Over the last few decades, there have been many outlandish claims about how an individual’s diet is the source of everything wrong in the world and how a simple change in what 1 chooses to eat can mean the difference between illness and health.
While there is scarce evidence to suggest that dietary decisions can alone cause many diseases (especially those of a genetic origin), there is merit in the idea that, at the very least, dietary choices can influence the course of a disease.
This is certainly the case when we look at the role of diet in multiple sclerosis.
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Multiple Sclerosis: Therapeutic Goals
Multiple sclerosis is an autoimmune disease of the central nervous system. It is characterized by inflammation and the loss of myelin, a combination that leads to neurodegeneration. Common symptoms include sensorimotor dysfunction, visual loss, and cognitive impairment.
There are 3 main forms of multiple sclerosis: primary progressive, secondary progressive, and relapsing-remitting. The main difference between these 3 forms of multiple sclerosis is the dissemination between the space and time of a clinical attack.
What causes multiple sclerosis? Recent studies suggest a mixture of genetic and environmental influences are to blame. Recognized risk factors include sun exposure, smoking, vitamin D deficiency, viral infections, and obesity. The range of exposure to these risk factors have been used to explain the heterogeneity of symptoms seen in patients with multiple sclerosis.
Read more about multiple sclerosis etiology
Recent research has also uncovered various mechanisms of multiple sclerosis pathology. For example, mitochondrial injury and structural changes have been implicated in causing oxidative damage in patients with multiple sclerosis, which is thought to play a key role in the progressive phase of the disease. In addition, inflammatory cytokines and reactive oxygen species have been discovered to damage myelin and axons, which eventually leads to cell death.
Scientists have concluded that any therapeutic interventions in multiple sclerosis must achieve 3 aims: modulating the inflammatory state, protecting against neurodegeneration, and repairing the nervous system. That so many different therapies with different immunomodulatory mechanisms exist to treat multiple sclerosis point to the complexity of the pathophysiological processes underpinning this disease.
The Dietary Connection
So where does diet come in? At a fundamental level, we know that dietary choices affect health parameters such as body weight, cholesterol levels, and vascular risk factors — this much is uncontroversial. In this most general, of context, a healthy, balanced diet is good for the body and is thus ideal for anyone, with or without multiple sclerosis.
A theory that directly links dietary choices with disease outcomes in multiple sclerosis is that foods that reduce oxidative stress can protect against chronic demyelination and axonal damage. Foods that have been shown to play a role in regulating oxidative stress include vitamin D and fatty acids.
In addition to its properties in reducing oxidative stress, vitamin D plays a significant role in bone health and calcium homeostasis. Studies have found that patients with multiple sclerosis are often deficient in vitamin D and that vitamin D supplementation can help inhibit the production of CD4+ T cells, which has the overall effect of slowing disease progression.
In terms of fatty acids, a number of studies have pointed out that foods that are rich in omega-3 polyunsaturated fatty acids, such as fish, nuts, and seeds, can reduce inflammation, protect against demyelination, and promote remyelination. In addition, studies suggest that foods rich in omega-3 polyunsaturated fatty acids can reduce the frequency of relapses.
Read more about multiple sclerosis treatment
Studies have also shown that a high intake of fruits and vegetables are associated with reduced disease activity and disability. A study evaluating the effects of a high vegetable/low protein diet discovered that it is associated with a reduction in proinflammatory cytokines and an increase in antiinflammatory monocytes.
On the other hand, foods that are high in carbohydrates and fats have been shown to play a possible role in promoting the inflammatory cascade. Scientists have discovered that these foods can promote the production of a number of inflammatory factors, such as tumor necrosis factor, interleukins, and prostaglandins. Patients who consume high amounts of saturated fat content are also at a higher risk of experiencing relapse episodes.
Dietary Restriction as a Therapeutic Strategy
Given the ample evidence that dietary choices can influence the disease course of multiple sclerosis, should physicians prescribe dietary restriction as a therapeutic strategy?
Certainly, general guidelines on which foods to consume more of and which foods to avoid are appropriate. However, intentional, long-term dietary restriction poses its own problems, namely that it may cause dietary imbalances and promote an obsessive focus on an individual’s diet. Hence, a dietitian should ideally be consulted to offer advice and oversee any nutritional adjustments.
Another simple way in which an individual can gauge the quality of their dietary intake is by keeping an eye on their body mass index (BMI). Obesity has been shown to activate inflammatory pathways that increase the infiltration of immune cells into the central nervous system. Once again, a dietitian is best positioned to offer advice on maintaining BMI at healthy levels.
“Mechanistic experiments highlight potential effects of diet on both immunomodulatory and neurodegenerative processes in [multiple sclerosis],” Sand wrote in Current Nutrition Reports. “Further research on this topic, ranging from continued basic science studies to clinical trials, is currently ongoing.”
References
Stoiloudis P, Kesidou E, Bakirtzis C, et al. The role of diet and interventions on multiple sclerosis: a review. Published online March 9, 2022. doi:10.3390/nu14061150
Katz Sand I. The role of diet in multiple sclerosis: mechanistic connections and current evidence. Curr Nutr Rep. Published online August 16, 2018. doi:10.1007/s13668-018-0236-z
