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The Sugar-Anxiety Connection You Need To Know About

William Cole, IFMCP, DNM, D.C.
Author: Expert reviewer:
Updated on December 30, 2020
William Cole, IFMCP, DNM, D.C.
Functional Medicine Practitioner
By William Cole, IFMCP, DNM, D.C.
Functional Medicine Practitioner
Will Cole, IFMCP, DNM, D.C., is a leading functional medicine practitioner with a certification in natural medicine and a doctor of chiropractic degree.
Ashley Jordan Ferira, Ph.D., RDN
Expert review by
Ashley Jordan Ferira, Ph.D., RDN
mbg Vice President of Scientific Affairs
Ashley Jordan Ferira, Ph.D., RDN is Vice President of Scientific Affairs at mindbodygreen. She received her bachelor's degree in Biological Basis of Behavior from the University of Pennsylvania and Ph.D. in Foods and Nutrition from the University of Georgia.
Last updated on December 30, 2020

It’s easy to consider anxiety and other mental health problems as completely separate issues than your physical health. But in reality, the way you feel mentally can be directly correlated to how you feel physically and even more importantly—what you're putting in your body. Excess sugar, in particular, is an often overlooked but important potential contributor to mental health and wellness.

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Understanding the connection between sugar and the brain.

Anxiety and depression often go hand in hand. For some people, it's more anxiety; for others it's predominantly depression, but they are highly connected and comorbid (occur together). 

Patients with anxiety and/or depression are often prescribed selective serotonin reuptake inhibitor (SSRI) medications, which prevent the reuptake of serotonin, making more serotonin available for your brain. When these medications were originally developed over 30 years ago, it was believed that anxiety and depression were caused by low levels of serotonin1, the “feel good hormone.”

It turns out that the mechanisms aren't quite so binary. Serotonin and its role in brain function are much more nuanced2 than originally thought (and still being worked out).

In fact just a few years ago, a study in the journal 3Nature3 revealed a new anxiety-regulating circuit in the brains of mice. SSRIs (which increase serotonin) activated this novel circuit and produced anxiety (kind of counterproductive, right?). Well, that same paradox has been reported in humans, with certain patients suffering from worse anxiety when taking SSRIs, especially the first few weeks.

Guess what also raises serotonin levels? Sugar. From studies in rodents, we know that lower serotonin levels in the brain stimulate sugar craving4. But long-term intake of a high-sugar diet desensitizes serotonin receptors5 (meaning more sugar may be needed to satisfy the craving).

In humans, higher sugar intake from sweet foods and beverages significantly increases one's odds of having a mental health disorder6, making the case for lower intake of sugar to support psychological health.

While more research is needed, it’s possible that if you struggle with anxiety and/or depression, by eating added sugars, you're contributing to the neurochemical reaction of these mental health pathways and further perpetuating the issue. Maybe Mary Poppins wasn't too far off when she sang "a spoonful of sugar helps the medicine go down."

Linking your gut health to your mental health.

The gut microbiome and its beneficial “bugs” are important for optimal health. Our gut microbiota are malleable and can be negatively or positively affected by our diet choices. High sugar intake can shake up the balance of our gut microbes7, increasing ones tied to inflammation and metabolic dysfunction.

So you can either choose to feed good bacteria or bad bacteria—and sugar appears to feed bad bacteria and can contribute to yeast overgrowths like Candida. When bad bacteria predominate, it creates an imbalance that can lead to chronic systemic inflammation8 (which is linked to many diseases, including anxiety and depression9).

Even if you don’t have digestive symptoms, you can still have underlying digestive problems—they may just be manifesting themselves in different areas of your body, like your brain or nervous system. In fact, supporting gut microbiota through probiotics and dietary interventions (e.g., low FODMAP diet) has been shown to improve anxiety10.

Did you know that your gut and brain are connected11 from the very start? The two organs develop from the exact same fetal tissue in the womb and continue to communicate together your whole life through the vagus nerve and the gut-brain axis. 

