Battling the Blues — Part 3: Nurture your gut |

Battling the Blues — Part 3: Nurture your gut

Lined with more than 100 million nerve cells, the gut is “practically a brain unto itself,” wrote Emily Underwood in a 2018 article in Science magazine.
File photo

Editor’s note: This is part three in a series of four articles exploring the causes of — and ways to combat — winter blues. The focus of the series is on mental health and strategies for improving your state of mind through physical activity, spirituality, diet and community and connections.

STEAMBOAT SPRINGS — As research increasingly connects diet and mood, an entirely new field is emerging, dubbed “nutritional psychiatry.”

And it all starts in the gut, explained Cara Marrs, a registered dietitian nutritionist with UCHealth Yampa Valley Medical Center.

Ninety-five percent of serotonin is produced in the gut, Marrs said of the nuertotransmittor that regulates sleep, appetite, pain and mood. Serotonin is known as the “happy chemical” because of its contribution to happiness and overall well-being.

The gut and brain have a direct line of access and communication, Marrs said, and having the right balance of good bacteria in your gut is very important.

Lined with more than 100 million nerve cells, the gut is “practically a brain unto itself,” wrote Emily Underwood in a 2018 article in Science magazine.

The gut talks to the brain, Underwood wrote, but it has only been in more recent research that scientists are discovering just how direct and efficient of a connection the organs have. “The findings could lead to new treatments for obesity, eating disorders and even depression and autism — all of which have been linked to a malfunctioning gut.”

Foods with probiotics
  • Yogurt
  • Kefir
  • Sauerkraut
  • Tempeh
  • Kimchi
  • Miso
  • Kombucha
  • Pickles
  • Traditional buttermilk

Because your brain is always in need of fuel and what you eat provides that fuel, “what you eat directly affects the structure and function of your brain and, ultimately, your mood,” writes Dr. Eva Selhub on the Harvard Health Blog.

Marrs noted “a lot of studies are showing that people with depression have an altered gut micro flora bacteria.”

Altered, she said, can mean your gut has too much of a nonbeneficial bacteria or toxin or not enough good bacteria.

And that good bacteria that is already in there must be fed, Marrs said.

Many studies compare what they refer to as a “Western” or “Standard American Diet” with other “traditional” diets, like the Mediterranean or Japanese diets.

The prevalent amount of processed food and refined sugar in the Western diet, “feeds the nonbeneficial bacteria,” Marrs said. “They flourish. High sugar is what bad bacteria thrives on.” And a diet high in refined sugar is increasingly being connected to depression.

In people who eat those “traditional diets,” studies found the risk of depression lowered by about 25% to 35%, Marrs said.

“Diets high in refined sugars, for example, are harmful to the brain,” writes Selhub. “In addition to worsening your body’s regulation of insulin, they also promote inflammation and oxidative stress. Multiple studies have found a correlation between a diet high in refined sugars and impaired brain function — and even a worsening of symptoms of mood disorders, such as depression.”

So, what does the good bacteria thrive on?

Fiber, Marrs said.

Foods with Fiber
  • Beans
  • Broccoli
  • Berries
  • Avocados
  • Popcorn
  • Whole Grains
  • Apples
  • Dried Fruits
  • Potatoes
  • Nuts

The “traditional” diets tend to be high in vegetables, fruits, unprocessed grains, fish and seafood and composed of only small amounts of lean meats and dairy. That means high in fiber with “tons of omega-3 fatty acids,” Marrs said. 

Probiotics are also key to a well-functioning gut.

If your diet consists only of fast food, said Marrs, “don’t bother taking probiotics.”

That’s because those probiotics need to be fed with the good stuff — like vegetables and other foods high in fiber.

And in terms of taking probiotic supplements, Marrs said that varies by the individual, and everyone should consult their doctor or nutritionist.

But if you already have a “good functioning gut,” you can keep it functioning well by eating foods that contain probiotics, like cultured yogurt and fermented vegetables, Marrs said. “If you don’t have a good functioning gut — then you need something more potent.” Supplements can vary widely in terms of potency and shelf life, Marrs noted, and thus best to consult an expert.

“Some ways in which we can protect our microbiome balance is to include both prebiotic and probiotic foods in our diets,” writes Dr. Umadevi Naidoo in the Psychiatric Times.

 “A prebiotic is a soluble fiber that helps feed the good organisms (probiotics) in our gut. Probiotics already live inside the large intestine. The more prebiotics that the probiotics have to eat, the more efficiently they will work. Examples of prebiotic foods include onions, leeks, asparagus, bananas, Jerusalem artichokes, chicory root, garlic (and) dandelion greens. Probiotic foods that supply these bacteria include fermented foods, such as sauerkraut, yogurt with active cultures, pickles, kefir, kimchi, kombucha (and) miso.” And look at the labels, advises Naidoo in order to avoid extra sugar and preservatives.

Another element that can connect diet to mood is nutrient deficiency, Marrs said.

If you have depressive symptoms, look at your diet, she advises, and make sure you are getting everything you need.

In an era of extreme diets that cut out entire categories of nutrients, not having some good fat, like walnuts and salmon, or having zero carbohydrates, which increase serotonin, may be affecting your mood, she said. “It’s about having a balance.”

A lack of vitamins D or B12 can increase symptoms of depression, she said.

There is also the brain-derived neurotropic factor — BDNF — Marrs said, which plays a role in neurogenesis in the hippocampus portion of the brain. Neurogenesis is the process by which new neurons are formed.

In some preliminary studies on animals, Marrs said, results are showing foods high in omega-3 fatty acids and phytonutrients — chemicals produced by plants — like flavonoids help stimulate BDNF.

And conversely, the more “Western” diet may be leading to decreased neurogenesis.

Some people find benefit in adding adaptogens to their diet, which are herbal pharmaceuticals that can have neuroprotective elements, anti-fatigue properties, antidepressive effects, and act as a stimulant for central nervous system. Those include ginseng, ashwagandha and rhodiola, Marrs said.

It is also important to make sure you are hydrated, she noted, as dehydration can significantly effect how we feel.

The biggest takeaway when linking diet and mood, said Marrs, is acknowledging there is indeed a connection. “What we eat has a lot to do with our brain health and our mood,” she said. And specifically, “the bacteria in our guts play such an essential role in our overall health.”

With that awareness, Marrs advises eating food as close to its natural source and form as possible and making sure your diet isn’t devoid of the things it needs, like key nutrients and good fats. And nurture that gut — make sure you are getting enough fiber and probiotics. 

“I want people to understand that what they eat is important,” Marrs said, and that paying more attention to our diets can improve mental health as well as physical health.

To reach Kari Dequine Harden, call 970-871-4205, email or follow her on Twitter @kariharden.

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