Dehydration and Back Pain: How Water Affects Spine Health
You might think your spine is mostly bone. But there’s actually a lot of water in the spinal discs that are tucked in between the vertebrae, or bones of the spine.
These discs act like shock absorbers. They enable the spine to support weight and provide flexibility to the spine. The large water content of the discs helps them carry out these roles.
When the discs lose water, they no longer work as well as they did before, which can cause back pain and other symptoms.
The discs naturally lose some water as you age. But dehydration can also occur when you are not getting enough water, either by itself or in your food. If the dehydration is severe enough, it may increase the risk of injury to the spine or aggravate an existing spine condition.
How Does Water Support a Healthy Spine?
The spinal discs contain up to 85 percent water. Most of this water is present in the the soft center of the disc, or nucleus pulposus. The tough outer ring of the disc, the annulus fibrosis, also contains water, but in lower amounts. This high water content in the discs helps the spine function normally.
Dr. Ehsan Jazini, a spine surgeon at Virginia Spine Institute, in Reston, Virginia, says the discs act like shock absorbers, which enable the spine to resist being compressed during activities like sitting, running and walking.
When you are sitting or standing, the spinal discs are compressed by the weight (also known as the load) that they are supporting. This causes some of the water to be squeezed out of the disc. Some research shows that the spinal discs in the lower spine (lumbar spine) lose about 20 percent of their water over the course of a day’s activities.
At night, when you lie down, most of the load on the discs is removed. When that happens, water flows slowly back into the disc. However, for this to happen, the body has to be adequately hydrated.
“It is important to continuously rehydrate this critical structure in order to provide adequate cushion in our spine,” says Jazini, “[This] lowers the risk of back pain and of developing a more serious spinal condition.”
The daily flow of water into and out of the spinal discs also has another important purpose — feeding the discs.
“The disc obtains its nutrients through a constant loss and gain of fluid,” says Jazini. “Dehydration upsets this balance and does not allow proper nutrients to flow to the disc, leading to increased risk of injury and degeneration.”
Can Dehydration Cause Back Pain?
If the body is dehydrated, it may not be able to replenish the water in the spinal discs. Jazini says that can cause the discs to remain compressed. This can make it harder for the discs to cushion the vertebrae and may reduce the flexibility of the spine.
In rats who were dehydrated, the spinal discs had lower water content, compared to rats that were allowed to drink as much water as they needed. As a result, the dehydrated rats had stiffer discs, which the researchers said may lead to a less flexible spine. Although this study was done in rats, Dearing says it is likely true for people as well.
If the water content of the discs drops, the discs no longer function normally. This dehydration may lead to spine problems that can cause lower back pain or other symptoms.
“This decreased mobility increases the risk of injury to the collagen fibers that make up the disc material,” says Jazini. “Injury to the discs can cause inflammation and herniation of disc material and lead to compression of the [spinal nerves].”
Dehydration can also affect the muscles and tendons that support the spinal column, which Jazini says are “critically dependent” on proper hydration. This could negatively affect the spine.
“Decreased flexibility in the muscles that surround our spinal column increase the risk of injury to the spinal elements, including the discs, facet joints and facet capsules,” says Jazini.
While severe dehydration can affect the water content of spinal discs, they usually lose some water as you age.
Everyone’s spine changes differently, of course. But in one study, the water content of the center part of the disc decreased from 85 percent at age 14 to 75 percent at age 91. The outer ring of the disc also lost water, but to a lesser degree.
Other changes to the spinal discs also occur as you age. Together, these can lead to degenerative disc disease, a condition that is common in older adults.
How Can You Stay Hydrated?
Most studies done in people of hydration and spine health have looked at age-related disc degeneration. So it’s not clear how dehydrated you need to be before your spine is affected. But that doesn’t mean you should neglect drinking enough water each day.
“Drinking plenty of water is so important for everyone, but especially if you have degenerative disc disease,” says Dearing.
She adds that staying hydrated can help your spine in other ways, not just by maintaining the water content of the spinal discs.
“[Hydration] helps to curb appetite, which can be beneficial for those who are overweight or obese and are dealing with arthritis” she says, “and it helps to flush toxins out of our body.”
Staying hydrated is also important for other aspects of health, including heart health and protecting yourself from heat stroke.
So how much water should you drink per day to stay hydrated? Many people have heard the rule: “drink at least eight 8-oz glasses of water a day.” While this saying has been around for a long time, there’s not a lot of science to back it up.
Most people will do fine by drinking water when they are thirsty — the thirst instinct is very reliable. Although in older adults, it may not be as accurate, so they may need to be more mindful of staying hydrated.
Of course, there are times when you will need to increase your fluid intake — during exercise, in hot weather, or when you have vomiting or diarrhea.
So when you are thirsty, what fluid should you reach for? Water is always a good option. But most fresh foods also contain water, especially fruits and vegetables. Other beverages can work too, but you should be careful not to consume too many calories in liquid form. And alcohol is a diuretic, so you could end up losing some of the water in your urine.
Whichever hydration method you choose, keep in mind that you’re doing it for your health, including the health of your spine.
”Hydration is a very simple aspect of spinal health which is commonly overlooked,” says Jazini. “This basic wellness component can make a big difference in avoiding spinal conditions.”