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The Science of Happiness Part 1: Serotonin

"Multiple studies found that people with depression, anxiety, and insomnia often have low levels of serotonin."

Health experts agree that finding happiness is actually less art and more science. On today’s live show with Dr. Nancy Lin, PhD, learn how specific hormones and neurotransmitters affect emotions and mood, and profoundly impact how happy we feel. One neurotransmitter in particular, called serotonin, is directly linked to happiness levels. Today’s show explains it all in Part 1 of Dr. Nancy’s long awaited series on “the science of happiness”.

Video Highlights

  • 00:28: The Science of Happiness
  • 05:25: Happiness Trivia
  • 11:39: What is Serotonin?
  • 13:16: Brain-Derived Serotonin
  • 15:24: One Essential Amino Acid
  • 25:37: Serotonin-Boosting Recipes
  • 31:19: Wrap-Up

The Science of Happiness

So many people spend a lifetime in search of happiness, and we try all sorts of things — buying new clothes or gadgets, trying fad diets, going on fancy vacations, and wishing for things that we think will make us happy, only to find out that there really isn’t a pot of happiness at the end of a material rainbow. In other words, possessions alone cannot make us happy.  Sure, a new car, a promotion, or a trip to a tropical location might give us our mood a temporary lift, but soon enough the feelings ofanxiety,stress,depression, and sadness creep back into our lives, and often more intensely than before.

The medical community has come along way in our pursuit of understanding happiness, and specifically what it is and how it happens — and while many health experts agree that doctors are still too quick to prescribeantidepressants and other prescription medications to “cure” a lack of happiness, the one thing we should all agree on is that finding happiness is not an art — it’s a science; a science that starts with understanding hormones and neurotransmitters affect us.

In addition, we now know that it’s not just the hormones interacting with our brains that determine happiness, but also how a number of other important connections, both internally and externally, including ourgut health and several controllable environmental factors. These includevitamin andmineral deficiencies and exposure to pesticides, heavy metals, and othertoxins that also have a profound effect on how your body produces and uses serotonin.

So, that’s what we are going to focus on over the course of the next two shows: serotonin and the science of happiness. In today’s episode, we’re going to really dive into what serotonin is and show you how it affects your brain; we’ll also discuss how being deficient in certain vitamins and minerals can significantly impact your serotonin levels. Dr. Nancy will also explain how one specific amino acid is absolutely essential for your serotonin levels and overall happiness! Plus, she’ll share two of her favorite super easy, super healthy, and super delicious serotonin-boosting recipes.

Happiness Trivia

Before we get too far, let’s lighten the mood (ha!) with some happiness trivia and facts that you might find interesting.

  • The age at which people tend to report feeling the happiest is 35 years old. That’s the average age people say they have the most energy, wisdom, and income at the same time, leading many people to say their mid 30’s are their happiest years. Other research found that people in their mid-50’s tend to smile the most; and another interesting study found that people’s self-perception of happiness tends to be lowest around age 45, but then starts to build and peak in your 70’s. So it appears that there isn’t one “Best” or “Happiest” year, but the good news is that research suggests that most people are generally happier with age.  
  • Most of the serotonin in your body is found in yourintestines! In addition to being involved with determining our happiness levels and affecting our mood, serotonin is found in large quantities in the intestines and is also plays a key role indigestion and in reducingappetite.  
  • Research into the health effects of happiness has found that people who report being happy: experience lessheart disease and havelower blood pressure, havestronger immune systems, get sick less often, experience fewer aches and pains, andlive longer than people who do not consider themselves happy!
  • Thirty-three percent of Americans say they are happy. So, 1 out of every 3 people report that they are happy, which means 67% of us reportnot being happy! So, are there connections between how happy we feel and chronic health issues? The answer is yes — and our chronic health issues, ourstress, our lack ofquality sleep, ourpoor diets, and a general lack ofexercise all contribute significantly to how serotonin and other essential neurotransmitters are produced and synthesized in our bodies.

What is Serotonin?

So you may be wondering what serotonin actually is. Is it a neurotransmitter or is it a hormone? The answer is, it’s both!Serotonin is actually a small molecule that functions both as a neurotransmitter in the central nervous system and as a hormone throughout the rest of your body. Brain-derived serotonin (BDS) acts as a neurotransmitter and mainly affects your mood, while gut-derived serotonin (GDS) acts as a hormone and regulates a wide variety of processes, includingdigestion,bone density, appetite, and helps with the formation of blood clots.

