By Cindi Juncal

We’ve all heard the adage, “You are what you eat,” referring to how the foods we consume eventually become the bones, blood, muscles and tissues that make us what we see when we look in the mirror. 

The trillions of cells we have in our bodies today are not all the exact same ones that we had yesterday. As cells age and become damaged, we replicate and create more, some more frequently than others. For example, a stomach cell lives about a day or two, a skin cell for about a month, but a cell in the middle of our eye lenses can last an entire lifetime. How healthy those new cells are is very likely linked to how well we’ve been eating. 

A diet filled with highly processed food that’s low on nutrients doesn’t give our body much to work with. But a clean, nutrient rich, whole foods eating plan can help us build cells that work better and are less susceptible to premature aging and disease.

In one of my previous articles (Preventing Cognitive Decline Should Be a No-Brainer), I detailed how Drs. Dean and Ayesha Sherzai, co-directors of the Brain Health and Alzheimer’s Prevention Program at Loma Linda University Medical Center, had determined through decades of extensive research that 90% of Alzheimer’s cases could be prevented - and the main determining factor was nutrition. In their book, The Alzheimer’s Solution, they wrote:

“Because of its fundamental role in sustaining and regenerating the body, food is the single greatest tool we have in the fight against Alzheimer’s. As lifestyle physicians and researchers, we cannot overstate the importance of food for brain health: it is by far the most important lifestyle factor. The dietary choices we make every day influence the prevention, delay, or progression of cognitive decline. Our clinical research has shown again and again, with patients of all ages and degrees of neurodegenerative disease, that adhering to a brain-healthy diet results in better cognition. It’s that simple.”

The evidence is abundant and fairly indisputable that what we eat can give us a healthy brain. But what about a happy one?

Nutritional psychiatry is an emerging field that refers to the treatment and prevention of mental disorders through dietary modifications and nutrient-based supplementation. Until recently, most prescriptions for psychiatric disorders have focused on treating the symptoms and while many are effective, they also come with the potential for severe and unwanted side effects. 

Current research on the link between food and brain health has not only been established with dementia and Alzheimer’s, but also with depression, psychosis and schizophrenia-spectrum disorders. One of the strongest potential pathways to this relationship between what we eat and how we feel is through the stomach - or more specifically, the gut biome.

Dr. Eva Selhub, a contributing editor and staff member at Harvard Medical School, is also an internationally recognized expert, physician, author, speaker and consultant in the fields of stress, resilience, and mind-body medicine. She penned an article for the Harvard Health Blog in September of last year titled, “Nutritional Psychiatry: Your Brain on Food.” In it, she likens our brain to a fancy sports car, explaining that it functions best when given premium fuel. She elaborates:

“Unfortunately, just like an expensive car, your brain can be damaged if you ingest anything other than premium fuel. If substances from "low-premium" fuel (such as what you get from processed or refined foods) get to the brain, it has little ability to get rid of them. Diets high in refined sugars, for example, are harmful to the brain. 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.”

Even without a randomized, double-blind control study, we’ve always known that excessive amounts of sweets were bad for us. But in a simple attempt to help wrap our sugar-laden brains around the mechanics of how it disrupts or deregulates our mental functions, think of it this way: If highly processed junk foods and their added sugars are the antagonists to our well-being, then SEROTONIN is the getaway car, or at least the unwitting conduit, between our gut and our brain.

Serotonin is a neurotransmitter that helps regulate a plethora of body functions. It acts as our mood regulator, influencing our biological and neurological processes such as aggression, anxiety, cognition, mood, appetite, sleep - even inhibiting pain. When serotonin is at normal levels, you feel more focused, emotionally stable, happier and calmer - which is why it’s often called the “feel good” hormone. Low levels of serotonin are associated with depression. According to Dr. Selhub, “Since about 95% of your serotonin is produced in your gastrointestinal tract, and your gastrointestinal tract is lined with a hundred million nerve cells, or neurons, it makes sense that the inner workings of your digestive system don’t just help you digest food, but also guide your emotions.”

To further emphasize the importance of fueling with high quality food, she goes on to explain that the function of these neurons are greatly influenced by the billions of ‘good bacteria’ that make up our gut biome. These microscopic militia protect the lining of our intestines, forming a Hulk-like barrier against the bad guys and other toxins. In addition to limiting inflammation, they improve how we absorb important nutrients from our food and make sure that those neural pathways to our brain are always lit green. Turns out, the best way to ensure that we have plenty of healthy and diverse good bacteria is to eat a healthy and diverse diet, full of fruits and vegetables, whole grains and other sources of fiber like legumes and beans.

Selhub also points to studies that compared ‘traditional’ diets like the Mediterranean diet and the Japanese diet to the typical ‘Western’ diet. The results showed that the risk of depression was 25%-35% lower in those who ate the traditional diets, which are high in the foods mentioned above, as well as fish and seafood and only modest amounts of lean meats and dairy. She noted that the traditional diets were “void of processed and refined foods and sugars, which are staples of the ‘Western’ dietary pattern. In addition, many of these unprocessed foods are fermented, and therefore act as natural probiotics.”

Most experts conclude that while promising, the field of nutritional psychiatry is one that needs additional studies and clinical trials to establish more definite connections between diet and mood, encourage specific dietary recommendations, and inform new public health policies. In the meantime, we can certainly apply some of our own research and start paying attention to how what we eat influences how we feel. 

Dr. Selhub recommends trying to eat “clean” for 2-3 weeks, cutting out all processed foods and sugar and seeing if you feel any differently. I would add: drink plenty of water, make sure to move as much as possible, take lots of deep breaths outside with the sun on your face and your feet in the sand, and be sure to hold hands or hug someone you love. I think that sounds like a pretty good recipe…