Vitamin D is involved with balance, which is the ability to maintain your vertical center line with minimal postural sway. Sway is horizontal movement even when standing still. A certain amount of sway is inevitable due to small changes within the body, such as breathing or shifting body weight. Sway is also affected by external sources such as floor vibration and wind currents.
I have written about vitamin D and balance before.
Maintaining balance requires coordination from multiple sensory systems including the inner ear, muscles and nerves, the brain (especially the cerebellum), and eyesight. The senses must detect changes of body position regardless of whether the body moves or the surface moves. In addition, other factors can affect balance such as light conditions, floor surface changes, alcohol, drugs, and inner ear disease.
Balance deteriorates with age. Age-related decline appear to be inevitable and contributes to poor balance in older adults. As a result, the elderly are at an increased risk of falls. In fact, one in three adults aged 65 and over will fall each year.
Dr. Susan Muir and colleagues of the University of Angers in France recently conducted a unique study. They wanted to find out if vitamin D levels above 30 ng/ml or even higher were associated with balance. It is generally accepted that low 25(OH)D levels are associated with poor balance, but no one has ever tested to see if levels of 50 ng/ml are associated with better balance than levels of 30 ng/ml.
Annweiler C, Muir SW, Nabeel S, Gopaul K, Beauchet O, Montero-Odasso M. Higher serum vitamin D concentration is associated with better balance in older adults with supra-optimal vitamin D status. J Am Geriatr Soc. 2013 Jan;61(1):163-5.
In order to test balance, they used 35 older adults with 25(OH)D levels > 30 ng/ml recruited from a larger study of the elderly. They tested their balance on a firm surface but also when standing on a 3-inch thick foam pad. It is harder to keep your balance on soft and compliant surface than on a hard surface.
The authors found that better balance on a soft surface was correlated with higher 25(OH)D levels, but the same correlation did not exist for the hard surface. Multiple linear regression analysis showed that serum 25(OH)D concentration was inversely associated with balance on the compliant surface (P = .02), but not on a firm surface. That is, they found patients with the highest levels, around 55 ng/ml, had better balance than patient with levels around 30 – 35 ng/ml.
This provides some evidence that maybe 30 ng/ml is not good enough. I think it’s better to keep your vitamin D levels in natural ranges.