Diet and MS: The Gut Microbiome Connection

We all know that the digestive system is the mediator between what we eat and how those foods affect our bodies and health. More recently, however, scientists have begun to identify all the ways the gut microbiome – a vast reservoir of microbes within the digestive system – influences our immune system and its disorders, including multiple sclerosis.

Andrew Woo, MD, PhD, is a neuro-immunologist in private practice at Santa Monica Neurological Consultants in Santa Monica, CA, and Assistant Clinical Professor of Neurology at the David Geffen School of Medicine at the University of California – Los Angeles and Cedars-Sinai Medical Center. Dr. Woo is also a member of MSAA’s Board of Directors.

Dr. Woo explains, “You have about 39 trillion microorganisms in your gut – including bacteria, viruses, and fungal elements. By comparison, you have about 30 trillion cells in your body. The microorganisms in the intestines exist in a symbiotic community. Some support health; others are detrimental to health.

“Research has shown that the microbiota play a huge role in several autoimmune conditions, including not only MS but also rheumatoid arthritis, Crohn’s disease, psoriasis, and asthma. More recently, research in animal models has linked the gut microbiome to conditions such as Alzheimer’s disease, Parkinson’s disease, and even mood disorders.”

Dr. Woo adds that studies have shown important differences in the gut microbiome in people with MS compared to the general population. “For example, levels of a microorganism known as methanobrevibacter smithii are six to seven times higher in people with MS than in other people. Similarly, people with MS tend to have relatively lower levels of other microorganisms, such as bacteria from the porphyromonadaceae and faecalibacterium groups. What is the significance of these differences? Researchers are still working out the mechanisms and processes involved, but we know that gut bacteria break down carbohydrates to produce short-chain fatty acids, which exercise an anti-inflammatory effect,” he notes.

Dr. Woo adds that three short-chain fatty acids – propionic acid, acetic acid, and butyric acid – support the immune system’s T-regulatory cells, which play a key role in controlling inflammation.

So can people with MS use dietary approaches to alter their microbiome?

Dr. Woo responds to that question with a resounding, “Yes!”

He explains that several foods are high in short-chain fatty acids, including oats, barley, lentils, apples, nectarines, asparagus, bananas, and garlic. A number of small and moderate-sized studies also support use of supplements as a means of obtaining short-chain fatty acids, Dr. Woo says.

He points to a 2017 randomized controlled pilot trial in which 51 people with secondary-progressive MS were assigned to receive either 1,200 mg a day of alpha lipoic acid or placebo. After two years of follow-up, the 27 people who took alpha lipoic acid had significantly less loss of brain volume than people in the placebo group, although they had a higher incidence of gastrointestinal upset.1

Dr. Woo adds that a 2020 study involving 91 people with MS found that 14 days of taking a propionic acid supplement altered the composition of the gut microbiome and changed those people’s balance of the T-regulatory cells that fight inflammation and TH17 cells, another type of T cell that drives inflammation.2 Other research, he notes, is examining the potential anti-inflammatory effects of bile acid supplements, such as tauroursodeoxycholic acid, or TUDCA, a substance long used by Chinese herbalists for a variety of purposes.

Looking beyond specific microorganisms and their availability from foods and supplements, Dr. Woo adds that a wealth of data has shown that intermittent fasting not only drives weight loss but also rebalances the gut microbiome in a way that decreases inflammation. By following an intermittent fasting approach such as eating only during an 8-hour period each day, “You literally change the bacteria in your gut into the good bacteria, the ones that produce more short-chain fatty acids. This comes from altering the timing of your eating, not what you’re eating. It takes a lot of discipline, but it’s crazy to me that you can have this effect just based on when you eat,” he adds.

For this reason, he explains, he sometimes recommends that patients adopt intermittent fasting to alter their gut microbiome and then transition to a Mediterranean-style diet.

The neuroimmunologist emphasizes that dietary efforts to improve the course of MS should be part of a comprehensive approach that also includes engaging in regular physical activity, obtaining adequate sleep, and taking disease-modifying therapy selected through a shared decision-making process with an MS clinician.

And his final piece of advice? Well, if you can find one, consider an occasional sardine brandy latte. He explains, “A Belgian study that followed more than 1,300 people with MS over the course of several years found that eating fish and drinking coffee and alcohol reduced the risk of progression in those with relapsing forms of the disease.”3 Beyond counseling moderation with alcohol and caffeine intake, Dr. Woo urges, “So drink up. It tastes disgusting, I know, but maybe we can come up with a cool name for it.”


1 Spain R, Powers K, Murchison C, et al. lipoic acid in secondary progressive MS: a randomized controlled pilot trial. Neurol Neuroimmunol Neuroinflamm. 2017;4(5):e374.

2 Duscha A, Gisevius B, Hirschberg S, et al. Propionic acid shapes the multiple sclerosis disease course by an immunomodulatory mechanism. Cell. 2020;180:1067-1080.

3 D’Hooghe MB, Haentjens P, Nagels G, De Keysey J. Alcohol, coffee, fish, smoking and disease progression in multiple sclerosis. Eur J Neurol. 2011;19:616-624.

Hear More Insights from Dr. Woo on Diet, MS, and the Microbiome

MSAA recently featured Dr. Woo on a podcast titled “The 3 M’s of MS: Mangia, Microbiome, and Molecules.” On the podcast, the neuroimmunologist and member of MSAA’s Board of Directors provides greater detail on how the microbiome and diet affect MS, and on approaches people with MS can take to alter their gut microbiome. Tune in at or search “MSAA Podcast” wherever you listen to podcasts.