Table of Content

• Symptoms of depression and vitamin D deficiency

• Risk factors for vitamin D deficiency

• Mechanism of action of vitamin D on reducing depressive symptoms

• Effect of vitamin D supplements on depressive symptoms

• Vitamin D dosage

• Take-Home Points

• FAQ on Can Vitamin D Help Ward Off Depression

Introduction

Vitamin D, or the sunshine vitamin (the body can produce it when your skin gets exposed to the sun), is an essential, fat-soluble nutrient that promotes cell growth and immune function and keeps bones healthy and strong. The two major forms of vitamin D are vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol).

Depression is a common mental disorder. The WHO reports show that about 280 million people have depression. Depression can cause the affected person to suffer considerably, function poorly, and even could lead to suicide. Researchers have noted that many patients with depression also have low circulating vitamin D levels in their blood. Though the potential benefit of vitamin D is not precisely clear, improvements in symptoms of depression were seen in patients after they started taking vitamin D supplements. However, additional large-scale studies are needed to establish that vitamin D supplementation could play a role in preventing and treating depression.

Symptoms of depression and vitamin D deficiency

Depression and vitamin D deficiency have different symptoms, but one can experience both conditions simultaneously. 

Symptoms of depression include

• Overwhelming feelings of desperation, helplessness, and sadness.

• Insomnia 

• Hypersomnia

• Loss of appetite

• Loss of interest 

• Forgetfulness

• Lethargy

• Headaches or back pains

• Excessive weight loss or weight gain

• Concentration issues

• Loss of sexual interest

• Anxiety

• Thoughts of death or suicide

Symptoms of vitamin D deficiency include:

• Fatigue 

• Pain and weakness in your joints and muscles

• Aching bones

Vitamin D deficiency causes rickets in children, where the bones become soft, weak, deformed, and painful. In adults, vitamin D deficiency causes osteomalacia, which causes bone pain and muscle weakness.

Risk factors for vitamin D deficiency

There are several risk factors for vitamin D deficiency, they include:

1. Limited sun exposure

Sun is the primary source of vitamin D for many people. The human body can produce vitamin D when the skin gets exposed to the sun, hence known as the sunshine vitamin. Sun exposure depends on factors like the time of year, the time of day, and the local climate.

2. Diet

Certain foods are naturally rich in vitamin D, like fish liver oils, animal fats, vitamin D-fortified orange juice, cereal, salmon, mackerel, etc. Not including vitamin D rich food items on a diet could lead to vitamin D deficiency.

3. Age 

As one ages, the human body becomes less efficient at producing vitamin D.

4. Obesity

Compared to people with an average weight, people with obesity may need to absorb more additional vitamin D to reach recommended nutrient levels. 

5. Geographical location

People farther away from the equator are likely to have lower vitamin D levels as they get less sun exposure.

6. Dark skin tone

People with dark skin tones have high melanin content. Melanin appears to interfere with vitamin D production in the body. 

Mechanism of action of vitamin D on reducing depressive symptoms

The action of vitamin D in lowering depressive symptoms is indistinct. However, there are various mechanisms by which vitamin D may improve psychological symptoms. 

Research studies show that the increased neural calcium levels due to increased glutamate are a significant factor for the onset of depression. Vitamin D modulates the expression of buffers and calcium pumps, decreasing calcium levels and controlling calcium signaling pathways. Moreover, vitamin D induces the transcription of serotonin synthesizing gene tryptophan hydroxylase 2 in the brain, which contains a vitamin D response element and contributes to improving psychiatric symptoms. Additionally, vitamin D activates receptors in the brain in areas in which it regulates behavior, promotes neurotrophin release, and protects the brain against oxidative damage and inflammation. 

Effect of vitamin D supplements on depressive symptoms

1. A study on the impact of vitamin D supplements on symptoms of depression was conducted in obese and overweight persons. 

Participants in this clinical trial were randomized into one of three groups where vitamin D (20,000 IU cholecalciferol) was given once per week, twice per week, or not at all (placebo) for one year. All participants received 500 mg of calcium supplementation daily. Findings showed that for the two groups that received vitamin D, there was a significant improvement in depression which was more prominent in those with higher depression at baseline.

