To Your Health: Could a Healthier Gut Mean a Healthier Brain?

02 Nov To Your Health: Could a Healthier Gut Mean a Healthier Brain?

Welcome back to the series which offers a deep dive into the world of health, wellness, and disease prevention with Telluride local Dr. Alan Safdi.

Dr. Alan is a board-certified physician in Internal Medicine and Gastroenterology, a Fellow of the American College of Gastroenterology, and a respected leader in healthcare. His blogs have featured and will continue to showcase the most current information in his fields: health, wellness and longevity.

In this installment of  “To Your Heath,” Dr. Alan does a deep dive the relationship between our gut health and a healthier brain.

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Healthier Gut, Healthier Brain?

New research suggests that the trillions of microorganisms living in our intestines may influence not only digestive health but also brain function, immunity, and cardiovascular health.

For years, physicians have recognized that the gastrointestinal tract does much more than digest food and absorb nutrients. Our intestines contain trillions of microorganisms, including bacteria, viruses, and fungi, collectively known as the gut microbiome.
W
hen I was in medical school, there was very little discussion of nutrition and absolutely no discussion of the microbiome.

What Is the Gut-Brain Axis?

The gut-brain axis is a complex, two-way communication system connecting the gastrointestinal tract and the brain.

Certain gut bacteria help produce short-chain fatty acids, such as butyrate, when they ferment dietary fiber. These compounds support the intestinal barrier and may influence inflammation and metabolic health.

The relationship works in both directions. Stress can influence intestinal function, while changes in the intestinal environment may influence signals reaching the brain.

Can Probiotics Help Preserve Memory?

An intriguing study published in the Journal of Alzheimer’s Disease in 2026 suggests that certain probiotics may have beneficial effects on early cognitive impairment.

In this randomized, double-blind, placebo-controlled trial, 87 older adults with early cognitive impairment completed 24 weeks of treatment with either a three-strain probiotic supplement or a placebo.

The probiotic given to participants has the code name KL-P301, and it consists of three bacterial strains, including subspecies of Bifidobacterium animalis, Limosilactobacillus fermentum, and Levilactobacillus brevis.

Participants taking the probiotics demonstrated improvements in selected measures of memory and visuospatial function compared with the placebo group.

Of particular interest, they also experienced a significant reduction in blood levels of phosphorylated tau 181 (pTau181), a biomarker associated with Alzheimer’s disease pathology.

It is important to remember that pTau181 is a biomarker, and a change in a blood marker is not the same as a change in how a person feels, functions, or progresses over time.

However, the study was relatively small and lasted only six months. It did not demonstrate that probiotics prevent Alzheimer’s disease or reverse dementia. Larger, longer-term trials are necessary.

Probiotics Versus Prebiotics: What’s the Difference?

Probiotics are live microorganisms that, when consumed in adequate amounts, provide a demonstrated health benefit. They are found in certain supplements and fermented foods containing appropriate live cultures.

But not all probiotic products are equally effective. Different bacterial strains have different biological effects, and benefits demonstrated with one strain cannot automatically be attributed to another. A supplement containing numerous strains is not necessarily better than one containing a single well-studied strain. The findings in this study apply to this specific formulation, not to multistrain products in general.

Prebiotics are substances, often specialized dietary fibers, that beneficial microorganisms use as food.

Good dietary sources of prebiotic compounds and other microbiome-supporting fibers include:

• Oats, barley, and other whole grains
• Beans, lentils, and chickpeas
• Onions, garlic, leeks, and asparagus
• Bananas, particularly those that are less ripe
• Apples and a wide variety of vegetables
• Foods containing resistant starch, such as cooked and cooled potatoes

Why Antibiotics Can Affect the Microbiome Long After Treatment!

Antibiotics are among the most important advances in modern medicine. They save countless lives and are essential for treating many bacterial infections.

A large 2026 study involving nearly 15,000 individuals found associations between previous antibiotic exposure and differences in intestinal bacterial communities years later, sometimes after only one course.

This does not mean antibiotics should be avoided when medically necessary. Rather, it reinforces the importance of using them appropriately and avoiding prescriptions for conditions such as uncomplicated viral infections, where they provide no benefit.

Beyond the Brain: Heart and Immune System!

A substantial portion of the body’s immune activity is associated with the gastrointestinal tract. Intestinal microorganisms help regulate immune responses and maintain the protective intestinal barrier.

Researchers have also identified connections between the microbiome and cardiovascular health. Gut bacteria influence the metabolism of dietary compounds and produce substances that may affect inflammation, cholesterol metabolism, blood pressure, and vascular health.

While these relationships are biologically compelling, research is still determining which specific interventions improve long-term cardiovascular or neurological outcomes.

Exercise and the Microbiome!

Exercise deserves a place in this conversation, and not only because it is good for the gut. Regular physical activity is one of the best supported ways we have to protect the brain and the heart. It lowers blood pressure, improves insulin sensitivity, supports healthy cholesterol levels, and is consistently associated with a lower risk of cognitive decline and dementia.

Exercise also appears to influence the microbiome, with studies of physically active people finding greater microbial diversity and more bacteria that produce butyrate. But most of this evidence is observational, and we do not yet know how much of exercise’s benefit is carried through the microbiome rather than other pathways, such as improved blood flow and reduced inflammation.

The practical point is simple. If you are weighing a probiotic supplement against a daily walk, the walk has far stronger evidence behind it. Most guidelines recommend at least 150 minutes per week of moderate aerobic activity, plus strength training twice a week, and meaningful benefits begin with even modest increases for people who are currently sedentary.

Who Should Be Cautious With Probiotic Supplements?

For most healthy adults, probiotics are generally well tolerated, with bloating and gas being the most common complaints. But live organisms are not risk free for everyone. Always discuss taking probiotics with your primary care doctor and other providers prior to starting them.

The risk is highest for people who are severely immunocompromised, critically ill, or who have a central venous catheter, and for those with severe acute pancreatitis. In rare cases, organisms from probiotic products have been found in the bloodstream of vulnerable patients.

Practical Steps to Support Your Gut Microbiome!

Eat a wide variety of plant foods. Vegetables, fruits, legumes, nuts, seeds, and whole grains provide different fibers and nutrients that nourish intestinal microorganisms.
Include naturally fermented foods when appropriate. Yogurt with live cultures, kefir, and other fermented foods can contribute microorganisms to the diet, although not all qualify as clinically proven probiotics.

Stay physically active. Aim for regular aerobic activity and strength training. Exercise supports the brain, the heart, and the immune system, and it may favorably influence the microbiome as well.

Bottom Line!

Our understanding of the gut microbiome is evolving rapidly, yet it remains one of the least understood systems in the body, which is part of what makes it both exciting and easy to oversell.

The recent study linking a specific probiotic combination with improvements in selected cognitive measures and Alzheimer’s-related blood biomarkers is promising, but it represents an early step rather than proof of dementia prevention. Anyone concerned about their memory should discuss evaluation and prevention with their physician rather than rely on a supplement.

Probiotics may offer benefits in selected circumstances, but they should complement, rather than replace, a varied, fiber-rich diet and regular exercise.

Taking care of your gut may be one more way of taking care of your brain, heart, and immune system.