Vegetarians appear to be at a much lower risk for yet another common ailment

A major cause of back pain may be nerves that have grown deeply into degenerating discs. A disc is a leathery cushion that separates one vertebra from another. Normally, its tough outer sheath covers a soft inner core. If the sheath deteriorates, the interior tissues can herniate outward, pushing on a nerve root or even on the spinal cord itself.

Normally, pain nerves do not enter past the outer surface of the disc. Researchers examining specimens removed at surgery found that, in patients with a history of back pain, nerves had grown into degenerated discs, following blood vessels that grow as part of the repair process.

What causes the degeneration in the first place? For many people, the problem is clogged arteries. The lumbar arteries that nourish the spine are among the first to develop atherosclerotic plaques. Advanced blockages are present in some people - perhaps as many as 10 per cent - by age 20. A blocked lumbar artery means that the vertebrae and discs are cut off from their normal supply line for oxygen and nutrients. They also have more difficulty repairing damage and eliminating cellular waste products that can irritate nerve endings.

In autopsy studies, people who had a history of back pain have been found to have an average of two completely blocked arteries to the lower back and at least one more that was narrowed but not yet blocked. People who had not had back pain had fewer blockages.

A low-fat, vegetarian diet along with regular exercise, avoiding smoking and reducing stress, can prevent and even reverse artery blockages elsewhere in the body. Perhaps it can also help prevent or even treat back pain.

Good Medicine, Spring 1997. Based on facts in: Kauppila LI. Can low-back pain be due to lumbar-artery disease? Lancet 1995;346:888-9.