Thyroid UK
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bulking agent microcrystaline cellulose ?

Hi all i sent for a remedy for candida and one of the ingredients was microcrystaline cellulose i have an under active thyroid so wanted to make sure would not interfere with thyroxine went online and found out it does, rang company who supplied it and spoke to one of their medical team who told me that he knew it interfered with levothyroxine as this is time release (which i didnt know) and it interfers with the releasing of it and as this is what i take and most tablets have this in them just wanted some thoughts on it ?

5 Replies

Microcrystalline cellulose is fibre from wood pulp so we can't digest it and is insoluble, which will interfere with the uptake in the gut of many medications but probably ironically is used as a filler in many medications and supplements and is even found in most thyroxine replacement meds such as ndt (not sure if it is in levo but it is in synthroid so it is likely) you'll have a massive job trying to avoid it i work for a company that makes medicines and supplements for pets and farm animals and it is in 95% of our products so it wouldn't surprise me if the same can be said for human medicines and supplements if it is any consolation it is usually a fractional amount so the effects will be minimal.


thanks for replying i did look at all my supplements and you are right it is in everyone will have to look for combinations to minimize how much i take having trouble at moment so anything i can do to make things better i will do once again thank you.


My frequent cry is to avoid taking levothyroxine near anything else - food, drink (other than water), supplement or medicine. So many things interact with it in the gut and affect absorption that the only safe answer is to keep a gap in time.

Taking microcrystalline cellulose in various forms many hours away from levothyroxine should not have any discernible effect.

It can be used to provide a time release effect in some medicines - but none of the UK levothyroxine products (and few, if any,anywhere else) are supposed to be time release of any sort.



i always leave at least 2hrs before i have anything to eat or drink supplements later after lunch i didnt think they were time release but thought i would ask thank you for your reply its been a great help


I am intolerant to maize starch, which is another commonly used bulking agent! I get around it by NOT having tablets with it in!!


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