Neuro

This marker sits in Build -- the raw material for making and renewing structure.

Two cofactors that work as a pair. Both are required to build red blood cells and to run methylation, the reaction that recycles homocysteine and builds neurotransmitters. Because they overlap, folate can mask a B12 shortfall in the blood count while the neurological cost of that shortfall continues -- which is why they are read together rather than separately.

Typical range: Standard B12 is roughly 200-900 pg/mL, a range set to catch frank deficiency rather than sufficiency. Functional-optimal (opinion): above about 400-500 pg/mL is commonly cited. Serum B12 is an imperfect measure of what is inside the cell, which is why methylmalonic acid is the better follow-up when symptoms and serum disagree.

Food first: Liver, shellfish, oily fish, eggs and dairy for B12; nutritional yeast and fortified foods on a plant-only pattern. Dark leafy greens, legumes, asparagus and avocado for folate. Cooking water leaches folate, so steam rather than boil.

A more specific and sensitive marker of vitamin B12 status than serum B12 itself, especially useful when B12 sits in a borderline range.

Typical range: Standard: under 0.4 micromol/L typically normal (assay-dependent); elevated MMA with borderline-low B12 confirms true B12 deficiency at the cellular level.

Food first: Animal products (meat, fish, eggs, dairy) or fortified foods/supplements for vegans; absorption also requires adequate stomach acid and intrinsic factor.

When to see someone: A raised MMA alongside a normal B12 can also reflect reduced kidney function or, rarely, another metabolic condition -- so it is read next to kidney function rather than taken on its own as proof of B12 deficiency.

This marker sits in Build -- the raw material for making and renewing structure.

The level of an amino acid byproduct of protein metabolism that reflects how well B-vitamin-driven remethylation is converting it back to methionine.

Typical range: Standard: 4-15 micromol/L (lab-dependent), with above 15 often used as a cutoff suggestive of B12/folate insufficiency. Functional-optimal (opinion): under 7-8 micromol/L commonly cited as a better cardiovascular-risk target, tighter than the standard upper limit.

Food first: Leafy greens and legumes (folate), animal products/fortified foods (B12), poultry/fish/potatoes/bananas (B6).

When to see someone: Kidney disease independently raises homocysteine regardless of B-vitamin status -- always interpret alongside kidney markers (eGFR/creatinine). Very high-dose B6 (>100mg/day long-term) can cause peripheral neuropathy.

This marker sits in Build -- the raw material for making and renewing structure.

Homocysteine is an amino acid byproduct that rises when B-vitamin-dependent "remethylation" back to methionine is inadequate; elevated homocysteine is associated with cardiovascular risk and, observationally, with recurrent pregnancy loss.

Typical range: Conventional: roughly 4-15 micromol/L (lab-dependent); functional-medicine opinion favors <7-8 micromol/L, tighter than the standard upper limit.

Food first: Leafy greens and legumes (folate), animal products/fortified foods (B12), poultry/fish/potatoes/bananas (B6); a standard prenatal vitamin covers this for most B-vitamin-replete women. Supplementing the *specific* deficient B-vitamin lowers homocysteine reliably; extra B-vitamins in an already-replete woman do not further lower homocysteine.

When to see someone: Very high-dose B6 (>100 mg/day long-term) can cause peripheral neuropathy. High-dose folic acid (as in the emerging miscarriage-prevention data above) can mask an underlying B12 deficiency by normalizing red-cell size while the neurological effects of B12 deficiency continue unchecked -- always check B12 alongside folate, especially in vegans/vegetarians or after bariatric surgery. Kidney disease independently raises homocysteine regardless of B-vitamin status.

This marker sits in Exchange -- moving iron across boundaries and handing it between carriers.

Total circulating copper, of which roughly 95% is normally bound to ceruloplasmin and about 5% is loosely bound to albumin and small peptides (the "free" or "non-ceruloplasmin-bound" fraction).

Typical range: Roughly 70-140 mcg/dL for men, 80-155 mcg/dL for women (ranges vary somewhat by lab/method).

Food first: Beef/chicken liver, oysters and shellfish, cacao are copper-dense whole foods the functional model favors; standard nutrition guidance agrees these are good copper sources for people with confirmed low intake or deficiency.

When to see someone: Copper has a genuinely narrow window in both directions. Overload is Wilson's disease, a genetic condition causing serious liver and neurological damage that needs hepatology or genetics management. A raised serum copper on its own should prompt checking ceruloplasmin and ruling out inflammation, pregnancy or oestrogen therapy -- all of which raise it -- before it is read as dysregulation.

This marker sits in Exchange -- moving iron across boundaries and handing it between carriers.