However, the clinical trial included only overweight and obese adults. And participants did not have to have depression at baseline to be a part of the trial.

2. A randomized trial investigated the effect of vitamin D supplementation on well-being. Well-being was measured using a brief questionnaire based on conventional depression screening tools. One group of patients received 600 IU daily; the other group received 4000 IU daily for three months. Both groups saw significant improvement in well-being over time after treatment. Although the group receiving the higher dose had a more substantial response than the lower dose group, the difference was not statistically significant.

3. A meta-analysis in 2019 integrated the results of clinical trials providing vitamin D supplements to participants with depression and reported a significant decrease in several laboratory values related to inflammation. However, it is indefinite whether these changes were accountable for an antidepressant effect or whether other benefits were coinciding.

A recent meta‐analysis and systematic review on the effect of vitamin D supplementation on depressive symptoms in adults concluded that vitamin D supplementation equal to or exceeding 2,000 IUs every day might help lower depressive symptoms. However, they noted their results have extremely low certainty.

Vitamin D dosage

The amount of vitamin D required depends on factors like age, ethnicity, geographical location, season, clothing, etc. Talking with a healthcare provider and checking vitamin D levels before taking higher doses is essential.

The NIH (National Institutes of Health) recommends an average daily intake of 10 – 20 micrograms or 400 – 800 IU. However, some studies suggest a higher daily intake of 25 – 100 micrograms or 1,000 – 4,000 IU is required to maintain optimal blood levels.

25(OH)D is the body’s storage form of vitamin D. Thus, measuring 25(OH)D in the blood helps assess vitamin D levels.

The IOM (Institute of Medicine) and the Nordic Nutrition Council base their advice on the following blood levels:

• Deficient: 25(OH)D less than 12 ng/ml or 25 nmol/l.

• Insufficient: 25(OH)D less than 20 ng/ml or 50 nmol/l.

• Sufficient: 25(OH)D greater than 20 ng/ml or 50 nmol/l.

Specialists, including the Endocrine Society, suggest aiming for higher blood levels nearer to 30 ng/ml or 75 nmol/l. Taking high doses of vitamin D without the help of a medical expert over time could lead to vitamin D toxicity, resulting in increased calcium levels, digestive problems, kidney stones, and neurological changes.

Sources of vitamin D

1. Sun exposure

The best technique to maintain healthy vitamin D levels is sun exposure to the legs and arms for five to ten minutes, two or three times per week. But the amount of sunlight needed varies, and unprotected sun exposure increases cancer risk. 

2. Nutritional sources of vitamin D

Very few foods contain considerable amounts of vitamin D.

• oily fish – such as salmon, sardines, and mackerel.

• egg yolks

• red meat

• liver

• fortified foods – some fat spreads and cereals.

Take-Home Points

• Studies show that people with depression have low vitamin D levels. Though the potential benefit of vitamin D is not precisely clear, improvements in symptoms of depression were seen in patients after they started taking vitamin D supplements. However, investigation findings on this potential link are mixed.

• Symptoms of vitamin D deficiency and depression are different, but it’s possible to experience both conditions simultaneously. The risk factors for vitamin D deficiency include age, darker skin, obesity, limited sun exposure, etc. 

• A meta‐analysis and systematic review on the effect of vitamin D supplementation on depressive symptoms in adults concluded that vitamin D supplementation equal to or exceeding 2,000 IUs every day might help lower depressive symptoms. However, they noted their results have extremely low certainty.

• The NIH (National Institutes of Health) recommends an average daily intake of 10–20 micrograms or 400–800 IU. However, some studies suggest a higher daily intake of 25–100 micrograms or 1,000–4,000 IU is required to maintain optimal blood levels. Specialists, including the Endocrine Society, suggest aiming for higher blood levels (25(OH)D) nearer to 30 ng/ml or 75 nmol/l. 

• The sources of vitamin D are sunshine, fatty fish, fish liver oils, egg yolks, fortified foods, and supplements.