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Micronutrients - Even Tiny Amounts Count

Micronutrients - Even Tiny Amounts Count

Consuming enough of the macronutrients fat, protein, carbohydrates, and water in the diet is vital to the proper functioning of a human. Many people are familiar with diets that focus on the ratios between these macronutrients to gain a particular effect, for example, the fat-heavy “keto” diet. However, what often gets left out of the discussion of human nutrition is micronutrients. Vitamin D3 is a micronutrient that is often a part of routine tests, but aren’t there other important micronutrients? Could additional testing shed light on hard-to-diagnose symptoms?

What are Micronutrients?

The word micronutrient can be interpreted as “small amount that provides nourishment,” and is often used interchangeably with the words “vitamins” and “minerals.” These bits of nourishment are vital to human health because, despite being a tiny fraction of the whole system, they have a large impact on metabolism, growth, and development.

Micronutrients are typically divided into 4 categories, according to the characteristics they share: fat-soluble vitamins, water-soluble vitamins, macrominerals, and trace minerals. In the body, water-soluble vitamins can be dissolved by water, and any excess amount is typically expelled through the urine. However, excess fat-soluble vitamins typically get stored in tissues if they are not used right away. This makes fat-soluble vitamins more of a risk for overdosing. Macrominerals are inorganic nutrients that the body needs in substantial quantities (“macro” meaning “large”) because they are involved in multiple, critical functions and systems of the body. Trace minerals are required in much smaller amounts, but are still crucial to overall good health. To give you an idea of what range micronutrients cover, here are examples:

Water-soluble vitamins: B vitamins (B1, B2, B3, B5, B6, B9/folate, B12/cobalamin) and vitamin C

Fat-soluble vitamins: A, D, E, and K

Macrominerals: calcium, chloride, magnesium, phosphorus, potassium, sulfur

Trace minerals: copper, iodine, iron, manganese, molybdenum, selenium, zinc

Human Bodies Can’t Make Most Micronutrients

The human body requires micronutrients to run properly, so a deep deficiency of even a single micronutrient can have profound repercussions. Oddly, the body is designed to derive micronutrients from the diet and cannot create most micronutrients on its own. That is one reason why the functional medicine approach puts such a high value on nutrition and considers it an extremely important piece of the whole picture of health.

But I Eat a Good Diet. So I’m Good, Right?

Many micronutrients are simply “under-consumed.” The 2015-2019 Dietary Guidelines indicate that many people eat a widely varied diet. However, they aren’t consuming the necessary quantity of vegetables, fruits, whole grains, or dairy that supply specific micronutrients, including vitamins A, D, E, and C (1).

Additionally, it’s not just what you eat, or the quantity of what you eat; it’s what you absorb! Some people have an incredibly healthy diet, but their body simply isn’t breaking down and absorbing what is going in. There are a variety of reasons why malabsorption of nutrients might happen, including:

  • A compromised small intestine wall, where the lining doesn’t process the food particles adequately, or conversely allows large food molecules to move into the blood circulation (called “leaky gut), or both

  • A lack of adequate enzymes to break down foods into their smallest components, possibly as a result of aging, genetics, or an acute food poisoning event

  • Conditions affecting the GI tract such as ulcerative colitis (UC) or Celiac disease.

The Snowball Effect

Micronutrients are vital to a well-functioning system, so if you’re truly deficient, it is likely to result in a noticeable symptom. What symptoms emerge depends on the micronutrient you lack. If you’re severely deficient in iron, a trace mineral, you could experience grinding fatigue. You don’t need a lot of iron, but if you are missing what little you do need, it becomes quite noticeable. Magnesium, a macromineral, is involved in over 300 chemical reactions in the body, so if you are not getting enough, it could result in a wide variety of symptoms that could affect muscle contractions, functioning of the nerves, and even blood pressure. If you want to see a list of symptoms noting specific nutrient deficiencies as a possible cause, this is a good chart.

