Depression

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What is depression?

We all feel fed up, miserable and sad at certain times in our lives. Most of the time, these feelings last for a week or two and don’t interfere with our day-to-day lives. Often times, speaking with a friend or family member will help ease these feelings. However, if you have depression, these feelings don’t improve and may carry on for weeks or months.

Depression can vary from mild to severe. In mild cases, you may feel low in spirits but can carry on with your everyday life; though, it may feel more challenging and less enjoyable. When depression is at its most severe it may lead to an inability to function in everyday life, asocial behavior, decreased interests, low energy, impairments in memory and concentration, ruminations of guilt and suicidal thoughts.

How common is depression?

Depression is a common condition. In the United States around 1 in 10 people have depression, and around 1 in 3 of these cases will have a severe case. You’re more likely to have depression if you:[1]

  • Have a long-term health problem, such as diabetes, heart disease or arthritis
  • Lead an unhealthy lifestyle; for example if you smoke, drink heavily, are inactive or overweight
  • Are female
  • Are between 45-64 years of age
  • Are black or Hispanic

What does depression feel like?

The symptoms of depression can come on gradually and may go unnoticed for some time. When this happens, it is often a friend or family member to first notices how your behavior and personality have changed.  Sometimes the symptoms of depression can be physical, and you may think you’re just under the weather or tired.

Below are some of the main symptoms of depression; although symptoms range from person to person.[2],[3]

  • Lose interest in life and can’t enjoy anything
  • Find it difficult to make decisions or concentrate
  • Feel unhappy most of the time
  • Feel tired and have problems sleeping
  • Lose confidence and self esteem
  • Avoid being with other people
  • Feel numb, despairing and empty
  • suicidality

If you have these symptoms, and they have lasted for more than a few weeks, talk to your physician.

What causes depression?

Depression is a biological disease, like multiple sclerosis, It has a strong genetic characteristic. Depression can be triggered by a number of different things. Sometimes there is one main trigger, such as the death of a loved one, but there a number of different factors that may play a part. Although the factors leading to depression differs between individuals, the most common triggerss include:[4]

  • Major life changes, such as divorce, changing your job, moving home or the death of a loved one.
  • Physical illness – particularly life threatening illness such as cancer, painful conditions such as arthritis and hormonal problems such as an underactive thyroid gland.
  • Personal circumstances – being alone or stressed for example
  • Family history of depression – if your parent has depression, you’re much more likely to have it yourself.
  • Individual personality traits – some people seem to be more vulnerable to depression. This may be due to early life experiences or genetic predisposition.
  • Regular heavy drinking

What is the link between depression and vitamin D?

Vitamin D plays a vital role in bone health and researchers are now discovering that vitamin D may play a role in many other areas of health also.

Vitamin D receptors have been found in many parts of the brain.[5] Receptors are found on the surface of a cell where they receive chemical signals. By attaching themselves to a receptor, these chemical signals direct a cell to do something, for example to act in a certain way, or to divide or die.

Some of the receptors in the brain are receptors for vitamin D, which means that vitamin D is acting in some way in the brain. These receptors are found in the areas of the brain that are linked to the development of depression. For this reason, vitamin D has been linked with depression and with other mental health problems.

Exactly how vitamin D works in the brain isn’t fully understood. One theory is that vitamin D affects the amount of chemicals called monoamines, such as serotonin, and how they work in the brain.5 Many anti-depressant medications work by increasing the amount of monoamines in the brain. Therefore, researchers have suggested that vitamin D may also increase the amount of monoamines, which may help treat depression.[6]

What does the research say in general about vitamin D and depression?

The amount of research about vitamin D and depression, as well as other mental health problems, is growing. It’s only recently that large scaled studies on vitamin D and depression have been conducted.

