Could laying by the pool help prevent Parkinson’s disease (PD)? It may sound too good to be true, but a study has found a link between regular exposure to sunshine to having a lower risk of developing PD as an older adult.

This study was conducted in France in order to examine the association of sun exposure, which offers ultraviolet B (UV-B) light, to the risk of developing PD. They found that in adults under 70 years old, higher exposure to UV-B light is associated with a lower risk of developing PD. People under 50 years old with consistently high UV-B exposure had the most significant reduction in their risk of developing PD as they grew older. In older age groups, the risk reduction was less significant but still existed.

On the flip side, people under 70 who had the lowest exposure to UV-B light had the largest risk of developing PD. For people older than 70, low UV-B light exposure was a less significant risk factor for developing PD, and for those over 80, there was very little correlation between sunshine and PD.

There’s a good reason why sunlight is related to neurological disorders such as Parkinson’s disease and many others. The key is the relationship between sunshine to vitamin D production in the human body. When the skin is exposed to UV-B light from the sun, it converts a type of cholesterol (7-dehydrocholesterol) present in the skin to a vitamin D precursor, which is then transferred to the liver and kidneys and is ultimately converted to active vitamin D. The body can produce adequate amounts of vitamin D through this process as long as there is sufficient sun exposure, but as we age, the process becomes less effective for many people. This might explain why UV-B exposure is less protective against PD in older adults.

Vitamin D is one of the many nutrients that has an important role in neurological function and protecting the nervous system. Vitamin D acts on specific cells in the immune system to reduce inflammation, a condition that can be damaging to nerves and negatively influence brain function. Vitamin D may also help reduce autoimmune reactions by balancing the immune system. Vitamin D helps bring calcium into the bone and reduces the risk of excess calcium being deposited in brain tissue. Additionally, the nervous system has vitamin D receptors, so the nutrient can influence neurotransmitter synthesis and nerve growth.

Vitamin D deficiency is thought to be a factor in many other neurological diseases, such as multiple sclerosis, dementia, and Alzheimer’s disease. Numerous studies show that having a low vitamin D level is associated with an increased risk of developing cognitive problems, especially in adults over 60.

If you live in a location where it is difficult to get adequate sun exposure (such as northern latitudes), or if you are concerned about developing skin cancer, you can take vitamin D3 in pill-form to supplement your vitamin D intake. Your physician can have your vitamin D levels tested, and if you find they are very low, you can take up to 10,000 IU vitamin D daily until your levels are restored. For general supplementation, take 1000- 2000 IU daily. Vitamin D is a fat soluble nutrient, and is best absorbed when taken with food with a little fat in it. Although vitamin D cannot singlehandedly prevent neurological diseases, it’s certainly an important piece of the puzzle to remember!

Research:

Kravietz, A. et al. Association of UV radiation with Parkinson disease incidence: A nationwide French ecologic study. Environmental Research, 2017.

Przybelski RJ1, Binkley NC. Arch Biochem Biophys. 2007 Apr 15;460(2):202-5. Is vitamin D important for preserving cognition? A positive correlation of serum 25-hydroxyvitamin D concentration with cognitive function.