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July 2013



Why do horses need iodine?
All mammals, including humans and horses, need iodine for optimal health.   Iodine’s role in enabling the body to produce thyroid hormones is well known.  According to Dr David Brownstein, every cell in the body contains and utilizes iodine and it is involved in the production of all the other hormones of the body. Adequate iodine levels are necessary for proper immune system function; iodine also has potent antibacterial, antiparasitic, antiviral and anticancer properties. 


Iodine is found naturally in seawater in small amounts, and in large amounts in seaweed.    Soils in coastal regions are likely to have adequate iodine levels that may be taken up by plants growing in those soils.   Soils in mountainous or inland areas are likely to have low levels of iodine, as will plants growing in those areas.  Consequently, horses grazing pastures or consuming feeds that are low in iodine may benefit from supplementation.


What form of iodine can be used?
Some forms of iodine can be extremely toxic but iodine researcher Dr Guy Abraham states that inorganic nonradioactive forms of iodine are very safe, even longterm in amounts as high as 100,000 times the RDA for humans.    Dr Abraham’s review of the literature revealed that both iodine and iodide (the reduced from of iodine with an extra electron) are needed for optimal function of every organ and cell of the human body.


Lugol’s Solution, available from compounding pharmacies, contains both iodine (5%)  and potassium iodide (10%).  Two drops (0.1ml) contains 5mg of iodine and 7.5mg of iodide.   In some countries, the strength of Lugol’s Solution has been reduced.

Seaweed products such as kelp contain iodine but the amount may vary considerably if the product has not been standardized. Another problem is that seaweeds grown in polluted coastal waters may be heavily contaminated with heavy metals such as arsenic, cadmium, lead or mercury.


How much iodine do horses need?
The amount of daily iodine needed by people is an area that remains controversial.   Many physicians are now recommending much higher amounts for their patients than the conservative RDA.   Family physician Dr David Brownstein has been prescribing a high intake for his patients for two decades, with outstanding results.   He has found that 6mg per day is the minimum amount need by most adults; this is 40 times more than the Recommended Daily Allowance.


The RDA for horses is 3.5mg for a 500kg horse.


It is suggested that horse-owners should read the relevant literature concerning whole-body iodine sufficiency before making any decisions about supplementation for their own horses.   Soils and/or forage testing may be advisable to determine existing iodine intake.


Iodine supplementation may not be appropriate for horses with gastric problems, such as hindgut acidosis where normal ratios of gut flora are disturbed, as the effect of iodine’s antibacterial properties on gut flora in horses is currently unknown.    
A veterinarian should be consulted for advice.

Recommended reading:


1.  Iodine for Health
Donald W. Miller, Jr., MD



2.  Iodine, Why You Need It,

     Why You Can’t Live Without It 4th Edition
David Brownstein, MD
Medical Alternatives Press

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