The research in this area has given some conflicting results..[7]

Some of the reasons why mixed results have been produced from studies on vitamin D and depression include:

  • The use of different dosages of vitamin D supplements for different lengths of time
  • Varying parameters defining vitamin D sufficiency and efficacy of treatment
  • Different study populations, that is studying people without depression
  • The use of different tools to measure depression and mental health
  • Administering vitamin D at different frequencies – in some studies, people are asked to take vitamin D every day, whereas in other studies, people take vitamin once a week.
  • Failure to obtain baseline and final 25(OH)D levels to confirm levels were raised in the treatment group
  • Studying subjects who have relatively high baseline levels

In some research studies, the amount of vitamin D given has been small, much less that the 5000 IU a day that the Vitamin D Council recommends. Insufficient doses of vitamin D  decreases the likelihood of producing significant clinical findings.

Due to the variability in research studies, and because this is a relatively new area of research, it’s very difficult to say with any certainty what role vitamin D has in either preventing or treating depression.

So, what does recent research tell us about vitamin D levels and depression?

There are a number of strong research studies from the last few years that looked specifically at vitamin D levels and depression.

In a review of the research about vitamin D and depression in 2013,[8] researchers  analyzed all of the published research about depression and vitamin D up until February 2011. They included the high quality research studies that explored whether:

  • a lack of vitamin D in the blood is linked with being depressed
  • a lack of vitamin D in the blood makes it more likely an individual will develop depression
  • taking a vitamin D supplement can improve or prevent depression

The researchers found more than 5000 research articles; however, just 13 explored this area effectively. More than 31000 people took part in these 13 studies. The results showed that there is a relationship between low levels of vitamin D in the blood and depression. However, the research didn’t show whether vitamin D was the cause or effect of depression. There was also no clear answer as to whether taking supplements was effective at treating or preventing depression.

A 2008 research study from Norway[9] found that people with a low level of vitamin D in their blood had more symptoms of depression. This research also found that taking vitamin D, particularly in large amounts, improved the symptoms of depression. The biggest effect happened in those people with more severe symptoms.

However, this research only looked at people that were overweight, so it’s not possible to say whether the results would be similar for everyone. All of the participants also took a calcium supplement, and the researchers suggest that this could have affected the results; for example the effects may be attributed to the combination of vitamin D and calcium, rather than vitamin D on its own.

An analysis of Internet searches on “depression” over the period 2004-2009 found wintertime peaks in 54 geographical locations, including Australia and the United States.[10] The authors considered this finding evidence for the seasonal occurrence of depression. Vitamin D levels are lowest in winter, which might explain much of the findings.

A second research study from Norway[11] looked at whether the symptoms of depression were related to vitamin D blood levels. The study also looked at whether taking a vitamin D supplement affected the symptoms of depression in people who had low vitamin D levels. The results showed that:

  • low levels of vitamin D in the body are linked to the symptoms of depression
  • when people with low vitamin D levels took a supplement, it improved their vitamin D levels, but had no effect on their symptoms of depression
  • low vitamin D levels could be the result, rather than the cause of depression

Although this study used a sufficient dosage of vitamin D supplement, it lasted only six months. The researchers suggest that because depression is a condition that tends to develop slowly and last a long time; a longer study might have shown different results. The study participants also had either no symptoms of depression or very mild symptoms, possibly influencing the results.

A study of young adults in New Zealand found that there was a modestly higher depression score for those with lower vitamin D levels.[12] There was no difference in the time spent outdoors between those with a lower or higher depression score.

A study of people who suffered ischemic stroke caused by blood clot in China found that six months after the stroke, those with vitamin D levels below 11 ng/mL had a much higher prevalence of depression than those with higher concentrations.[13]

A study in Sweden found that those who attempted suicide had significantly lower vitamin D levels than non-suicidal depressed patients or healthy controls.[14] They also had higher concentrations of pro-inflammatory cytokines, which have been observed in other suicidal patients. Cytokines are small proteins emitted by cells to signal other cells. Vitamin D is known to reduce the levels of pro-inflammatory cytokines.

A 20-year study in Iowa found that for people with major depressive disorder, there was a slight increase in depressive symptoms in the winter months, peaking in March. However, new episodes were highest from October through January, peaking in January.[15]

A study in The Netherlands involving 1102 people aged 18-65 years with current depressive disorder and 790 with former but not current depressive disorder found lower vitamin D levels among those with current depressive disorder and lower symptom severity for those with higher vitamin D levels. There was also a significant correlation between vitamin D status and developing depressive symptoms at a 2-year follow up.[16]

A cross-sectional study in Finland found a significant inverse correlation between depressive disorder and vitamin D status. Those with vitamin D levels above 22 ng/mL (56 nmol/L) had a 35% lower risk of depressive disorder than those with vitamin D levels below 14 ng/mL (34 nmol/L).[17] However, since a cross-sectional is essentially a snapshot of people and their health, the results are not as strong as those from most other study designs.

