There’s an old adage from the 1800s that begins, “Tell me what you eat, and I will tell you what you are.” Over decades, that adage turned into what most are familiar with today: You are what you eat. To this day, it’s occasionally used as a clever way to inspire healthy eating. But now there is more than enough science to back it up, and it’s one of the cornerstones of how functional nutrition improves health, mood and behavior.

At its core, functional nutrition stresses the intake of whole foods with micronutrient diversity. It’s this combination that helps individuals address clinical disturbances and live healthier lives, which is a concept that Tami Best teaches every day.

As a former dancer and having completed several long-distance races, including the Philadelphia and Boston marathons, Best has the pedigree of an elite athlete. She will be the first to tell you, though, that getting to any finish line starts with sound nutrition, and some of her best qualities will not appear on any résumé, as it’s her determination and willingness to help others that continue to inspire her.

“I was very fortunate as a young adult to immediately have an affinity toward healthy eating,” Best says. “I recognized at a very young age the power of nutrition. I knew when I was eating well that I danced better, I felt better as a person, and I very quickly recognized that was the field I wanted to go into.”

You don’t have to be an athlete, however, to see the benefits of functional nutrition. With more than 25 years of experience in health care, Best is bringing her experience as a registered dietitian to Promise of Vitality, a company she founded in June 2017 to provide functional nutrition and lifestyle solutions for individuals. With advanced certification in functional nutrition from the American Academy of Nutrition and Dietetics, as well as training from The Institute of Functional Medicine, Best is proving that science and nutrition are working hand in hand.

As Best explains, functional medicine determines how and why illness occurs and restores said health by addressing the root causes of disease. At the core of this understanding is nutrition.

Functional medicine practitioners go through what’s called a functional medicine matrix and examine predisposing factors. Then, they examine lifestyle choices or contributors that a person is doing that may be a factor in why one’s body is going awry.

To combat this disruption, functional nutrition focuses on whole foods, promoting clean and organic eating, and getting adequate protein.

Another major component is balancing quality fats. For many years, dietitians stressed a low-fat diet. However, that has led to replacing fats with refined sugars, an abundance of sodium and highly processed foods. Best says there are some fats to discourage, but she stresses the need to balance quality fats such as omega-3 fats, extra virgin olive oil, avocados, nuts and ensuring enough fiber is in one’s diet.

As part of functional nutrition, these fats help reduce insulin resistance and stabilize blood sugars, as well as decrease metabolic syndrome, which has been linked with increases in weight, blood pressure, and blood cholesterol, according to a study from the BMC Nutrition Journal. These types of fats also help improve blood flow and have been linked with helping reduce the risk of depression.

Best emphasizes that functional nutrition also stresses individuals getting a variety of food as opposed to a variety of products. Many products that are on our grocery shelves include ingredients such as highly processed corn, wheat and soy, and they come in a plethora of different packages, cans, and boxes. But in terms of quality nutrition, it isn’t there.

Incorporating functional nutrition not only improves one’s body, Best says, but it has also been proven to improve mood, behavior and reduce symptoms of depression.

“I find this to be the most fascinating piece of functional nutrition,” she says. “The gut is something we label like the second brain. It’s our enteric nervous system, and there is a constant interplay in back and forth messaging that goes between your central nervous system and your enteric nervous system.”

Best says when you put that poor-quality food in your gut, the result is going to be an impact on the central nervous system — your brain health. The results can lead to struggles with anxiety or depression, and many people who Best advises at Promise of Vitality come to her feeling down. She says if she can find that factor in their life that is causing them to want to make a change in their diet, then she can connect with that individual.

“If you can get to some core, meaningful things that are happening in somebody’s life and help them recognize how making these changes will impact their life in a positive way, then they start to be driven to make the changes,” Best says. “It’s not just talking at them. They’re really taking control of the situation, and that’s when I’ve been able to see the greatest success in individuals in terms of making long-term changes.”

Seeing that variety of people who are what they eat and helping them to revolutionize themselves is special for Best. She has seen people who are looking to lose weight, improve their mood, overcome thyroid issues, have multiple intestinal issues and more. But all those symptoms start with a root cause: poor eating.

“Oftentimes, you can get really quick results by introducing the core functional nutrition approach,” she says. “I would say results come very quickly for individuals, and I would say as soon as ten days — once people adopted some of these core principles — they are seeing results.”