Avoiding fluoride is a practice of filtering drinking water and replacing fluoride toothpaste to lower a lifetime intake most people never chose. Mottled enamel in children, bone that fractures more readily, underactive thyroid, disturbed sleep and lower childhood reasoning become measurable as intake rises, several clearly above roughly 1.5 milligrams per litre of water; below that they are argued over. Proven protection against tooth decay is given up. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Drinking-water fluoride | Below 0.3 mg/L | Confirms the filter is removing fluoride |
| Urinary fluoride, creatinine-corrected | Below 0.5 mg/L in adults | Captures total intake from all sources |
| Plasma fluoride | Below 0.02 mg/L | Detects ongoing high exposure |
| TSH | 0.5–2.0 mIU/L | Thyroid is the endpoint most plausibly affected below 2.5 mg/L |
| Free T4 and free T3 | Upper half of the laboratory range | Distinguishes true thyroid suppression from an isolated TSH shift |
| Urinary iodine | 100–200 µg/L | Low iodine is where fluoride's thyroid effect concentrates |
| eGFR | Above 90 mL/min/1.73 m² | Kidneys clear fluoride; poor clearance raises retention |
| Serum and red-cell magnesium | Serum 0.85–1.0 mmol/L; red-cell in the upper half of range | Reverse osmosis strips magnesium along with fluoride |
| Serum calcium, 25-hydroxyvitamin D and parathyroid hormone | Calcium 2.2–2.4 mmol/L; vitamin D 40–60 ng/mL; parathyroid hormone in the lower half of range | Tracks the bone axis that fluoride accumulation disturbs |
| Bone mineral density by DXA | No fluoride-specific target exists; track change from the individual's own baseline | Fluoride raises density without raising strength, so trend matters more than value |
| Decayed, missing and filled surfaces on dental examination | No new lesions between reviews | The single outcome that fluoride withdrawal most plausibly worsens |
Cadence: Water at three months to confirm the filter works, then annually. Urinary fluoride at three months, thereafter every 12 months. Thyroid function six to eight weeks after any major change in water source, then annually. Dental review six-monthly. Bone density every two to three years in those over fifty.