When you have chronic inflammation, it can lead to damage of your protective blood-brain barrier and what us functional medicine doctors like to call "leaky brain." And because your brain’s immune system is working even harder to fight off invaders due to barrier destruction, it can lead to an inflammatory-autoimmune response. So it’s really no surprise that anxiety and depression are more common in patients with autoimmune diseases12 due to the inflammatory effect on the central nervous system.

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Familiarizing yourself with blood sugar.

Another piece of the anxiety puzzle comes into play when we really examine blood sugar. Excess sugar intake contributes to blood sugar spikes and insulin resistance over time. And when your blood sugar is out of whack, it throws off13 your hypothalamic-pituitary-adrenal axis (HPA axis), which is responsible for releasing your stress hormone cortisol14 (think fight-or-flight response).

If you're constantly throwing off your adrenals with sugar, you’ll never really calm down which can further perpetuate the feelings of anxiety. If you want your HPA axis to function properly, keeping your blood sugar levels in check is paramount.

Plus, when your blood sugar levels are off, it can increase those "hangry" feelings; you'll find yourself wanting sweet and salty foods to feel satisfied. But that’s the problem: You never get off the hamster wheel that is blood sugar imbalance and anxiety. 

A diet high in sugar and high-glucose foods (i.e., high glycemic index) can play a direct role15 in the development and progression of anxiety and depression. So making smart choices about sugar and carb intake can support mental health (and overall health).

Finding out if sugar is a problem for you.

Running labs is a great way to understand where your baseline is and how much you need to change your diet to see improvement. As a functional medicine practitioner, these are the most common labs that I run to assess gut, brain, and blood sugar function and health:

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1. Gut health labs.

These labs check your gut bacteria and give you a better indication of whether or not your gut health has been compromised:

  • A comprehensive stool analysis: This can assess the bacterial diversity of your gut.
  • Zonulin and Occludin Antibodies: These are two proteins that help control gut permeability. If you have antibodies, it could mean there's damage to the intestinal tight junctions.
  • Actomyosin Antibodies: Presence of these could mean there was destruction of healthy gut lining.
  • Lipopolysaccharide (LPS) Antibodies: These are bacterial endotoxins located in your gut. If antibodies are found in your blood, that could be a sign of leaky gut syndrome.
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2. Autoimmune reactivity brain labs.

These blood labs can look for raised antibodies against parts of the brain, ruling out neurological autoimmune reactivity.

3. Blood sugar labs.

These are some of the labs I run to determine if your blood sugar is out of whack and contributing to your anxiety.

  • Serum insulin: Normal: < 25 mIU/mL; Optimal range: < 3 mlU/mL
  • C-peptide: Optimal range: 0.8 to 3.1 ng/mL
  • Fasting blood sugar: Normal: < 100 mg/dL; Optimal range: 75 to 90 mg/dL
  • HbA1c: Normal: < 5.6 percent; Optimal range: < 5.3 percent
  • Triglycerides: Normal: < 150 mg/dL; Optimal range: < 100 mg/dL
  • HDL: Optimal range: 60 to 100 mg/dL
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Once you have a better understanding of where your health stands, the next step to calming your anxiety is to stop feeding it with sugar. Of course, natural sugars from fruit are fair game and even having a treat here and there is definitely not a bad thing. However, it’s important to be smart about satisfying your sweet tooth by using natural sweeteners instead. Raw honey is one of my favorite options due to its high antioxidant content.

Hop on over to my sweetener guide to find the perfect sweetener for you!

William Cole, IFMCP, DNM, D.C.
William Cole, IFMCP, DNM, D.C.

Will Cole, IFMCP, DNM, D.C., is a leading functional medicine expert who consults people around the globe, starting one of the first functional medicine telehealth centers in the world. Named one of the top 50 functional and integrative doctors in the nation, Dr. Will Cole provides a functional medicine approach for thyroid issues, autoimmune conditions, hormonal imbalances, digestive disorders, and brain problems. He is the host of the popular The Art Of Being Well podcast and the New York Times bestselling author of Intuitive Fasting, Ketotarian,The Inflammation Spectrum, and the brand new book Gut Feelings: Healing the Shame-Fueled Relationship Between What You Eat and How You Feel.

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