If you know anything about the women-are-inherently-inferior attitude that prevailed in the U.S. at one time, you will not be surprised to learn that no woman ever wrote a column for a major newspaper until Sara Willis began doing so for the New York Ledger in 1852.

What also might not surprise you is that Willis, using the pen name Fanny Fern, occasionally wrote about the flaws in men and the male-dominated world and developed a large female fan base in part because of that.What may surprise you, however, is that by 1855 that male-dominated world made Willis the highest paid columnist in the U.S. (although you could argue that there's nothing really unusual about the passion for profit prevailing over anything, even prejudice).One sure surprise: a saying you've heard dozens of times - "The way to a man's heart is through his stomach" - comes from one of Willis' columns. But Willis is referring to romance, so why cite the line in a health column? Because, as another chronicler of the human condition, Bob Dylan observes, "The times they are a-changin'."Research suggests that the stomach is also the way to a man's brain.For years, scientists knew that after food has been eaten, your nervous system sends out the signals to the digestive tract to break down the food, creating some waste but mostly energy. Additionally, your nervous system also communicates with the brain, but all that transpires from this communication is not known. Researchers have found, however, that changes in gut bacteria influence this communication.Discovery of this influence suddenly makes gut bacteria study an exciting subject.Research published in the April issue of Biological Psychiatry determined gut bacteria's influence on the brain in an interesting way: through transplantation. First, one group of mice was fed a high-fat diet; a second and a third, a normal diet. After that, the third group received gut bacteria from the other two groups.Shortly afterward, the mice who got gut bacteria from the high-fat diet group exhibited changed behavior. They were more anxious, didn't do as well on memory tests, and engaged in repetitive behaviors, a sign of mental disturbance.The mice who got the gut bacteria from the normal-diet group did not.Adverse physical affects occurred in the mice receiving gut bacteria from the high-fat diet group as well. They developed the markers for inflammation that can lead to heart disease and stroke.A second study presented at the Annual Meeting of the Society for the Study of Ingestive Behavior in July also found that high-fat diets unfavorably affect gut bacteria and increase inflammation. Moreover, the mice in this study also lost something that humans hellbent on weight control need to not only keep but also hone: the ability to sense when enough food is enough.This loss occurred in the mice fed the high-fat diet, according to Krzysztof Czaja, DVM, PhD, associate professor of neuroanatomy at the University of Georgia College of Veterinary Medicine and principal investigator in the aforementioned study, because the messages sent by the nervous system as a result of the high-fat diet reorganized brain circuits.But specifically losing the enough-is-enough sensation from a high-fat diet and the subsequent change in gut bacteria may ultimately wind up being the proverbial tip of the iceberg. That's because processed foods in general seem to unfavorably alter gut bacteria.For instance, the emulsifiers ubiquitously used to improve food texture and extend shelf life in processed foods have been found to reduce the bacterial diversity in the digestive tracts of laboratory mice. Now consider the dozens of preservatives, dyes, and other unnatural elements present in processed foods, and it's easy to understand why the Yanomami tribesmen of the Amazon rainforest have 50 percent more bacterial diversity in their stomachs than typical Americans.Between 70 and 80 percent of your immune cells reside in the stomach, so what's lost in most Americans is much of the good gut bacteria that keeps you healthy.But just as troubling is the previously mentioned link between the makeup of your gut bacteria and your mental state. According to Healthline.com, the rate of diagnosed cases of depression is increasing by 20 percent each year. In fact, the CDC has determined that depression is the leading cause of disability in Americans between the ages of 15 and 44.So what should you do to keep a change in your gut bacteria from changing your mental state for the worse?Eating fermented foods - like traditional yogurt and sourdough bread, sauerkraut, pickles and other vegetables pickled in brine, miso, soy sauce, and sour cream - helps, as does increasing your fiber.Naturally you also want to eliminate as much of your consumption of processed foods as practically possible, but don't feel as if they have to be replaced by prebiotics, foods that promote the growth of good gut bacteria, or foods or supplements with probiotics, the good gut bacteria itself.While consuming these couldn't hurt, their use is considered a crapshoot by many experts simply because there's an infinite number of ways the estimated 100 trillion bacteria found in the gut affect one another.