary research that found vitamin D supplements may be beneficial in preventing or managing COVID-19, the respiratory disease caused by the novel coronavirus. While those studies are still in their early stages, other research shows that vitamin D may help prevent respiratory illnesses.
For example, one study in 2017 looked at data from 25 clinical trials that examined the impact of vitamin D on respiratory infections including pneumonia, bronchitis, and sinusitis.
Of the 11,321 study participants, researchers found that people who took vitamin D were 12 percent less likely to develop respiratory illness compared with people who did not take the vitamin. While that percentage may seem impressive, study authors noted there were limitations. For example, they didn’t have data on who had received a flu shot, which may have affected their risk for respiratory illness.
With regard to the flu, studies have produced a variety of results about vitamin D and flu mitigation or prevention. One study in 2018 found that vitamin D didn’t make the flu shot more effective. However, other research found that school-age children who took vitamin D, compared with a placebo, were 42 percent less likely to get the flu.
The connection is potentially there. 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.
Vitamin D and schizophrenia
Schizophrenia is a severe brain disorder that affects between 0.25 and 0.64 percent of American adults. Symptoms of schizophrenia, which commonly appear between ages 16 and 30, include hallucinations, incoherent speech, delusions, paranoia, catatonia, withdrawal from others, and trouble focusing or paying attention.
People who are vitamin D deficient may be twice as likely to be diagnosed with schizophrenia compared with people with sufficient vitamin D levels. In one study in 2014, Researchers reviewed findings from 19 observational studies that analyzed the possible relationship between schizophrenia and vitamin D deficiency and observed a link between the two factors.
The researchers pointed out that randomized controlled trials are necessary to determine if treatment for low vitamin D may help prevent schizophrenia. They also pointed out that schizophrenia is more prevalent in areas at high altitudes and cold climates. This may suggest a lack of sunshine, thus a lack of vitamin D, may put children at higher risk for schizophrenia. However, more studies are needed.
Although there is no cure for schizophrenia, treatments for schizophrenia include medication, psychosocial therapy, cognitive behavioral therapy, and family education and support groups.
Dementia and vitamin D deficiency
A study published in August 2014 in the journal Neurology found that moderate and severe vitamin D deficiency in older adults was associated with a doubled risk for some forms of dementia, including Alzheimer’s disease. Dementia involves a decline in thinking, behavior, and memory that negatively affects daily life. Alzheimer’s disease is the most common form of dementia, accounting for as many as 80 percent of dementia cases, according to the Alzheimer’s Association.
The study looked at over 1,600 people ages 65 or older who did not have dementia at the beginning of the study. Compared with people who had normal vitamin D levels, those with low levels of the vitamin had a 53% increased risk of developing all-cause dementia, while those who were severely deficient had a 125% increased risk. In addition, the researchers found people who had lower levels of vitamin D were about 70% more likely to develop Alzheimer’s disease specifically, and that those who were severely deficient were over 120% more likely to develop AD.
These studies have been observational. Thus, they don’t prove a direct cause-and-effect relationship between vitamin D deficiency, dementia, and Alzheimer’s.
Regardless of the relationship between vitamin D and dementia, know that following tried-and-true health advice, like eating a healthy diet, exercising regularly, and tending to your mental health can help reduce your risk of dementia.
Vitamin D Deficiency and Diabetes
The connection between low levels of vitamin D and diabetes is clear. The connection is clear, although researchers are working on determining why.
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.
Another possible link is related to the role of vitamin D in inflammation because people with type 2 diabetes also have higher chronic inflammation.
A review published in March 2017 in Biochemical Journal found that when vitamin D is deficient, many cellular processes in the body begin to break down, and this sets the stage for the onset of diseases such as diabetes.
Still, people at risk for diabetes shouldn’t start an aggressive supplement regime. A large, multicenter study called D2d, which was funded in part by the National Institutes of Health, found that it’s still unclear that supplementing with vitamin D prevents type 2 diabetes, since the findings in that well-designed study, which was published in August 2019 in the New England Journal of Medicine, were not statistically significant.
Prostate cancer and low vitamin D
A study published in 2014 found that supplementing with vitamin D can help. A found a link between low blood levels of vitamin D and aggressive prostate cancer in European American and African American men.
Researchers looked at vitamin D levels in 667 men ages 40 to 79 who were undergoing prostate biopsies. The connection between vitamin D and prostate cancer seemed especially strong in African American men, with results suggesting that African American men with low vitamin D levels were more likely to test positive for the cancer than the other men with normal vitamin D levels.
These findings were observational. Still, the research suggests you may help reduce your risk of the disease by ensuring you get adequate vitamin D. You should also make regular doctor’s visits and watch for common prostate cancer symptoms to receive a prompt diagnosis and treatment if you’re affected.
Prostate cancer occurs mostly in older men, with the average age of diagnosis being about 66. Other than skin cancer, it’s the most common cancer in men and the second most common cause of cancer death in American men.
Vitamin D deficiency and heart disease
Numerous studies have shown an association between low vitamin D blood levels and heart disease and related complications, according to a review published in January 2014 in Circulation Research, but science has not clearly established whether supplementation can reduce these risks. The review cites research that points to vitamin D levels as a potential culprit for health problems related to heart disease, including atherosclerosis, high blood pressure, diabetes, and stroke.
You can reduce your risk of heart disease by maintaining a healthy weight, exercising regularly, and eating a diet rich in lean meat, nuts, and fruits and veggies, according to the American Heart Association.