The major copper-transport protein made in the liver; it carries the large majority of circulating copper and functions as a ferroxidase enzyme, oxidizing ferrous iron (Fe2+) to ferric iron (Fe3+) so iron can bind to transferrin and be moved and stored safely. This ferroxidase role is well-established, mainstream biochemistry. **[SOLID]** (source: Vashchenko G, MacGillivray RT, Nutrients, 2013; StatPearls, NCBI Bookshelf)

Typical range: Roughly 20-40 mg/dL in most adult reference ranges (some labs cite 27-37 mg/dL); varies by assay.

Food first: Copper-rich foods (liver, shellfish) support the substrate side; retinol-rich foods (liver, egg yolk, dairy fat, cod liver oil) are the the functional model-favored vitamin A source, on the theory that preformed retinol (not beta-carotene) is what's needed.

When to see someone: A low ceruloplasmin together with a high non-ceruloplasmin-bound ("free") copper and/or neurological or liver symptoms warrants a Wilson's disease workup with a specialist -- this is a serious genetic condition, not something to self-manage with a mineral protocol.

The balance of anti-inflammatory omega-3s versus more inflammation-associated omega-6 derivatives making up cell membranes.

Typical range: No universal clinical range; the "Omega-3 Index" (EPA+DHA as % of red blood cell fatty acids) research uses above 8% as a cardioprotective target and under 4% as high-risk, though Function's assay methodology may differ. Omega-6/Omega-3 ratio: functional-medicine opinion often targets under 4:1, versus a typical modern Western-diet ratio of 15:1-20:1 -- this ratio target itself is debated in the literature.

Food first: Fatty fish (salmon, sardines, mackerel) 2-3x/week or algae-based EPA/DHA supplement for non-fish-eaters; reducing industrial seed-oil-heavy processed food intake lowers excess linoleic acid/arachidonic acid load somewhat.

When to see someone: Omega-3 supplementation above ~3g/day can increase bleeding risk, especially alongside anticoagulant/antiplatelet medications, and some data suggest very high intake may be linked to atrial fibrillation risk in certain populations -- moderate dosing (1-2g/day combined EPA+DHA) is the more conservative approach.

This marker sits in Build -- the raw material for making and renewing structure.

The storage form of vitamin D, the standard measure of a hormone-like nutrient that regulates calcium absorption, immune function, and hundreds of genes.

Typical range: Standard (Endocrine Society): deficient under 20 ng/mL, insufficient 20-29, sufficient 30+. Functional-optimal (opinion): 40-60 ng/mL widely cited by functional-medicine practitioners, but the Endocrine Society's 2024 update explicitly declined to set an optimal target for healthy adults -- treat "40-60" as opinion, not consensus.

Food first: Fatty fish, egg yolks, fortified dairy/milk alternatives, and sensible sun exposure; supplementation (typically 1000-4000 IU/day) is often needed to reach sufficiency.

When to see someone: Vitamin D toxicity is rare but real at sustained doses above 10,000 IU/day without monitoring -- causes hypercalcemia. People with granulomatous disease (e.g., sarcoidosis) or hyperparathyroidism need medical supervision before supplementing.

This marker sits in Transform -- the cofactors enzymes need to turn fuel into usable energy.

Blood level of one of the most abundant minerals in the body, involved in over 300 enzymatic reactions including energy production, muscle/nerve function, and blood pressure regulation.

Typical range: Standard: 1.7-2.2 mg/dL serum. Functional-optimal (opinion): upper half of range often preferred, though some functional practitioners argue RBC magnesium is a better status marker than serum -- Function does not appear to test RBC magnesium specifically. Serum reflects under 1% of total body magnesium, so it's an imperfect status marker.

Food first: Leafy greens, nuts, seeds, legumes, whole grains, dark chocolate. Magnesium glycinate or citrate forms are generally better absorbed/tolerated than oxide.

When to see someone: High-dose magnesium supplements cause diarrhea before they cause serious harm in people with normal kidneys, but anyone with reduced kidney function (low eGFR) needs medical guidance before supplementing -- magnesium is renally cleared and can accumulate to dangerous levels.

This marker sits in Transform -- the cofactors enzymes need to turn fuel into usable energy.

Magnesium concentration inside red blood cells, which -- because RBCs live about 120 days -- reflects a longer-term, more stable snapshot of intracellular magnesium status than serum magnesium, which represents less than 1% of total body magnesium and can shift acutely with stress hormones. This physiological rationale (serum magnesium as a poor proxy for tissue status) is well-supported. **[SOLID]**

Typical range: Roughly 4.0-6.8 mg/dL depending on the lab (e.g., Quest ~4.0-6.4 mg/dL, LabCorp ~4.2-6.8 mg/dL).

Food first: Leafy greens, nuts, seeds, legumes, whole grains, dark chocolate; supplemental forms like magnesium glycinate or citrate are generally better tolerated than oxide.

