Many Depressed Older Adults Lack Vitamin D

May 6, 2008 -- Soaking in plenty of sunshine and drinking lots of milk might help fight off depression in your golden years.

Researchers reporting in the May issue of Archives of General Psychiatry have linked low blood levels of vitamin D -- the "sunshine vitamin" -- and increased parathyroid hormone levels to depression among older adults.

When the body lacks the proper amount of vitamin D, the parathyroid produces too much parathyroid hormone. Overactive parathyroid glands, or hyperparathyroidism, often accompany symptoms of depression.

Some experts have suggested that vitamin D deficiency may contribute to depression, but few studies have examined the link.

For the current study, Witte J. G. Hoogendijk, MD, PhD, and colleagues at VU University Medical Center at Vrije Universiteit Amsterdam, Netherlands, screened 1,282 adults aged 65-95 for depression symptoms and ran blood tests to check their vitamin D and parathyroid hormone levels.

Diagnostic psychiatric evaluation revealed that 26 of the study participants had major depression and 169 had minor depression. The researchers' analysis showed that more than a third of the men and more than half of the women in the study were vitamin D deficient. Vitamin D levels were 14% lower among those with depression then in those who were not depressed.

Individuals with depression had higher levels of parathyroid hormone when compared to those without the illness. Parathyroid hormone levels were about 5% higher in the study participants with minor depression and 33% higher in those with major depression.

Depression is not a normal part of growing older. Major life changes later in life, such as chronic illness, retirement, death of a spouse, and decreased ability to perform everyday tasks, increase an older adult's risk of depression. The findings from this study suggest that some forms of depression can be treated by consuming more vitamin D and increasing sensible sunlight exposure. The body makes vitamin D from sunlight exposure to the skin.

But the study leaves researchers with an unanswered question: Which came first, the biological changes or the depression? Hoogendijk's team encourages additional studies to determine whether the changes in blood levels of vitamin D and parathyroid hormone occur before or after a person becomes depressed.