As micronutrient deficiencies persist, the symptoms can get worse. This is a double-edged sword because you may feel much worse, but having severe and distinct symptoms such as the ones below (3) can make it more likely to be diagnosed quickly:

  • bones that break easily, or bone pain due to vitamin D deficiency

  • night blindness due to vitamin A deficiency

  • gums that bleed easily, or nosebleeds due to vitamin K deficiency

  • weakness or dizziness due to lack of iron

If micronutrient deficiencies are left uncorrected for even longer periods, ill health can become more and more apparent, and risks for other conditions may manifest. Slowly ill health can begin to build on itself, with a weakened immune system allowing more ill health to follow, such as a weak immune response to infections, cognitive impairment such as loss of concentration, memory, or focus, and increased risks for diseases such as cancer, type II diabetes, diseases of the cardiovascular system, and osteoporosis(4).

Testing to the Rescue

Luckily, technological advancements in science and medicine have seen the proliferation of tests for micronutrient deficiencies. Urine and blood can be tested for the presence of a particular nutrient, or a metabolite (chemical breakdown product) that allows a reliable assessment of a nutrient’s status. There are genetic tests that can tell you if you are genetically susceptible to Celiac disease, which could lead to nutrient malabsorption. There are also genetic tests for mutations that slow the conversion rate of B9 or B12 micronutrients to an activated form that can be used by the body (MTHFR polymorphisms). Luckily, one of the most common micronutrient deficiencies is tested during routine annual physicals. However, other micronutrient testing is rarely done by default. What’s the process for discovering and addressing a micronutrient deficiency? Let’s step through a hypothetical micronutrient testing situation, using vitamin D3 as our example and “nutrient of interest.”

Hypothetical Vitamin D3 Testing Scenario

Presenting symptoms: You keep getting upper respiratory infections, and you feel run down all the time. It seems like you get whatever infection comes around and you feel like you’re getting worse and worse. The cough that used to come and go is now permanent. You have no energy.

First office visit: You discuss your symptoms with one of our practitioners. We order a blood draw first, to test for vitamin D3 status but also order a thyroid panel and a test for iron deficiency. You’ll come back on another day to get your blood test because you’ve been asked to stop taking your multivitamin for a few days, and you should fast for 12 hours before your blood draw.

Second office visit: You come in for your first blood draw. You have fasted and followed the instructions for getting a good sample.

You get a diagnosis: Your lab results come in. Your thyroid is fine, and your iron level is okay, but your vitamin D3 status is very low. Our practitioner suggests a particular dose of vitamin D3 to be taken daily, and you are scheduled for re-testing of your vitamin D3 in 8 weeks.

Third office visit (8 weeks later): Your blood is drawn for your second vitamin D3 test. You’ve been taking the suggested dosage of vitamin D3 since your diagnosis, and you report that you are feeling better. You don’t feel as run down, and the nagging cough has finally gone away. Oddly, some back pain you thought was unrelated (and did not report) went away.

Your second vitamin D3 results come in: Our office calls and says your vitamin D3 levels are very close to the range we have proposed for you, considering your unique circumstances and your health history. You are told to keep at the current dosage for 4 more weeks, then drop to a lower maintenance dose and continue taking it as part of your routine. In another 3 months, you can come back to re-test your vitamin D3.

Test Then Tweak; Rinse, Repeat

In this way, testing and then tweaking dosages of the nutritional supplement to correct a deficiency, you are led to the blood level of vitamin D3 that rectifies the deficiency and will usually alleviate symptoms. By working with us and raising your vitamin D3 nutrient level to an adequate level, statistically, you have:

  • Increased your immune defenses against COVID-19 and slowed the progression of severity (5)

  • Reduced overall severity and criticality of COVID-19 infection (6)

  • Increased likelihood of testing negative for SARS-CoV2 (those deficient in vitamin D3 were more likely to test positive as blood levels dropped) (7)

  • Moved away from the vitamin D3 levels associated with increased mortality (death) from COVID-19 (8)

  • Reduced your risk of getting toxic levels of vitamin D3 by working with your practitioner and periodically testing blood levels

  • And last but certainly not least, reduced the risks for 15 types of cancer (9).

Why It’s Important to Work with a Knowledgeable Practitioner

Dealing with a vitamin D3 deficiency may be straightforward, but trying to address multiple micronutrient deficiencies can get tricky. We will monitor your test results and help you adjust dosages of supplements, so you get enough nutritional supplementation to rectify a deficiency, but not so much that you reach toxic blood levels. If your deficiency is not resolved by nutritional supplementation, we can help look for the reason and develop strategies to strengthen and heal you.

