The Happiest Women Have Lower Levels of These Gut Bacteria

A new study suggests that your digestive health has more to do with your mood than you might realize.

In the study, conducted by Brigham and Women's Hospital and the Harvard T.H. Chan School of Public Health, women who reported feeling happier in a survey had lower levels of Firmicutes bacterium CAG 94 and Ruminococcaceae bacterium D16 in stool samples. Conversely, women who reported feeling more negatively had more of those same bacteria in their stool.

Some notes before we go into this too deeply: The study was based on 206 white women from the ages of 49 to 67, so it's not a huge study, nor a particularly diverse one, but one that we can look into further.

That said, these findings aren't too surprising to experts, who agree that good gut health is linked to better mental health. Here's what to know.

Related: 10 Ideas to Improve Gut Health

There's a Link Between Abdominal Pain, Indigestion and Anxiety

The study's sample obviously has a lot in common, but the findings may well be universal to a degree, experts agreed.

"Since menopause can last seven to 14 years, starting around ages 45 to 55, it is possible that some of these women also experienced mood disruptions related to either their cycle or hormones driving menopause," Dr. Noelle Patno, Ph.D., tells Parade. "On the other hand, an earlier study including both men and women also suggested that the gut microbiome may be associated with mood changes as well. In general, symptoms of abdominal pain and irregularity do often coincide with anxious and depressive symptoms."

“There is definitely a clear link between women's emotional health and their gut health, with our bodies literally having a direct connection via the vagus nerve to send messages between the gut and the brain," says Kara Landau, R.D. at Gut Feeling Consultancy and nutrition advisor to the Global Prebiotic Association. "It is known that when you have poor gut health, or dysbiosis (an imbalance of good to bad bacteria in your gut), inflammatory molecules are released by the gut bacteria, and it is also widely accepted that inflammation is linked to anxiety and depression."

According to Landau, the link between stress and gut health may be bi-directional—as in, there's some "chicken or the egg" here—making gut health even more important to emotional health overall and vice versa.

"When someone is feeling stressed, this can also lead to negative impacts on the gut," she says. "Therefore, findings ways to manage stress, and to nourish the gut, both play a role in improving mental well-being and overall gut health.”

Related: The Worst Habit for Gut Health

What Foods Can Help Gut Health and Mental Health?

You can adjust your diet in ways that may benefit your emotional well-being, experts agree. Here's what they recommend.

Fermented Foods

These can include:

  • Cottage cheese (dry curd)

  • Farmer's cheese

  • Kefir

  • Kimchi

  • Kombucha

  • Miso

  • Pickles (in salt brine, not vinegar)

  • Sauerkraut

  • Tempeh

  • Plain yogurt

Dr. Sean Byers, MD, explains, "A healthy gut microbiome is associated with better digestion, immunological function and mental health, and fermented foods include live cultures of beneficial bacteria that can help support this microbiome. In addition, eating fermented foods has been shown to decrease inflammation in the digestive tract and the body, which may lead to enhanced health and well-being."

Related: The One Food Experts Swear By for Gut Health

Whole Foods With Prebiotic Fiber

Chances are you aren't eating enough of the fiber-rich foods that can improve your emotional and gut health, Dr. Vincent Pedre, MD, author of The Gut Smart Protocol, says.

"Most women only get about 10 to 20 grams of fiber in their diet, but if you want to create a positive impact on your gut health to improve your brain health, aim for at least 40 grams daily," Dr. Pedre advises. "This is the equivalent of six to eight servings per day of fiber-rich vegetables and fruit."

Whole foods rich in prebiotic fiber can be great for gut health, which may extend to your emotional health as well, Dr. Patno says.

Experts recommend:

  • Apples

  • Asparagus

  • Bananas

  • Barley

  • Chicory root

  • Dandelion greens

  • Flaxseeds

  • Garlic

  • Leeks

  • Oats

  • Onions

  • Seaweed

  • Wheat bran

"Supporting a generally healthy microbiome starts with reducing foods that selectively feed 'bad' bacteria (like added sugars), and aiming to include soluble fibers that 'good' bacteria love to eat," Dr. Patno says. "Gut bacteria can metabolize fiber to produce short-chain fatty acids, which are also thought to support the brain. Boosting the health of your gut microbiome by choosing healthier carbohydrate sources could potentially contribute to better emotional health as well."

