Functional Nutrition Testing: The Answers Your Doctor Misses

You've had the bloodwork, seen the specialists, and followed the recommendations. So why are you still struggling with symptoms? Here's how functional nutrition testing may help uncover overlooked pieces of your nutritional health.

You've had the bloodwork done. You've seen the specialists. Maybe you've even been scoped every which way you can be scoped, only to walk away with a diagnosis like irritable bowel syndrome (IBS) and very few answers about why you're still feeling the way you do.

Maybe you're constantly exhausted. You're struggling with weight-loss resistance, chronic bloating, joint pain, or inflammation. Or perhaps you're dealing with gastrointestinal issues that have you planning your entire day around where the nearest bathroom is.

You've been told your labs are normal. You've been told to eat less and exercise more. Maybe someone has even suggested that your symptoms are all in your head.

But you're still looking for answers.

What if nutritional deficiencies, blood sugar imbalances, digestive concerns, or other metabolic factors are contributing to symptoms that haven't been fully explained?

I'm Meg Marie O'Rourke, a registered dietitian and functional nutritionist with over 20 years of experience. Some people call me the Anti-Diet Dietitian, and I was put on this earth to change the way you think about food.

At Harmony with Food, I work with people who have spent years searching for answers. Through personalized nutrition, appropriate nutritional assessments, and my six-step methodology, I help clients explore aspects of their nutritional health that may deserve additional attention.

And one of the most important things I've learned throughout my career is that understanding your health requires looking at the entire picture.

Your digestive symptoms, blood sugar regulation, eating habits, nutritional status, medications, supplements, and medical history can all provide valuable information.

This November, during National Alzheimer's Disease Awareness Month, we're also going to explore how some of these same nutritional and metabolic factors relate to brain health.

Because your digestive system, metabolism, and brain are interconnected.

And as I always say:

Test, don't guess.

Why Your Medical Tests May Not Tell the Whole Story

Let me explain something I see frequently in my practice.

People come to me after undergoing extensive medical evaluations.

They've had colonoscopies, endoscopies, bloodwork, and other diagnostic procedures. Some have been diagnosed with IBS, Crohn's disease, ulcerative colitis, or microscopic colitis.

Others are struggling with unexplained fatigue, weight-loss resistance, persistent bloating, or symptoms that interfere with their everyday lives.

They've seen physicians, tried medications, changed their diets, and experimented with supplements.

And sometimes they're still not feeling better.

Conventional medical testing is essential for identifying and treating disease. However, the tests ordered during a medical evaluation depend on the symptoms being investigated and the conditions a healthcare provider is considering.

That means certain nutrition-related questions may not have been addressed.

For example:

• Have specific nutritional deficiencies been evaluated when symptoms or medical history suggest they may be present?

• Have blood glucose and other relevant metabolic markers been reviewed?

• Could medications be affecting nutrient absorption or nutritional status?

• Are dietary patterns or food tolerances contributing to ongoing digestive symptoms?

• Has anyone reviewed the entire supplement routine for unnecessary products or potential interactions?

These are questions I explore when working with clients.

Functional nutrition testing involves selecting and interpreting appropriate assessments in the context of a person's symptoms, diet, medical history, and health goals.

The purpose is to gather useful information that can guide individualized nutrition decisions.

And sometimes, asking a different question helps us identify a factor that hasn't received enough attention.

What Is Functional Nutrition Testing?

Functional nutrition testing is an approach to evaluating nutritional and metabolic health based on a person's individual circumstances.

It may involve reviewing established laboratory results, identifying gaps in previous assessments, and discussing additional tests when clinically appropriate.

For example, someone experiencing persistent fatigue may benefit from an evaluation of specific nutritional deficiencies, depending on their symptoms and medical history.

A person struggling with metabolic concerns may need closer attention to blood sugar regulation.

Someone experiencing chronic digestive discomfort may benefit from a detailed dietary assessment, investigation of food tolerances, or appropriate medical evaluation for gastrointestinal conditions.

The tests themselves are only part of the process.

The value comes from understanding what the results mean, how they relate to your symptoms, and

whether they point toward useful nutritional changes.

Not every person needs the same testing.

Not every symptom requires an extensive laboratory panel.

And ordering more tests doesn't automatically produce better answers.

That's why I begin by reviewing what we already know before determining what additional information might be useful.

Let's examine four areas that frequently come up in my work.

1. Blood Sugar and Insulin Testing: Understanding Your Metabolic Health

Blood sugar regulation influences much more than the amount of glucose circulating in your bloodstream.

It's connected to energy metabolism, cardiovascular health, and long-term neurological function.

When I review someone's metabolic health, I want to understand whether blood glucose regulation has been adequately evaluated.

Two commonly used clinical measurements are fasting blood glucose and hemoglobin A1c.

Hemoglobin A1c provides an estimate of average blood glucose levels over approximately three months.

Depending on the individual's medical history and symptoms, a healthcare professional may consider other appropriate metabolic assessments.

These results can help identify diabetes, prediabetes, and concerns that may require further evaluation.

What Does Blood Sugar Have to Do With Alzheimer's Disease?

Here's an example of why metabolic health deserves attention.

Researchers have identified a relationship between Type 2 diabetes, insulin resistance, and the risk of developing Alzheimer's disease.

You may have heard Alzheimer's referred to as Type 3 diabetes.

It's important to clarify that Type 3 diabetes is not an officially recognized diagnosis for Alzheimer's disease.

The phrase is sometimes used informally when discussing research on impaired insulin signaling in the brain.

Your brain uses approximately 20% of your body's energy, and glucose is a major source of that energy.

Insulin signaling also plays important roles in normal brain function.

Researchers have observed disruptions in insulin-related pathways in Alzheimer's disease, and Type 2 diabetes is associated with an increased risk of dementia.

These findings don't mean that Alzheimer's is simply another form of diabetes or that managing blood sugar guarantees protection against cognitive decline.

They do reinforce the importance of understanding metabolic health.

And this is where appropriate testing becomes valuable.

Knowing your blood glucose and A1c results can help identify established health concerns that deserve attention before additional complications develop.

Depending on your circumstances, managing those concerns may involve nutrition changes, physical activity, medication, or other recommendations from your healthcare provider.

Even something as simple as taking a 20-minute walk after a meal may support blood glucose regulation.

The first step is understanding which factors are relevant to your individual health.

2. Micronutrient Testing: Could a Nutritional Deficiency Be Contributing to Your Symptoms?

Let's talk about vitamins and minerals.

I frequently meet people who are taking several supplements without knowing whether they actually need them.

Vitamin D, magnesium, B vitamins, omega-3 fatty acids, probiotics—you name it.

Some people have an entire collection of supplement bottles sitting on their kitchen counter.

And yet, they may still be struggling with fatigue, digestive symptoms, or other concerns.

Here's what I want to know:

Are we addressing an identified nutritional need, or are we simply hoping that taking more supplements will improve how we feel?

Certain vitamin and mineral deficiencies can produce symptoms that overlap with other health conditions.

Vitamin B12 is a particularly important example.

B12 plays essential roles in neurological function and the production of healthy red blood cells.

A deficiency can contribute to fatigue, numbness, tingling, and difficulties with memory or concentration.

Certain medical conditions, dietary patterns, and medications can increase the likelihood of deficiency.

For example, long-term metformin use can contribute to reduced vitamin B12 levels in some individuals.

When clinically appropriate, evaluating B12 status can help identify a treatable nutritional deficiency.

Other nutrients may deserve attention depending on the person's symptoms, diet, and medical history.

However, commercially available micronutrient panels vary in clinical validity, and testing every possible nutrient is not necessarily appropriate.

I want testing to answer a meaningful question.

If we identify a deficiency, we can work with the appropriate healthcare professionals to determine how to address it.

If testing doesn't indicate a deficiency, that information can also help us avoid unnecessary supplementation.

The goal is to make nutritional decisions based on relevant evidence and individual needs.

3. Gut Microbiome Testing: What Can Your Digestive Health Tell Us?

Now we're getting into one of my favorite subjects.

Your gut.

Your gastrointestinal tract contains trillions of microorganisms, collectively known as the gut microbiome.

These microorganisms are involved in digestion, metabolism, immune function, and the production of various compounds.

Some gut bacteria ferment dietary fiber and produce short-chain fatty acids, including butyrate.

Butyrate helps support the intestinal lining and plays a role in regulating inflammation.

Scientists are also investigating how the gut microbiome communicates with other systems throughout the body.

And one of the most fascinating areas of research involves the relationship between the gut and the brain.

Understanding the Gut-Brain Connection

Your digestive system and brain communicate through an interconnected network involving the nervous system, immune system, hormones, and other signaling pathways.

Researchers call this the gut-brain axis.

This relationship has attracted considerable attention in studies involving digestive disorders, metabolic health, inflammation, and neurological conditions.

In 2023, researchers at Washington University reported differences in gut microbial profiles among individuals with early biological signs of Alzheimer's disease who had not yet developed noticeable cognitive symptoms.

That's an interesting finding.

It suggests that researchers may be able to learn more about neurological health by examining relationships between the gut microbiome and biological changes occurring elsewhere in the body.

However, the study did not establish that gut bacteria caused Alzheimer's disease.

And it does not mean that a commercial microbiome test can diagnose, predict, or prevent Alzheimer's.

This distinction is important.

The research is developing, and there is currently no universally established ideal microbiome composition for every person.

Commercial microbiome testing also has clinical limitations, particularly when it comes to using results to direct specific treatments.

Where Does Functional Nutrition Fit In?

When someone comes to me with persistent digestive complaints, I want to understand their symptoms in context.

What are they eating?

When do the symptoms occur?

Have they identified particular foods that seem to aggravate their digestion?

What medical evaluations have already been completed?

Are they taking medications or supplements that could influence gastrointestinal function?

Depending on the situation, we may discuss whether additional nutritional or medical assessments would be appropriate.

Microbiome testing is one area we may consider, while recognizing the limitations of what commercial results can currently tell us.

I also emphasize a food-first approach.

Research from Stanford University found that consuming a diet rich in fermented foods over approximately

10 weeks increased gut microbial diversity and reduced certain inflammatory markers.

Foods such as yogurt, kefir, and sauerkraut may be useful additions for individuals who tolerate them.

Dietary fiber from vegetables, fruits, beans, and whole grains can also support digestive health.

But personalized nutrition requires us to consider individual circumstances.

Someone with lactose intolerance may have difficulty with certain dairy products.

Another person may experience digestive symptoms after consuming fermented foods.

And someone with an established gastrointestinal condition may need specific dietary guidance.

Understanding your symptoms, nutritional needs, and medical history helps determine which recommendations are appropriate for you.

That's the foundation of my approach.

4. Supplement and Medication Evaluation: Are You Taking What Your Body Actually Needs?

Here's another issue I see regularly.

People take supplements willy-nilly.

They hear something is good for inflammation, so they start taking it.

They read about probiotics and buy a bottle.

Then they hear about omega-3 fatty acids, magnesium, vitamin D, or another product promising better health.

Before long, they've developed an entire supplement routine without reviewing how those products work together.

But supplements can interact with medications, and certain nutrients may be unnecessary or inappropriate depending on a person's medical history.

For example, grapefruit can interfere with the metabolism of certain statin medications.

And as I mentioned earlier, long-term metformin use can influence vitamin B12 status.

Probiotics also deserve careful consideration.

Different strains can have different effects, and there is no specific probiotic currently proven to prevent Alzheimer's disease.

The product with the highest number of organisms on the label isn't necessarily the best choice.

That's why I want to know what someone is taking and what they're hoping to accomplish.

Are the supplements addressing a specific nutritional concern?

Is there evidence supporting their use for that individual?

Could any products interact with prescription medications?

Would changes to the person's diet be more appropriate?

These are the kinds of questions I explore through my "Are You a Supplement Nutcase?" evaluation.

The service focuses on reviewing a person's existing supplement routine and helping them understand whether their current approach aligns with their nutritional needs.

And when questions involve prescription medications or potential medical interactions, coordination with a physician or pharmacist is essential.

My philosophy remains simple:

Test, don't guess.

Why Alzheimer's Research Reinforces the Importance of Understanding Your Health

Because November is National Alzheimer's Disease Awareness Month, I want to return briefly to what researchers are discovering about nutrition, metabolic health, and cognitive function.

Alzheimer's disease is a complex neurological condition influenced by multiple biological and environmental factors.

According to the Alzheimer's Association, more than seven million Americans age 65 and older are living with Alzheimer's disease.

I understand the challenges surrounding this disease from personal professional experience.

Earlier in my career, I worked in locked Alzheimer's care units, where I witnessed the difficulties patients and families experienced.

Today, researchers continue investigating how blood sugar regulation, cardiovascular health, inflammation, nutrition, genetics, and other factors may relate to dementia risk.

A 2024 report from The Lancet Commission identified 14 potentially modifiable risk factors for dementia.

These include diabetes, high blood pressure, elevated LDL cholesterol, physical inactivity, smoking, hearing loss, and social isolation, among others.

The Commission estimated that addressing these risk factors could prevent or delay nearly half of dementia cases worldwide.

That is a population-level estimate, and it does not mean every individual case can be prevented.

Still, the research highlights opportunities to identify and manage established health concerns.

Nutrition is also part of the discussion.

A study from Rush University found that individuals who closely followed the MIND diet had an approximately 53% lower observed risk of Alzheimer's disease, while those who followed it moderately had an approximately 35% lower observed risk.

These were observational findings, so they do not establish that following the diet directly prevents Alzheimer's.

The MIND diet emphasizes foods such as leafy greens, berries, nuts, whole grains, beans, olive oil, and fish.

In 2025, the U.S. POINTER study also provided evidence that structured lifestyle interventions involving healthy eating, physical activity, cognitive stimulation, and social engagement can support cognitive function among older adults at risk for decline.

What do these findings tell us?

Our metabolic and nutritional health deserves attention throughout our lives, and identifying relevant risk factors gives us opportunities to make informed decisions.

A blood glucose test, an appropriate nutritional assessment, or a medication review may help identify concerns that warrant further attention.

Of course, no single nutritional test can determine whether someone will develop Alzheimer's disease.

And broad commercial testing panels have not been established as tools for Alzheimer's prevention.

The value of individualized assessment is in understanding the health factors we can appropriately evaluate and address.

That's the connection I want people to understand.

How My BioUnique Boutique Collective Approaches Personalized Nutrition

My interest in functional nutrition is deeply personal.

More than 15 years ago, I experienced my own gastrointestinal health struggles.

Although I was already a registered dietitian, I was working in different areas of nutrition at the time.

My experience with dietary changes and exploring additional nutrition-related testing influenced the direction of my career.

Eventually, I developed my BioUnique Boutique Collective and six-step methodology.

Today, I work with busy, health-minded people who want to better understand their nutritional health and address concerns such as digestive symptoms, weight-loss resistance, and metabolic imbalances.

The process begins with understanding the individual.

Your symptoms.

Your medical history.

Your eating habits.

Your medications and supplements.

Your existing laboratory results.

Your health goals.

From there, we look at which nutritional factors may deserve further evaluation and what practical changes

might be appropriate.

My six-step methodology provides a structured approach to reviewing those concerns and developing individualized nutrition strategies.

And when symptoms suggest a medical condition requiring additional evaluation, working with the appropriate healthcare provider is part of the process.

I want clients to understand the information available to them, ask informed questions, and participate actively in decisions about their health.

Because improving your nutritional health begins with understanding what is actually happening in your body.

Why Wait Until January to Start Investigating Your Health?

We're entering one of the busiest times of the year.

Halloween has come and gone, Thanksgiving is approaching, and before you know it, we'll be surrounded by holiday parties, gatherings, and all the wonderful food that comes with the season.

For many people, January 1st becomes the date when they decide they're finally going to prioritize their health.

But why wait?

If you've been experiencing digestive symptoms, unexplained fatigue, or concerns about your metabolic health, you can begin asking questions now.

Maybe that means scheduling an appointment to discuss symptoms you've been experiencing for years.

Maybe it's reviewing your most recent bloodwork with your healthcare provider.

Perhaps it's taking a closer look at your supplement routine.

Or maybe it's making small changes to your daily eating habits, getting more physical activity, or paying closer attention to your sleep.

You don't have to change everything at once.

And you can absolutely enjoy Thanksgiving while making thoughtful choices about your nutrition.

I've put together healthy Thanksgiving recipes and menu-planning ideas at HarmonyWithFood.com.

They're designed to offer delicious options and make holiday planning a little easier.

Ready to Explore the Missing Pieces of Your Nutritional Health?

If you've been struggling with digestive problems, unexplained fatigue, weight-loss resistance, or other nutrition-related concerns, I'd love to help you explore your next steps.

At Harmony with Food, I offer a $97 Functional Nutrition Health Assessment.

You'll meet directly with me.

We'll discuss your concerns, review relevant health information, and explore whether additional nutrition-related assessments may be appropriate.

I'll also show you sample reports so you can better understand what different assessments measure and how their findings may be interpreted.

For individuals who want a closer look at their supplements, I also offer my $597 "Are You a Supplement Nutcase?" evaluation.

This service reviews your current supplement routine, considers potential interactions, and helps determine whether your approach aligns with your nutritional needs.

And for clients seeking ongoing personalized guidance, my BioUnique Boutique Collective offers a structured six-step methodology.

You can learn more about these services, access free educational resources, and read testimonials at HarmonyWithFood.com.

Your Symptoms Deserve Answers. Your Health Deserves Attention.

If there's one thing I want you to take away from this discussion, it's that persistent symptoms deserve thoughtful investigation.

You've had the bloodwork.

You've seen the specialists.

Perhaps you've received a diagnosis and followed the recommended treatment.

And maybe you're still wondering why you don't feel the way you want to feel.

There may be nutritional, digestive, or metabolic factors worth discussing with your healthcare team.

We've explored how blood sugar assessments can identify important metabolic concerns.

We've discussed how targeted micronutrient testing may reveal deficiencies that contribute to symptoms.

We've examined the gut microbiome, its relationship with digestive health, and emerging research on the gut-brain connection.

And we've considered why evaluating medications and supplements is an important part of understanding your nutritional health.

The research on Alzheimer's disease offers another reminder of how interconnected our biological systems are.

Your brain, your gut, your metabolism, and your nutritional status all contribute to the larger picture of your health.

The goal of functional nutrition testing is to investigate relevant nutritional factors, understand the findings, and use that information to guide appropriate decisions.

You deserve to understand your results.

You deserve to ask questions.

And you deserve a thoughtful, individualized approach to your health.

Be your own healthcare advocate. Ask questions. Understand your results. Make decisions based on evidence and your individual needs.

And remember my favorite philosophy:

Test, don't guess.

I'm Meg Marie O'Rourke, your Anti-Diet Dietitian and functional nutritionist at Harmony with Food.

Visit HarmonyWithFood.com to learn more about my programs, access free podcasts and blogs, and explore ways to support your nutritional health.

If you or someone you love is experiencing memory changes, contact a qualified healthcare professional. The Alzheimer's Association also offers a free 24/7 helpline at 1-800-272-3900.

And as I always say:

If you know anyone who eats food, tell them about the Harmony with Food Show!

Medical disclaimer: Meg Marie O'Rourke is a registered dietitian and functional nutritionist, not a physician. She does not diagnose medical conditions or prescribe medications. This article is for educational purposes and does not replace individualized medical care. Functional nutrition assessments should be selected according to established clinical indications and interpreted in coordination with qualified healthcare professionals. Commercial gut microbiome and broad micronutrient testing have important clinical limitations, and their use for predicting or preventing Alzheimer's disease has not been established.