People living with multiple sclerosis (MS) might want to put down the salt shaker and rethink their diet.
Researchers from the Raúl Carrea Institute for Neurological Research in Buenos Aires, Argentina, discovered a link between high levels of salt in the diet and worsening MS symptoms, according to a study recently published in the Journal of Neurology, Neurosurgery, and Psychiatry.
Dr. Mauricio Farez and his team examined urine samples from 70 people with relapsing MS, measuring salt, creatinine (an indicator of inflammation), and vitamin D levels. Low levels of vitamin D have been shown to play a role in the MS disease process.
Samples were taken three times over the course of nine months, and volunteers were followed for two years. They were given several brain scans to assess the severity of their MS.
After taking into account many factors besides diet, such as age, smoking status, gender, and disease duration, researchers found a connection between disease activity and elevated salt in the urine. According to the study, “Individuals with high-sodium intake had a 3.4-fold greater chance of developing a new lesion on the MRI and on average had eight more T2 lesions on MRI.”
In order to be certain that their methods were sound, the researchers repeated the same study with 52 more volunteers with relapsing MS. Their findings were the same.
The Chicken or the Egg?
Since the study was observational, researchers don’t know precisely why those with more active MS have higher salt levels in their urine.
“Although we observed that patients with high sodium intake usually have higher disease activity and we think it's because salt intake may worsen MS, we cannot exclude that patients with worse disease for an unknown reason consume more salt,” Farez told Healthline in an interview. “Our study just shows this association, but a lot more work is needed to fully understand the relationship between salt and MS.”
Farez admits there could be any number of reasons for his team's findings. For example, “salt intake is associated with your dietary habits, and in turn, your dietary habits are associated with different types of microbes in your gut,” he explained, “and those microbes may have an impact on your immune system, and this is a hot topic right now in MS research.”
“Another possibility,” Farez added, “is the direct effect of sodium in the generation of the immune cells responsible in part for the autoimmune attack in MS. This has been nicely shown in two studies published in Nature last year.”
Where Salt Lurks in Your Diet
“Sodium is essential for life, and broadly speaking, it is required to maintain the body's fluid balance,” explained Farez, “including blood volume and pressure as well the correct functioning of cells, in particular brain, nerves, and muscles. Therefore, its levels are tightly regulated, keeping a balance between what we consume through diet and what we excrete in urine, feces, and sweat.”
Being sprinkled from the shaker isn’t the only way salt gets into our foods. "Processed foods, breads, burgers, pizza, cured meats, chicken nuggets, etc. can have a tremendous amount of sodium," Farez said. "For example, [the World Health Organization] recommends less than 2 grams of sodium per day, and if you don't pay attention you can surpass that limit quite easily. By having a pizza slice (around 750 mg), a sandwich (bread 500 mg, cured meat, cheese 1,000 mg), you already exceeded the recommended amount.”
Indeed, salt hides in almost everything we eat. Even a seemingly harmless condiment like ketchup contains as much as 190mg in a single tablespoon. Other sources include canned vegetables, packaged foods like macaroni and cheese kits, and frozen meals.
The best way to avoid getting too much salt in your diet is to eat unprocessed foods. Choose fresh vegetables over frozen, but if they aren’t available, frozen is a better option than canned. It might surprise you to learn just how much sodium lurks in packaged foods. Rice-a-Roni Spanish Rice, for instance, contains a whopping 1,250 mg per serving — more than half of the recommended daily allowance.
Should You Lose the Salt?
So, could restricting salt intake have an effect on MS disease activity?
“We don't know yet,” said Farez. “We need more and larger studies to confirm our findings, and eventually randomized clinical trials to be able to confirm that MS patients may benefit from lower sodium intake.”
According to Farez, people who eat more than 6 grams of sodium per day are more likely to die from cardiovascular diseases, “and there is now evidence that cardiovascular diseases might be more frequent in MS patients. Thus, consuming less than 6 grams of sodium per day might not be a bad idea after all for anyone, in particular for MS patients,” he said.
Regardless of which came first (high salt intake or MS activity), you might want to think twice before salting either your chicken or your eggs.