Understanding Nutrients, Vitamins & Minerals testing
Micronutrients — vitamins and minerals — are the cofactors, coenzymes, and structural components that enable the estimated 37.2 trillion biochemical reactions occurring in the human body every second. Unlike macronutrients that provide energy, micronutrients enable the chemical transformations that convert food into function. Vitamin D activates over 1,000 genes. B12 enables DNA synthesis and myelin production. Magnesium participates in over 300 enzymatic reactions. Iron enables haemoglobin to carry oxygen. Without adequate levels, these processes falter silently.
Subclinical micronutrient deficiency — levels below optimal but above the clinical threshold for deficiency disease — is strikingly common in industrialised countries despite caloric abundance. A 2021 CDC analysis found over 90% of Americans fail to meet dietary targets for vitamin D, calcium, and potassium. Ageing, chronic disease, medications, GI conditions, and restrictive diets all amplify depletion. Blood testing is the only reliable method to know your actual status — dietary recall and supplementation without data leads to both under- and over-supplementation.
How Nutrients connects across the body
Nutrients health does not exist in isolation — it is deeply intertwined with every major system.
Immune System
Vitamins D, C, and zinc are essential for both innate and adaptive immune responses. Vitamin D modulates T-regulatory cell activity, reducing autoimmune reactivity while maintaining pathogen defences. Severe vitamin D deficiency (below 20 ng/mL) is associated with a 2× increased risk of respiratory infections. Zinc deficiency impairs neutrophil and natural killer cell function; even mild deficiency reduces cytokine production by 30–50%. Iron deficiency impairs lymphocyte proliferation and reduces bactericidal activity of neutrophils.
Neurological Function & Mental Health
B vitamins (B6, B9/folate, B12) are central to neurotransmitter synthesis and methylation pathways. B12 is required for myelin sheath formation — deficiency causes progressive nerve demyelination with symptoms of neuropathy, ataxia, and cognitive decline. Folate deficiency increases homocysteine and is independently associated with depression. Vitamin D receptors are found throughout the brain, including regions governing mood; low vitamin D is correlated with higher depression and seasonal affective disorder prevalence. Magnesium modulates NMDA receptor activity and is often depleted in anxiety disorders.
Bone, Muscle & Connective Tissue
Calcium, vitamin D, magnesium, phosphorus, and vitamin K2 together govern bone mineralisation. Vitamin D drives intestinal calcium absorption; without it, bone absorbs calcium from itself (resorption) regardless of dietary intake. Vitamin K2 directs calcium into bone rather than arterial walls, reducing vascular calcification risk. Magnesium is an underappreciated bone mineral — 50% of total body magnesium is in bone. Vitamin C is the essential cofactor for collagen synthesis, required for tendon, ligament, bone matrix, and skin integrity.
Energy Production & Mitochondria
The mitochondrial electron transport chain that generates ATP requires iron-sulphur clusters, copper, CoQ10, B vitamins (B1, B2, B3, B5), and magnesium as essential cofactors. Iron deficiency impairs mitochondrial function before anaemia develops, explaining why people with low-normal haemoglobin but low ferritin experience fatigue. B12 and folate deficiency disrupt methylation pathways that regulate gene expression and cellular repair. Iodine deficiency, by impairing thyroid hormone synthesis, slows mitochondrial activity throughout the body.
Supporting Nutrients health
Nutrition
- Eat a diverse, whole-food diet — micronutrient density correlates strongly with food variety. Organ meats (liver, kidney) are the most nutrient-dense foods per calorie and contain exceptional concentrations of B12, iron, copper, and zinc.
- For vegetarians and vegans: B12 is found exclusively in animal products and must be supplemented. Iron, zinc, and calcium from plant sources have lower bioavailability; pairing with vitamin C and cooking methods improves absorption.
- Test before supplementing high-dose fat-soluble vitamins (A, D, E, K) — these accumulate and can cause toxicity at excessive doses, unlike water-soluble vitamins.
- Minimise calcium supplementation without co-administering vitamin K2 (100–200mcg MK-7) to direct calcium to bone rather than arteries.
Absorption & Bioavailability
- Medications commonly deplete micronutrients: metformin reduces B12 absorption, PPIs impair magnesium and B12 uptake, statins reduce CoQ10 synthesis, and diuretics deplete potassium, magnesium, and zinc.
- GI conditions (celiac disease, Crohn's, small intestinal bacterial overgrowth) dramatically impair nutrient absorption — testing micronutrient levels is essential in anyone with GI symptoms or autoimmune conditions.
Supplementation Principles
- Optimal vitamin D status (50–80 ng/mL) typically requires 2,000–5,000 IU daily for most adults, particularly those with limited sun exposure, dark skin, or obesity (which sequesters vitamin D in adipose tissue).
- Magnesium glycinate or malate provides superior bioavailability compared to magnesium oxide, which is primarily a laxative with poor cellular absorption.
Clinical note
Micronutrient testing should use the most clinically meaningful assay for each nutrient. Serum B12 measures total B12 but misses functional deficiency — methylmalonic acid (MMA) and homocysteine are more sensitive indicators. Serum magnesium is poorly reflective of tissue stores; RBC magnesium is preferred. 25(OH)D is the correct vitamin D test; 1,25(OH)2D should only be tested in specific clinical contexts.