Note that there is a variety of tests that can shed light on nutritional deficiencies and other health conditions. Our practitioners will be able to pick the best tests to help you discover the root cause of your symptoms. We can explain how the tests will be performed because some nutrient testing requires a blood test, some require a urine test, and some require both! There are also certain instructions for obtaining a good sample that may need to be customized for your situation. For example, the request to refrain from certain medications or nutritional supplements before the test. Lastly, taking some nutritional supplements can affect the efficacy of medications, so we can help you vet any contraindications to current medications.

As you can see, identifying and addressing micronutrient deficiencies is a process rather than a one-time visit to our practice. Powerful tests combined with our experience can help you navigate the path toward your highest state of health. As each issue is addressed, and each micronutrient deficiency is resolved, the burden on your body becomes lighter and lighter. Your body once again has the fuel and the building blocks needed. Repairs that your body once had to put on the back burner can now be addressed slowly over time by the amazing, self-healing system it is.


Jonathan Vellinga, M.D.

Jonathan Vellinga, MD is an Internal Medicine practitioner with a broad interest in medicine. He graduated Summa cum laude from Weber State University in Clinical Laboratory Sciences and completed his medical degree from the Medical College of Wisconsin.​

Upon graduation from medical school, he completed his Internal Medicine residency at the University of Michigan. Dr. Vellinga is board-certified with the American Board of Internal Medicine and a member of the Institute for Functional Medicine.




  1. U.S. Department of Health and Human Services and U.S. Department of Agriculture. 2015–2020 Dietary Guidelines for Americans. 8th Edition. December 2015. Available at

  2. Gröber U., Schmidt J., Kisters K. Magnesium in Prevention and Therapy. Nutrients. 2015 Sep 23;7(9):8199-226. doi: 10.3390/nu7095388. PMID: 26404370; PMCID: PMC4586582.

  3. Cleveland Clinic. Malabsorption. Retrieved July 19, 2022 from

  4. Oregon State University. Micronutrient Inadequacies in the US Population. Retrieved Retrieved July 19, 2022 from

  5. Im J.H., Je Y.S., Baek J., Chung M.H., Kwon H.Y., Lee J.S. Nutritional status of patients with COVID-19. Int J Infect Dis. 2020 Nov;100:390-393. doi: 10.1016/j.ijid.2020.08.018. Epub 2020 Aug 11. PMID: 32795605; PMCID: PMC7418699.

  6. Dror A.A., Morozov N., Daoud A., Namir Y., Yakir O., Shachar Y., Lifshitz M., Segal E., Fisher L., Mizrachi M., Eisenbach N., Rayan D., Gruber M., Bashkin A., Kaykov E., Barhoum M., Edelstein M., Sela E. Pre-infection 25-hydroxyvitamin D3 levels and association with severity of COVID-19 illness. PLoS One. 2022 Feb 3;17(2):e0263069. doi: 10.1371/journal.pone.0263069. PMID: 35113901; PMCID: PMC8812897.

  7. Kaufman H.W., Niles J.K., Kroll M.H., Bi C., Holick M.F. SARS-CoV-2 positivity rates associated with circulating 25-hydroxyvitamin D levels. PLoS One. 2020 Sep 17;15(9):e0239252. doi: 10.1371/journal.pone.0239252. PMID: 32941512; PMCID: PMC7498100.

  8. Karonova T.L., Andreeva A.T., Golovatuk K.A., Bykova E.S., Simanenkova A.V., Vashukova M.A., Grant W.B., Shlyakhto E.V. Low 25(OH)D Level Is Associated with Severe Course and Poor Prognosis in COVID-19. Nutrients. 2021 Aug 29;13(9):3021. doi: 10.3390/nu13093021. PMID: 34578898; PMCID: PMC8468115.

  9. Grant, W.B. Roles of Solar UVB and Vitamin D in Reducing Cancer Risk and Increasing Survival. Anticancer Research March 2016, 36 (3) 1357-1370]


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