Vitamin D and depression in women

A study published in 2012[18] from researchers in the United States showed that there was no difference in depression symptoms between those women who took vitamin D and those women who took dummy tablets.

The study looked at a very large group of women and was the first study of this kind to do so.  Though, the study used a very small dosage of vitamin D, 400 IU daily. For this reason, the researchers suggest that the amount of vitamin D that the women took may have been too small to have an effect on the symptoms of depression. The participants taking vitamin D also took a calcium supplement, and the researchers also suggest that this could have affected the results. For example it could be vitamin D and calcium together, rather than vitamin D on its own, that effects depression.

Another study from 2012[19] showed that taking vitamin D supplements had no effect on depression in older women. The women in the study took either a vitamin D supplement, or hormone therapy, or both together.  Researchers also took blood samples to see whether there was a link between the symptoms of depression and vitamin D receptors on the cells of the body. No link was found.

This was a large, high quality research study, which ran for a long time (three years). However, the researchers suggest that there may not have been enough women with depression who also had very low levels of vitamin D taking part, and this may have affected the results.

A study in Japan involving pregnant women found that those obtaining an average of 340 IU/d vitamin D3 had half the risk of depression as those obtaining 124 IU/d.[20] It appears that much of the vitamin D was obtained from dietary fish, but that fish oil did not affect the findings.

A recent meta-analysis of “good” studies (ones that met most or all of the condition outlined above) concluded vitamin D is as an effective anti-depressant as prescription antidepressants.

Key points from research

  • Research does seem to show a link between low levels of vitamin D in the blood and symptoms of depression.
  • Research hasn’t yet shown clearly whether low vitamin D levels cause depression, or whether low vitamin D levels develop because someone is depressed
  • Lack of vitamin D may be one of many factors that contribute to a depressed mood. There are many of factors  that cause depression, such as genetics, which means it’s difficult to say for certain that when depression improves it is vitamin D that is causing the improvement.
  • The effects of vitamin D on depression may take a long time to work, years for example.[21] This means that research carried out over short periods of time may not show any impact of vitamin D on depression.
  • People who have depression go outdoors less, so they are less likely to have adequate vitamin D in their blood.
  • Some researchers have suggested that giving vitamin D supplements may work for depression when someone has very low levels of vitamin D to begin with. Taking a vitamin D supplement may work less well for people who already have sufficient vitamin D levels.
  • Taking vitamin D may only have a role to play if an individual is already depressed.

What does this mean for me?

Research does seem to show that there is a link between vitamin D and depression. However, we don’t know exactly what that link is.

Research has not yet clearly shown whether low levels of vitamin D cause depression, or whether depression causes low levels of vitamin D. This means that we don’t know whether taking a vitamin D supplement, or getting more vitamin D by exposing the skin to the sun, will help to prevent or ease the symptoms of depression in some people. Depression has many causes. It looks as if vitamin D deficiency is one of many causes. .

If you have depression and want to take vitamin D, it is unlikely to make your symptoms worse or cause you any harm (as long as you’re taking less than 10,000 IU/day). However, you may not see any improvement in your symptoms either.

If you have depression you shouldn’t take vitamin D in place of other treatments or anti-depressant medicines. Speak to your physician for more advice about treatments and taking supplements.

Did you know?

Exposing your skin to the sun to get vitamin D enhances your mood and energy. Generally, a little bit of sun exposure is linked to a better mood, while tanners commonly report feeling more relaxed than non-tanners. One research study found that β-endorphins increase after sun exposure, and β-endorphins make you feel good! Thus, those feeling depressed should try to spend some time in the sun when one’s shadow is shorter than one’s height, daily if possible.

References

[1]  Treatment Works: Get Help for Depression and Anxiety. Centers for Disease Control and Prevention.

