Q: I just got the results of an MRI on my back. It shows a slight bulge at the L45 disc. My doctor advises exercise to improve the nutrition of the spine. What does nutrition have to do with a bulging disc?

A: The intervertebral discs between the bones of your spine are your main shock absorbers. They have to withstand thousands of pounds of load and repeated stresses with every step, twist, and turn that you take. Proper nutrition is essential to the disc's health and repair processes needed on a daily basis.

Nutrition as your physician used the term is referring to the blood supply to the disc. A good blood flow brings oxygen and nutrients needed for discs to remain healthy and in good repair.

Studies show that low levels of oxygen to the disc results in low pH balance. pH is a measure of the acid-base levels in the body. Discs with low disc ph build up high levels of lactates. The combination of breakdown in disc nutrition and high biomechanical loads on the discs may be what leads to disc degeneration.

Exercise increases blood flow, which in turn helps wash away lactates and other byproducts of cellular metabolism. The increased blood supply also brings fresh oxygen to restore the disc.

Although what you eat and the nutrition you get from food is important, in this case the nutrition your physician mentioned is most likely to come from daily exercise. Just what is the best exercise remains unknown. All studies so far point to almost any kind of exercise as helpful so long as it raises your heart rate and increases your blood flow.

Mark Schoene. A Tribute to Alf Nachemson: The Spine Interview. In The BACK Letter. February 2007. Vol. 22. No. 2. Pp. 13, 18-21.