Since we are talking about serotonin's effect on happiness, we’re going to focus primarily on serotonin's effect on mood and emotions, so today we’ll be talking about BDS — or brain-derived serotonin.

Brain-Derived Serotonin

In addition to affecting emotions and boosting your mood, adequate levels of BDS produces healthy sleeping patterns as well as being commonly linked to feeling good and actually living longer.

Serotonin helps regulate your mood naturally. When your serotonin levels are normal, you feel:

  • Happier
  • Calmer
  • More focused
  • Less anxious
  • More emotionally stable

Multiple studies found that people with depression, anxiety, and insomnia often have low levels of serotonin.

However, what people don’t know and what the medical community does a really poor job educating people about, is that interactions between mood and serotonin may actually be a two-way street.  In other words, while serotonin levels certainly affects mood, it appears that your mood also affects your serotonin levels!

The same research also demonstrated thatexposure to bright light also has a profound impact on your serotonin levels.  In fact, research comparing the brains of people who died in the summer to the brains of people who died in the winter consistently showed that serotonin levels where much higher in the brains of those who died in the summer. 

One Essential Amino Acid

Serotonin is found in our brains, our blood cells, our central nervous system, and our digestive systems — and is essential for improving our happiness — but where does it come from?  Wouldn’t it be great if we were able to improve the body’s ability to create serotonin? 

Well there is! And it’s not as difficult as you might think. We’re going to share how you can improve your serotonin levels, but first we need to talk about a super important, essential amino acid called tryptophan. You’ve probably heard of tryptophan before — you may be thinking of Thanksgiving, right?  It’s an amino acid found in turkey, and it’s supposedly what makes everyone so sleepy after our big Thanksgiving dinners... but that's really not true. Tryptophan is a precursor of serotonin and melatonin; both are important for sleep, but turkey tends to get a bad rap. It really isn’t what makes us tired after our feast,so don’t blame the turkey for your post-celebration slumber; the heavy load of carbohydrates, including potatoes, rolls, and pumpkin pie that made up the rest of the meal are likely the real causes of our holiday sluggishness!

Tryptophan is an essential amino acid, which means that it’s an amino acid that can’t be made by your body and must be consumed through food or supplements.  Research tells us that tryptophan is absolutely essential for our serotonin levels — in fact, serotonin is processed and synthesized directly from tryptophan. Without tryptophan, there is no serotonin!

Foods that Increase Tryptophan

Fortunately, there are several natural, healthy foods (in addition to turkey) that provide significant amounts of tryptophan, including:

  • Beets
  • Chickpeas and beans
  • Eggs
  • Wild caught salmon
  • Nearly all types of nuts
  • Pineapple
  • Chia, Pumpkin, and Hemp seeds

Just consuming foods high in tryptophan alone often isn't enough to increase serotonin levels in our brains — that’s a really important point that not many people realize. There is a little-known secret that will help increase the amount of  tryptophan that is absorbed into your blood and delivered to your brain: eat these foods with complex carbohydrates. That’s right! How many medical professionals do you hear telling people to eat more carbs? In this case, it appears that eating foods that contain tryptophan with a complex carbohydrate increases the amount that’s actually absorbed by your brain.

In order to be converted to brain-derived serotonin, tryptophan needs to be absorbed by your brain, but the problem is that tryptophan is constantly competing with 19 other amino acids, which often results in a reduced absorption, and ultimately, lower levels of serotonin in your brain. Carbohydrates cause your body to produce and release more insulin, which actually increases the absorption of other amino acids, leaving a higher concentration of tryptophan in your blood which can then be accessed and absorbed by the brain. So, a healthy side of complex carbs such as wild rice, quinoa, or sweet potato, will really help the tryptophan, and ultimately serotonin levels in your brain.  


It’s also important to point out thatexercise — especially moderate exercise, or “exercise to moderate fatigue” — plays a huge role in stabilizing our mood and especially our happiness. As we continue to learn more about the science of happiness, research has discovered that during exercise, there is a substantial increase in the amount of tryptophan in your blood, (specifically your blood plasma), and as a result, there is an increase in the amount of tryptophan available to the brain. Then tryptophan becomes serotonin, and serotonin stabilizes your emotions and improves your mood, with the end result of an overall increase in happiness.

