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Nutrition Testing: How to Guide Wise Food and Supplement Choices

We all know that excellent nutrition is foundational to our energy, strength, and wellbeing, and it begins with eating healthy food suited to our unique needs. High quality nutritional supplements can support what we do with food and solve urgent problems that we can’t correct with food alone. Food and nutritional supplements are powerful medicine–helping us make needed corrections in our biology, solving a multitude of problems.

How do we find out what our nutritional needs are? This article is about nutrition testing and how to guide our food and supplement choices with precision.

There are No One-Size-Fits-All Solutions

Everyone is unique–our genetics, our environments, the demands we place on our bodies, our goals and preferences. Our differences mean we all need our own solutions. Sure, there are reasonable generalizations we can make about how we might all incorporate supplements into our nutritional strategies, but we’ve all got biological idiosyncrasies to consider. How do we discover what those are?

Nutrition Testing

I’m a huge fan of nutrition testing and use it for most people I work with in my medical practice. This, along with a thorough history, review of current problems and symptoms, and a physical exam, allow us to find nutritional problem areas that would have been very hard to predict otherwise. Nutrition testing has the power to show us where we are internally vulnerable and what needs to be addressed before problems (or disasters) arise.

But is nutrition testing absolutely necessary? Many people lack the financial means or health insurance that covers the cost of the best nutritional tests. This is the reality I have to face with my clients every day. We do the best we can. While nutrition lab testing is ideal, we can also put together a powerful individualized nutrition strategy without them.

Nutrition Tests Available from Commercial Labs

These are tests that can be routinely done with a simple written order from your physician, taken to your local commercial lab and are covered by most insurances. While they’re not as comprehensive as I’d like them to be, they provide lots of useful information and I work with these often.

  1. CBC (complete blood count): a good general assessment of bone marrow function that indicates adequacy of nutrients involved in the creation of blood cells–like iron, folate, and B12.
  2. CMP (comprehensive metabolic profile): a nice overview of electrolyte levels, kidney and liver function, glucose, protein, and albumen (a specialized protein).
  3. Homocysteine: an excellent marker for functional folate, B12, and B6 vitamin status.
  4. Hemoglobin A1C: also called glycosylated hemoglobin–this measures the amount of glucose that has glommed onto the hemoglobin protein inside red blood cells. This is a very useful test by indicating your average blood sugar over the previous three months (the average life span of red blood cells).
  5. Iron and Ferritin: measures of available iron and iron storage.
  6. MMA (methyl malonic acid): functional indicator of B12 status and differentiates between B12 and folate deficiencies when the homocysteine is elevated.
  7. Cystathionine level: functional indicator of B6 status.
  8. 25-hydroxy vitamin D: good marker of vitamin D status.
  9. Blood levels for vitamins, minerals, antioxidants: These are only helpful when levels are very low or high. They tell us nothing about nutrient function within the body, which is driven by an individual’s unique needs and genetics. A “normal” level of any given nutrient is based on statistical averages and may well be completely inadequate for your unique body and its needs.

Functional Nutrition Testing

These are available from labs that specialize in functional nutrition testing. My favorite functional lab is Genova Diagnostics Laboratory located in Asheville, North Carolina. They provide test kits that are easy to use and can be taken to your local lab for blood draw, blood processing, and shipping. There are a growing number of functional labs throughout the country, a testament to the rising need and interest in this incredibly useful form of testing.

  1. Organic Acid testing: provides comprehensive information about micronutrient need, the microbiome, digestion and absorption, energy metabolism, neurotransmitters, and detoxification.
  2. Amino acid panel: gives us information about dietary protein adequacy, digestion and absorption, and micronutrient adequacy.
  3. Fatty acids analysis: allows us to see the fatty acid distribution present in the red blood cell membrane–an excellent functional analysis of how fats are utilized within our tissues, and what our needs are.
  4. Oxidative Stress markers: key indicators for the potentially destructive process of unprotected oxidation and need for antioxidants.
  5. RBC minerals and heavy metals: a reliable way to assess recent exposures (past 120 days) to minerals and heavy metals like mercury and lead.

