Bacterial cells in our skin and gut outnumber human cells ten to one.

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Probiotics have become so popular they can be found on most grocery store shelves and are now touted in popular dairy products, such as yogurt. While most people connect probiotics with better digestive health, scientists are finding healthy gut bacteria also play a powerful role in brain health and even the prevention of Alzheimer’s.

A healthy brain begin in your stomach

If you want to know how to improve memory and cognition, it might surprise you to know that a healthy brain begins in your stomach. Here’s why: Bacterial cells in our skin and gut outnumber human cells ten to one. We also carry more than 3 million bacterial genes, in contrast to only 30,000 of our own human genes. The good news is we are meant to play host to that many bacteria. The bad news is many facets of modern life, particularly our industrialized diets, have skewed the balance of these bacteria so that the bad often outnumber the good. Newer research is increasingly linking this dominance of pathogenic (“bad”) bacteria with a number of chronic health problems, including obesity, inflammation, autoimmune disease, and poor brain health—all of which raise the risk of Alzheimer’s.

Gut health begins at birth

Researchers have found the composition of our gut bacteria at birth and in early childhood shape development of the brain, suggesting bacteria play a role in childhood brain developmental disorders. The balance of good and bad bacteria in the gut has also been shown to play a role in how our brain functions as adults. Studies show gut bacteria influences signaling between nerve cells in the brain and the  activation of specific genes in the brain. In fact, studies of germ-free mice show they are less anxious and more relaxed than germ-inoculated mice, demonstrating the influence of bacteria on how our brain operates.

What this means for long-term brain health and Alzheimer’s prevention is that if you were born with an improper bacterial balance, as many children are today due to poor maternal diet and environmental toxicity, and if your current gut bacteria status is imbalanced, you may need to take extra precautions to lower your risk for Alzheimer’s.

How to improve memory

Gut infections—an overgrowth of harmful gut bacteria—are common today. Many factors influence this delicate balance, including:

• Diet. A whole foods diet that includes properly fermented foods, such as sauerkraut and kimchi, helps maintain healthy gut flora. Processed foods, vegetable oils, sugars, sodas, fast foods, and other “modern” foods degrade the integrity of the intestines and foster the growth of infectious bacteria.
• Antibiotic use. Antibiotics are miracle drugs that save lives. However, they are overused today at the doctor’s office, in animal feed, in hand soaps, and more. As a result, pathogenic bacteria become resistant to them and flourish. Also, although a course of antibiotics may be necessary to wipe out an infection, they also wipe out the good bacteria. It’s important to re-inoculate your gut with good bacteria with a quality probiotic for up to a year after taking antibiotics.
• Chronic stress. Chronic stress degrades the integrity and function of the digestive tract, leaving the gut more vulnerable to bacterial infection. A hectic lifestyle isn’t the only thing that causes chronic stress. Undiagnosed food intolerances (such as to gluten or dairy), eating a diet high in sugary, starchy foods, and health issues (such as chronic inflammation) all cause chronic stress.
• Environmental toxins. Pollutants, chemical food additives, toxins in common household and beauty products, and other environmental chemicals can disrupt the balance of gut bacteria. Also, the more imbalanced your gut bacteria are, the more vulnerable you are to environmental toxins.

Cultivating healthy gut bacteria

Wondering how to improve memory?  Begin in your stomach!  With bacterial cells outnumbering human cells ten to one, we would do well take good care of them! Be sure to start a healthy eating program and supplement regimen.

Remember, a healthy brain that is less likely to develop Alzheimer’s starts with a healthy gut and a good balance of bacteria. This involves a whole-body approach and it may require the guidance of your functional medicine or integrative physician, especially if you have been exposed to environmental toxins, chemicals, or have a history of chronic medication use including antibiotics.

This article originally appeared in 2012 and has been updated.