Thyroid UK
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high fiber diet / levo

good evening,

i would like to be clarified if it is possible, whats the magnitude of a high fiber diet and levothyroxine absorption. i can talk about my personal case im a newbie vegetarian, and everybody knows that this diet include a lot of fiber in its menu,

my question is ofc related to this situation, i had made a lot of research concerning the impact of high fiber diet can have here, but i couldnt find in terms of percentage , what could be worst case scenario in terms of levo absorption?20%,? 30%?.......whats the real deal here

11 Replies

Is there a specific reason you believe your levo won't be absorbed well due to your diet or are you speculating because of the effect fibre has on intestinal transit? As far as I'm aware absorption of nutrients isn't impaired by fibre in the gut. If you're taking levo on an empty stomach I shouldn't think there will be any issues.

1 like

tx for the reply, im posting this bcause theres a lot of information, and medical studies proving that this pseudo malabsorption occurs, and we the patients, have to watch this situation closely.....


I was instructed to take my thyroxine first thing in the am at least 20 mins before ingesting any food. Also I note that in Australia thyroxine has to be stored in fridge, presumably to increase shelf life or prevent loss of activity where in UK it's stored at ambient temperature


I don't eat or drink anything but water for 1 1/2 hour after taking levo. It should be absorbed by then. I woldn't worry about fibers if you let some decent time pass before eating - but I'm not a doctor (just a patient 😉)


Are you sure they weren't talking about unabsorbed fiber which presents no calories? Some fiber goes right through the system without breaking down. From Webmd: Insoluble fiber remains more intact as it passes through the digestive system. That makes insoluble fiber especially helpful in preventing or easing constipation.

You should have no problem with absorbing levo if you take it on an empty stomach.

Of course low stomach acid may affect all manners of absorption.


tx for your reply, i know prob i shouldnt be that worried about this topic, but the information on the internet its so contracdictory that its impossible not be concerned with this.

i want you guys to check this study where they talk about the possible interaction between high fiber diet and levo, i want to hear from u guys,

tx in advance for the interest


Vegan, it was too difficult to get to the article. I would say this after 20 years looking at thyroid articles and other issues. Your blood tests will be based on what you do absorb therefore you can set it up any way you wish but then you should stick with it. Whether you take it 15 minutes before eating or one hour after eating, your body will adapt to that dose and I've read with T3, food isn't an issue at all.

What was the gist of the article?


I'll add that someone posted last week about the percentage absorbed and I think it had to do with other medications or supplements like minerals perhaps. If you care to do a search, maybe you can find it.


anymore thoughts about this study?


Many Dr.s are recommending the taking of thyroid supplements on an empty stomach, at least 30 minutes before ingesting anything other than water. Coffee, specifically has been shown to diminish absorption of thyroid supplements. The absorption issue is of particular noteworthiness when we look at all those who report trouble with thyroid supplement blood levels staying at a constant.

It was true in my case. I began (after more than 20 years of taking the supplement without regard to when or what else was being ingested), I began taking the supplement (NatureThroid) upon first arising, even before showering, and the blood level stabilized dramatically. My Dr. said such an "absorption" problem depended largely on the individuals digestive enzyme level as well.

I to have begun a largely vegetarian diet, and have added a good quality "Digestive Enzyme" to my other supplements of Vitamin D, Vitamin E with Selenium, and natural anit-fungals like Olive Leaf Extract. The blood levels of Thyroid Supplement have ceased to be unstable.

Very good question! Taking Thyroid supplements on an empty stomach has worked very well for me.


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