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THYROID FUNCTION

Fluoride

F — Element #9

also known as Sodium fluoride, Fluoride ion, Stannous fluoride, Calcium fluoride

A mineral that hardens tooth enamel and supports bone structure. Most people get fluoride from drinking water, toothpaste, and tea — supplementation is rarely needed and can be harmful at higher doses.

Role in the body Incorporates into tooth enamel and bone mineral as fluorapatite, which is more resistant to acid than the calcium phosphate it replaces

Recommended daily intake
  • Adult Men · 4 mg (adequate intake)
  • Adult Women · 3 mg (adequate intake)
  • Children 4 8 · 1 mg
  • Infants · 0.01 mg (under 6 months)
Upper intake limit

10 mg/day for adults; lower for children

Signs of deficiency
  • Increased cavity risk
  • Slightly lower bone mineral density
  • Strengthens tooth enamel and reduces cavities
  • Supports bone mineral density at appropriate intakes
  • Naturally present in most public water supplies and many teas
  • Topical application through toothpaste delivers most of the dental benefit

Active in F⁻ (fluoride ion), Fluorapatite [Ca₅(PO₄)₃F] in enamel.

Excess intake during childhood causes dental fluorosis — white spots, streaks, or pitting on teeth
Long-term excess can cause skeletal fluorosis — joint pain, stiffness, and brittle bones
Rarely needs to be taken as a supplement — water and toothpaste usually cover daily needs
Children should be supervised when brushing — swallowing toothpaste regularly can push intake too high
Use caution combining fluoridated water with fluoride supplements
Acute high-dose ingestion is a poisoning emergency

NIH ODS — Fluoride · MedlinePlus — Fluoride · Britannica — Fluoride

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The curious few.
50 founding spots left

Know what you're putting in your body.

158 herbs, nutrients, and compounds. What the science says, what tradition knew, and what to watch for. Founding members keep this running.

$60 /year

Founding rate — locked for life. Regular price after launch: $96/year.

  • ✓ Full access to all 158+ entries
  • ✓ Print-ready reference card for every herb
  • ✓ Monthly curated set — 5 herbs, one body system
  • ✓ The Sunday Letter — weekly research digest
  • ✓ Bookmarks synced across devices
  • ✓ Founding rate locked forever
Become a founding member

Cancel any time. No questions asked.