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Fluoride

In the body: Too much fluoride over years can lead to skeletal fluorosis, from occasional joint pain or stiffness to weakened bones, muscle wasting and nerve problems; in the United States it is extremely rare. In children whose teeth are still forming, it can mottle the teeth.

Rated by dose, one serving each: none of the 3 rated foods goes past the limit.

Too much of a nutrient. For a food measured against it: the grams that reach the upper intake level, eaten every day.

All hazards

The limit

  • The agency’s figure10 mg/day
  • BasisHealth Canada DRI, adults 19-50 y: fluoride AI 4 mg/day (men), 3 (women); upper intake level (UL) 10 mg/day (upper intake level (UL))
  • Average adult intake EFSA's tolerable upper intake level for adults is 7 mg/day (2005); EFSA set an adequate intake in 2013.
  • Applies toall sources (water, beverages, foods, dental products)
  • Source Health Canada, dietary reference intakes

Reviewed foods that carry it

3 reviewed foods carry it, 3 of them rated by dose. 4 measurements in all. A preparation measured more than once gets one line, the measurement the dataset leads with or a stricter one, named beside the food; the others fold under it.

How often you can eat it

One realistic serving each, rated by dose, not by presence. The most restrictive rating comes first, then the largest dose per serving.

  1. Black tea, brewed

    Nothing to watch: under the limit

    932 µg
    per serving
    9.3% of the 10 mg-a-day limit shown above

    US food database (USDA SR Legacy) · grade C

    This amount varies a lot from one batch to the next: the figures we hold for this food differ twofold or more. Every figure on this site uses the same one, the food’s listed value.

    How it’s rated

    No cap: the tolerable upper intake level for fluoride is 10 mg/day for adults, from all sources (Health Canada, NASEM); EFSA's is 7 mg/day from age 15 (2005). One cup of brewed black tea carries 0.93 mg on the USDA listing, 9.3% of 10 mg (13% of 7); about 11 cups would reach 10 mg and 7.5 cups 7 mg. Measured teas vary a lot: filter-bag black teas from Slovenia averaged 0.89 mg a cup (the strongest 1.20 mg), five Bangkok brands 0.64 mg, and loose-leaf tea 0.21 mg.

    Intake: one 250 mL (250 g) cup a day, 70 kg adult · Level in the food: 372.9 µg/100 g (listed value, n = 63)

  2. Diet cola

    Nothing to watch: under the limit

    224 µg
    per serving
    2.2% of the 10 mg-a-day limit shown above

    US food database (USDA SR Legacy) · grade C

    How it’s rated

    No cap: the tolerable upper intake level for fluoride in adults is 10 mg/day (Health Canada). One serving carries 224 µg, 2.2% of it. The concentration comes from a compiled food-composition listing, not a Canadian survey.

    Intake: one 375 mL reference amount (375.4 g at 1.00101 g/mL) a day, 70 kg adult · Level in the food: 59.8 µg/100 g (listed value, n = 142)

  3. Green tea, brewed

    Nothing to watch: under the limit

    0.212 mg
    per serving
    per cup (250 mL)
    2.1% of the 10 mg-a-day limit shown above

    Pavlovic 2023 · grade A

    How it’s rated

    No cap: the upper intake level for fluoride is 10 mg/day for adults (Health Canada/NASEM); EFSA's is 7 mg/day. Loose-leaf green tea averages 0.85 mg/L (9 products, ultrapure water), so one 250 mL cup carries 0.212 mg, 2.1% of 10 mg (3.0% of 7), and 47.2 cups would reach 10 mg. Products ranged 0.34–1.43 mg/L (strongest cup 0.36 mg), and tap water adds its own fluoride.

    Intake: one 250 mL (250 g) cup a day, 70 kg adult · Level in the food: 0.85 mg/L (mean of 9 loose leaf green products, n = 9)

    Measured on: Pavlovic 2023, 35 commercial teas bought in Slovenia in 2022 (filter bags in shops, loose teas in teahouses); green loose-leaf teas (GL1-GL9), n = 9 products, each infused 1 g in 100 mL boiling ultrapure water for 5 min (a filter bag even for loose leaf), 2-3 replicate measurements per product; mean of the per-product means, computed here from Table 2. mg/L taken equal to µg/g at 1.00 g/mL.

    1 other measurement of this food
    1. Slovenia 2022, 5 filter-bag green teas

      Nothing to watch: under the limit

      0.723 mg
      per serving
      per cup (250 mL)
      7.2% of the 10 mg-a-day limit shown above

      Pavlovic 2023 · grade A

      How it’s rated

      No cap: the upper intake level for fluoride is 10 mg/day for adults (Health Canada/NASEM); EFSA's is 7 mg/day. Green filter-bag tea averages 2.892 mg/L (5 products, brewed in ultrapure water), so one 250 mL cup carries 0.723 mg, 7.2% of 10 mg (10.3% of 7), and 13.8 cups would reach 10 mg. Products ranged 2.76–3.08 mg/L (strongest cup 0.77 mg), and tap water adds its own fluoride.

      Intake: one 250 mL (250 g) cup a day, 70 kg adult · Level in the food: 2.892 mg/L (mean of 5 filter bag green products, n = 5)

      Measured on: Pavlovic 2023, 35 commercial teas bought in Slovenia in 2022 (filter bags in shops, loose teas in teahouses); green filter-bag teas (GF1-GF5), n = 5 products, each infused 1 g in 100 mL boiling ultrapure water for 5 min (a filter bag even for loose leaf), 2-3 replicate measurements per product; mean of the per-product means, computed here from Table 2. mg/L taken equal to µg/g at 1.00 g/mL.

Sources