A large Irish study has shown for the first time ever that people from 50 years of age and older, who are vitamin D-deficient, are more likely to develop depression.
The study also showed that vitamin D deficiencies are more widespread among seniors, and that taking a vitamin D supplement can make a significant difference. The study supports earlier studies that also link vitamin D deficiency to an increased risk of depression, including winter depression. It is essential to get enough vitamin D all year round, as the nutrient is important for many different processes in the brain and even helps protect against local inflammation that is associated with depression.
Depression is rather common, especially among older people, where the disease not only impairs their quality of life but may even speed up the ageing process, while sending people into retirement homes ahead of time and even leading to early death. The new study was headed by a team of scientists from the Irish Longitudinal Study on Ageing (TILDA) at Trinity College Dublin. The study shows that lack of vitamin D increases (by 75%) the risk of older people developing depression during a follow-up period of four years. The study is the largest of its kind and is published in JAMDA The Journal of Post-Acute and Long-Term Care Medicine.
Depression is rather complex, and the majority of older people, who thrive poorly, are not even properly diagnosed. It is important to prevent depression, and according to the Irish scientists from Dublin, one must include all risk factors that may be able to trigger a depression, including lack of vitamin D, which is very easy and also inexpensive to deal with.
Vitamin D’s many functions and the widespread deficiency problems
Vitamin D is also known as the “sunshine nutrient” because we produce it when we expose ourselves to sunlight. At our latitude, however, we are only able to synthesize the vitamin when the sun sits sufficiently high in the sky.
Over the past decades, researchers have linked vitamin D deficiencies with a host of different diseases such as osteoporosis, influenza, diabetes, cancer, and inflammatory conditions like sclerosis. All the body’s cells have vitamin D receptors, and that is also case with the cells in our hippocampus and other parts of the brain and nervous system. There are only few studies that have found a link between lack of vitamin D and depression, and only a limited number of studies have followed the study participants for extended periods of time or taken into account other factors that may affect how and if a depression develops.
It has therefore been important to look closer at vitamin D deficiency, as 25% of older people lack the nutrient during the winter period, and around 13 percent lack vitamin D during the summer. Another reason why many people lack vitamin D is that aged and thin skin has difficulty with synthesizing the nutrient.
The study suggests that the brain needs vitamin D
The whole purpose of the new Irish study was to investigate the relation between vitamin D levels in the blood and the risk of developing depression. The scientists studied 4,000 people aged 50 years and older. Those, who had a depression at baseline, were excluded from the study. The researchers then studied the remaining participants after another four years and found that:
- Vitamin D deficiency was associated with a 75% increased risk of developing depression over the four-year period
- The results were the same after the scientists had adjusted for other risk factors such as chronic illness, mental activity, and cardiovascular diseases
- No changes were observed, except in those who took vitamin D supplements or anti-depressive medicine
According to the scientists, the study shows that vitamin D directly affects the brain. Because depressions are characterized by structural and functional changes to the brain, it is possible that vitamin D has a protective effect by pulling the brake on these changes. Also, depression is characterized by local inflammation, and vitamin D has an anti-inflammatory effect. To support this, other studies show that lack of vitamin D is associated with neurodegenerative conditions like dementia, Parkinson’s disease, and sclerosis.
The results are important – and we must not ignore vitamin D deficiency
The new Irish study is the largest and most representative study to link a vitamin D deficiency to the risk of developing depression. The researchers behind the study find the results highly important, as it is comparatively easy and inexpensive to increase people’s vitamin D status with help from vitamin-enriched foods and the use of supplements. In Ireland, it is up to each food manufacturer to decide whether or not he wants to make use of vitamin D enrichment, and only few choose this option.
The study’s results may also even be useful to health authorities by informing how to use vitamin D to help prevent and treat a depression. That way, it is possible to improve quality of life for older people, many of which already suffer from depression without having been diagnosed with the problem.
Vitamin D and winter depression
Many people, women in particular, are prone to feeling depressed during the winter period. An American study that is published in the journal Psychiatry Research shows a link between low levels of vitamin D in the blood and clinical symptoms of depression in otherwise healthy people. Dr. Kerr, who headed the study, points to the fact that blood levels of vitamin D are closely related to the changing seasons. It is therefore a good idea to take a high-dosed vitamin D supplement during the winter period and perhaps a somewhat smaller dosage during the summer, provided one does not get enough sunshine.
|Most Danes only get around 2-4 micrograms of vitamin D from their diets, and that is not enough. Lack of sun during the summer period, winter darkness, ageing, and being overweight all increase the need for the vitamin.|
Official recommendations for vitamin D – and our actual need
The reference intake (RI) for adults is 5 micrograms. The Danish Health Authority recommends a 10-microgram supplement of vitamin D to pregnant women, infants, people with dark skin, and individuals that do not get enough sunlight. Supplements with 20 micrograms are recommended for nursing home residents and people older than 70 years. Many scientists claim that the actual need for vitamin D may be even higher and suggest getting anywhere from 30-100 micrograms per day.
Robert Bruggs et al. Vitamin D Deficiency is Associated With an Increased Likelihood of Incident Depression in Community-Dwelling Older adults
Liam Davenport: Vitamin D Levels Predict Depression. Medscape Medical News 2015
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