What is Vitamin D?
Vitamin D is a steroid vitamin, a group
of fat-soluble prohormones, which encourages the absorption and metabolism of
calcium and phosphorous. People who are exposed to normal quantities of
sunlight do not need vitamin D supplements because sunlight promotes sufficient
vitamin D synthesis in the skin. Five forms of vitamin D have been discovered,
vitamin D1, D2, D3, D4, D5.
The two forms that seem to matter to humans the most are vitamins D2
(ergocalciferol) and D3 (cholecalciferol).
What do we need
vitamin D for?
- It is crucial for the
absorption and metabolism of calcium and phosphorous, which have various
functions, especially the maintenance of healthy bones.
- It is an immune system
regulator.
- It may be an important way
to arm the immune system against disorders like the common cold, say
scientists from the University of Colorado Denver School of Medicine,
Massachusetts General Hospital and Children's Hospital Boston.
- It may reduce the risk of
developing multiple sclerosis. Multiple sclerosis is much less common the
nearer you get to the tropics, where there is much more sunlight,
according to Dennis Bourdette, chairman of the Department of Neurology and
director of the Multiple Sclerosis and Neuroimmunology Center at Oregon
Health and Science University, USA.
- Vitamin D may have a key
role in helping the brain to keep working well in later life, according to
a study of 3000 European men between the ages of 40 and 79.
- Vitamin D helps to prevent Alzheimer's Disease, based on multiple studies.
- Vitamin D is probably
linked to maintaining a healthy body weight, according to research carried
out at the Medical College of Georgia, USA.
- It can reduce the severity
and frequency of asthma symptoms, and also the likelihood of
hospitalizations due to asthma, researchers from Harvard Medical School
found after monitoring 616 children in Costa Rica.
- It has been shown to
reduce the risk of developing rheumatoid arthritis in women.
- A form of vitamin D could
be one of our body's main protections against damage from low levels of
radiation, say radiological experts from the New York City Department of
Health and Mental Hygiene.
- Various studies have shown that people with adequate levels of vitamin D have a significantly lower risk of developing cancer, compared to people with lower levels. Vitamin D deficiency was found to be prevalent in cancer patients regardless of nutritional status, in a study carried out by Cancer Treatment Centers of America.
Vitamin D and
depression
On top of all the
positive impact on the health, which has been mentioned before, a number of
studies report also certain connection between vitamin D levels and the risk of
depression. Low vitamin D levels may be related to depression rather than
contributing to the disorder. In addition, an increased risk of depression may
be related to several vitamin D–sensitive diseases.
For example:
- Elderly Dutch community residents with minor or
major depression had vitamin D blood levels that were 14% lower than
residents without depression.
- Italian women with lower vitamin D levels - less
than 20 ng/mL (50 nmol/L) - had twice the risk of developing depression.
For Italian men, the risk was increased 60%.
- Postmenopausal women with one vertebrae fracture had
20% more depressive symptoms than women without a fracture. Women with at
least three vertebrae fractures had three-fold the rate of depression
compared to women without multiple fractures. Low vitamin D levels are an
important risk factor for vertebral fracture.
- Syrian women with heart disease, high blood
pressure, or kidney disease were three times more likely to have
depression. Syrian men with rheumatism and respiratory disease had an even
greater risk of depression. There is good evidence that low vitamin D
levels are a risk factor for all of these diseases.
- A lifetime history of depression may be a risk
factor for later development of Alzheimer's disease. Depression may
increase the risk of mild cognitive impairment that turns into
Alzheimer's. Patients with Alzheimer’s and depression have more pronounced
hallmarks of the Alzheimer’s brain than patients with Alzheimer’s who are
not depressed. Studies indicate vitamin D deficiency may also be a risk
factor in Alzheimer’s.
- One study showed that, in the United States, vitamin
D deficiency occurred more often in certain people. These people were
African-Americans, living in cities, obese, and depressed. People with
vitamin D levels below 20 ng/mL (50 nmol/L) had an 85% increased risk of
depression compared to those with vitamin D levels greater than 30 ng/mL
(75 nmol/L).
A new research, completed by UT Southwestern Medical Center in 2011, positively confirmed the previous
studies’ outcomes that low levels of vitamin D and depression are indeed going
hand in hand. People with the lowest levels of vitamin D were more likely to
report symptoms of depression, compared to people with higher blood levels of
vitamin D. This relationship was strongest among people with a history of
depression.
How vitamin D works
Exactly how vitamin
D and depression may be linked is not exactly clear yet. Vitamin D deficiency
may result in depression, or depression may increase risk for low vitamin D
levels.
For example,
depressed people may spend more time indoors, and are less likely to eat a
healthy diet and take care of themselves, all of which could affect vitamin D
levels. On the other hand, there are vitamin D receptors everywhere in the
body, including the brain. These receptors need vitamin D to do their job.
Based on the
proposed explanations, vitamin D may lower the risk of depression by:
- Reducing the risk of diseases that may trigger depression,
such as cancer, cardiovascular disease, and multiple sclerosis.
- Vitamin
D may affect neurotransmitters, inflammatory markers and other factors,
which could help explain the relationship with depression.
- Reducing the production of cytokines. Cytokines are
proteins that increase inflammation and have been shown to be a possible
risk factor for depression.
- Vitamin
D is believed to play a role in maintaining the brain’s signaling pathways
and reducing inflammation. Not enough D and inflammation degrades brain
cells in a way that leads to depression symptoms—feeling tired all the
time, an inability to enjoy your favorite things, and even thoughts of
suicide.
Yes, some of the statements above interconnect each other, and the key
consideration is that vitamin D fights with inflammation, which might play a
substantial role in the depression development.
Prevention
There are no reported
studies showing that vitamin D supplements reduce the risk of depression.
However, given the evidence, it is possible that vitamin D could have a
positive effect on those who suffer from depression.
Based on studies of
cancer, cardiovascular disease, and influenza, vitamin D levels above 40 ng/mL
(100 nmol/L) may reduce the risk of depression.
Treatment
Treating vitamin D
deficiency in people with depression may result in improvement in long-term
health and quality of life.
According to a
recent review, treating vitamin D deficiency in people with depression or other
mental disorders may result in improvement in both long-term health and quality
of life. Reports confirm that vitamin D has a positive effect on depression:
- Women in Washington State increased their vitamin D
levels to 47 ng/mL (118 nmol/L) by taking 5000 IU of vitamin D each day
during the winter. In some of these women, their depressive symptoms
lessened as indicated by the decrease in their scores on a depression
test.
- Overweight and obese Norwegian women took 20,000 or
40,000 IU per week of vitamin D and their symptoms of depression
decreased. Their scores were also lower on a depression test.
- Based on studies of other diseases, vitamin D blood levels of 40–50 ng/mL (100–125 nmol/L) appear to reduce the severity of depression.
The Institute of Medicine recently raised its recommendations for vitamin
D. The institute recommends that people aged 1 to 70 take 600 international
units (IUs) of vitamin D per day, and people older than 71 should aim for 800
IUs.
Sources
and Additional Information:
