Functional Lab Testing Explained

Functional lab testing explained well, together with other laboratory tests, can provide useful information about nutritional status, metabolic patterns, and environmental exposures.

On this page, I outline commonly used functional and conventional tests, what they measure, and how they are typically used for educational and planning purposes.

These tests do not provide diagnoses on their own and are always best interpreted in context — alongside symptoms, history, and professional guidance.

Often, people get tested "for something" and if this something comes back "normal", they are told nothing is wrong or "it is all in your head".

This is not always correct, because certain nutrient deficiencies important for brain health and mental health can sometimes not be found in "regular" lab tests.

If you are persistently feeling unwell, fatigued, sad, anxious or have unexplained physical symptoms, we recommend seeing a functional or integrative medical practitioner.

This page is meant to be a start to find your way through the labyrinth of medical terminology when it comes to lab tests and explain what they mean in clear language.

Omega 3/6 Ratio

Many functional medicine physicians consider the Omega 3/6 ratio/index test to be one of the most important tests for your overall wellbeing and brain & mental health. The omega‑3/omega‑6 ratio reflects the balance of fatty acids in cell membranes and can offer insight into dietary patterns that influence inflammation and overall metabolic health. This test goes beyond intake estimates by measuring how these fats are incorporated in the body, making it a useful educational tool when discussing nutrition, brain health, and long‑term wellness planning. Read more about the importance and benefits and watch Dr. Christine's interview with Dr. Bill Harris, co-inventor of the Omega- 3 index here: https://docchristine.com/omega-3-index-and-brain-health/
We recommend using his lab, Omegaquant.com

Vitamin D Test

Vitamin D plays an important role in bone health, immune function, and overall resilience. Testing vitamin D levels can help identify whether intake or sun exposure may be insufficient, allowing for more informed conversations about nutrition and lifestyle support. Vitamin D is one of the most important vitamins for your overall health, but levels that are too high can cause unwanted side effects like tissue calcification. Use this calculator to find your optimal Vitamin D level and the recommended supplementation dosage.

Organic Acids Test

The Organic Acids Test provides a functional snapshot of metabolic processes, including nutrient status, energy production, and gut‑related markers. It can offer insights into how the body is processing key biochemical pathways, especially when symptoms are complex or nonspecific.

The organic acids urine test (OAT) helps to detect basic metabolic issues that impact physical and mental health. Its markers help find imbalances in your gut flora (dysbiosis), fungal markers, mold markers, detoxification pathways, nutritional markers (amino acids, certain vitamins), mitochondrial health, fatty acids metabolism and more.

The OAT can be a very cost-effective test to detect issues and help find root causes. It is admittedly complicated to understand and demands special training and experience to interpret.

Information from my recommended lab: (USA) https://mosaicdx.com/test/organic-acids-test/

Hair Mineral Analysis

Hair mineral analysis reflects longer‑term patterns of mineral exposure and balance. While it does not diagnose disease, it may be used as a complementary tool to explore trends in mineral status and environmental exposures over time. Our hair retains many minerals, whether nutritional or toxic, much longer than blood or urine and is easily accessible. Hair mineral testing does not require cutting your hair and does not leave visible "holes", if done correctly.

Information from my favorite Canadian lab: https://www.canaltlabs.com/hairmineralanalysis

Food Sensitivity Testing

Food sensitivity testing looks at immune responses to commonly consumed foods. Food Sensitivity Testing has been long viewed as useless or even dangerous. In many practitioner's experience (and our own) is can be a valuable addition to a program of nutrition evaluation and adjustment when based on an extensive history and a good follow-up to avoid nutritional deficiency and a too restrictive diet. Testing can shorten the time needed to eliminate and re-introduce foods by narrowing the foods needed to be tested with this method. Read more about my thoughts about it here: https://docchristine.com/food-sensitivity-tests-facts-and-fiction/

Information from my favorite Canadian lab: https://www.canaltlabs.com/foodintolerance

Mold Exposure Testing

Mold exposure testing assesses markers associated with environmental mold contact. It can be useful when there is concern about indoor air quality or unexplained symptoms potentially related to environmental factors. Certain molds - through their toxins - can impact brain function and hamper normal energy metabolism. It is a great additional test as an add-on to the Organic Acids Test or a follow-up if it indicates the possibility mold toxicity or this is clinically suspected.

Environmental Toxins

Environmental toxin testing evaluates exposure to selected chemicals or heavy metals. These tests are used to better understand environmental load and support informed conversations about reducing ongoing exposure where possible. Environmental toxins can contribute to the worsening or triggering of diseases. In suspected cases this can be a valuable addition to the Organic Acids Test.

Other Tests

Some lab tests don’t fit neatly into standard categories but may still offer helpful information in specific situations. When appropriate, these are reviewed with a focus on education, context, and practical next questions rather than conclusions.

Additional Resources Where You Can Find Functional Lab Testing Explained

We recommend to always work with a functional medicine practitioner, functional medicine physician, or a naturopathic doctor experienced in brain health and mental health to purchase functional medicine tests and explain test results in the context of your individual history and symptoms.

Here are some laboratories that we recommend and have used. Certain labs let you order your laboratory tests yourself and provide additional information on how to take the tests and interpret the results.

Life Extension Foundation (Supplements and Lab Tests): https://www.lifeextension.com/

Mosaic Diagnostics (previously Great Plains Lab): https://mosaicdx.com/

Doctors Data: https://www.doctorsdata.com/

CanAlt Labs: https://www.canaltlabs.com/

Omegaquant - Omega-3/6, fatty acids, DHA and Vitamin D Testing Experts: https://omegaquant.com/

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