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.