“If I had known I was going to live this long, I would have taken better care of myself.”
That quote, which has been attributed to Eubie Blake, resonates well enough to have been repeated by Mickey Mantle, Mae West, and Erma Bombeck, among others. But is it true? Can aging be more tolerable if we take better care of ourselves?
A recent review in the journal Gut Microbiome by Marcus Boehme, Katherine Guzzetta, and colleagues finds that we can indeed improve our twilight years with some specific techniques. In particular, we can optimize our brain by modifying our community of gut microbes—our microbiota. The authors of the study say, “The gut microbiota may be a potential novel target to ameliorate symptoms of brain aging and promote healthy cognition.” That’s good news, because it’s easy to optimize your gut microbes, and you’ll find some tips at the end of this post.
Aging may improve wine or cheese, but it does no favors to our brains. For some, the decline comes with age-related diseases including mild cognitive impairment, Alzheimer’s, Parkinson’s, and multiple sclerosis.
Unbalanced gut microbiota can contribute to age-related mental decline. A study by Aura Ferreiro, Gautam Dantas, and colleagues at Washington University School of Medicine found that a specific profile of microbes is associated with Alzheimer’s. That makes the microbiota a powerful target for managing brain health. The gut microbiota consists of some 30 trillion microbes and plays a critical role in maintaining health, including brain health. The gut microbiota communicates with the brain through various pathways, including hormones, nerves, immunity, and microbial secretions. The conversation goes both ways.
These pathways have been illuminated by the study of germ-free animals, which are known to have a different stress response than their germier cousins. Researchers have also used fecal transplants and antibiotic treatments to modify the microbiota to see how these treatments affect the brain. These studies are solidifying how the gut–brain axis influences cognition, dementia, and brain disease.
Walling off the brain
The brain is immune privileged, meaning it tries to block both microbes and immune cells by maintaining a blood–brain barrier (BBB). But inflammation due to a leaky gut can wear down the BBB, allowing microbes and toxins into the brain, followed closely by immune cells trying to corral and eliminate them. The immune system lacks subtlety and can cause major collateral damage, including the death and destruction of nerve cells, leading to memory loss and cognitive dysfunction.
The composition of the gut microbiota is comparatively stable through youth and midlife, but as we get older, it changes in composition and diversity. The effects of aging on gut microbiome diversity are highly variable, influenced by factors such as diet and environment. Fortunately, much of that is up to us.
There are some good clues about the role of the microbiota: Studies have shown reduced microbial diversity in elderly individuals in nursing homes, associated with degraded health. On the flip side, other studies have observed increased microbial diversity in centenarians living among the general population.
Understanding the causal relationship between gut microbiota and healthy brain aging may lead to the development of new microbial therapies. One thing seems sure: Microbial diversity is key.
How to repair your gut-brain axis
Here are four suggestions backed by recent research to keep your microbes diverse and your brain as young as possible.
1. Exercise
Take it from a writer: It’s easy to sit on your butt all day. It’s also a surefire way to grow frail and unhealthy.
You need to move in order to pump your lymph. So much of the gut–brain story is about immune health, and the lymphatic system is how immune cells get around. There is no heart to pump lymph, so it just sloshes around, prodded by your muscles as you move. If you don’t move, your lymph can’t circulate. Exercise is known to lower inflammation, which may be the most important factor when it comes to health and successful aging. In addition, exercise improves the integrity of your gut lining, further reducing the odds of inflammation.
As we age, we start to lose muscle tone. So, even if you’ve never exercised in your life, you may need to take it up when you get older. Surprisingly, you can build muscle at any age. Exercise works quickly. You can grow new muscle within days of weightlifting. Your gut microbes are also improved with exercise, and, with that, substances are released that can stimulate the growth of new brain cells.
If you have health problems, talk to your doctor before you start an exercise program. But even if all you can manage is bed stretches, you should consider it.
