Many studies have linked high levels of vitamin D in the body with the reduction in diseases such as cancer and Parkinson's disease. Recent studies have now shown that vitamin D also has the potential to combat forms of depression, mood disorders and mental decline.

Depression

Two recent studies have linked low vitamin D levels with mood disturbance.[1,2]. One study looked at the effects of vitamin D deficiency in the elderly, and found a link between reduced cognitive function in people with low levels of this vitamin.

Another study published in 2008 in the Journal of Internal Medicine found that low vitamin D status was associated with more severe depressive symptoms [3]. This study treated 441 overweight or obese individuals with either 20,000 international units (IU) or vitamin D per week, 40,000 IU per week, or placebo for a period of 1 year.

The results showed vitamin D therapy, compared to placebo, led to significant improvement in depressive symptoms. These results suggest that vitamin D deficiency has the ability to cause depression, and it adds to the growing evidence that keeping vitamin D levels up may help to combat depression, particularly in the winter when vitamin D levels tend to be at their lowest.

Seasonal Affective Disorder (SAD)

Seasonal Affective Disorder (SAD) is a condition in which a shortage of sun can trigger varying mood changes and depression in people with normal mental health. It is associated with the shorter days of winter, and sufferers are advised to seek increased sunlight exposure.

It is already known that sunlight can stimulate the production of vitamin D in the skin, but research has now shown that this vitamin also has important benefits for the brain [4]. A study looked at individuals who were treated with either small doses (600 IU) or higher doses (4000 IU) of vitamin D each day for at least six months. Both dosages of vitamin D led to improvements in the participants' mood and general well-being, with those on the higher dose of vitamin D benefiting the most.

Mental Decline

New research has found that vitamin D can help to keep away mental decline that affects people in old age.

The paper will appear in a forthcoming issue of the Journal of Geriatric Psychology and Neurology [5]. It looked at people aged 65 and over and found that compared to those with the highest vitamin D levels, those with the lowest were more than twice as likely to have impaired understanding.

The body makes vitamin D when it is exposed to the sun, or it can be obtained from foods such as oily fish, but older people's skin is less able to absorb vitamin D from sunlight, so they are more reliant on obtaining it from other sources.

The team of researchers were from the UK and US, and they assessed people's cognition, or comprehension skills. People who have impaired cognitive function are more likely to develop dementia. The study found that as levels of vitamin D went down, levels of cognitive impairment went up.

Dr Iain Lang, one of the researchers who worked on the study, said:

"For those of us who live in countries where there are dark winters without much sunlight, like the UK, getting enough vitamin D can be a real problem - particularly for older people, who absorb less vitamin D from sunlight.

"One way to address this might be to provide older adults with vitamin D supplements.

"This has been proposed in the past as a way of improving bone health in older people, but our results suggest it might also have other benefits."

Vitamin D is important in maintaining bone health, in the absorption of calcium and phosphorus, and in helping the immune system.

The body makes vitamin D when it is exposed to the sun, or it can be obtained from foods such as oily fish, wholegrain bread, eggs and cereals.

References

• [1] Wilkins CH, et al. Vitamin D deficiency is associated with low mood and worse cognitive performance in older adults. Am J Geriatr Psychiatry. 2006;14(12):1032-40.

• [2] Murphy PK, et al. Vitamin D and mood disorders among women: an integrative review. J Midwifery Womens Health. 2008;53(5):440-6.

• [3] Jorde R, et al. Effects of vitamin D supplementation on symptoms of depression in overweight and obese subjects: randomized double blind trial, J Intern Med, Sept 2008; [Epub ahead of print].

• [4] Partonen T, et al. Bright light improves vitality and alleviates distress in healthy people. J Affect Disord. 2000;57:55-61.

• [5] Llewellyn D J, Langa K, Lang I. Serum 25-Hydroxyvitamin D Concentration and Cognitive Impairment Journal of Geriatric Psychiatry and Neurology, Dec 2008;