I use a test panel from Genova Diagnostics called NutrEval, which combines all of the above functional nutrition assessments into one convenient test kit, using a simple fasting urine and blood collection. This is one of the most comprehensive assessments of micronutrients, macronutrients, antioxidants (including glutathione),and physiological processes (energy metabolism, detoxification, microbiome, digestion, absorption, neurotransmitters) that demonstrate nutrient need available on the market today.

A Rational Supplement Strategy to Use Without Testing: 

Refer to my 2016 article for detailed explanation of each of these recommended essential nutritional supplements.

  1. Food first.
  2. A high-quality multi-vitamin-mineral per manufacture’s or trusted healthcare provider’s instructions.
  3. Magnesium: 200 mg at bedtime, up to 1500-2000 mg daily, to bowel tolerance, depending on need (see article).
  4. Vitamin D: 2000-10,000 IU daily, depending on need.
  5. Fish oil: 1000-2000 mg of total EPA plus DHA daily.
  6. Probiotics: 15-60 billion units daily of lactobacilli, bifidobacteria, and saccaromyces boulardii.
  7. N-acetyl Cysteine (NAC): 600 mg twice daily.
  8. Curcumin (turmeric extract): 400-2000 mg taken 2-3 times daily, depending on need.
  9. Protein supplements to support total daily need: Those of us over 30 need 35 grams of protein at each meal to stimulate muscle protein synthesis–high quality supplements support this.
  10. Branched-chain amino acids (BCAAs): Supports muscle protein synthesis–use 10 grams daily or after workouts.
  11. Digestive Enzymes: so many of us can benefit! Take with meals.

Nutrition Testing-Driven Supplementation:

Having test results allows us to fine tune how we strategize food plans and nutritional supplementation to the unique and ever-changing needs of each individual. Here are some examples of common test findings in my medical practice and their supplement solutions:

  1. Elevated homocysteine level: this indicates a functional deficiency of folic acid, vitamins B12 or B6. I decide which one(s) are the problem by also looking at the MMA and cysathionine levels (see above). Along with food recommendations, I also advise supplementation with biologically available forms of the nutrients–methyl folate, methyl-B12, or 5-pyridoxal phosphate (B6).
  2. Low B12 and/or elevated MMA: this indicates vitamin B12 deficiency. B12 is easily replaced with a sublingual form of methyl-B12. I generally use 5 mg once daily, completely dissolved under the tongue (for absorption across the lining of the mouth due to uncertain gut absorption).
  3. Low hemoglobin (from CBC) and/or low iron or ferritin: this indicated iron deficiency. I recommend high iron-containing foods, but because iron tends to be poorly absorbed this way, supplemental iron is often needed: iron chelated to gluconate or glycinate. A typical dose is ferrous gluconate or glycinate 15-35 mg taken with food, along with vitamin C 1000 mg to improve absorption. The specific dose should be determined by degree of need. It is also critical to discover the underlying cause of the iron loss, typically caused by blood loss.
  4. High fasting or post-meal glucose or elevated hemoglobin A1C: this indicates a problem with insulin sensitivity, glucose utilization, or inflammation. The strategy depends highly on a food plan that reduces carbohydrates (especially the simple or refined varieties), and optimizes protein and healthy fats. We may also opt to use supplements to improve insulin-glucose regulation in the body such as berberines, chromium, glucomannan, fish oil, probiotics, and vitamin D.
  5. Low 25-hydroxy vitamin D level: note that the typical reference range used by most labs goes much lower than what we know to be optimal vitamin D levels. While more research is needed in this area, a level of 50 to 70 ng/ml is probably optimal. Your dose will be the amount that helps you achieve that range. In my practice this is typically 2000-10,000 IU taken daily.
  6. Organic acid testing abnormalities: this is a huge topic with many considerations. These results will point us to where in our physiologies there may be problems. Food and supplement recommendations depend on the pattern of results. It is best to use a Functional Medicine-trained practitioner with experience using this type of testing to help you.
  7. Low levels of plasma amino acids: this often indicates inadequacies in protein intake as well as proper digestion and absorption. I frequently help clients optimize protein intake through their diets and with high quality protein supplements. We also work to improve digestion using the support of digestive enzymes and betaine hydrochloric acid.
  8. Low levels of omega-3 fats, EPA, DHA, and 0mega-6 GLA: this deficiency pattern is common and helps to promote inflammation and problems with cell membrane function–especially within the brain and nervous system (contributing to mood disorders, cognitive dysfunction, and sleep disorders). Along with an increase in consumption of wild-caught fish and pasture-raised meat, I recommend high quality fish oils (1000-2000 mg EPA plus DHA daily) and GLA (200-400 mg daily) from borage seed.