[2] Depression. Royal College of Psychiatrists.

[3] Depression. Mind, the mental health charity.

[4] Depression. Royal College of Psychiatrists.

[5] Eyles, D.W., Smith, S., Kinobe, R., et al., Distribution of the vitamin D receptor and 1 alpha-hydroxylase in human brain. J Chem Neuroanat, 2005. 29(1): p. 21-30.

[6] Kjaergaard, M., Waterloo, K., Wang, C.E, et al., Effect of vitamin D supplement on depression scores in people with low levels of serum 25-hydroxyvitamin D: nested case-control study and randomised clinical trial. Br J Psychiatry, 2012. 201(5): p. 360-8.

[7] Anglin, R.E., Samaan, Z., Walter, S.Det al., Vitamin D deficiency and depression in adults: systematic review and meta-analysis. Br J Psychiatry, 2013. 202: p. 100-7.

[8] Anglin, R.E., Samaan, Z., Walter, S.Det al., Vitamin D deficiency and depression in adults: systematic review and meta-analysis. Br J Psychiatry, 2013. 202: p. 100-7.

[9] Jorde, R., Sneve, M., Figenschau, Y, et al., Effects of vitamin D supplementation on symptoms of depression in overweight and obese subjects: randomized double blind trial. J Intern Med, 2008. 264(6): p. 599-609.

[10] Yang AC, Huang NE, Peng CK, Tsai SJ. Do seasons have an influence on the incidence of depression? The use of an internet search engine query data as a proxy of human affect. PLoS One. 2010;5(10):e13728.

[11] Kjaergaard, M., Waterloo, K., Wang, C.E, et al., Effect of vitamin D supplement on depression scores in people with low levels of serum 25-hydroxyvitamin D: nested case-control study and randomised clinical trial. Br J Psychiatry, 2012. 201(5): p. 360-8.

[12] Polak, M.A., Houghton, L.A., Reeder, A.I., et al., Serum 25-hydroxyvitamin D concentrations and depressive symptoms among young adult men and women. Nutrients, 2014. 6(11): p. 4720-30.

[13] Yue, W., Xiang, L., Zhang, Y.J., et al., Association of serum 25-hydroxyvitamin D with symptoms of depression after 6 months in stroke patients. Neurochem Res, 2014. 39(11): p. 2218-24.

[14] Grudet, C., Malm, J., Westrin, A., et al., Suicidal patients are deficient in vitamin D, associated with a pro-inflammatory status in the blood. Psychoneuroendocrinology, 2014. 50: p. 210-9.

[15] Cobb BS, Coryell WH, Cavanaugh J, et al. Seasonal variation of depressive symptoms in unipolar major depressive disorder. Compr Psychiatry. 2014;55(8):1891-9.

[16]  Milaneschi Y, Hoogendijk W, Lips P, et al. The association between low vitamin D and depressive disorders. Mol Psychiatry. 2014 Apr;19(4):444-51.

[17] Jääskeläinen T, Knekt P, Suvisaari J, et al. Higher serum 25-hydroxyvitamin D concentrations are related to a reduced risk of depression. Br J Nutr. 2015;113(9):1418-26.

[18] Bertone-Johnson, E.R., Powers, S.I., Spangler, L., et al., Vitamin D supplementation and depression in the women’s health initiative calcium and vitamin D trial. Am J Epidemiol, 2012. 176(1): p. 1-13.

[19] Yalamanchili, V. and J.C. Gallagher, Treatment with hormone therapy and calcitriol did not affect depression in older postmenopausal women: no interaction with estrogen and vitamin D receptor genotype polymorphisms. Menopause, 2012. 19(6): p. 697-703.

[20] Miyake, Y., Tanaka, K., Okubo, H., et al., Dietary vitamin D intake and prevalence of depressive symptoms during pregnancy in Japan. Nutrition, 2015. 31(1): p. 160-5.

[21] Dean, A.J., Bellgrove, M.A., Hall, T., et al., Effects of vitamin D supplementation on cognitive and emotional functioning in young adults–a randomised controlled trial. PLoS One, 2011. 6(11): p. e25966.

This page was last updated December 22, 2015.

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