Nutritional Deficiency
1. Root Cause Overview
Nutritional deficiencies are widespread even in developed countries due to soil depletion, food processing, malabsorption syndromes, medication-nutrient interactions, and increased physiological demands. Subclinical deficiencies — below optimal but above clinical deficiency thresholds — are particularly common and drive fatigue, cognitive dysfunction, immune impairment, and metabolic dysfunction without obvious clinical signs. Key at-risk nutrients include vitamin D, magnesium, zinc, B12, iron, omega-3 fatty acids, and iodine.
2. Common Signs & Symptoms
- Fatigue and low energy (iron, B12, vitamin D, magnesium)
- Brain fog and cognitive impairment (B12, omega-3, iodine)
- Muscle cramps and weakness (magnesium, potassium, vitamin D)
- Brittle nails and hair loss (iron, zinc, biotin, selenium)
- Poor wound healing (zinc, vitamin C, vitamin A)
- Recurrent infections (zinc, vitamin D, vitamin A, selenium)
- Mood disturbances: depression, anxiety (B12, omega-3, vitamin D, magnesium)
- Peripheral neuropathy (B12, B6, thiamine)
- Bone pain or stress fractures (vitamin D, calcium, magnesium)
- Glossitis, angular cheilitis (B2, B3, B12, iron)
3. Labs to Consider
CBC, ferritin/iron/TIBC, B12/MMA, folate, vitamin D (25-OH-D), zinc, magnesium, thyroid panel.
Choose the lab option based on what you want to assess within this root cause.
Micronutrient Panel
SpectraCell Laboratories
4. Clinical Priorities
Test before supplementing whenever possible so that interventions match the pattern of deficiency rather than relying on blanket replacement. Also assess for reasons deficiencies may be developing or persisting, such as low intake, malabsorption, hypochlorhydria, digestive enzyme insufficiency, medication use, inflammation, or increased physiological demand. Use food-first strategies where practical, then prioritise correction of the most clinically relevant deficiencies before adding broader support.
Where to Start: Top 2 Supplements
Vitamin D deficiency affects over 40% of adults globally and is the most clinically impactful correctable deficiency. Influences immune function, mood, bone health, metabolic function, and cardiovascular risk. Always test before supplementing and retest at 3 months to confirm repletion.
Subclinical magnesium deficiency affects approximately 50% of adults and is a primary driver of fatigue, sleep disruption, muscle cramps, anxiety, and metabolic dysfunction. Standard serum magnesium is an insensitive marker — treat empirically if symptoms are present and diet is poor.
5. Diet Strategy
Adopt a nutrient-dense whole-food dietary pattern: organ meats (B12, iron, zinc, A, CoQ10), fatty fish (omega-3, vitamin D, selenium), dark leafy greens (folate, magnesium, vitamin K), colourful vegetables (antioxidants, vitamin C), nuts and seeds (zinc, magnesium, selenium, vitamin E), and legumes (iron, folate, B-vitamins). Minimise nutrient-depleting foods: refined grains, sugar, alcohol, and ultra-processed foods. Pair iron-rich foods with vitamin C to enhance absorption.
6. Lifestyle Strategy
Optimise sunlight exposure for vitamin D synthesis (15–30 min/day on skin without sunscreen). Reduce nutrient-depleting lifestyle factors: chronic stress (depletes magnesium, zinc, B5, vitamin C), excessive alcohol (depletes B-vitamins, zinc, magnesium), and smoking (depletes vitamin C, zinc). Review all medications for nutrient-depleting effects (metformin depletes B12; statins deplete CoQ10; PPIs deplete B12, magnesium, zinc; oral contraceptives deplete B6, folate, zinc).