Where to Find Help For Your Personalized Nutrition and Nutrient Supplement Plan

Most of our health problems have nutrition and lifestyle solutions. As critical a role nutrition plays in our health, wellbeing, and resilience, state-of-the-art conventional healthcare practitioners know surprisingly little about it. Somewhere along the line mainstream medicine became all about treating emergencies and acute problems, focusing on technological and pharmacological ways to address these. That’s all fine and good, but most of us are seeking care for chronic problems and to optimize our health and wellbeing. This requires thoughtful consideration of nutrition.

For this reason, it is important that you choose as your healthcare partner someone who understands human systems biology, its interconnection with the environment, lifestyle, mind, and spirit. Find someone who is tuned into sustainable ways to support your biology for optimal function and disease prevention through food, nutrition, and lifestyle. They should be very well trained in nutritional biochemistry, able to help you solve the nutritional puzzles that lead to the common problems many of us struggle with.

Look for a physician, nurse practitioner, or physician’s assistant who has done extensive training in Functional Medicine, ideally through the Institute for Functional Medicine, which provide in-depth nutritional biochemistry training through its certification program. As public support and enthusiasm for Functional Medicine has increased, there has been an influx of training programs, many of them more geared for paraprofessionals, offering protocoled approaches to health problems. Be wary of this. This is one of the major flaws in conventional medicine approaches to health problems and I see it recapitulated in alternative or integrative approaches trying to attract clients by offering simplified approaches. We are each unique and sometimes we have to get our hands dirty with the complexity and uncertainty of our bodies and our lives.

Other excellent partners are nutritionists and dietitians trained in Functional Nutrition. Conventionally trained dietitians often do not know how to assess or recommend therapeutic nutrition plans and much of their information is sorely out-dated. It is not uncommon to have mainstream nutrition professionals recommending obsolete high-carb, low fat, low cholesterol diets and know nothing about micronutrients.

Look carefully at your healthcare practitioner’s credentials and experience. Ask questions about how they treat the specific conditions you are interested in. Remember, this is your team–you must vet them.


Institute for Functional Medicine

Integrative and Functional Nutrition Academy

Karyn Shanks, MD. Nutritional Healing: My Top Ten Nutritional Supplements. 2016.

Karyn Shanks, MD. Protein: How Much Do We Need to Support Optimal Health? 2016.

Karyn Shanks, MD. Vitamin D: Boost Your Winter Mojo. 2016.

Lisa Scranton, MS, RDN, LD. My Journey as a Functional Medicine Nutritionist. 2016.

Karyn Shanks MD


Karyn Shanks, MD, is a physician who lives and practices in Iowa City. Her work is inspired by the revolutionary science of Functional Medicine, body-mind wisdom, and the transformational journeys of thousands of clients over her twenty-eight year career. She believes that the bones of healing are in what we do for ourselves.

1 Comment"

    Thank you, Ellie. I recommend biochemical testing to assess nutrient function–static blood levels are not as useful. There are several excellent
    functional labs who do this testing.


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