Vitamin D is created from direct sunlight on the skin when outdoors. Vitamin D helps regulate the amount of calcium and phosphate in the body. These nutrients are needed to keep bones, teeth and muscles healthy. People that lack the vitamin may experience achy bones. A more subtle sign is a change in a person’s mood.
According to Holland and Barrett, a common sign is a low mood. As the health body explained: “The so-called happy hormone (serotonin) falls with lack of sun exposure. If you feel low or irritable, it could be a sign.”
The relationship between vitamin D and mood is backed by growing evidence. One study conducted a review of more than 100 leading articles and found a relationship between vitamin D and seasonal depression.
“Seasonal affective disorder is believed to affect up to 10 percent of the population, depending upon geographical location, and is a type of depression related to changes in season,” said Alan Stewart of the University of Georgia College of Education.
He added: “People with SAD have the same symptoms every year, starting in fall and continuing through the winter months.”
Stewart said, based on the team’s investigations, vitamin D was likely to be a contributing factor in seasonal depression.
As he explained: “We believe there are several reasons for this, including that vitamin D levels fluctuate in the body seasonally, in direct relation to seasonally available sunlight.
“For example, studies show there is a lag of about eight weeks between the peak in intensity of ultraviolet radiation and the onset of SAD, and this correlates with the time it takes for UV radiation to be processed by the body into vitamin D.”
Vitamin D is also involved in the synthesis of serotonin and dopamine within the brain, both chemicals linked to depression, according to the study researchers.
“Evidence exists that low levels of dopamine and serotonin are linked to depression, therefore it is logical that there may be a relationship between low levels of vitamin D and depressive symptoms,” said Michael Kimlin, a Cancer Council Queensland Professor of Cancer Prevention Research.
Another study revealed a link between a lack of vitamin D and depression in later life.
The study, published in The Journal of Post-Acute and Long-Term Care Medicine (JAMDA), showed for the first time in Ireland that a deficiency in vitamin D was associated with a substantial increased risk of depression (75 per cent) over a four-year follow up period.
The study investigated the links between vitamin D and depression in older Irish adults and then re-examined the participants four years later to see if vitamin D status affected the risk of developing depression.
The authors found that:
Vitamin D deficiency was associated with a 75 per cent increase in the risk of developing depression by four years
This finding remained robust after controlling for a wide range of relevant factors including depressive symptoms, chronic disease burden, physical activity and cardiovascular disease
Furthermore, excluding participants taking anti-depressant medication and vitamin D supplementation from the analyses did not alter the findings
Commenting on the significance of the research, first author of the study and Specialist Registrar in Geriatric Medicine, St James’ Hospital Dublin, Dr Robert Briggs, said: “This is the largest representative and most comprehensive study of depression risk and vitamin D status in older adults ever conducted in Ireland. Our findings will provide useful information to help inform public health policy — particularly regarding the proposition of the usefulness of vitamin D treatment/supplementation for depression.”
Senior author of the study, and Research Fellow with TILDA, Dr Eamon Laird, added: “This study shows that vitamin D is associated with a health condition other than bone health. What is surprising is the large effect on depression even after accounting for other control variables. This is highly relevant for Ireland as our previous research has shown that one in eight older adults are deficient in the summer and one in four during the winter. Moreover, only around eight per cent of older Irish adults report taking a vitamin D supplement.”
“Given that vitamin D is safe in the recommended intakes and is relatively cheap, this study adds to the growing evidence on the benefits of vitamin D for health. It also helps to continue to impress the need on our public health bodies to develop Irish vitamin D recommendations for the general public. Up to this point, these are severely lacking.”
According to the NHS, from about late March/early April to the end of September, most people should be able to get all the vitamin D they need from sunlight.
Vitamin D is also found in a small number of foods.
- Oily fish – such as salmon, sardines, herring and mackerel
- Red meat
- Egg yolks
Fortified foods – such as most fat spreads and some breakfast cereals
“Another source of vitamin D is dietary supplements,” noted the health body.
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