Vitamin B6 and Vitamin D

In addition to eating a combination of foods that contain tryptophan and complex carbohydrates, and engaging in regular exercise, making sure you are not deficient in specific vitamins, minerals, and nutrients that support serotonin production is also an extremely important step to support your emotional stability and your overall happiness. You know that over 90% of Americans are deficient in at least one vitamin or essential mineral, right?  That means there’s a good chance that you are too.  

Two really important vitamins that are required in order to convert tryptophan into serotonin are Vitamin B6 andVitamin D. In fact, both vitamins are considered to becofactors, which means they are required in order to convert tryptophan into serotonin. Study after study shows that people who suffer from severe depression almost always have low concentrations of not only serotonin, but also vitamin B6 and vitamin D.  One way to make sure you’re never deficient in either by taking a daily multivitamin such as theSmarter Nutrition Multi. It only sources its minerals and most of its vitamins — including vitamin B6 and vitamin D are from natural, plant-based sources like spinach, broccoli, peaches, pears, and pumpkin and sunflower seeds.

Serotonin-Boosting Recipes

Tryptophan Smoothie 

This recipe is great for breakfast, lunch, or a post-workout snack!

Here’s what you’ll need:

  • 1 medium organic banana 
  • ½ cup frozen organic raspberries
  • ½ cup frozen organic blueberries
  • 1 cup organic almond milk
  • 1 tbsp. chia seeds
  • 1 tbsp. hemp seeds
  • 1 tsp. coconut oil
  • Water

The berries contain flavonoids which boost serotonin production and improve communication between brain cells, the banana is a source of carbs and is high inantioxidants, serotonin and dopamine, the seeds are loaded with tryptophan, and coconut oil is rich in omega-3 a fatty acid that is essential for brain health.

This is really simple to make. All you need to do is add all the ingredients to a blender and blend until smooth. Add water to get just the right consistency.  

Turkey, Avocado & Spinach Salad

Here’s what you’ll need:

  • A few handfuls of organic baby spinach or arugula
  • A diced avocado
  • A handful of walnuts, sunflower seeds, and pumpkin seeds
  • ¼ cup of wild rice or quinoa (leftovers are fine)
  • A cup or so of diced turkey
  • 1 hard boiled egg, chopped

Toss the ingredients into a bowl, top with your favorite vinaigrette or olive oil, and you have a quick, healthy lunch or dinner loaded with tryptophan, vitamin B, vitamin D, and omega-3 fatty acids needed to ensure your serotonin levels are stable.


Serotonin, often known as the “happiness hormone” is actually both a hormone and a neurotransmitter that has been shown not only to stabilize mood, but also increase your overall happiness. In addition, we talked about the two specific different types of serotonin — brain-derived serotonin and gut-derived serotonin.We spent most of today’s episode talking about brain-derived serotonin (BDS). However, it's important to point out that the majority of serotonin is found in the gut and specifically in the intestines — which we will cover during part two of our serotonin series.

We also talked about the importance of one specific essential amino acid called tryptophan, the serotonin process, and several natural, healthy food sources that are rich in the amino acid. Those include chickpeas, beans, nuts, seeds, turkey, eggs, and even pineapple. Tryptophan is the base of serotonin, meaning it’s what serotonin is created from, but remember, you have a lot of different amino acids competing for attention in your body. Research has found that eating tryptophan-rich foods with complex carbohydrates increases the absorption of tryptophan, ultimately increasing your body’s ability to create, absorb, and use serotonin. Research also shows us that serotonin levels decrease when we are deficient in vitamin B6 and vitamin D, which we need in order to convert tryptophan into serotonin, so in order to make sure you are not deficient in these essential vitamins, we recommend taking theSmarter Multivitamin every day to ensure your serotonin levels stay within a normal, healthy range.

We covered quite a bit of really important information pertaining to the role serotonin — and tryptophan — plays in supporting your happiness and sense of contentment, joy, and overall well-being.  

I hope you found today’s episode helpful and informative. Stay tuned for part two of our serotonin series where we will dive deeper into the relationship between serotonin, your digestive health, and happiness!

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