If you have Hashimoto’s thyroiditis or suffer from any form of hypothyroidism, you are likely to be struggling to keep your thyroid operating effectively.
Some forms of food and drink affect the thyroid very directly, and quickly. (Read more about Thyroid Uppers and Downers) This is because they either increase or decrease thyroid hormone production, help/hinder the conversion of T4 into T3, or help/hinder the ability of the converted hormone to enter the body’s cells to do its work.
What’s Wrong with Tea?
Tea has been found to be extremely high in fluoride, and fluoride has been found to act adversely on the thyroid and endocrine system generally. Until the 1950s, fluoride was used to treat hyperthyroidism (in other words, to ‘turn down’ the thyroid, making it produce and convert fewer hormones).
Fluoride content is measured in parts per million (ppm). 1 ppm is equivalent to 1 milligram of fluoride in 1 litre of water.
Consider the following:
- The World Health Organisation recommends optimum levels of 1-1.2 ppm (parts per million), and an upper limit of 1.5 ppm for fluoridated water. (The US the Public Health Service says fluoride should not exceed 1.2 ppm in drinking water.)
- The dose of fluoride found to depress the thyroid gland was 2.3 to 4.5 mg/day.
- A major Canadian study published in 1995 reported average fluoride content in tea to be 4.57 mg/l. (2).
- A Polish study in 1995 found fluoride content of up to 340 ppm in 16 varieties of black tea (3).
- A March 2008 tea and fluoride study published in Food and Chemical Toxicology found up to 4.5, 1.8, and 0.5 mg/L fluoride in black, green and white teas, respectively, when brewed for 5 minutes. 61 teas were included in the sample.
How Does The Fluoride Get into the Tea?
Tea leaves, especially older leaves, accumulate more fluoride from soil and air pollution than any other edible plant. This seems to be why green tea (younger leaves) have less fluoride than black tea (leaves with a longer growing time). The fluoride is released during steeping in boiling water, and normal steeping time is around five minutes. The longer a tea bag is steeped, the more fluoride is released. After ten minutes, the fluoride and aluminium content almost doubles.
How Does Fluoride Affect the Thyroid?
The pituitary gland – the master controlling gland for the endocrine system – is known to take up several times as much fluorine as any other soft tissue. This means that the endocrine system, including the thyroid function, is quickly and adversely affected by fluoride.
In concentrations as low as 1ppm fluoride damages the thyroid system in four ways. Bear in mind that one cup of black tea contains 3.73ppm – nearly four times this amount (see Are Some Teas Better Than Others? below). These are the four ways fluroide causes damage to the thyroid:
- Disrupting the body’s messaging system.The thyroid control mechanism (pituitary/thyroid/hypothalamus glands) is compromised by fluoride, reducing the TSH output from the pituitary gland – which means less thyroid hormone is produced.
- Blocking receptor sites.The thyroid gland has receptor sites that respond to TSH (thyroid stimulating hormone) to make thyroid hormones. Fluoride competes for these receptor sites, ‘blocking’ the TSH, so less of the stimulating hormone reaches the thyroid gland, and it produces fewer hormones.
- Slowing down hormone production.Fluoride slows down the actual manufacture of thyroid hormones within the thyroid gland. The hormones are made during a process by which iodine is attached to an amino acid (tyrosine) and converted to the two significant thyroid hormones, thyroxine (T4) and triiodothyronine (T3) is slowed down. (Fluorine is a halogen, and chemically related to iodine but very much more active. It displaces iodine, so the uptake of iodine is greatly reduced.)
- Fluoride’s stimulation of certain G proteins (which govern uptake of substances into each cell of the body), has the effect of switching off the ability of the cell to uptake active thyroid hormone.
Are Some Teas Better than Others?
A report by the US Department of Agriculture (USDA) (4) lists the amount of fluoride in hundreds of types of food and drink. Among the findings, tea scores incredibly highly for fluoride content, along with certain carbonated drinks. In terms of choosing what to drink, the report seems to suggest the following:
- Choose green tea over black tea. Brewed black tea has 3.73 ppm (the decaffeinated form has less –2.69ppm), whereas green tea has only 1.15 ppm. But note that decaffeinated green tea has a higher fluoride content than the normal form, at 2.72 ppm.
- Drink brewed coffee, if you must (0.91ppm) - because a cereal-based coffee substitute weighed in at 1.25ppm
- Avoid highly processed tea. Instant tea powder with lemon and sugar has 5.8 ppm.
- If you like herbal teas, stick with them. Camomile tea was measured at 0.13ppm (against black tea’s 3.73ppm).
- Of all the drinks measured, only tea contained more than 1.0 ppm of fluoride. So if you have a thyroid problem, you need to be aware of how a tea-drinking habit may be harming your thyroid, and preventing your medication from working effectively..
- See the full report here.
Read more: Why Isn't My Thyroxine Working?
References
- National Academies Press - "Fluoride in Drinking Water" March 2006. Full Report: http://darwin.nap.edu/books/030910128X/html/
- Dabeka WD, McKenzie AD - "Survey of lead, cadmium, fluoride, nickel, and cobalt in food composites and estimation of dietary intakes of these elements by Canadians in 1986-1988" Journal of AOAC International 78:4, 897-909 (1995)
- Nabrzyski M, Gajewska R - "Aluminium and fluoride in hospital daily diets and in teas" Z Lebensm Unters Forsch 201(4):307-10 (1995)
- USDA. USDA National Fluoride Database of Selected Beverages and Foods, Release 2.
 |