2. Eat Probiotics
Probiotics have been shown to be a safe and simple way to enhance cognition in the elderly. Researchers have found that certain strains of probiotics can improve cognition and memory in older adults with mild cognitive impairment. One study showed improved cognition using Lactobacillus rhamnosus GG. A Japanese study also showed memory improvements using Bifidobacterium breve, while a Korean study showed that consuming soybeans fermented with Lactobacillus plantarum improved attention span.
New studies have uncovered specific bacterial species, including Akkermansia muciniphila and Faecalibacterium prausnitzii, that seem to play a role in optimizing brain function. These bacteria can improve cognitive deficits in animal models and have the potential for improving cognition in people as well.
A simple way to get probiotics is through fermented foods like yogurt, sauerkraut, kimchi, kefir, and pickles. Choose ferments with live bacteria if you can. They are in the refrigerator section, not the middle of the store.
Many of the above-listed bacteria have recently become available as supplements. Typically, it takes several days to notice an effect, so keep notes on what is working and try not to mix multiple formulas at once, so you can reduce confusion.
These studies are refreshingly hopeful, but not totally consistent. Most studies find positive effects on cognitive function in patients with Alzheimer’s using mixtures of probiotics, while others are inconclusive. These are early days for this research, but all studies have found probiotics to be easily tolerated with few if any, side effects. You can’t say the same for many of the current crop of psychoactive drug treatments.
3. Eat Prebiotics
In addition to probiotics, prebiotics, which feed the beneficial microorganisms in our gut, have also been explored for their potential to improve cognitive health in aging. Studies have found that prebiotic mixtures containing inulin and related fructooligosaccharides can reduce frailty, a risk factor for cognitive decline. Other studies have shown that supplementation with prebiotics can improve neuroinflammation, brain metabolites, and gut hormones, potentially influencing cognitive performance.
Because diversity is an important metric of gut health, you should look for a mixture of various prebiotics. Polyphenols are also considered to be prebiotics, so you might want to add those to your regimen as well.
The simplest way to consume prebiotics is by eating colorful, high-fiber veggies and fruits. These include artichokes, onions, legumes, asparagus, and berries. If you can’t get enough of these foods in your diet, consider a supplement, especially one with a mix of different fibers and polyphenols.
Our gut has lots of acids and enzymes, but it still has a hard time digesting fiber and polyphenols. Thus, they make it intact to the colon, which houses the bulk of your microbiota. The beneficial microbes in your gut consider these tough molecules to be delicacies. That’s how prebiotics helps to balance your gut, and—via the gut–brain axis—improve your mind.
4. Go Mediterranean
The Mediterranean diet has been shown to improve brain health in aging. Components of the Mediterranean diet, such as omega-3 fatty acids and polyphenols, have known protective effects on the aging brain. These nutrients can also balance the gut microbiota, which likely contributes to their positive effects on cognition. Studies have demonstrated associations between adherence to the Mediterranean diet, improved gut microbiota composition, decreased frailty, improved cognition, and reduced inflammatory markers. All this, and it tastes delicious, too.
In sum
Each of these four interventions works to improve the diversity of the gut microbiota, which beefs up the integrity of the gut lining, reduces inflammation, and produces molecules that can improve brain renewal and growth.
The field of microbiota-based strategies for improving cognitive function in aging is still evolving. Further research, including larger controlled trials, is needed to establish the best mix of exercise, probiotics, prebiotics, and diet in promoting cognitive health. But the downside of these interventions is practically nonexistent, so it can’t hurt to give them a try!
References
Boehme, Marcus, Katherine Elizabeth Guzzetta, Caroline Wasén, and Laura Michelle Cox. “The Gut Microbiota Is an Emerging Target for Improving Brain Health during Aging.” Gut Microbiome 4 (2023): e2.
Ferreiro, Aura L., JooHee Choi, Jian Ryou, Erin P. Newcomer, Regina Thompson, Rebecca M. Bollinger, Carla Hall-Moore, et al. “Gut Microbiome Composition May Be an Indicator of Preclinical Alzheimer’s Disease.” Science Translational Medicine 15, no. 700 (June 14, 2023): eabo2984.