“The association between vitamin D deficiency and depressive disorders is well established based on the existing research,” says Dr. Angelos Halaris, professor of psychiatry at Loyola University School of Medicine in Chicago. “In my practice, what I have found is that when patients are not fully responding to antidepressants and their vitamin D blood levels are low, once we add vitamin D supplements the response to medication improves.”
[Read: Vitamin D Benefits.]
What Is Vitamin D Deficiency?
An estimated 200 million Americans are not getting enough vitamin D from sunlight or diet. When your skin is exposed to sunshine, it builds vitamin D from the precursor of cholesterol (7-dehydrocholesterol) in the skin cells. Individuals with fair skin and those who are younger convert sunshine into vitamin D far better than those who are darker-skinned and 70 years and older.
Using data from the National Health and Nutrition Examination Survey from 2011 to 2012, researchers calculated a nearly 40% prevalence rate of vitamin D deficiency among Americans. The highest rates were observed in Blacks and Hispanics.
“Vitamin D deficiency is very common and ongoing research has shown its impact on physical and mental well-being,” says Dr. Michael Holick, professor of medicine, physiology and biophysics at Boston University School of Medicine. “Vitamin D influences many cellular functions in the body through its anti-inflammatory and neuroprotective properties.”
[READ: Signs of Vitamin D Deficiency.]
Signs of Vitamin D Deficiency and Depression
The National Health and Nutritional Examination Survey confirmed that people with vitamin D deficiency are at significantly higher risk of depression than individuals with normal levels. A study from the Netherlands found that those living with depression showed 14% lower circulating concentrations of vitamin D (25-hydroxyvitamin D, a form of vitamin D) than those not diagnosed with depression.
In addition to depressive symptoms, there are several signs of vitamin D deficiency to look for, including:
— Bone weakness (fractures) and aches and pains in bones and muscles, especially in older adults.
— Neurocognitive dysfunction.
— Muscle weakness.
— Poor concentration.
— Rickets, including bone pain, poor growth, soft bones in children.
At the first signs of lingering or significant sadness, talk to your doctor about what might be causing these emotions and whether or not you are experiencing depression.
Signs to look for include:
— Decreased productivity.
— Difficulty thinking or concentrating.
— Diminished interest in socializing or activities.
— Fatigue or decreased energy.
— Irritability or anger.
— Loss of appetite.
— Low self-esteem or lack of motivation.
— Physical aches and pain.
— Reckless behavior, such as alcohol and drugs or gambling.
— Sadness and worthlessness.
— Suicidal thoughts.
— Trouble sleeping or changes in sleeping patterns.
— Weight changes.
Vitamin D and Depression Treatment
While vitamin D deficiency research has been ongoing for several decades, only within the past few years have researchers examined whether vitamin D supplements improve mood and lessen depressive symptoms. “The current research is promising, but we recognize that there needs to be large, well-controlled studies to confirm whether vitamin D supplements have an effect on treating depression,” Halaris says.
Additionally, Halaris points out, there’s an urgent need to establish reliable blood-level ranges that will help doctors to prescribe the right dose of vitamin D supplement. “It should be based on the blood level in conjunction with the intensity of the presenting symptoms.”
Highlights of current research:
A paper, led by researchers at Loyola University in Chicago, examined the use of vitamin D supplements in 46 women living with Type 2 diabetes and depression. The authors found that there was a significant decrease in depression and anxiety, and a trend for a stronger benefit from the vitamin D supplements in women who were not being treated with antidepressants or anti-anxiety medications.
A study published in Nutrition looked at nine trials that included more than 4,900 individuals diagnosed with depression. Using varying levels of vitamin D supplements and intervention periods, the analysis found that there was no significant reduction in depression following treatment with vitamin D supplements.
An Australian researcher examined 15 studies with wide variation in study design and populations. The analysis showed a significant improvement in depression with vitamin D supplementation greater than 800 daily units.
All three acknowledge the need for further research examining the effects of vitamin D supplementation among individuals with depression.
Sources of Vitamin D
The Endocrine Society recommends that most adults, including pregnant and lactating women, should get 1,500 to 2,000 international units of vitamin D each day. Infants under one year of age and children and adolescents 18 and under should receive 400 to 1,000 and 600 to 1,000 units a day, respectively. People with a body mass index of greater than 30 — which indicates levels of overweight or obesity — need two to three times more vitamin D to meet the recommended requirements, according to the Society.
There are very few foods naturally rich in vitamin D. For example, eating 3.5 ounces of salmon may provide about 500 to 1,000 units of the daily recommended levels. A tablespoon of cod liver oil has about 1,300 units of vitamin D. An egg yolk contains approximately 20 international units of vitamin D.
To boost your vitamin D levels, consider adding these supplements and foods to your shopping list:
— Vitamin D supplements. Most multivitamins today include 1,000 units of vitamin D, up from 400 units just a few years ago. Specific vitamin D supplements are also available at pharmacies, vitamin shops and grocery stores.
— UV-exposed foods. Mushrooms contain no vitamin D, but they make vitamin D when exposed to ultraviolet light or sunlight exposure and can be a good dietary source of vitamin D.
— Vitamin D-rich foods. The list of foods naturally rich in vitamin D includes wild-caught salmon, mackerel, tuna, sardines and other fatty fish, cod liver oil and egg yolk.
— Vitamin D-fortified foods. Examples include orange juice, milk and cereal.
One key misperception is that tanning beds and sun lamps are a good source of vitamin D because they mimic sunlight. Some of the bulbs used in tanning beds emit only UVA light and therefore are unable to produce vitamin D in human skin. However, most tanning beds emit a small amount of UVB light thereby producing some vitamin D in the skin. Tanning sessions come with a major downside by increasing the risk of skin cancer such as melanoma, squamous cell carcinoma and basal cell carcinoma.
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Update 11/21/22: This story was previously published at an earlier date and has been updated with new information.