Diet and MS
New Directions in MS Research: New Therapeutic Approaches
It is certainly intriguing to consider that dietary modification could be utilized in some way to impact the course of MS for a given individual. Up until this point, scant evidence has been found to show that changing one’s diet is beneficial for MS, though multiple researchers are now looking into the question with well-designed trials.
A recently published study randomized 61 people to a low-fat plant based diet, versus a control group for 12 months. Investigators did not find any differences in MS activity between the groups, though improvements were seen in fatigue scores, body mass index (BMI) measures, and cholesterol panels. The study authors did note that the small size of the study may have impeded their ability to identify greater effects on the condition.73
One trial currently running is a study of 100 people randomized to a paleolithic74 diet (no dairy or gluten) versus a low-fat diet (the Swank diet). This study lacks a control group, which may hinder the results. A smaller pilot study of 30 people has commenced, which randomizes a group of patients to a modified Mediterranean diet versus controls. A third75 study that is being conducted will place people in two dietary groups, either a calorie-restricted group (78 percent of recommended calories daily) versus a group that will practice intermittent fasting; the intermittent fasting group will eat the recommended calorie intake for five days of the week and will eat only 25 percent of recommend calorie intake the other two days of the week. These dietary trials stand to inform and shape future treatment plans for individuals with MS.
An array of recent research ranging from molecular studies to animal models and even some preliminary human data, has implicated levels of dietary salt – sodium chloride, or NaCl – as potentially affecting MS outcomes. In research presented in 201376, high dietary salt was found to increase autoimmune neuro-inflammation by markedly boosting a Th17 helper T cell-driven autoimmune response in EAE (an animal model of MS). Th17 is an immune-system cell (lymphocyte) involved with the inflammation that causes damage to the myelin and nerves with MS. This Th17-boosting property of dietary salt was also seen in humans.
In a separate study,77 higher-salt consumption was associated with increased clinical and MRI disease activity in people with MS. Seventy patients with RRMS were followed over two years, tracking sodium intake. This was in conjunction with clinical and MRI assessment every three-to-six months or at the time of relapse. Researchers found that individuals with high-sodium intake had 3.4-times greater odds of developing a new lesion on the MRI, and on average, had eight more T2 lesions on MRI. MS relapse rates were higher among those with high-sodium intake as well.
In 2015, many additional studies were published showing a connection between salt and MS.78 Krementsov and colleagues fed high-salt and low-salt diets to three genetically different groups of mice and compared their EAE disease course. The researchers showed that in certain strains of mice, high-salt diets led to worsening of EAE. Furthermore, in one strain of mice, this effect was gender-specific, occurring only in females. Because the investigators did not find an alteration in the Th1/Th17 ratio mentioned above, they postulated that the salt caused an increased permeability of the blood-brain barrier leading to attacks by the immune system.
Two other studies were able to show a change in immune cells after exposure to high-salt environments. Hafler and colleagues showed changes in a cell type important for the regulation of the immune system called the “Treg” cell. The Treg cell is thought to play a key role in suppressing those cells that might initiate autoimmune disease. The researchers found the effect of decreased Treg function both in individual cells exposed to high salt as well as in mice fed a high-salt diet.79
Muller and colleagues looked at a different type of immune cell that is important in MS: the macrophage. A macrophage is a type of white blood cell that works to ingest and destroy foreign substances. In cells, they found that a certain type of macrophage was less able to block the autoimmune activities of damaging T cells in a high-salt environment. In mice, they found that a high-salt diet led to decreased abilities of macrophages to aid in wound healing.
The theory that salt may increase MS inflammation remains to be proven, and interventional studies will need to be performed to establish causality. However, this theory could have far-reaching practical dietary implications for individuals with MS.