Vitamin D and ageing brains

Vitamin D is known as the sunshine vitamin because it is made in your skin in response to sunlight. In a country like Australia you might expect vitamin D deficiency to be extremely rare…but you would be wrong. Vitamin D deficiency is incredibly common, particularly among the older people. Now a new study has found that lack of vitamin D adversely affects the brain and may be implicated in the cognitive decline that goes with ageing.

In 2012 researchers from Deakin University published results of the first survey of vitamin D status in Australia. The survey showed that nearly one third of Australian adults are suffering vitamin D deficiency. Additionally, the prevalence of vitamin D deficiency increased with age, especially in women; 26 per cent of women aged 25-34 years were deficient which increased to 57 per cent for those aged 75 years and over. This matters because low levels of vitamin D can contribute to a number of serious conditions such as softened bones, diseases that cause progressive muscle weakness leading to an increased risk of falls, osteoporosis, cardiovascular disease, certain types of cancer, and type 2 diabetes. On top of all this the new research shows low levels of vitamin D are bad for your brain too.

The study showed that middle-aged rats that were fed a diet low in vitamin D for several months developed free radical damage to the brain. They also did less well on cognitive function tests for learning and memory.

In the brains of the mice with low vitamin D levels there were high levels of several proteins that lead to nitrosative stress, possibly causing cognitive decline. Nitrosative stress is when reactive nitrogen species act together with reactive oxygen species (ROS) to damage cells. So it appears that lack of vitamin D increases oxidative stress in the brain possibly leading to declines in brain function.

Could it be that in an understandable rush to avoid ultraviolet damage to skin we have gone overboard and are now not getting enough sun? The recommendation from these researchers is that as we age we need at least 10-15 minutes in the sun each day. Otherwise, and rather paradoxically, lack of vitamin D could be putting the “d” in “mental d-cline”.