7. Supplement Strategy
Full supplement list below. See Section 4 (Clinical Priorities) for the recommended Top 2 starting supplements. Add additional supplements based on lab results and clinical response at 4–6 week reassessment.
| Supplement | Dosage | Indication | Evidence | Key Results | Example |
|---|---|---|---|---|---|
| Vitamin D3 + K2 [1] Hypercalcaemia at excessive doses; always test before supplementing and retest at 3 months | 2,000–5,000 IU vitamin D3 + 100–200 mcg MK-7/day (titrate to 50–80 ng/mL serum) | Vitamin D deficiency (affects >40% of adults); immune, bone, metabolic, and mood support | Multiple RCTs and meta-analyses | Corrects deficiency; improves immune function, mood, bone density, and reduces infection risk | Thorne Vitamin D/K2 |
| Magnesium Glycinate [2] Loose stools at high doses; caution in renal impairment | 300–400 mg elemental magnesium/day | Magnesium deficiency (affects ~50% of adults); ATP synthesis, nerve function, sleep, glucose metabolism | Multiple RCTs | Corrects deficiency; improves sleep, blood pressure, glucose metabolism, and muscle function | Pure Encapsulations Magnesium Glycinate |
| Methylcobalamin (B12) [3] Generally very well tolerated; rare acne with high-dose B12 | 1,000–5,000 mcg/day sublingual or IM injection for confirmed deficiency | B12 deficiency (common in vegans, elderly, metformin users, PPI users); neurological and haematological support | Clinical trials and mechanistic evidence | Corrects megaloblastic anaemia; improves neurological function; reduces homocysteine | Jarrow Formulas Methyl B-12 |
| Iron Bisglycinate (for confirmed iron deficiency) [4] Constipation, nausea (less with bisglycinate form); iron overload risk — only supplement with confirmed deficiency | 25–50 mg elemental iron/day (with vitamin C, away from calcium and tea) | Iron deficiency anaemia; ferritin repletion; energy and cognitive support | RCT and clinical evidence | Effective iron repletion with superior GI tolerability vs. ferrous sulphate; improved haemoglobin and ferritin | Thorne Iron Bisglycinate |
| Omega-3 Fatty Acids (EPA + DHA) [5] Fish burp; anticoagulant interaction at high doses; avoid in fish allergy | 2–4 g/day (EPA + DHA combined) | Omega-3 deficiency (widespread in Western diets); anti-inflammatory; cardiovascular, brain, and metabolic support | Multiple RCTs and meta-analyses | Reduced triglycerides, inflammation, and cardiovascular risk; improved cognitive function and mood | Nordic Naturals Ultimate Omega |
| Zinc Bisglycinate [6] Nausea if taken without food; long-term high-dose depletes copper | 25–50 mg/day (short-term); 15–25 mg/day (maintenance) | Zinc deficiency; immune function; wound healing; taste and smell; testosterone support | Multiple RCTs | Corrects deficiency; improves immune function, wound healing, and reproductive health | Thorne Zinc Bisglycinate |
8. Safety Notes
Never supplement iron without confirmed deficiency (serum ferritin, iron studies) — iron overload is dangerous. Do not supplement fat-soluble vitamins (A, D, E, K) without testing — toxicity is possible. Long-term high-dose zinc depletes copper — always pair with copper monitoring or a copper-containing formula. Refer for unexplained severe deficiencies (malabsorption, coeliac disease, IBD, pernicious anaemia) for specialist evaluation.
9. Citations & References
- [1]
- [2]Magnesium GlycinateDiNicolantonio JJ, O'Keefe JH, Wilson W. Subclinical magnesium deficiency: a principal driver of cardiovascular disease and a public health crisis. Open Heart. 2018;5(1):e000668.View source
- [3]Methylcobalamin (B12)Stabler SP. Vitamin B12 deficiency. N Engl J Med. 2013;368(2):149–160.View source
- [4]Iron Bisglycinate (for confirmed iron deficiency)Tolkien Z, Stecher L, Mander AP, Pereira DI, Powell JJ. Ferrous sulfate supplementation causes significant gastrointestinal side-effects in adults: a systematic review and meta-analysis. PLoS One. 2015;10(2):e0117383.View source
- [5]Omega-3 Fatty Acids (EPA + DHA)Mozaffarian D, Wu JHY. Omega-3 fatty acids and cardiovascular disease: effects on risk factors, molecular pathways, and clinical events. J Am Coll Cardiol. 2011;58(20):2047–2067.View source
- [6]Zinc BisglycinatePrasad AS. Zinc in human health: effect of zinc on immune cells. Mol Med. 2008;14(5–6):353–357.View source
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