Related: How Your Gut Impacts Your Immune System

Foods High in Tryptophan

Dr. Patno says that the same chemical we all blame for our Thanksgiving food comas (as opposed to our actual overindulging) is actually great for gut health. Some good sources of tryptophan include:

  • Apples

  • Bananas

  • Cheese

  • Chicken

  • Oats

  • Peanuts

  • Prunes

  • Turkey

  • Tuna

  • Whole milk

  • Whole wheat bread

Dr. Patno explains that tryptophan "is also the starting material our cells use to make the neurotransmitter serotonin. When serotonin is made in the brain, it is responsible for mood and emotional regulation."

There's an added layer, she says, to its gut-mental health connection: "When serotonin is made by cells in the lining of the gut, it acts in gut motility, to help keep you 'regular.'"

Related: What Are Probiotics?

Foods Rich in Healthy Fats

Dr. Patno likes the Mediterranean diet for its richness not just in whole foods and fiber, but also in healthy fats.

"Insufficient quantities of healthy fats or fiber could disrupt the gut microbiome and gut motility as well as dysregulate mood," she says.

You can find healthy fats in:

  • Almonds

  • Avocados

  • Brazil nuts

  • Cheese

  • Chia seeds

  • Eggs

  • Flaxseed

  • Herring

  • Macadamia nuts

  • Mackerel

  • Olives

  • Olive oil

  • Salmon

  • Sardines

  • Tofu

  • Trout

  • Tuna

  • Walnuts

  • Unsweetened yogurt

Related: 18 Foods Great for Gut Health

What Foods May Harm Gut Health and Emotional Health?

While whole foods are fabulous for gut health and possibly correlated with emotional well-being, a lot of the foods we turn to for comfort may be doing more harm than good. These include:

  • Candy

  • Ice cream

  • Instant noodles

  • Packaged snacks

  • Pizza

  • Soda and soft drinks

  • Yogurt with artificial sweeteners

"Processed and high-sugar foods, such as refined grains, sweets and sugary drinks, can have a negative impact on both gut health and emotional health," Barbara Kovalenko, R.D., and nutrition consultant at Lasta says. "These foods can disrupt the balance of healthy gut bacteria and may contribute to inflammation in the body, which has been linked to depression and other mood disorders."

Dr. Patno explained that inflammation and oxidative stress in the gut may disrupt the microbiota and impact gut-brain communication. This may be why you find yourself feeling lousy after snacking on processed foods.

Even scarier? According to Dr. Patno, "Some studies also suggest that gut inflammation can lead to neurodegeneration over the long term."

For some people, eliminating alcohol, caffeine, dairy and gluten, as well as processed foods and added sugars, may help, Dr. Pedre says.

"Gluten and dairy lead to inflammation and leaky gut, which increases the chances of mental health issues like depression. Sugar, alcohol and caffeine create a false boost in dopamine (our 'feel-good' chemical) in the brain, followed by a crash," Dr. Pedre explains. "The next day, or even within hours, they leave you feeling down and depressed. In order to get off this rollercoaster, it’s best to avoid these foods while undergoing a gut-healing protocol."

Related: Is This the Worst Food for Gut Health?

What Else Can We Do To Improve Gut and Emotional Health?

Aside from your diet, there are other moves you can take to improve both your emotional and gut health.

Get Up and Move

You knew this one was coming, didn't you? Experts agree that moderate exercise is crucial to a healthy gut as well as to good mental health, providing better oxygen flow and endorphins. Just don't overdo it, Landau warns: Working out for too long or too intensely can lead to a leaky gut, which is as awful as it sounds.

Related: The Best Workout for Gut Health, According to Experts

Get Some Sleep

Rest is as important as exercise in terms of maintaining a healthy mind and a healthy gut. Landau explains, "Sleep is necessary for clearing brain metabolites, and supporting cognition and mood, while disrupted sleep is linked to disrupted gut motility."

Plus, let's be real—you probably already know you're grumpy when you're tired!

Related: 10 Ways to Restore Gut Health

Consider Prebiotic Supplements

In addition to a healthy diet, Landau says you can look into taking prebiotic supplements specifically created to improve mood.

“Psychobiotics is the scientific term used to describe nutrients that positively impact the gut to support mental health," she told us. "There are specific strains of probiotics, as well as particular types of prebiotics, that have been clinically proven to support mental wellbeing; such as the probiotic strain Lactospore or the prebiotic GOS."

One study on the GOS prebiotic showed a positive impact on mood in women ages 18 to 25, as well as enhanced gut bacteria diversity (which is a good thing). Landau also pointed out that a separate study on GOS showed that participants who took a GOS supplement daily showed a reduction in waking cortisol levels, "which is another measure used to assess improvements in anxiety management."

Next, check out what GI docs say is the best prebiotic for gut health.