When to see someone: Anyone with reduced kidney function (low eGFR) needs medical guidance before supplementing magnesium at the functional model-recommended doses -- magnesium is renally cleared and can accumulate to dangerous levels in kidney disease. High-dose oral magnesium commonly causes diarrhea before anything more serious in people with normal kidneys.

This marker sits in Exchange -- moving iron across boundaries and handing it between carriers.

The full iron-status picture -- stored iron (ferritin), circulating iron, the percentage of iron-carrying capacity in use, and how much carrying capacity is available.

Typical range: Standard: Ferritin ~15-150 ng/mL (women), ~20-250 ng/mL (men); Iron 60-170 mcg/dL; Saturation 20-50%; TIBC 250-450 mcg/dL. Functional-optimal (opinion): ferritin 50-100 ng/mL often cited as a better functional target than the low end of normal, particularly in women with fatigue.

Food first: Heme iron (red meat, poultry, fish) is more bioavailable than plant iron; pair plant iron with vitamin C (citrus, peppers, tomatoes); avoid taking iron with coffee, tea, or calcium supplements, which block absorption.

When to see someone: Iron is the mineral where confirming the deficiency first genuinely matters. Overload -- from haemochromatosis or from sustained over-supplementation -- causes irreversible damage to the liver, heart and pancreas, and hereditary haemochromatosis affects roughly 1 in 200 people of Northern European ancestry. Ferritin also rises with inflammation, so it can read falsely normal in someone who is both deficient and inflamed; read it alongside saturation, TIBC and CRP.

This marker sits in Maintain -- the cleanup and defence system, and whether it is switched on.

The liver's output of a systemic inflammation signal, used in cardiology as an add-on risk marker alongside lipids.

Typical range: Standard: under 1.0 mg/L low cardiovascular risk, 1.0-3.0 average, above 3.0 high risk (AHA/CDC cutoffs).

Food first: Mediterranean-pattern eating (olive oil, fatty fish, vegetables, nuts), weight loss if overweight, and smoking cessation move hs-CRP more reliably than any single nutrient.

When to see someone: hs-CRP rises with any acute infection or injury -- a single elevated reading isn't meaningful without ruling out a cold, dental work, or recent exercise. Curcumin supplements can interact with blood thinners.

The level of a toxic heavy metal with no known safe or beneficial level in the body, accumulating in bone and affecting the brain, kidneys, and cardiovascular system with chronic exposure.

Typical range: Standard: under 3.5 mcg/dL is the current CDC reference/action level for adults -- there is no optimal nonzero level; lower is always better.

Food first: Ensure adequate dietary calcium, iron, and vitamin C, especially in children and pregnant women (the highest-risk groups for lead's neurodevelopmental effects).

When to see someone: Nutritional strategies reduce absorption of *ongoing* low-level exposure -- they do not treat significant lead toxicity, which requires medical evaluation and, in some cases, chelation therapy. Any meaningfully elevated lead level needs a source investigation, not just a supplement response.

The level of a toxic heavy metal, most commonly elevated in adults from eating fish/seafood higher on the food chain.

Typical range: Standard: under 10 mcg/L (whole blood) is a commonly used general-population reference, though this varies by lab and by whether inorganic vs. methylmercury is being measured; there is no optimal nonzero level.

Food first: Choose lower-mercury fish (salmon, sardines, shrimp, cod) over high-mercury species (swordfish, king mackerel, shark, bigeye tuna) to get omega-3 benefits without excess mercury load; adequate selenium intake is theoretically protective but shouldn't be a reason to eat high-mercury fish liberally.

When to see someone: Elevated mercury in pregnant women or young children warrants dietary source investigation and possibly medical guidance given fetal/childhood neurodevelopmental sensitivity; don't rely on selenium supplementation as a way to "offset" ongoing high-mercury fish consumption.

Whether something is occupying the seat a nutrient was meant to sit in. This is a tier-one entry not because everyone needs a full toxic-element workup, but because almost nobody is offered one at all -- and a standard panel is silent on it. Deficiency gets investigated. The other half of the equation usually does not.

Typical range: There is no single number here. Blood lead and mercury reflect recent exposure rather than what is stored in tissue; a normal blood level does not rule out a body burden accumulated over years. Aluminium and glyphosate are not on any standard panel at all. That absence is the point of this entry -- it is a gap in the usual workup, not a result.

Food first: The protective pattern is unglamorous and consistent: sufficient minerals so there is no vacancy to fill, adequate protein for the conjugation pathways, sulphur-bearing vegetables such as brassicas, garlic and onions, and enough fibre to carry conjugated compounds out rather than allowing reabsorption. Iodine sufficiency specifically, because the halogen competition is at a single named door. Filtered water, and reducing the intake side wherever it is identifiable.